Kemono-Downloader/main.py

import sys
import os
import time
import requests
import re
import threading
import queue
import hashlib
import http.client
import traceback
import random
from collections import deque

from concurrent.futures import ThreadPoolExecutor, CancelledError, Future

from PyQt5.QtGui import (
    QIcon,
    QIntValidator
)
from PyQt5.QtWidgets import (
    QApplication, QWidget, QLabel, QLineEdit, QTextEdit, QPushButton,
    QVBoxLayout, QHBoxLayout, QFileDialog, QMessageBox, QListWidget, QDesktopWidget,
    QRadioButton, QButtonGroup, QCheckBox, QSplitter, QSizePolicy, QDialog,
    QFrame,
    QAbstractButton
)
from PyQt5.QtCore import Qt, QThread, pyqtSignal, QMutex, QMutexLocker, QObject, QTimer, QSettings, QStandardPaths
from urllib.parse import urlparse

try:
    from PIL import Image
except ImportError:
    Image = None

from io import BytesIO

try:
    print("Attempting to import from downloader_utils...")
    from downloader_utils import (
        KNOWN_NAMES,
        clean_folder_name,
        extract_post_info,
        download_from_api,
        PostProcessorSignals,
        PostProcessorWorker,
        DownloadThread as BackendDownloadThread,
        SKIP_SCOPE_FILES,
        SKIP_SCOPE_POSTS,
        SKIP_SCOPE_BOTH,
        CHAR_SCOPE_TITLE, # Added for completeness if used directly
        CHAR_SCOPE_FILES, # Added
        CHAR_SCOPE_BOTH   # Added
    )
    print("Successfully imported names from downloader_utils.")
except ImportError as e:
    print(f"--- IMPORT ERROR ---")
    print(f"Failed to import from 'downloader_utils.py': {e}")
    KNOWN_NAMES = []
    PostProcessorSignals = QObject
    PostProcessorWorker = object
    BackendDownloadThread = QThread
    def clean_folder_name(n): return str(n)
    def extract_post_info(u): return None, None, None
    def download_from_api(*a, **k): yield []
    SKIP_SCOPE_FILES = "files"
    SKIP_SCOPE_POSTS = "posts"
    SKIP_SCOPE_BOTH = "both"
    CHAR_SCOPE_TITLE = "title"
    CHAR_SCOPE_FILES = "files"
    CHAR_SCOPE_BOTH = "both"

except Exception as e:
    print(f"--- UNEXPECTED IMPORT ERROR ---")
    print(f"An unexpected error occurred during import: {e}")
    traceback.print_exc()
    print(f"-----------------------------", file=sys.stderr)
    sys.exit(1)

try:
    from tour import TourDialog
    print("Successfully imported TourDialog from tour.py.")
except ImportError as e:
    print(f"--- TOUR IMPORT ERROR ---")
    print(f"Failed to import TourDialog from 'tour.py': {e}")
    print("Tour functionality will be unavailable.")
    TourDialog = None
except Exception as e:
    print(f"--- UNEXPECTED TOUR IMPORT ERROR ---")
    print(f"An unexpected error occurred during tour import: {e}")
    traceback.print_exc()
    TourDialog = None


MAX_THREADS = 200
RECOMMENDED_MAX_THREADS = 50
MAX_FILE_THREADS_PER_POST_OR_WORKER = 10

HTML_PREFIX = "<!HTML!>"

CONFIG_ORGANIZATION_NAME = "KemonoDownloader"
CONFIG_APP_NAME_MAIN = "ApplicationSettings"
MANGA_FILENAME_STYLE_KEY = "mangaFilenameStyleV1"
STYLE_POST_TITLE = "post_title"
STYLE_ORIGINAL_NAME = "original_name"
SKIP_WORDS_SCOPE_KEY = "skipWordsScopeV1"
ALLOW_MULTIPART_DOWNLOAD_KEY = "allowMultipartDownloadV1"

CHAR_FILTER_SCOPE_KEY = "charFilterScopeV1"
# CHAR_SCOPE_TITLE, CHAR_SCOPE_FILES, CHAR_SCOPE_BOTH are already defined or imported

DUPLICATE_FILE_MODE_KEY = "duplicateFileModeV1"
# DUPLICATE_MODE_RENAME is removed. Renaming only happens within a target folder if needed.
DUPLICATE_MODE_DELETE = "delete"
DUPLICATE_MODE_MOVE_TO_SUBFOLDER = "move" # New mode



class DownloaderApp(QWidget):
    character_prompt_response_signal = pyqtSignal(bool)
    log_signal = pyqtSignal(str)
    add_character_prompt_signal = pyqtSignal(str)
    overall_progress_signal = pyqtSignal(int, int)
    finished_signal = pyqtSignal(int, int, bool, list)
    external_link_signal = pyqtSignal(str, str, str, str)
    # Changed to object to handle both (int, int) for single stream and list for multipart
    file_progress_signal = pyqtSignal(str, object)


    def __init__(self):
        super().__init__()
        self.settings = QSettings(CONFIG_ORGANIZATION_NAME, CONFIG_APP_NAME_MAIN)

        # Determine path for Known.txt in user's app data directory
        app_config_dir = ""
        try:
            # Use AppLocalDataLocation for user-specific, non-roaming data
            app_data_root = QStandardPaths.writableLocation(QStandardPaths.AppLocalDataLocation)
            if not app_data_root: # Fallback if somehow empty
                app_data_root = QStandardPaths.writableLocation(QStandardPaths.GenericDataLocation)

            if app_data_root and CONFIG_ORGANIZATION_NAME:
                app_config_dir = os.path.join(app_data_root, CONFIG_ORGANIZATION_NAME)
            elif app_data_root: # If no org name, use a generic app name folder
                app_config_dir = os.path.join(app_data_root, "KemonoDownloaderAppData") # Fallback app name
            else: # Absolute fallback: current working directory (less ideal for bundled app)
                app_config_dir = os.getcwd()

            if not os.path.exists(app_config_dir):
                os.makedirs(app_config_dir, exist_ok=True)
        except Exception as e_path:
            print(f"Error setting up app_config_dir: {e_path}. Defaulting to CWD for Known.txt.")
            app_config_dir = os.getcwd() # Fallback
        self.config_file = os.path.join(app_config_dir, "Known.txt")

        self.download_thread = None
        self.thread_pool = None
        self.cancellation_event = threading.Event()
        self.active_futures = []
        self.total_posts_to_process = 0
        self.processed_posts_count = 0
        self.download_counter = 0
        self.skip_counter = 0

        self.worker_signals = PostProcessorSignals()
        self.prompt_mutex = QMutex()
        self._add_character_response = None

        self.downloaded_files = set()
        self.downloaded_files_lock = threading.Lock()
        self.downloaded_file_hashes = set()
        self.downloaded_file_hashes_lock = threading.Lock()

        self.show_external_links = False
        self.external_link_queue = deque()
        self._is_processing_external_link_queue = False
        self._current_link_post_title = None
        self.extracted_links_cache = []

        self.basic_log_mode = False
        self.log_verbosity_button = None
        self.manga_rename_toggle_button = None

        self.main_log_output = None
        self.external_log_output = None
        self.log_splitter = None
        self.main_splitter = None
        self.reset_button = None
        self.progress_log_label = None

        self.link_search_input = None
        self.link_search_button = None
        self.export_links_button = None

        self.manga_mode_checkbox = None
        self.radio_only_links = None
        self.radio_only_archives = None
        
        self.skip_scope_toggle_button = None
        self.char_filter_scope_toggle_button = None

        self.all_kept_original_filenames = []

        self.manga_filename_style = self.settings.value(MANGA_FILENAME_STYLE_KEY, STYLE_POST_TITLE, type=str)
        self.skip_words_scope = self.settings.value(SKIP_WORDS_SCOPE_KEY, SKIP_SCOPE_POSTS, type=str)
        self.char_filter_scope = self.settings.value(CHAR_FILTER_SCOPE_KEY, CHAR_SCOPE_TITLE, type=str)
        self.allow_multipart_download_setting = self.settings.value(ALLOW_MULTIPART_DOWNLOAD_KEY, False, type=bool) # Default to OFF
        self.duplicate_file_mode = self.settings.value(DUPLICATE_FILE_MODE_KEY, DUPLICATE_MODE_DELETE, type=str) # Default to DELETE
        print(f"ℹ️ Known.txt will be loaded/saved at: {self.config_file}")



        self.load_known_names_from_util()
        self.setWindowTitle("Kemono Downloader v3.2.0")
        # self.setGeometry(150, 150, 1050, 820) # Initial geometry will be set after showing
        self.setStyleSheet(self.get_dark_theme())
        self.init_ui()
        self._connect_signals()

        self.log_signal.emit("ℹ️ Local API server functionality has been removed.")
        self.log_signal.emit("ℹ️ 'Skip Current File' button has been removed.")
        if hasattr(self, 'character_input'):
            self.character_input.setToolTip("Names, comma-separated. Group aliases: (alias1, alias2) for combined folder name 'alias1 alias2'. E.g., yor, (Boa, Hancock)")
        self.log_signal.emit(f"ℹ️ Manga filename style loaded: '{self.manga_filename_style}'")
        self.log_signal.emit(f"ℹ️ Skip words scope loaded: '{self.skip_words_scope}'")
        self.log_signal.emit(f"ℹ️ Character filter scope loaded: '{self.char_filter_scope}'")
        self.log_signal.emit(f"ℹ️ Multi-part download preference loaded: {'Enabled' if self.allow_multipart_download_setting else 'Disabled'}")
        self.log_signal.emit(f"ℹ️ Duplicate file handling mode loaded: '{self.duplicate_file_mode.capitalize()}'")


    def _connect_signals(self):
        if hasattr(self.worker_signals, 'progress_signal'):
             self.worker_signals.progress_signal.connect(self.handle_main_log)
        if hasattr(self.worker_signals, 'file_progress_signal'):
            self.worker_signals.file_progress_signal.connect(self.update_file_progress_display)
        if hasattr(self.worker_signals, 'external_link_signal'):
            self.worker_signals.external_link_signal.connect(self.handle_external_link_signal)

        self.log_signal.connect(self.handle_main_log)
        self.add_character_prompt_signal.connect(self.prompt_add_character)
        self.character_prompt_response_signal.connect(self.receive_add_character_result)
        self.overall_progress_signal.connect(self.update_progress_display)
        self.finished_signal.connect(self.download_finished)
        self.external_link_signal.connect(self.handle_external_link_signal)
        self.file_progress_signal.connect(self.update_file_progress_display)

        if hasattr(self, 'character_search_input'): self.character_search_input.textChanged.connect(self.filter_character_list)
        if hasattr(self, 'external_links_checkbox'): self.external_links_checkbox.toggled.connect(self.update_external_links_setting)
        if hasattr(self, 'thread_count_input'): self.thread_count_input.textChanged.connect(self.update_multithreading_label)
        if hasattr(self, 'use_subfolder_per_post_checkbox'): self.use_subfolder_per_post_checkbox.toggled.connect(self.update_ui_for_subfolders)
        if hasattr(self, 'use_multithreading_checkbox'): self.use_multithreading_checkbox.toggled.connect(self._handle_multithreading_toggle)

        if hasattr(self, 'radio_group') and self.radio_group:
            self.radio_group.buttonToggled.connect(self._handle_filter_mode_change)

        if self.reset_button: self.reset_button.clicked.connect(self.reset_application_state)
        if self.log_verbosity_button: self.log_verbosity_button.clicked.connect(self.toggle_log_verbosity)

        if self.link_search_button: self.link_search_button.clicked.connect(self._filter_links_log)
        if self.link_search_input:
            self.link_search_input.returnPressed.connect(self._filter_links_log)
            self.link_search_input.textChanged.connect(self._filter_links_log)
        if self.export_links_button: self.export_links_button.clicked.connect(self._export_links_to_file)

        if self.manga_mode_checkbox: self.manga_mode_checkbox.toggled.connect(self.update_ui_for_manga_mode)
        if self.manga_rename_toggle_button: self.manga_rename_toggle_button.clicked.connect(self._toggle_manga_filename_style)

        if hasattr(self, 'link_input'):
            self.link_input.textChanged.connect(lambda: self.update_ui_for_manga_mode(self.manga_mode_checkbox.isChecked() if self.manga_mode_checkbox else False))
        
        if self.skip_scope_toggle_button:
            self.skip_scope_toggle_button.clicked.connect(self._cycle_skip_scope)

        if self.char_filter_scope_toggle_button:
            self.char_filter_scope_toggle_button.clicked.connect(self._cycle_char_filter_scope)
        
        if hasattr(self, 'multipart_toggle_button'): self.multipart_toggle_button.clicked.connect(self._toggle_multipart_mode)
        if hasattr(self, 'duplicate_mode_toggle_button'): self.duplicate_mode_toggle_button.clicked.connect(self._cycle_duplicate_mode)


    def load_known_names_from_util(self):
        global KNOWN_NAMES
        if os.path.exists(self.config_file):
            try:
                with open(self.config_file, 'r', encoding='utf-8') as f:
                    raw_names = [line.strip() for line in f]
                    KNOWN_NAMES[:] = sorted(list(set(filter(None, raw_names))))
                log_msg = f"ℹ️ Loaded {len(KNOWN_NAMES)} known names from {self.config_file}"
            except Exception as e:
                log_msg = f"❌ Error loading config '{self.config_file}': {e}"
                QMessageBox.warning(self, "Config Load Error", f"Could not load list from {self.config_file}:\n{e}")
                KNOWN_NAMES[:] = []
        else:
            log_msg = f"ℹ️ Config file '{self.config_file}' not found. Starting empty."
            KNOWN_NAMES[:] = []

        if hasattr(self, 'log_signal'): self.log_signal.emit(log_msg)
        
        if hasattr(self, 'character_list'):
            self.character_list.clear()
            self.character_list.addItems(KNOWN_NAMES)

    def save_known_names(self):
        global KNOWN_NAMES
        try:
            unique_sorted_names = sorted(list(set(filter(None, KNOWN_NAMES))))
            KNOWN_NAMES[:] = unique_sorted_names

            with open(self.config_file, 'w', encoding='utf-8') as f:
                for name in unique_sorted_names:
                    f.write(name + '\n')
            if hasattr(self, 'log_signal'): self.log_signal.emit(f"💾 Saved {len(unique_sorted_names)} known names to {self.config_file}")
        except Exception as e:
            log_msg = f"❌ Error saving config '{self.config_file}': {e}"
            if hasattr(self, 'log_signal'): self.log_signal.emit(log_msg)
            QMessageBox.warning(self, "Config Save Error", f"Could not save list to {self.config_file}:\n{e}")

    def closeEvent(self, event):
        self.save_known_names()
        self.settings.setValue(MANGA_FILENAME_STYLE_KEY, self.manga_filename_style)
        self.settings.setValue(SKIP_WORDS_SCOPE_KEY, self.skip_words_scope)
        self.settings.setValue(CHAR_FILTER_SCOPE_KEY, self.char_filter_scope)
        self.settings.setValue(ALLOW_MULTIPART_DOWNLOAD_KEY, self.allow_multipart_download_setting)
        self.settings.setValue(DUPLICATE_FILE_MODE_KEY, self.duplicate_file_mode) # Save current mode
        self.settings.sync()

        should_exit = True
        is_downloading = self._is_download_active()

        if is_downloading:
             reply = QMessageBox.question(self, "Confirm Exit",
                                          "Download in progress. Are you sure you want to exit and cancel?",
                                          QMessageBox.Yes | QMessageBox.No, QMessageBox.No)
             if reply == QMessageBox.Yes:
                 self.log_signal.emit("⚠️ Cancelling active download due to application exit...")
                 
                 # Direct cancellation for exit - different from button cancel
                 self.cancellation_event.set()
                 if self.download_thread and self.download_thread.isRunning():
                     self.download_thread.requestInterruption()
                     self.log_signal.emit("   Signaled single download thread to interrupt.")
                 
                 # For thread pool, we want to wait on exit.
                 if self.download_thread and self.download_thread.isRunning():
                     self.log_signal.emit("   Waiting for single download thread to finish...")
                     self.download_thread.wait(3000)
                     if self.download_thread.isRunning():
                         self.log_signal.emit("   ⚠️ Single download thread did not terminate gracefully.")

                 if self.thread_pool:
                     self.log_signal.emit("   Shutting down thread pool (waiting for completion)...")
                     self.thread_pool.shutdown(wait=True, cancel_futures=True)
                     self.log_signal.emit("   Thread pool shutdown complete.")
                     self.thread_pool = None
                 self.log_signal.emit("   Cancellation for exit complete.")
             else:
                 should_exit = False
                 self.log_signal.emit("ℹ️ Application exit cancelled.")
                 event.ignore()
                 return

        if should_exit:
            self.log_signal.emit("ℹ️ Application closing.")
            if self.thread_pool:
                 self.log_signal.emit("   Final thread pool check: Shutting down...")
                 self.cancellation_event.set()
                 self.thread_pool.shutdown(wait=True, cancel_futures=True)
                 self.thread_pool = None
            self.log_signal.emit("👋 Exiting application.")
            event.accept()


    def init_ui(self):
        self.main_splitter = QSplitter(Qt.Horizontal)
        left_panel_widget = QWidget()
        right_panel_widget = QWidget()
        left_layout = QVBoxLayout(left_panel_widget)
        right_layout = QVBoxLayout(right_panel_widget)
        left_layout.setContentsMargins(10, 10, 10, 10)
        right_layout.setContentsMargins(10, 10, 10, 10)


        url_page_layout = QHBoxLayout()
        url_page_layout.setContentsMargins(0,0,0,0)
        url_page_layout.addWidget(QLabel("🔗 Kemono Creator/Post URL:"))
        self.link_input = QLineEdit()
        self.link_input.setPlaceholderText("e.g., https://kemono.su/patreon/user/12345 or .../post/98765")
        self.link_input.textChanged.connect(self.update_custom_folder_visibility)
        url_page_layout.addWidget(self.link_input, 1)

        self.page_range_label = QLabel("Page Range:")
        self.page_range_label.setStyleSheet("font-weight: bold; padding-left: 10px;")
        self.start_page_input = QLineEdit()
        self.start_page_input.setPlaceholderText("Start")
        self.start_page_input.setFixedWidth(50)
        self.start_page_input.setValidator(QIntValidator(1, 99999))
        self.to_label = QLabel("to")
        self.end_page_input = QLineEdit()
        self.end_page_input.setPlaceholderText("End")
        self.end_page_input.setFixedWidth(50)
        self.end_page_input.setValidator(QIntValidator(1, 99999))
        url_page_layout.addWidget(self.page_range_label)
        url_page_layout.addWidget(self.start_page_input)
        url_page_layout.addWidget(self.to_label)
        url_page_layout.addWidget(self.end_page_input)
        left_layout.addLayout(url_page_layout)

        left_layout.addWidget(QLabel("📁 Download Location:"))
        self.dir_input = QLineEdit()
        self.dir_input.setPlaceholderText("Select folder where downloads will be saved")
        self.dir_button = QPushButton("Browse...")
        self.dir_button.clicked.connect(self.browse_directory)
        dir_layout = QHBoxLayout()
        dir_layout.addWidget(self.dir_input, 1)
        dir_layout.addWidget(self.dir_button)
        left_layout.addLayout(dir_layout)


        self.filters_and_custom_folder_container_widget = QWidget()
        filters_and_custom_folder_layout = QHBoxLayout(self.filters_and_custom_folder_container_widget)
        filters_and_custom_folder_layout.setContentsMargins(0, 5, 0, 0)
        filters_and_custom_folder_layout.setSpacing(10)

        self.character_filter_widget = QWidget()
        character_filter_v_layout = QVBoxLayout(self.character_filter_widget)
        character_filter_v_layout.setContentsMargins(0,0,0,0)
        character_filter_v_layout.setSpacing(2)
        
        self.character_label = QLabel("🎯 Filter by Character(s) (comma-separated):")
        character_filter_v_layout.addWidget(self.character_label)

        char_input_and_button_layout = QHBoxLayout()
        char_input_and_button_layout.setContentsMargins(0, 0, 0, 0)
        char_input_and_button_layout.setSpacing(10)

        self.character_input = QLineEdit()
        self.character_input.setPlaceholderText("e.g., yor, Tifa, (Reyna, Sage)")
        char_input_and_button_layout.addWidget(self.character_input, 3)

        self.char_filter_scope_toggle_button = QPushButton()
        self._update_char_filter_scope_button_text()
        self.char_filter_scope_toggle_button.setToolTip("Click to cycle character filter scope (Files -> Title -> Both)")
        self.char_filter_scope_toggle_button.setStyleSheet("padding: 6px 10px;")
        self.char_filter_scope_toggle_button.setMinimumWidth(100)
        char_input_and_button_layout.addWidget(self.char_filter_scope_toggle_button, 1)

        character_filter_v_layout.addLayout(char_input_and_button_layout)


        self.custom_folder_widget = QWidget()
        custom_folder_v_layout = QVBoxLayout(self.custom_folder_widget)
        custom_folder_v_layout.setContentsMargins(0,0,0,0)
        custom_folder_v_layout.setSpacing(2)
        self.custom_folder_label = QLabel("🗄️ Custom Folder Name (Single Post Only):")
        self.custom_folder_input = QLineEdit()
        self.custom_folder_input.setPlaceholderText("Optional: Save this post to specific folder")
        custom_folder_v_layout.addWidget(self.custom_folder_label)
        custom_folder_v_layout.addWidget(self.custom_folder_input)
        self.custom_folder_widget.setVisible(False)

        filters_and_custom_folder_layout.addWidget(self.character_filter_widget, 1)
        filters_and_custom_folder_layout.addWidget(self.custom_folder_widget, 1)

        left_layout.addWidget(self.filters_and_custom_folder_container_widget)


        # --- Word Manipulation Section (Skip Words & Remove from Filename) ---
        word_manipulation_container_widget = QWidget()
        word_manipulation_outer_layout = QHBoxLayout(word_manipulation_container_widget)
        word_manipulation_outer_layout.setContentsMargins(0,0,0,0) # No margins for the outer container
        word_manipulation_outer_layout.setSpacing(15) # Spacing between the two vertical groups

        # Group 1: Skip Words (Left, ~70% space)
        skip_words_widget = QWidget()
        skip_words_vertical_layout = QVBoxLayout(skip_words_widget)
        skip_words_vertical_layout.setContentsMargins(0,0,0,0) # No margins for the inner group
        skip_words_vertical_layout.setSpacing(2) # Small spacing between label and input row

        skip_words_label = QLabel("🚫 Skip with Words (comma-separated):")
        skip_words_vertical_layout.addWidget(skip_words_label)

        skip_input_and_button_layout = QHBoxLayout()
        skip_input_and_button_layout = QHBoxLayout()
        skip_input_and_button_layout.setContentsMargins(0, 0, 0, 0)
        skip_input_and_button_layout.setSpacing(10)
        self.skip_words_input = QLineEdit()
        self.skip_words_input.setPlaceholderText("e.g., WM, WIP, sketch, preview")
        skip_input_and_button_layout.addWidget(self.skip_words_input, 1) # Input field takes available space
        self.skip_scope_toggle_button = QPushButton()
        self._update_skip_scope_button_text()
        self.skip_scope_toggle_button.setToolTip("Click to cycle skip scope (Files -> Posts -> Both)")
        self.skip_scope_toggle_button.setStyleSheet("padding: 6px 10px;")
        self.skip_scope_toggle_button.setMinimumWidth(100)
        skip_input_and_button_layout.addWidget(self.skip_scope_toggle_button, 0) # Button takes its minimum
        skip_words_vertical_layout.addLayout(skip_input_and_button_layout)
        word_manipulation_outer_layout.addWidget(skip_words_widget, 7) # 70% stretch for left group

        # Group 2: Remove Words from name (Right, ~30% space)
        remove_words_widget = QWidget()
        remove_words_vertical_layout = QVBoxLayout(remove_words_widget)
        remove_words_vertical_layout.setContentsMargins(0,0,0,0) # No margins for the inner group
        remove_words_vertical_layout.setSpacing(2)
        self.remove_from_filename_label = QLabel("✂️ Remove Words from name:")
        remove_words_vertical_layout.addWidget(self.remove_from_filename_label)
        self.remove_from_filename_input = QLineEdit()
        self.remove_from_filename_input.setPlaceholderText("e.g., patreon, HD") # Placeholder for the new field
        remove_words_vertical_layout.addWidget(self.remove_from_filename_input)
        word_manipulation_outer_layout.addWidget(remove_words_widget, 3) # 30% stretch for right group

        left_layout.addWidget(word_manipulation_container_widget)
        # --- End Word Manipulation Section ---


        file_filter_layout = QVBoxLayout()
        file_filter_layout.setContentsMargins(0,10,0,0)
        file_filter_layout.addWidget(QLabel("Filter Files:"))
        radio_button_layout = QHBoxLayout()
        radio_button_layout.setSpacing(10)
        self.radio_group = QButtonGroup(self)
        self.radio_all = QRadioButton("All")
        self.radio_images = QRadioButton("Images/GIFs")
        self.radio_videos = QRadioButton("Videos")
        self.radio_only_archives = QRadioButton("📦 Only Archives")
        self.radio_only_links = QRadioButton("🔗 Only Links")
        self.radio_all.setChecked(True)
        self.radio_group.addButton(self.radio_all)
        self.radio_group.addButton(self.radio_images)
        self.radio_group.addButton(self.radio_videos)
        self.radio_group.addButton(self.radio_only_archives)
        self.radio_group.addButton(self.radio_only_links)
        radio_button_layout.addWidget(self.radio_all)
        radio_button_layout.addWidget(self.radio_images)
        radio_button_layout.addWidget(self.radio_videos)
        radio_button_layout.addWidget(self.radio_only_archives)
        radio_button_layout.addWidget(self.radio_only_links)
        radio_button_layout.addStretch(1)
        file_filter_layout.addLayout(radio_button_layout)
        left_layout.addLayout(file_filter_layout)

        checkboxes_group_layout = QVBoxLayout()
        checkboxes_group_layout.setSpacing(10)
        
        row1_layout = QHBoxLayout()
        row1_layout.setSpacing(10)
        self.skip_zip_checkbox = QCheckBox("Skip .zip")
        self.skip_zip_checkbox.setChecked(True)
        row1_layout.addWidget(self.skip_zip_checkbox)
        self.skip_rar_checkbox = QCheckBox("Skip .rar")
        self.skip_rar_checkbox.setChecked(True)
        row1_layout.addWidget(self.skip_rar_checkbox)
        self.download_thumbnails_checkbox = QCheckBox("Download Thumbnails Only")
        self.download_thumbnails_checkbox.setChecked(False)
        self.download_thumbnails_checkbox.setToolTip("Thumbnail download functionality is currently limited without the API.")
        row1_layout.addWidget(self.download_thumbnails_checkbox)
        self.compress_images_checkbox = QCheckBox("Compress Large Images (to WebP)")
        self.compress_images_checkbox.setChecked(False)
        self.compress_images_checkbox.setToolTip("Compress images > 1.5MB to WebP format (requires Pillow).")
        row1_layout.addWidget(self.compress_images_checkbox)
        row1_layout.addStretch(1)
        checkboxes_group_layout.addLayout(row1_layout)

        advanced_settings_label = QLabel("⚙️ Advanced Settings:")
        checkboxes_group_layout.addWidget(advanced_settings_label)
        
        advanced_row1_layout = QHBoxLayout()
        advanced_row1_layout.setSpacing(10)
        self.use_subfolders_checkbox = QCheckBox("Separate Folders by Name/Title")
        self.use_subfolders_checkbox.setChecked(True)
        self.use_subfolders_checkbox.toggled.connect(self.update_ui_for_subfolders)
        advanced_row1_layout.addWidget(self.use_subfolders_checkbox)
        self.use_subfolder_per_post_checkbox = QCheckBox("Subfolder per Post")
        self.use_subfolder_per_post_checkbox.setChecked(False)
        self.use_subfolder_per_post_checkbox.setToolTip(
            "Creates a subfolder for each post. If 'Separate Folders' is also on, it's inside the character/title folder."
        )
        self.use_subfolder_per_post_checkbox.toggled.connect(self.update_ui_for_subfolders)
        advanced_row1_layout.addWidget(self.use_subfolder_per_post_checkbox)
        advanced_row1_layout.addStretch(1)
        checkboxes_group_layout.addLayout(advanced_row1_layout)

        advanced_row2_layout = QHBoxLayout()
        advanced_row2_layout.setSpacing(10)
        
        multithreading_layout = QHBoxLayout()
        multithreading_layout.setContentsMargins(0,0,0,0)
        self.use_multithreading_checkbox = QCheckBox("Use Multithreading")
        self.use_multithreading_checkbox.setChecked(True)
        self.use_multithreading_checkbox.setToolTip(
            "Enables concurrent operations. See 'Threads' input for details."
        )
        multithreading_layout.addWidget(self.use_multithreading_checkbox)
        self.thread_count_label = QLabel("Threads:")
        multithreading_layout.addWidget(self.thread_count_label)
        self.thread_count_input = QLineEdit()
        self.thread_count_input.setFixedWidth(40)
        self.thread_count_input.setText("4")
        self.thread_count_input.setToolTip(
            f"Number of concurrent operations.\n"
            f"- Single Post: Concurrent file downloads (1-{MAX_FILE_THREADS_PER_POST_OR_WORKER} recommended).\n"
            f"- Creator Feed: Concurrent post processing (1-{MAX_THREADS}).\n"
            f"  File downloads per post worker also use this value (1-{MAX_FILE_THREADS_PER_POST_OR_WORKER} recommended)."
        )
        self.thread_count_input.setValidator(QIntValidator(1, MAX_THREADS))
        multithreading_layout.addWidget(self.thread_count_input)
        advanced_row2_layout.addLayout(multithreading_layout)

        self.external_links_checkbox = QCheckBox("Show External Links in Log")
        self.external_links_checkbox.setChecked(False)
        advanced_row2_layout.addWidget(self.external_links_checkbox)

        self.manga_mode_checkbox = QCheckBox("Manga/Comic Mode")
        self.manga_mode_checkbox.setToolTip("Downloads posts from oldest to newest and renames files based on post title (for creator feeds only).")
        self.manga_mode_checkbox.setChecked(False)
        advanced_row2_layout.addWidget(self.manga_mode_checkbox) # Keep manga mode checkbox here

        advanced_row2_layout.addStretch(1)
        checkboxes_group_layout.addLayout(advanced_row2_layout)
        left_layout.addLayout(checkboxes_group_layout)


        btn_layout = QHBoxLayout()
        btn_layout.setSpacing(10)
        self.download_btn = QPushButton("⬇️ Start Download")
        self.download_btn.setStyleSheet("padding: 8px 15px; font-weight: bold;")
        self.download_btn.clicked.connect(self.start_download)
        self.cancel_btn = QPushButton("❌ Cancel & Reset UI") # Updated button text for clarity
        self.cancel_btn.setEnabled(False)
        self.cancel_btn.clicked.connect(self.cancel_download_button_action) # Changed connection
        btn_layout.addWidget(self.download_btn)
        btn_layout.addWidget(self.cancel_btn)
        left_layout.addLayout(btn_layout)
        left_layout.addSpacing(10)

        known_chars_label_layout = QHBoxLayout()
        known_chars_label_layout.setSpacing(10)
        self.known_chars_label = QLabel("🎭 Known Shows/Characters (for Folder Names):")
        self.character_search_input = QLineEdit()
        self.character_search_input.setPlaceholderText("Search characters...")
        known_chars_label_layout.addWidget(self.known_chars_label, 1)
        known_chars_label_layout.addWidget(self.character_search_input)
        left_layout.addLayout(known_chars_label_layout)

        self.character_list = QListWidget()
        self.character_list.setSelectionMode(QListWidget.ExtendedSelection)
        left_layout.addWidget(self.character_list, 1)

        char_manage_layout = QHBoxLayout()
        char_manage_layout.setSpacing(10)
        self.new_char_input = QLineEdit()
        self.new_char_input.setPlaceholderText("Add new show/character name")
        self.add_char_button = QPushButton("➕ Add")
        self.delete_char_button = QPushButton("🗑️ Delete Selected")
        self.add_char_button.clicked.connect(self.add_new_character)
        self.new_char_input.returnPressed.connect(self.add_char_button.click)
        self.delete_char_button.clicked.connect(self.delete_selected_character)
        char_manage_layout.addWidget(self.new_char_input, 2)
        char_manage_layout.addWidget(self.add_char_button, 1)
        char_manage_layout.addWidget(self.delete_char_button, 1)
        left_layout.addLayout(char_manage_layout)
        left_layout.addStretch(0)

        log_title_layout = QHBoxLayout()
        self.progress_log_label = QLabel("📜 Progress Log:")
        log_title_layout.addWidget(self.progress_log_label)
        log_title_layout.addStretch(1)

        self.link_search_input = QLineEdit()
        self.link_search_input.setPlaceholderText("Search Links...")
        self.link_search_input.setVisible(False)
        self.link_search_input.setFixedWidth(150)
        log_title_layout.addWidget(self.link_search_input)
        self.link_search_button = QPushButton("🔍")
        self.link_search_button.setToolTip("Filter displayed links")
        self.link_search_button.setVisible(False)
        self.link_search_button.setFixedWidth(30)
        self.link_search_button.setStyleSheet("padding: 4px 4px;")
        log_title_layout.addWidget(self.link_search_button)

        self.manga_rename_toggle_button = QPushButton()
        self.manga_rename_toggle_button.setVisible(False)
        self.manga_rename_toggle_button.setFixedWidth(140)
        self.manga_rename_toggle_button.setStyleSheet("padding: 4px 8px;")
        self._update_manga_filename_style_button_text()
        log_title_layout.addWidget(self.manga_rename_toggle_button)

        self.multipart_toggle_button = QPushButton() # Create the button
        self.multipart_toggle_button.setToolTip("Toggle between Multi-part and Single-stream downloads for large files.")
        self.multipart_toggle_button.setFixedWidth(130) # Adjust width as needed
        self.multipart_toggle_button.setStyleSheet("padding: 4px 8px;") # Added padding
        self._update_multipart_toggle_button_text() # Set initial text
        log_title_layout.addWidget(self.multipart_toggle_button) # Add to layout
        
        self.duplicate_mode_toggle_button = QPushButton()
        self.duplicate_mode_toggle_button.setToolTip("Toggle how duplicate filenames are handled (Rename or Delete).")
        self.duplicate_mode_toggle_button.setFixedWidth(150) # Adjust width
        self.duplicate_mode_toggle_button.setStyleSheet("padding: 4px 8px;") # Added padding
        self._update_duplicate_mode_button_text() # Set initial text
        log_title_layout.addWidget(self.duplicate_mode_toggle_button)

        self.log_verbosity_button = QPushButton("Show Basic Log")
        self.log_verbosity_button.setToolTip("Toggle between full and basic log details.")
        self.log_verbosity_button.setFixedWidth(110)
        self.log_verbosity_button.setStyleSheet("padding: 4px 8px;")
        log_title_layout.addWidget(self.log_verbosity_button)

        self.reset_button = QPushButton("🔄 Reset")
        self.reset_button.setToolTip("Reset all inputs and logs to default state (only when idle).")
        self.reset_button.setFixedWidth(80)
        self.reset_button.setStyleSheet("padding: 4px 8px;")
        log_title_layout.addWidget(self.reset_button)
        right_layout.addLayout(log_title_layout)

        self.log_splitter = QSplitter(Qt.Vertical)
        self.main_log_output = QTextEdit()
        self.main_log_output.setReadOnly(True)
        self.main_log_output.setLineWrapMode(QTextEdit.NoWrap)
        self.main_log_output.setStyleSheet("""
            QTextEdit { background-color: #3C3F41; border: 1px solid #5A5A5A; padding: 5px;
                         color: #F0F0F0; border-radius: 4px; font-family: Consolas, Courier New, monospace; font-size: 9.5pt; }""")
        self.external_log_output = QTextEdit()
        self.external_log_output.setReadOnly(True)
        self.external_log_output.setLineWrapMode(QTextEdit.NoWrap)
        self.external_log_output.setStyleSheet("""
            QTextEdit { background-color: #3C3F41; border: 1px solid #5A5A5A; padding: 5px;
                         color: #F0F0F0; border-radius: 4px; font-family: Consolas, Courier New, monospace; font-size: 9.5pt; }""")
        self.external_log_output.hide()
        self.log_splitter.addWidget(self.main_log_output)
        self.log_splitter.addWidget(self.external_log_output)
        self.log_splitter.setSizes([self.height(), 0])
        right_layout.addWidget(self.log_splitter, 1)

        export_button_layout = QHBoxLayout()
        export_button_layout.addStretch(1)
        self.export_links_button = QPushButton("Export Links")
        self.export_links_button.setToolTip("Export all extracted links to a .txt file.")
        self.export_links_button.setFixedWidth(100)
        self.export_links_button.setStyleSheet("padding: 4px 8px; margin-top: 5px;")
        self.export_links_button.setEnabled(False)
        self.export_links_button.setVisible(False)
        export_button_layout.addWidget(self.export_links_button)
        right_layout.addLayout(export_button_layout)


        self.progress_label = QLabel("Progress: Idle")
        self.progress_label.setStyleSheet("padding-top: 5px; font-style: italic;")
        right_layout.addWidget(self.progress_label)
        self.file_progress_label = QLabel("")
        self.file_progress_label.setWordWrap(True)
        self.file_progress_label.setStyleSheet("padding-top: 2px; font-style: italic; color: #A0A0A0;")
        right_layout.addWidget(self.file_progress_label)


        self.main_splitter.addWidget(left_panel_widget)
        self.main_splitter.addWidget(right_panel_widget)
        initial_width = self.width()
        left_width = int(initial_width * 0.35)
        right_width = initial_width - left_width
        self.main_splitter.setSizes([left_width, right_width])

        top_level_layout = QHBoxLayout(self)
        top_level_layout.setContentsMargins(0,0,0,0)
        top_level_layout.addWidget(self.main_splitter)

        self.update_ui_for_subfolders(self.use_subfolders_checkbox.isChecked())
        self.update_external_links_setting(self.external_links_checkbox.isChecked())
        self.update_multithreading_label(self.thread_count_input.text())
        self.update_page_range_enabled_state()
        if self.manga_mode_checkbox:
            self.update_ui_for_manga_mode(self.manga_mode_checkbox.isChecked())
        if hasattr(self, 'link_input'): self.link_input.textChanged.connect(self.update_page_range_enabled_state)
        self.load_known_names_from_util()
        self._handle_multithreading_toggle(self.use_multithreading_checkbox.isChecked())
        if hasattr(self, 'radio_group') and self.radio_group.checkedButton():
            self._handle_filter_mode_change(self.radio_group.checkedButton(), True)
        self._update_manga_filename_style_button_text()
        self._update_skip_scope_button_text()
        self._update_char_filter_scope_button_text()
        self._update_duplicate_mode_button_text()

    def _center_on_screen(self):
        """Centers the widget on the screen."""
        try:
            screen_geometry = QDesktopWidget().screenGeometry()
            widget_geometry = self.frameGeometry()
            widget_geometry.moveCenter(screen_geometry.center())
            self.move(widget_geometry.topLeft())
        except Exception as e:
            self.log_signal.emit(f"⚠️ Error centering window: {e}")


    def get_dark_theme(self):
        return """
        QWidget { background-color: #2E2E2E; color: #E0E0E0; font-family: Segoe UI, Arial, sans-serif; font-size: 10pt; }
        QLineEdit, QListWidget { background-color: #3C3F41; border: 1px solid #5A5A5A; padding: 5px; color: #F0F0F0; border-radius: 4px; }
        QTextEdit { background-color: #3C3F41; border: 1px solid #5A5A5A; padding: 5px; color: #F0F0F0; border-radius: 4px; }
        QPushButton { background-color: #555; color: #F0F0F0; border: 1px solid #6A6A6A; padding: 6px 12px; border-radius: 4px; min-height: 22px; }
        QPushButton:hover { background-color: #656565; border: 1px solid #7A7A7A; }
        QPushButton:pressed { background-color: #4A4A4A; }
        QPushButton:disabled { background-color: #404040; color: #888; border-color: #555; }
        QLabel { font-weight: bold; padding-top: 4px; padding-bottom: 2px; color: #C0C0C0; }
        QRadioButton, QCheckBox { spacing: 5px; color: #E0E0E0; padding-top: 4px; padding-bottom: 4px; }
        QRadioButton::indicator, QCheckBox::indicator { width: 14px; height: 14px; }
        QListWidget { alternate-background-color: #353535; border: 1px solid #5A5A5A; }
        QListWidget::item:selected { background-color: #007ACC; color: #FFFFFF; }
        QToolTip { background-color: #4A4A4A; color: #F0F0F0; border: 1px solid #6A6A6A; padding: 4px; border-radius: 3px; }
        QSplitter::handle { background-color: #5A5A5A; }
        QSplitter::handle:horizontal { width: 5px; }
        QSplitter::handle:vertical { height: 5px; }
        QFrame[frameShape="4"], QFrame[frameShape="5"] { 
            border: 1px solid #4A4A4A; 
            border-radius: 3px;
        }
        """

    def browse_directory(self):
        current_dir = self.dir_input.text() if os.path.isdir(self.dir_input.text()) else ""
        folder = QFileDialog.getExistingDirectory(self, "Select Download Folder", current_dir)
        if folder:
            self.dir_input.setText(folder)

    def handle_main_log(self, message):
        is_html_message = message.startswith(HTML_PREFIX)
        display_message = message
        use_html = False

        if is_html_message:
             display_message = message[len(HTML_PREFIX):]
             use_html = True
        elif self.basic_log_mode:
            basic_keywords = [
                '🚀 starting download', '🏁 download finished', '🏁 download cancelled',
                '❌', '⚠️', '✅ all posts processed', '✅ reached end of posts',
                'summary:', 'progress:', '[fetcher]',
                'critical error', 'import error', 'error', 'fail', 'timeout',
                'unsupported url', 'invalid url', 'no posts found', 'could not create directory',
                'missing dependency', 'high thread count', 'manga mode filter warning',
                'duplicate name', 'potential name conflict', 'invalid filter name',
                'no valid character filters'
            ]
            message_lower = message.lower()
            if not any(keyword in message_lower for keyword in basic_keywords):
                 if not message.strip().startswith("✅ Saved:") and \
                    not message.strip().startswith("✅ Added") and \
                    not message.strip().startswith("✅ Application reset complete"):
                    return
        
        try:
             safe_message = str(display_message).replace('\x00', '[NULL]')
             if use_html:
                 self.main_log_output.insertHtml(safe_message)
             else:
                 self.main_log_output.append(safe_message)

             scrollbar = self.main_log_output.verticalScrollBar()
             if scrollbar.value() >= scrollbar.maximum() - 30:
                 scrollbar.setValue(scrollbar.maximum())
        except Exception as e:
             print(f"GUI Main Log Error: {e}\nOriginal Message: {message}")


    def _is_download_active(self):
        single_thread_active = self.download_thread and self.download_thread.isRunning()
        pool_active = self.thread_pool is not None and any(not f.done() for f in self.active_futures if f is not None)
        return single_thread_active or pool_active


    def handle_external_link_signal(self, post_title, link_text, link_url, platform):
        link_data = (post_title, link_text, link_url, platform)
        self.external_link_queue.append(link_data)
        if self.radio_only_links and self.radio_only_links.isChecked():
            self.extracted_links_cache.append(link_data)
        self._try_process_next_external_link()

    def _try_process_next_external_link(self):
        if self._is_processing_external_link_queue or not self.external_link_queue:
             return

        is_only_links_mode = self.radio_only_links and self.radio_only_links.isChecked()
        should_display_in_external_log = self.show_external_links and not is_only_links_mode

        if not (is_only_links_mode or should_display_in_external_log):
             self._is_processing_external_link_queue = False
             if self.external_link_queue:
                 QTimer.singleShot(0, self._try_process_next_external_link)
             return

        self._is_processing_external_link_queue = True
        link_data = self.external_link_queue.popleft()

        if is_only_links_mode:
            delay_ms = 80
            QTimer.singleShot(delay_ms, lambda data=link_data: self._display_and_schedule_next(data))
        elif self._is_download_active():
            delay_ms = random.randint(4000, 8000)
            QTimer.singleShot(delay_ms, lambda data=link_data: self._display_and_schedule_next(data))
        else:
            QTimer.singleShot(0, lambda data=link_data: self._display_and_schedule_next(data))


    def _display_and_schedule_next(self, link_data):
        post_title, link_text, link_url, platform = link_data
        is_only_links_mode = self.radio_only_links and self.radio_only_links.isChecked()

        max_link_text_len = 35
        display_text = link_text[:max_link_text_len].strip() + "..." if len(link_text) > max_link_text_len else link_text
        formatted_link_info = f"{display_text} - {link_url} - {platform}"
        separator = "-" * 45

        if is_only_links_mode:
            if post_title != self._current_link_post_title:
                self.log_signal.emit(HTML_PREFIX + "<br>" + separator + "<br>")
                title_html = f'<b style="color: #87CEEB;">{post_title}</b><br>'
                self.log_signal.emit(HTML_PREFIX + title_html)
                self._current_link_post_title = post_title
            self.log_signal.emit(formatted_link_info)
        elif self.show_external_links:
             self._append_to_external_log(formatted_link_info, separator)

        self._is_processing_external_link_queue = False
        self._try_process_next_external_link()


    def _append_to_external_log(self, formatted_link_text, separator):
        if not (self.external_log_output and self.external_log_output.isVisible()):
            return

        try:
            self.external_log_output.append(formatted_link_text)
            self.external_log_output.append("")

            scrollbar = self.external_log_output.verticalScrollBar()
            if scrollbar.value() >= scrollbar.maximum() - 50:
                scrollbar.setValue(scrollbar.maximum())
        except Exception as e:
             self.log_signal.emit(f"GUI External Log Append Error: {e}\nOriginal Message: {formatted_link_text}")
             print(f"GUI External Log Error (Append): {e}\nOriginal Message: {formatted_link_text}")


    def update_file_progress_display(self, filename, progress_info):
        if not filename and progress_info is None: # Explicit clear
            self.file_progress_label.setText("")
            return

        if isinstance(progress_info, list):  # Multi-part progress (list of chunk dicts)
            if not progress_info: # Empty list
                self.file_progress_label.setText(f"File: {filename} - Initializing parts...")
                return

            total_downloaded_overall = sum(cs.get('downloaded', 0) for cs in progress_info)
            # total_file_size_overall should ideally be from progress_data['total_file_size']
            # For now, we sum chunk totals. This assumes all chunks are for the same file.
            total_file_size_overall = sum(cs.get('total', 0) for cs in progress_info)
            
            active_chunks_count = 0
            combined_speed_bps = 0
            for cs in progress_info:
                if cs.get('active', False):
                    active_chunks_count += 1
                    combined_speed_bps += cs.get('speed_bps', 0)

            dl_mb = total_downloaded_overall / (1024 * 1024)
            total_mb = total_file_size_overall / (1024 * 1024)
            speed_MBps = (combined_speed_bps / 8) / (1024 * 1024)

            progress_text = f"DL '{filename[:20]}...': {dl_mb:.1f}/{total_mb:.1f} MB ({active_chunks_count} parts @ {speed_MBps:.2f} MB/s)"
            self.file_progress_label.setText(progress_text)

        elif isinstance(progress_info, tuple) and len(progress_info) == 2:  # Single stream (downloaded_bytes, total_bytes)
            downloaded_bytes, total_bytes = progress_info
            if not filename and total_bytes == 0 and downloaded_bytes == 0: # Clear if no info
                self.file_progress_label.setText("")
                return

            max_fn_len = 25
            disp_fn = filename if len(filename) <= max_fn_len else filename[:max_fn_len-3].strip()+"..."
            
            dl_mb = downloaded_bytes / (1024*1024)
            prog_text_base = f"Downloading '{disp_fn}' ({dl_mb:.1f}MB"
            if total_bytes > 0:
                tot_mb = total_bytes / (1024*1024)
                prog_text_base += f" / {tot_mb:.1f}MB)"
            else:
                prog_text_base += ")"
            
            self.file_progress_label.setText(prog_text_base)
        elif filename and progress_info is None: # Explicit request to clear for a specific file (e.g. download finished/failed)
            self.file_progress_label.setText("")
        elif not filename and not progress_info: # General clear
             self.file_progress_label.setText("")


    def update_external_links_setting(self, checked):
        is_only_links_mode = self.radio_only_links and self.radio_only_links.isChecked()
        is_only_archives_mode = self.radio_only_archives and self.radio_only_archives.isChecked()

        if is_only_links_mode or is_only_archives_mode:
             if self.external_log_output: self.external_log_output.hide()
             if self.log_splitter: self.log_splitter.setSizes([self.height(), 0])
             return

        self.show_external_links = checked
        if checked:
            if self.external_log_output: self.external_log_output.show()
            if self.log_splitter: self.log_splitter.setSizes([self.height() // 2, self.height() // 2])
            if self.main_log_output: self.main_log_output.setMinimumHeight(50)
            if self.external_log_output: self.external_log_output.setMinimumHeight(50)
            self.log_signal.emit("\n" + "="*40 + "\n🔗 External Links Log Enabled\n" + "="*40)
            if self.external_log_output:
                self.external_log_output.clear()
                self.external_log_output.append("🔗 External Links Found:")
            self._try_process_next_external_link()
        else:
            if self.external_log_output: self.external_log_output.hide()
            if self.log_splitter: self.log_splitter.setSizes([self.height(), 0])
            if self.main_log_output: self.main_log_output.setMinimumHeight(0)
            if self.external_log_output: self.external_log_output.setMinimumHeight(0)
            if self.external_log_output: self.external_log_output.clear()
            self.log_signal.emit("\n" + "="*40 + "\n🔗 External Links Log Disabled\n" + "="*40)


    def _handle_filter_mode_change(self, button, checked):
        if not button or not checked:
            return

        filter_mode_text = button.text()
        is_only_links = (filter_mode_text == "🔗 Only Links")
        is_only_archives = (filter_mode_text == "📦 Only Archives")

        if self.link_search_input: self.link_search_input.setVisible(is_only_links)
        if self.link_search_button: self.link_search_button.setVisible(is_only_links)
        if self.export_links_button:
            self.export_links_button.setVisible(is_only_links)
            self.export_links_button.setEnabled(is_only_links and bool(self.extracted_links_cache))
        if not is_only_links and self.link_search_input: self.link_search_input.clear()

        file_download_mode_active = not is_only_links

        if self.dir_input: self.dir_input.setEnabled(file_download_mode_active)
        if self.dir_button: self.dir_button.setEnabled(file_download_mode_active)
        if self.use_subfolders_checkbox: self.use_subfolders_checkbox.setEnabled(file_download_mode_active)
        if self.skip_words_input: self.skip_words_input.setEnabled(file_download_mode_active)
        if self.skip_scope_toggle_button: self.skip_scope_toggle_button.setEnabled(file_download_mode_active)
        if hasattr(self, 'remove_from_filename_input'): self.remove_from_filename_input.setEnabled(file_download_mode_active)
        
        if self.skip_zip_checkbox:
            can_skip_zip = not is_only_links and not is_only_archives
            self.skip_zip_checkbox.setEnabled(can_skip_zip)
            if is_only_archives:
                self.skip_zip_checkbox.setChecked(False)
        
        if self.skip_rar_checkbox:
            can_skip_rar = not is_only_links and not is_only_archives
            self.skip_rar_checkbox.setEnabled(can_skip_rar)
            if is_only_archives:
                self.skip_rar_checkbox.setChecked(False)

        other_file_proc_enabled = not is_only_links and not is_only_archives
        if self.download_thumbnails_checkbox: self.download_thumbnails_checkbox.setEnabled(other_file_proc_enabled)
        if self.compress_images_checkbox: self.compress_images_checkbox.setEnabled(other_file_proc_enabled)
        
        if self.external_links_checkbox: 
            can_show_external_log_option = not is_only_links and not is_only_archives
            self.external_links_checkbox.setEnabled(can_show_external_log_option)
            if not can_show_external_log_option:
                 self.external_links_checkbox.setChecked(False)


        if is_only_links:
            self.progress_log_label.setText("📜 Extracted Links Log:")
            if self.external_log_output: self.external_log_output.hide()
            if self.log_splitter: self.log_splitter.setSizes([self.height(), 0])
            if self.main_log_output: self.main_log_output.clear(); self.main_log_output.setMinimumHeight(0)
            if self.external_log_output: self.external_log_output.clear(); self.external_log_output.setMinimumHeight(0)
            self.log_signal.emit("="*20 + " Mode changed to: Only Links " + "="*20)
            self._filter_links_log()
            self._try_process_next_external_link()
        elif is_only_archives:
            self.progress_log_label.setText("📜 Progress Log (Archives Only):")
            if self.external_log_output: self.external_log_output.hide()
            if self.log_splitter: self.log_splitter.setSizes([self.height(), 0])
            if self.main_log_output: self.main_log_output.clear()
            self.log_signal.emit("="*20 + " Mode changed to: Only Archives " + "="*20)
        else:
            self.progress_log_label.setText("📜 Progress Log:")
            self.update_external_links_setting(self.external_links_checkbox.isChecked() if self.external_links_checkbox else False)
            self.log_signal.emit(f"="*20 + f" Mode changed to: {filter_mode_text} " + "="*20)

        subfolders_on = self.use_subfolders_checkbox.isChecked() if self.use_subfolders_checkbox else False
        
        manga_on = self.manga_mode_checkbox.isChecked() if self.manga_mode_checkbox else False
        
        enable_character_filter_related_widgets = file_download_mode_active and (subfolders_on or manga_on)

        if self.character_input:
            self.character_input.setEnabled(enable_character_filter_related_widgets)
            if not enable_character_filter_related_widgets:
                self.character_input.clear()
        
        if self.char_filter_scope_toggle_button:
            self.char_filter_scope_toggle_button.setEnabled(enable_character_filter_related_widgets)
        
        self.update_ui_for_subfolders(subfolders_on)
        self.update_custom_folder_visibility()


    def _filter_links_log(self):
        if not (self.radio_only_links and self.radio_only_links.isChecked()): return

        search_term = self.link_search_input.text().lower().strip() if self.link_search_input else ""
        self.main_log_output.clear()
        current_title_for_display = None
        separator = "-" * 45

        for post_title, link_text, link_url, platform in self.extracted_links_cache:
            matches_search = (
                not search_term or
                search_term in link_text.lower() or
                search_term in link_url.lower() or
                search_term in platform.lower()
            )
            if matches_search:
                if post_title != current_title_for_display:
                    self.main_log_output.insertHtml("<br>" + separator + "<br>")
                    title_html = f'<b style="color: #87CEEB;">{post_title}</b><br>'
                    self.main_log_output.insertHtml(title_html)
                    current_title_for_display = post_title
                
                max_link_text_len = 35
                display_text = link_text[:max_link_text_len].strip() + "..." if len(link_text) > max_link_text_len else link_text
                formatted_link_info = f"{display_text} - {link_url} - {platform}"
                self.main_log_output.append(formatted_link_info)

        if self.main_log_output.toPlainText().strip():
            self.main_log_output.append("")
        self.main_log_output.verticalScrollBar().setValue(0)


    def _export_links_to_file(self):
        if not (self.radio_only_links and self.radio_only_links.isChecked()):
            QMessageBox.information(self, "Export Links", "Link export is only available in 'Only Links' mode.")
            return
        if not self.extracted_links_cache:
            QMessageBox.information(self, "Export Links", "No links have been extracted yet.")
            return

        default_filename = "extracted_links.txt"
        filepath, _ = QFileDialog.getSaveFileName(self, "Save Links", default_filename, "Text Files (*.txt);;All Files (*)")

        if filepath:
            try:
                with open(filepath, 'w', encoding='utf-8') as f:
                    current_title_for_export = None
                    separator = "-" * 60 + "\n"
                    for post_title, link_text, link_url, platform in self.extracted_links_cache:
                        if post_title != current_title_for_export:
                            if current_title_for_export is not None:
                                f.write("\n" + separator + "\n")
                            f.write(f"Post Title: {post_title}\n\n")
                            current_title_for_export = post_title
                        f.write(f"  {link_text} - {link_url} - {platform}\n")
                self.log_signal.emit(f"✅ Links successfully exported to: {filepath}")
                QMessageBox.information(self, "Export Successful", f"Links exported to:\n{filepath}")
            except Exception as e:
                self.log_signal.emit(f"❌ Error exporting links: {e}")
                QMessageBox.critical(self, "Export Error", f"Could not export links: {e}")


    def get_filter_mode(self):
        if self.radio_only_links and self.radio_only_links.isChecked():
            return 'all' 
        elif self.radio_images.isChecked():
            return 'image'
        elif self.radio_videos.isChecked():
            return 'video'
        elif self.radio_only_archives and self.radio_only_archives.isChecked():
            return 'archive'
        elif self.radio_all.isChecked():
            return 'all'
        return 'all'


    def get_skip_words_scope(self):
        return self.skip_words_scope


    def _update_skip_scope_button_text(self):
        if self.skip_scope_toggle_button:
            if self.skip_words_scope == SKIP_SCOPE_FILES:
                self.skip_scope_toggle_button.setText("Scope: Files")
            elif self.skip_words_scope == SKIP_SCOPE_POSTS:
                self.skip_scope_toggle_button.setText("Scope: Posts")
            elif self.skip_words_scope == SKIP_SCOPE_BOTH:
                self.skip_scope_toggle_button.setText("Scope: Both")
            else:
                self.skip_scope_toggle_button.setText("Scope: Unknown")


    def _cycle_skip_scope(self):
        if self.skip_words_scope == SKIP_SCOPE_FILES:
            self.skip_words_scope = SKIP_SCOPE_POSTS
        elif self.skip_words_scope == SKIP_SCOPE_POSTS:
            self.skip_words_scope = SKIP_SCOPE_BOTH
        elif self.skip_words_scope == SKIP_SCOPE_BOTH:
            self.skip_words_scope = SKIP_SCOPE_FILES
        else:
            self.skip_words_scope = SKIP_SCOPE_FILES
        
        self._update_skip_scope_button_text()
        self.settings.setValue(SKIP_WORDS_SCOPE_KEY, self.skip_words_scope)
        self.log_signal.emit(f"ℹ️ Skip words scope changed to: '{self.skip_words_scope}'")

    def get_char_filter_scope(self):
        return self.char_filter_scope

    def _update_char_filter_scope_button_text(self):
        if self.char_filter_scope_toggle_button:
            if self.char_filter_scope == CHAR_SCOPE_FILES:
                self.char_filter_scope_toggle_button.setText("Filter: Files")
            elif self.char_filter_scope == CHAR_SCOPE_TITLE:
                self.char_filter_scope_toggle_button.setText("Filter: Title")
            elif self.char_filter_scope == CHAR_SCOPE_BOTH:
                self.char_filter_scope_toggle_button.setText("Filter: Both")
            else:
                self.char_filter_scope_toggle_button.setText("Filter: Unknown")

    def _cycle_char_filter_scope(self):
        if self.char_filter_scope == CHAR_SCOPE_FILES:
            self.char_filter_scope = CHAR_SCOPE_TITLE
        elif self.char_filter_scope == CHAR_SCOPE_TITLE:
            self.char_filter_scope = CHAR_SCOPE_BOTH
        elif self.char_filter_scope == CHAR_SCOPE_BOTH:
            self.char_filter_scope = CHAR_SCOPE_FILES
        else:
            self.char_filter_scope = CHAR_SCOPE_FILES
        
        self._update_char_filter_scope_button_text()
        self.settings.setValue(CHAR_FILTER_SCOPE_KEY, self.char_filter_scope)
        self.log_signal.emit(f"ℹ️ Character filter scope changed to: '{self.char_filter_scope}'")


    def add_new_character(self):
        global KNOWN_NAMES, clean_folder_name
        name_to_add = self.new_char_input.text().strip()
        if not name_to_add:
             QMessageBox.warning(self, "Input Error", "Name cannot be empty."); return False

        name_lower = name_to_add.lower()
        if any(existing.lower() == name_lower for existing in KNOWN_NAMES):
             QMessageBox.warning(self, "Duplicate Name", f"The name '{name_to_add}' (case-insensitive) already exists."); return False

        similar_names_details = []
        for existing_name in KNOWN_NAMES:
            existing_name_lower = existing_name.lower()
            if name_lower != existing_name_lower and (name_lower in existing_name_lower or existing_name_lower in name_lower):
                similar_names_details.append((name_to_add, existing_name))

        if similar_names_details:
            first_similar_new, first_similar_existing = similar_names_details[0]
            shorter, longer = sorted([first_similar_new, first_similar_existing], key=len)

            msg_box = QMessageBox(self)
            msg_box.setIcon(QMessageBox.Warning)
            msg_box.setWindowTitle("Potential Name Conflict")
            msg_box.setText(
                f"The name '{first_similar_new}' is very similar to an existing name: '{first_similar_existing}'.\n\n"
                f"This could lead to files being grouped into less specific folders (e.g., under '{clean_folder_name(shorter)}' instead of a more specific '{clean_folder_name(longer)}').\n\n"
                "Do you want to change the name you are adding, or proceed anyway?"
            )
            change_button = msg_box.addButton("Change Name", QMessageBox.RejectRole)
            proceed_button = msg_box.addButton("Proceed Anyway", QMessageBox.AcceptRole)
            msg_box.setDefaultButton(proceed_button)
            msg_box.setEscapeButton(change_button)
            msg_box.exec_()

            if msg_box.clickedButton() == change_button:
                self.log_signal.emit(f"ℹ️ User chose to change '{first_similar_new}' due to similarity with '{first_similar_existing}'.")
                return False

            self.log_signal.emit(f"⚠️ User proceeded with adding '{first_similar_new}' despite similarity with '{first_similar_existing}'.")

        KNOWN_NAMES.append(name_to_add)
        KNOWN_NAMES.sort(key=str.lower)

        self.character_list.clear()
        self.character_list.addItems(KNOWN_NAMES)
        self.filter_character_list(self.character_search_input.text())

        self.log_signal.emit(f"✅ Added '{name_to_add}' to known names list.")
        self.new_char_input.clear()
        self.save_known_names()
        return True


    def delete_selected_character(self):
        global KNOWN_NAMES
        selected_items = self.character_list.selectedItems()
        if not selected_items:
             QMessageBox.warning(self, "Selection Error", "Please select one or more names to delete."); return

        names_to_remove = {item.text() for item in selected_items}
        confirm = QMessageBox.question(self, "Confirm Deletion",
                                       f"Are you sure you want to delete {len(names_to_remove)} name(s)?",
                                       QMessageBox.Yes | QMessageBox.No, QMessageBox.No)
        if confirm == QMessageBox.Yes:
            original_count = len(KNOWN_NAMES)
            KNOWN_NAMES[:] = [n for n in KNOWN_NAMES if n not in names_to_remove]
            removed_count = original_count - len(KNOWN_NAMES)

            if removed_count > 0:
                 self.log_signal.emit(f"🗑️ Removed {removed_count} name(s).")
                 self.character_list.clear()
                 self.character_list.addItems(KNOWN_NAMES)
                 self.filter_character_list(self.character_search_input.text())
                 self.save_known_names()
            else:
                 self.log_signal.emit("ℹ️ No names were removed (they might not have been in the list).")


    def update_custom_folder_visibility(self, url_text=None):
        if url_text is None:
            url_text = self.link_input.text()

        _, _, post_id = extract_post_info(url_text.strip())
        
        is_single_post_url = bool(post_id)
        subfolders_enabled = self.use_subfolders_checkbox.isChecked() if self.use_subfolders_checkbox else False
        
        not_only_links_or_archives_mode = not (
            (self.radio_only_links and self.radio_only_links.isChecked()) or
            (self.radio_only_archives and self.radio_only_archives.isChecked())
        )

        should_show_custom_folder = is_single_post_url and subfolders_enabled and not_only_links_or_archives_mode
        
        if self.custom_folder_widget:
            self.custom_folder_widget.setVisible(should_show_custom_folder)

        if not (self.custom_folder_widget and self.custom_folder_widget.isVisible()):
            if self.custom_folder_input: self.custom_folder_input.clear()


    def update_ui_for_subfolders(self, checked): 
        is_only_links = self.radio_only_links and self.radio_only_links.isChecked()
        is_only_archives = self.radio_only_archives and self.radio_only_archives.isChecked()

        if self.use_subfolder_per_post_checkbox:
            self.use_subfolder_per_post_checkbox.setEnabled(not is_only_links and not is_only_archives)

        enable_character_filter_related_widgets = checked and not is_only_links and not is_only_archives
 

        if self.character_filter_widget:
            self.character_filter_widget.setVisible(enable_character_filter_related_widgets)
            if not self.character_filter_widget.isVisible():
                if self.character_input: self.character_input.clear()
                if self.char_filter_scope_toggle_button: self.char_filter_scope_toggle_button.setEnabled(False)
            else:
                if self.char_filter_scope_toggle_button: self.char_filter_scope_toggle_button.setEnabled(True)
        
        self.update_custom_folder_visibility()


    def update_page_range_enabled_state(self):
        url_text = self.link_input.text().strip() if self.link_input else ""
        _, _, post_id = extract_post_info(url_text)

        is_creator_feed = not post_id if url_text else False
        manga_mode_active = self.manga_mode_checkbox.isChecked() if self.manga_mode_checkbox else False

        enable_page_range = is_creator_feed and not manga_mode_active

        for widget in [self.page_range_label, self.start_page_input, self.to_label, self.end_page_input]:
            if widget: widget.setEnabled(enable_page_range)

        if not enable_page_range:
            if self.start_page_input: self.start_page_input.clear()
            if self.end_page_input: self.end_page_input.clear()


    def _update_manga_filename_style_button_text(self):
        if self.manga_rename_toggle_button:
            if self.manga_filename_style == STYLE_POST_TITLE:
                self.manga_rename_toggle_button.setText("Name: Post Title")
                self.manga_rename_toggle_button.setToolTip(
                    "Manga files: First file named by post title. Subsequent files in same post keep original names.\n"
                    "Click to change to original file names for all files."
                )
            elif self.manga_filename_style == STYLE_ORIGINAL_NAME:
                self.manga_rename_toggle_button.setText("Name: Original File")
                self.manga_rename_toggle_button.setToolTip(
                    "Manga files will keep their original names as provided by the site (e.g., 001.jpg, page_01.png).\n"
                    "Click to change to post title based naming for the first file."
                )
            else:
                self.manga_rename_toggle_button.setText("Name: Unknown Style")
                self.manga_rename_toggle_button.setToolTip("Manga filename style is in an unknown state.")


    def _toggle_manga_filename_style(self):
        current_style = self.manga_filename_style
        new_style = ""

        if current_style == STYLE_POST_TITLE:
            new_style = STYLE_ORIGINAL_NAME
            reply = QMessageBox.information(self, "Manga Filename Preference",
                                           "Using 'Name: Post Title' (first file by title, others original) is recommended for Manga Mode.\n\n"
                                           "Using 'Name: Original File' for all files might lead to less organized downloads if original names are inconsistent or non-sequential.\n\n"
                                           "Proceed with using 'Name: Original File' for all files?",
                                           QMessageBox.Yes | QMessageBox.No, QMessageBox.No)
            if reply == QMessageBox.No:
                self.log_signal.emit("ℹ️ Manga filename style change to 'Original File' cancelled by user.")
                return
        elif current_style == STYLE_ORIGINAL_NAME:
            new_style = STYLE_POST_TITLE
        else:
            self.log_signal.emit(f"⚠️ Unknown current manga filename style: {current_style}. Resetting to default ('{STYLE_POST_TITLE}').")
            new_style = STYLE_POST_TITLE

        self.manga_filename_style = new_style
        self.settings.setValue(MANGA_FILENAME_STYLE_KEY, self.manga_filename_style)
        self.settings.sync()
        self._update_manga_filename_style_button_text()
        self.log_signal.emit(f"ℹ️ Manga filename style changed to: '{self.manga_filename_style}'")


    def update_ui_for_manga_mode(self, checked):
        url_text = self.link_input.text().strip() if self.link_input else ""
        _, _, post_id = extract_post_info(url_text)

        is_creator_feed = not post_id if url_text else False

        if self.manga_mode_checkbox:
            self.manga_mode_checkbox.setEnabled(is_creator_feed)
            if not is_creator_feed and self.manga_mode_checkbox.isChecked():
                self.manga_mode_checkbox.setChecked(False)
                checked = self.manga_mode_checkbox.isChecked() 

        manga_mode_effectively_on = is_creator_feed and checked

        if self.manga_rename_toggle_button:
            self.manga_rename_toggle_button.setVisible(manga_mode_effectively_on)

        if hasattr(self, 'duplicate_mode_toggle_button'):
            self.duplicate_mode_toggle_button.setVisible(not manga_mode_effectively_on) # Hidden in Manga Mode

        if manga_mode_effectively_on:
            if self.page_range_label: self.page_range_label.setEnabled(False)
            if self.start_page_input: self.start_page_input.setEnabled(False); self.start_page_input.clear()
            if self.to_label: self.to_label.setEnabled(False)
            if self.end_page_input: self.end_page_input.setEnabled(False); self.end_page_input.clear()
        else:
            self.update_page_range_enabled_state()
        
        file_download_mode_active = not (self.radio_only_links and self.radio_only_links.isChecked())
        subfolders_on = self.use_subfolders_checkbox.isChecked() if self.use_subfolders_checkbox else False
        enable_char_filter_widgets = file_download_mode_active and (subfolders_on or manga_mode_effectively_on)

        if self.character_input:
            self.character_input.setEnabled(enable_char_filter_widgets)
            if not enable_char_filter_widgets: self.character_input.clear()
        if self.char_filter_scope_toggle_button:
            self.char_filter_scope_toggle_button.setEnabled(enable_char_filter_widgets)


    def filter_character_list(self, search_text):
        search_text_lower = search_text.lower()
        for i in range(self.character_list.count()):
            item = self.character_list.item(i)
            item.setHidden(search_text_lower not in item.text().lower())


    def update_multithreading_label(self, text):
        if self.use_multithreading_checkbox.isChecked():
            try:
                num_threads_val = int(text)
                if num_threads_val > 0 : self.use_multithreading_checkbox.setText(f"Use Multithreading ({num_threads_val} Threads)")
                else: self.use_multithreading_checkbox.setText("Use Multithreading (Invalid: >0)")
            except ValueError:
                self.use_multithreading_checkbox.setText("Use Multithreading (Invalid Input)")
        else:
            self.use_multithreading_checkbox.setText("Use Multithreading (1 Thread)")


    def _handle_multithreading_toggle(self, checked):
        if not checked:
            self.thread_count_input.setEnabled(False)
            self.thread_count_label.setEnabled(False)
            self.use_multithreading_checkbox.setText("Use Multithreading (1 Thread)")
        else:
            self.thread_count_input.setEnabled(True)
            self.thread_count_label.setEnabled(True)
            self.update_multithreading_label(self.thread_count_input.text())


    def update_progress_display(self, total_posts, processed_posts):
        if total_posts > 0:
            progress_percent = (processed_posts / total_posts) * 100
            self.progress_label.setText(f"Progress: {processed_posts} / {total_posts} posts ({progress_percent:.1f}%)")
        elif processed_posts > 0 :
             self.progress_label.setText(f"Progress: Processing post {processed_posts}...")
        else:
            self.progress_label.setText("Progress: Starting...")
        
        if total_posts > 0 or processed_posts > 0 :
            self.file_progress_label.setText("")


    def start_download(self):
        global KNOWN_NAMES, BackendDownloadThread, PostProcessorWorker, extract_post_info, clean_folder_name, MAX_FILE_THREADS_PER_POST_OR_WORKER
        
        if self._is_download_active():
            QMessageBox.warning(self, "Busy", "A download is already running."); return

        api_url = self.link_input.text().strip()
        output_dir = self.dir_input.text().strip()
        
        use_subfolders = self.use_subfolders_checkbox.isChecked()
        use_post_subfolders = self.use_subfolder_per_post_checkbox.isChecked()
        compress_images = self.compress_images_checkbox.isChecked()
        download_thumbnails = self.download_thumbnails_checkbox.isChecked()
        
        use_multithreading_enabled_by_checkbox = self.use_multithreading_checkbox.isChecked()
        try:
            num_threads_from_gui = int(self.thread_count_input.text().strip())
            if num_threads_from_gui < 1: num_threads_from_gui = 1
        except ValueError:
            QMessageBox.critical(self, "Thread Count Error", "Invalid number of threads. Please enter a positive number.")
            self.set_ui_enabled(True)
            return
            
        raw_skip_words = self.skip_words_input.text().strip()
        skip_words_list = [word.strip().lower() for word in raw_skip_words.split(',') if word.strip()]
        current_skip_words_scope = self.get_skip_words_scope()

        raw_remove_filename_words = self.remove_from_filename_input.text().strip() if hasattr(self, 'remove_from_filename_input') else ""
        effective_duplicate_file_mode = self.duplicate_file_mode # Start with user's choice
        allow_multipart = self.allow_multipart_download_setting # Use the internal setting
        remove_from_filename_words_list = [word.strip() for word in raw_remove_filename_words.split(',') if word.strip()]
        current_char_filter_scope = self.get_char_filter_scope()
        manga_mode_is_checked = self.manga_mode_checkbox.isChecked() if self.manga_mode_checkbox else False
        
        extract_links_only = (self.radio_only_links and self.radio_only_links.isChecked())
        backend_filter_mode = self.get_filter_mode()
        user_selected_filter_text = self.radio_group.checkedButton().text() if self.radio_group.checkedButton() else "All"

        if backend_filter_mode == 'archive':
            effective_skip_zip = False
            effective_skip_rar = False
        else:
            effective_skip_zip = self.skip_zip_checkbox.isChecked()
            effective_skip_rar = self.skip_rar_checkbox.isChecked()

        if not api_url: QMessageBox.critical(self, "Input Error", "URL is required."); return
        if not extract_links_only and not output_dir:
             QMessageBox.critical(self, "Input Error", "Download Directory is required when not in 'Only Links' mode."); return
        
        service, user_id, post_id_from_url = extract_post_info(api_url)
        if not service or not user_id:
            QMessageBox.critical(self, "Input Error", "Invalid or unsupported URL format."); return

        if not extract_links_only and not os.path.isdir(output_dir):
            reply = QMessageBox.question(self, "Create Directory?",
                                         f"The directory '{output_dir}' does not exist.\nCreate it now?",
                                         QMessageBox.Yes | QMessageBox.No, QMessageBox.Yes)
            if reply == QMessageBox.Yes:
                try: os.makedirs(output_dir, exist_ok=True); self.log_signal.emit(f"ℹ️ Created directory: {output_dir}")
                except Exception as e: QMessageBox.critical(self, "Directory Error", f"Could not create directory: {e}"); return
            else: self.log_signal.emit("❌ Download cancelled: Output directory does not exist and was not created."); return

        if compress_images and Image is None:
            QMessageBox.warning(self, "Missing Dependency", "Pillow library (for image compression) not found. Compression will be disabled.")
            compress_images = False; self.compress_images_checkbox.setChecked(False)

        manga_mode = manga_mode_is_checked and not post_id_from_url


        start_page_str, end_page_str = self.start_page_input.text().strip(), self.end_page_input.text().strip()
        start_page, end_page = None, None
        is_creator_feed = bool(not post_id_from_url)
        if is_creator_feed and not manga_mode:
            try:
                if start_page_str: start_page = int(start_page_str)
                if end_page_str: end_page = int(end_page_str)
                if start_page is not None and start_page <= 0: raise ValueError("Start page must be positive.")
                if end_page is not None and end_page <= 0: raise ValueError("End page must be positive.")
                if start_page and end_page and start_page > end_page: raise ValueError("Start page cannot be greater than end page.")
            except ValueError as e: QMessageBox.critical(self, "Page Range Error", f"Invalid page range: {e}"); return
        elif manga_mode:
            start_page, end_page = None, None 
        
        # effective_duplicate_file_mode will be self.duplicate_file_mode (UI button's state).
        # Manga Mode specific duplicate handling is now managed entirely within downloader_utils.py
        self.external_link_queue.clear(); self.extracted_links_cache = []; self._is_processing_external_link_queue = False; self._current_link_post_title = None
        self.all_kept_original_filenames = []

        raw_character_filters_text = self.character_input.text().strip()
        
        # --- New parsing logic for character filters ---
        parsed_character_filter_objects = []
        if raw_character_filters_text:
            raw_parts = []
            current_part_buffer = ""
            in_group_parsing = False
            for char_token in raw_character_filters_text:
                if char_token == '(':
                    in_group_parsing = True
                    current_part_buffer += char_token
                elif char_token == ')':
                    in_group_parsing = False
                    current_part_buffer += char_token
                elif char_token == ',' and not in_group_parsing:
                    if current_part_buffer.strip(): raw_parts.append(current_part_buffer.strip())
                    current_part_buffer = ""
                else:
                    current_part_buffer += char_token
            if current_part_buffer.strip(): raw_parts.append(current_part_buffer.strip())

            for part_str in raw_parts:
                part_str = part_str.strip()
                if not part_str: continue
                if part_str.startswith("(") and part_str.endswith(")"):
                    group_content_str = part_str[1:-1].strip()
                    aliases_in_group = [alias.strip() for alias in group_content_str.split(',') if alias.strip()]
                    if aliases_in_group:
                        group_folder_name = " ".join(aliases_in_group)
                        parsed_character_filter_objects.append({
                            "name": group_folder_name, # This is the primary/folder name
                            "is_group": True,
                            "aliases": aliases_in_group # These are for matching
                        })
                else:
                    parsed_character_filter_objects.append({
                        "name": part_str, # Folder name and matching name are the same
                        "is_group": False,
                        "aliases": [part_str] 
                    })
        # --- End new parsing logic ---

        filter_character_list_to_pass = None
        needs_folder_naming_validation = (use_subfolders or manga_mode) and not extract_links_only

        if parsed_character_filter_objects and not extract_links_only :
            self.log_signal.emit(f"ℹ️ Validating character filters: {', '.join(item['name'] + (' (Group: ' + '/'.join(item['aliases']) + ')' if item['is_group'] else '') for item in parsed_character_filter_objects)}")
            valid_filters_for_backend = []
            user_cancelled_validation = False

            for filter_item_obj in parsed_character_filter_objects:
                item_primary_name = filter_item_obj["name"]
                cleaned_name_test = clean_folder_name(item_primary_name)


                if needs_folder_naming_validation and not cleaned_name_test:
                    QMessageBox.warning(self, "Invalid Filter Name for Folder", f"Filter name '{item_primary_name}' is invalid for a folder and will be skipped for folder naming.")
                    self.log_signal.emit(f"⚠️ Skipping invalid filter for folder naming: '{item_primary_name}'")
                    continue

                # --- New: Check if any alias of a group is already known ---
                an_alias_is_already_known = False
                if filter_item_obj["is_group"] and needs_folder_naming_validation:
                    for alias in filter_item_obj["aliases"]:
                        if any(existing_known.lower() == alias.lower() for existing_known in KNOWN_NAMES):
                            an_alias_is_already_known = True
                            self.log_signal.emit(f"ℹ️ Alias '{alias}' (from group '{item_primary_name}') is already in Known Names. Group name '{item_primary_name}' will not be added to Known.txt.")
                            break
                # --- End new check ---

                if an_alias_is_already_known:
                    valid_filters_for_backend.append(filter_item_obj)
                    continue

                # Determine if we should prompt to add the name to the Known.txt list.
                # Prompt if:
                #   - Folder naming validation is relevant (subfolders or manga mode, and not just extracting links)
                #   - AND Manga Mode is OFF (this is the key change for your request)
                #   - AND the primary name of the filter isn't already in Known.txt
                should_prompt_to_add_to_known_list = (
                    needs_folder_naming_validation and
                    not manga_mode and  # Do NOT prompt if Manga Mode is ON
                    item_primary_name.lower() not in {kn.lower() for kn in KNOWN_NAMES}
                )

                if should_prompt_to_add_to_known_list:
                    reply = QMessageBox.question(self, "Add to Known List?",
                                               f"Filter name '{item_primary_name}' (used for folder/manga naming) is not in known names list.\nAdd it now?",
                                               QMessageBox.Yes | QMessageBox.No | QMessageBox.Cancel, QMessageBox.Yes)
                    if reply == QMessageBox.Yes:
                        self.new_char_input.setText(item_primary_name) # Use the primary name for adding
                        if self.add_new_character():
                            valid_filters_for_backend.append(filter_item_obj)
                    elif reply == QMessageBox.Cancel:
                        user_cancelled_validation = True; break
                    # If 'No', the filter is not used and not added to Known.txt for this session.
                else:
                    # Add to filters to be used for this session if:
                    # - Prompting is not needed (e.g., name already known, or not manga_mode but name is known)
                    # - OR Manga Mode is ON (filter is used without adding to Known.txt)
                    # - OR extract_links_only is true (folder naming validation is false)
                    valid_filters_for_backend.append(filter_item_obj)
                    if manga_mode and needs_folder_naming_validation and item_primary_name.lower() not in {kn.lower() for kn in KNOWN_NAMES}:
                        self.log_signal.emit(f"ℹ️ Manga Mode: Using filter '{item_primary_name}' for this session without adding to Known Names.")

            if user_cancelled_validation: return

            if valid_filters_for_backend:
                filter_character_list_to_pass = valid_filters_for_backend
                self.log_signal.emit(f"   Using validated character filters: {', '.join(item['name'] for item in filter_character_list_to_pass)}")
            else:
                self.log_signal.emit("⚠️ No valid character filters to use for this session.")
        elif parsed_character_filter_objects : # If not extract_links_only is false, but filters exist
            filter_character_list_to_pass = parsed_character_filter_objects
            self.log_signal.emit(f"ℹ️ Character filters provided (folder naming validation may not apply): {', '.join(item['name'] for item in filter_character_list_to_pass)}")


        if manga_mode and not filter_character_list_to_pass and not extract_links_only:
            msg_box = QMessageBox(self)
            msg_box.setIcon(QMessageBox.Warning)
            msg_box.setWindowTitle("Manga Mode Filter Warning")
            msg_box.setText(
                "Manga Mode is enabled, but 'Filter by Character(s)' is empty.\n\n"
                "For best results (correct file naming and folder organization if subfolders are on), "
                "please enter the Manga/Series title into the filter field.\n\n"
                "Proceed without a filter (names might be generic, folder might be less specific)?"
            )
            proceed_button = msg_box.addButton("Proceed Anyway", QMessageBox.AcceptRole)
            cancel_button = msg_box.addButton("Cancel Download", QMessageBox.RejectRole)
            msg_box.exec_()
            if msg_box.clickedButton() == cancel_button:
                self.log_signal.emit("❌ Download cancelled due to Manga Mode filter warning."); return
            else:
                self.log_signal.emit("⚠️ Proceeding with Manga Mode without a specific title filter.")


        custom_folder_name_cleaned = None
        if use_subfolders and post_id_from_url and self.custom_folder_widget and self.custom_folder_widget.isVisible() and not extract_links_only: 
            raw_custom_name = self.custom_folder_input.text().strip()
            if raw_custom_name:
                 cleaned_custom = clean_folder_name(raw_custom_name)
                 if cleaned_custom: custom_folder_name_cleaned = cleaned_custom
                 else: self.log_signal.emit(f"⚠️ Invalid custom folder name ignored: '{raw_custom_name}' (resulted in empty string after cleaning).")


        self.main_log_output.clear()
        if extract_links_only: self.main_log_output.append("🔗 Extracting Links...");
        elif backend_filter_mode == 'archive': self.main_log_output.append("📦 Downloading Archives Only...")
        
        if self.external_log_output: self.external_log_output.clear()
        if self.show_external_links and not extract_links_only and backend_filter_mode != 'archive': 
            self.external_log_output.append("🔗 External Links Found:")
        
        self.file_progress_label.setText(""); self.cancellation_event.clear(); self.active_futures = []
        self.total_posts_to_process = self.processed_posts_count = self.download_counter = self.skip_counter = 0
        self.progress_label.setText("Progress: Initializing...")

        effective_num_post_workers = 1
        effective_num_file_threads_per_worker = 1
        
        if post_id_from_url:
            if use_multithreading_enabled_by_checkbox:
                effective_num_file_threads_per_worker = max(1, min(num_threads_from_gui, MAX_FILE_THREADS_PER_POST_OR_WORKER))
        else:
            if use_multithreading_enabled_by_checkbox:
                effective_num_post_workers = max(1, min(num_threads_from_gui, MAX_THREADS))
                effective_num_file_threads_per_worker = max(1, min(num_threads_from_gui, MAX_FILE_THREADS_PER_POST_OR_WORKER))


        log_messages = ["="*40, f"🚀 Starting {'Link Extraction' if extract_links_only else ('Archive Download' if backend_filter_mode == 'archive' else 'Download')} @ {time.strftime('%Y-%m-%d %H:%M:%S')}", f"   URL: {api_url}"]
        if not extract_links_only: log_messages.append(f"   Save Location: {output_dir}")
        
        if post_id_from_url:
            log_messages.append(f"   Mode: Single Post")
            log_messages.append(f"     ↳ File Downloads: Up to {effective_num_file_threads_per_worker} concurrent file(s)")
        else:
            log_messages.append(f"   Mode: Creator Feed")
            log_messages.append(f"   Post Processing: {'Multi-threaded (' + str(effective_num_post_workers) + ' workers)' if effective_num_post_workers > 1 else 'Single-threaded (1 worker)'}")
            log_messages.append(f"     ↳ File Downloads per Worker: Up to {effective_num_file_threads_per_worker} concurrent file(s)")
            if is_creator_feed:
                if manga_mode: log_messages.append("   Page Range: All (Manga Mode - Oldest Posts Processed First)")
                else:
                    pr_log = "All"
                    if start_page or end_page: 
                        pr_log = f"{f'From {start_page} ' if start_page else ''}{'to ' if start_page and end_page else ''}{f'{end_page}' if end_page else (f'Up to {end_page}' if end_page else (f'From {start_page}' if start_page else 'Specific Range'))}".strip()
                    log_messages.append(f"   Page Range: {pr_log if pr_log else 'All'}")


        if not extract_links_only:
            log_messages.append(f"   Subfolders: {'Enabled' if use_subfolders else 'Disabled'}")
            if use_subfolders:
                 if custom_folder_name_cleaned: log_messages.append(f"   Custom Folder (Post): '{custom_folder_name_cleaned}'")
            if filter_character_list_to_pass:
                log_messages.append(f"   Character Filters: {', '.join(item['name'] for item in filter_character_list_to_pass)}")
                log_messages.append(f"     ↳ Char Filter Scope: {current_char_filter_scope.capitalize()}")
            elif use_subfolders:
                 log_messages.append(f"   Folder Naming: Automatic (based on title/known names)")


            log_messages.extend([
                f"   File Type Filter: {user_selected_filter_text} (Backend processing as: {backend_filter_mode})",
                f"   Skip Archives: {'.zip' if effective_skip_zip else ''}{', ' if effective_skip_zip and effective_skip_rar else ''}{'.rar' if effective_skip_rar else ''}{'None (Archive Mode)' if backend_filter_mode == 'archive' else ('None' if not (effective_skip_zip or effective_skip_rar) else '')}",
                f"   Skip Words (posts/files): {', '.join(skip_words_list) if skip_words_list else 'None'}",
                f"   Skip Words Scope: {current_skip_words_scope.capitalize()}",
                f"   Remove Words from Filename: {', '.join(remove_from_filename_words_list) if remove_from_filename_words_list else 'None'}",
                f"   Compress Images: {'Enabled' if compress_images else 'Disabled'}",
                f"   Thumbnails Only: {'Enabled' if download_thumbnails else 'Disabled'}",
                f"   Multi-part Download: {'Enabled' if allow_multipart else 'Disabled'}"
            ])
        else:
            log_messages.append(f"   Mode: Extracting Links Only")

        log_messages.append(f"   Show External Links: {'Enabled' if self.show_external_links and not extract_links_only and backend_filter_mode != 'archive' else 'Disabled'}")
        
        if manga_mode:
            log_messages.append(f"   Manga Mode (File Renaming by Post Title): Enabled")
            log_messages.append(f"     ↳ Manga Filename Style: {'Post Title Based' if self.manga_filename_style == STYLE_POST_TITLE else 'Original File Name'}")
            if filter_character_list_to_pass:
                 log_messages.append(f"     ↳ Manga Character Filter (for naming/folder): {', '.join(item['name'] for item in filter_character_list_to_pass)}")
                 log_messages.append(f"       ↳ Char Filter Scope (Manga): {current_char_filter_scope.capitalize()}")
            log_messages.append(f"     ↳ Manga Duplicates: Will be renamed with numeric suffix if names clash (e.g., _1, _2).")

        should_use_multithreading_for_posts = use_multithreading_enabled_by_checkbox and not post_id_from_url
        log_messages.append(f"   Threading: {'Multi-threaded (posts)' if should_use_multithreading_for_posts else 'Single-threaded (posts)'}")
        if should_use_multithreading_for_posts:
            log_messages.append(f"   Number of Post Worker Threads: {effective_num_post_workers}")
        log_messages.append("="*40)
        for msg in log_messages: self.log_signal.emit(msg)

        self.set_ui_enabled(False)

        unwanted_keywords_for_folders = {'spicy', 'hd', 'nsfw', '4k', 'preview', 'teaser', 'clip'}
        
        args_template = {
            'api_url_input': api_url,
            'download_root': output_dir,
            'output_dir': output_dir,
            'known_names': list(KNOWN_NAMES),
            'known_names_copy': list(KNOWN_NAMES),
            'filter_character_list': filter_character_list_to_pass,
            'filter_mode': backend_filter_mode,
            'skip_zip': effective_skip_zip,
            'skip_rar': effective_skip_rar,
            'use_subfolders': use_subfolders,
            'use_post_subfolders': use_post_subfolders,
            'compress_images': compress_images,
            'download_thumbnails': download_thumbnails,
            'service': service,
            'user_id': user_id,
            'downloaded_files': self.downloaded_files,
            'downloaded_files_lock': self.downloaded_files_lock,
            'downloaded_file_hashes': self.downloaded_file_hashes,
            'downloaded_file_hashes_lock': self.downloaded_file_hashes_lock,
            'skip_words_list': skip_words_list,
            'skip_words_scope': current_skip_words_scope,
            'remove_from_filename_words_list': remove_from_filename_words_list,
            'char_filter_scope': current_char_filter_scope,
            'show_external_links': self.show_external_links,
            'extract_links_only': extract_links_only,
            'start_page': start_page,
            'end_page': end_page,
            'target_post_id_from_initial_url': post_id_from_url,
            'custom_folder_name': custom_folder_name_cleaned,
            'manga_mode_active': manga_mode,
            'unwanted_keywords': unwanted_keywords_for_folders,
            'cancellation_event': self.cancellation_event,
            'signals': self.worker_signals,
            'manga_filename_style': self.manga_filename_style,
            'num_file_threads_for_worker': effective_num_file_threads_per_worker,
            'allow_multipart_download': allow_multipart, # Corrected from previous thought
            'duplicate_file_mode': effective_duplicate_file_mode # Pass the potentially overridden mode
        }

        try:
            if should_use_multithreading_for_posts:
                self.log_signal.emit(f"   Initializing multi-threaded {'link extraction' if extract_links_only else 'download'} with {effective_num_post_workers} post workers...")
                self.start_multi_threaded_download(num_post_workers=effective_num_post_workers, **args_template)
            else:
                self.log_signal.emit(f"   Initializing single-threaded {'link extraction' if extract_links_only else 'download'}...")
                dt_expected_keys = [
                    'api_url_input', 'output_dir', 'known_names_copy', 'cancellation_event',
                    'filter_character_list', 'filter_mode', 'skip_zip', 'skip_rar',
                    'use_subfolders', 'use_post_subfolders', 'custom_folder_name',
                    'compress_images', 'download_thumbnails', 'service', 'user_id',
                    'downloaded_files', 'downloaded_file_hashes', 'remove_from_filename_words_list',
                    'downloaded_files_lock', 'downloaded_file_hashes_lock', 
                    'skip_words_list', 'skip_words_scope', 'char_filter_scope', 
                    'show_external_links', 'extract_links_only',
                    'num_file_threads_for_worker',
                    'skip_current_file_flag',
                    'start_page', 'end_page', 'target_post_id_from_initial_url',
                    'manga_mode_active', 'unwanted_keywords', 'manga_filename_style', 'duplicate_file_mode',
                    'allow_multipart_download'
                ]
                args_template['skip_current_file_flag'] = None
                single_thread_args = {key: args_template[key] for key in dt_expected_keys if key in args_template}
                self.start_single_threaded_download(**single_thread_args)
        except Exception as e:
            self.log_signal.emit(f"❌ CRITICAL ERROR preparing download: {e}\n{traceback.format_exc()}")
            QMessageBox.critical(self, "Start Error", f"Failed to start process:\n{e}")
            self.download_finished(0,0,False, [])


    def start_single_threaded_download(self, **kwargs):
        global BackendDownloadThread
        try:
            self.download_thread = BackendDownloadThread(**kwargs)
            if hasattr(self.download_thread, 'progress_signal'): self.download_thread.progress_signal.connect(self.handle_main_log)
            if hasattr(self.download_thread, 'add_character_prompt_signal'): self.download_thread.add_character_prompt_signal.connect(self.add_character_prompt_signal)
            if hasattr(self.download_thread, 'finished_signal'): self.download_thread.finished_signal.connect(self.download_finished)
            if hasattr(self.download_thread, 'receive_add_character_result'): self.character_prompt_response_signal.connect(self.download_thread.receive_add_character_result)
            if hasattr(self.download_thread, 'external_link_signal'): self.download_thread.external_link_signal.connect(self.handle_external_link_signal)
            if hasattr(self.download_thread, 'file_progress_signal'): self.download_thread.file_progress_signal.connect(self.update_file_progress_display)

            self.download_thread.start()
            self.log_signal.emit("✅ Single download thread (for posts) started.")
        except Exception as e:
            self.log_signal.emit(f"❌ CRITICAL ERROR starting single-thread: {e}\n{traceback.format_exc()}")
            QMessageBox.critical(self, "Thread Start Error", f"Failed to start download process: {e}")
            self.download_finished(0,0,False, [])


    def start_multi_threaded_download(self, num_post_workers, **kwargs):
        global PostProcessorWorker
        if self.thread_pool is None:
            self.thread_pool = ThreadPoolExecutor(max_workers=num_post_workers, thread_name_prefix='PostWorker_')
        
        self.active_futures = []
        self.processed_posts_count = 0; self.total_posts_to_process = 0; self.download_counter = 0; self.skip_counter = 0
        self.all_kept_original_filenames = []

        fetcher_thread = threading.Thread(
            target=self._fetch_and_queue_posts,
            args=(kwargs['api_url_input'], kwargs, num_post_workers),
            daemon=True,
            name="PostFetcher"
        )
        fetcher_thread.start()
        self.log_signal.emit(f"✅ Post fetcher thread started. {num_post_workers} post worker threads initializing...")


    def _fetch_and_queue_posts(self, api_url_input_for_fetcher, worker_args_template, num_post_workers):
        global PostProcessorWorker, download_from_api
        all_posts_data = []
        fetch_error_occurred = False
        manga_mode_active_for_fetch = worker_args_template.get('manga_mode_active', False)

        signals_for_worker = worker_args_template.get('signals')
        if not signals_for_worker:
             self.log_signal.emit("❌ CRITICAL ERROR: Signals object missing for worker in _fetch_and_queue_posts.");
             self.finished_signal.emit(0,0,True, []);
             return

        try:
            self.log_signal.emit("   Fetching post data from API (this may take a moment for large feeds)...")
            post_generator = download_from_api(
                api_url_input_for_fetcher,
                logger=lambda msg: self.log_signal.emit(f"[Fetcher] {msg}"),
                start_page=worker_args_template.get('start_page'),
                end_page=worker_args_template.get('end_page'),
                manga_mode=manga_mode_active_for_fetch,
                cancellation_event=self.cancellation_event
            )

            for posts_batch in post_generator:
                if self.cancellation_event.is_set():
                    fetch_error_occurred = True; self.log_signal.emit("   Post fetching cancelled by user."); break
                if isinstance(posts_batch, list):
                    all_posts_data.extend(posts_batch)
                    self.total_posts_to_process = len(all_posts_data)
                    if self.total_posts_to_process > 0 and self.total_posts_to_process % 100 == 0 :
                        self.log_signal.emit(f"   Fetched {self.total_posts_to_process} posts so far...")
                else:
                    fetch_error_occurred = True; self.log_signal.emit(f"❌ API fetcher returned non-list type: {type(posts_batch)}"); break
            
            if not fetch_error_occurred and not self.cancellation_event.is_set():
                self.log_signal.emit(f"✅ Post fetching complete. Total posts to process: {self.total_posts_to_process}")

        except TypeError as te:
            self.log_signal.emit(f"❌ TypeError calling download_from_api: {te}\n   Check 'downloader_utils.py' signature.\n{traceback.format_exc(limit=2)}"); fetch_error_occurred = True
        except RuntimeError as re_err:
            self.log_signal.emit(f"ℹ️ Post fetching runtime error (likely cancellation or API issue): {re_err}"); fetch_error_occurred = True
        except Exception as e:
            self.log_signal.emit(f"❌ Error during post fetching: {e}\n{traceback.format_exc(limit=2)}"); fetch_error_occurred = True


        if self.cancellation_event.is_set() or fetch_error_occurred:
            self.finished_signal.emit(self.download_counter, self.skip_counter, self.cancellation_event.is_set(), self.all_kept_original_filenames)
            if self.thread_pool: self.thread_pool.shutdown(wait=False, cancel_futures=True); self.thread_pool = None
            return

        if self.total_posts_to_process == 0:
            self.log_signal.emit("😕 No posts found or fetched to process.");
            self.finished_signal.emit(0,0,False, []);
            return

        self.log_signal.emit(f"   Submitting {self.total_posts_to_process} post processing tasks to thread pool...")
        self.processed_posts_count = 0
        self.overall_progress_signal.emit(self.total_posts_to_process, 0)
        
        num_file_dl_threads_for_each_worker = worker_args_template.get('num_file_threads_for_worker', 1)


        ppw_expected_keys = [
            'post_data', 'download_root', 'known_names', 'filter_character_list', 'unwanted_keywords',
            'filter_mode', 'skip_zip', 'skip_rar', 'use_subfolders', 'use_post_subfolders',
            'target_post_id_from_initial_url', 'custom_folder_name', 'compress_images',
            'download_thumbnails', 'service', 'user_id', 'api_url_input',
            'cancellation_event', 'signals', 'downloaded_files', 'downloaded_file_hashes',
            'downloaded_files_lock', 'downloaded_file_hashes_lock', 'remove_from_filename_words_list',
            'skip_words_list', 'skip_words_scope', 'char_filter_scope',
            'show_external_links', 'extract_links_only', 'allow_multipart_download',
            'num_file_threads',
            'skip_current_file_flag',
            'manga_mode_active', 'manga_filename_style'
        ]
        # Ensure 'allow_multipart_download' is also considered for optional keys if it has a default in PostProcessorWorker
        ppw_optional_keys_with_defaults = {
            'skip_words_list', 'skip_words_scope', 'char_filter_scope', 'remove_from_filename_words_list',
            'show_external_links', 'extract_links_only',
            'num_file_threads', 'skip_current_file_flag', 'manga_mode_active', 'manga_filename_style'
        }


        for post_data_item in all_posts_data:
            if self.cancellation_event.is_set(): break
            if not isinstance(post_data_item, dict):
                self.log_signal.emit(f"⚠️ Skipping invalid post data item (not a dict): {type(post_data_item)}");
                self.processed_posts_count += 1;
                continue

            worker_init_args = {}; missing_keys = []
            for key in ppw_expected_keys:
                if key == 'post_data': worker_init_args[key] = post_data_item
                elif key == 'num_file_threads': worker_init_args[key] = num_file_dl_threads_for_each_worker
                elif key == 'signals': worker_init_args[key] = signals_for_worker
                elif key in worker_args_template: worker_init_args[key] = worker_args_template[key]
                elif key in ppw_optional_keys_with_defaults: pass
                else: missing_keys.append(key)

            if missing_keys:
                self.log_signal.emit(f"❌ CRITICAL ERROR: Missing keys for PostProcessorWorker: {', '.join(missing_keys)}");
                self.cancellation_event.set(); break

            try:
                worker_instance = PostProcessorWorker(**worker_init_args)
                if self.thread_pool:
                    future = self.thread_pool.submit(worker_instance.process)
                    future.add_done_callback(self._handle_future_result)
                    self.active_futures.append(future)
                else:
                    self.log_signal.emit("⚠️ Thread pool not available. Cannot submit more tasks."); break
            except TypeError as te: self.log_signal.emit(f"❌ TypeError creating PostProcessorWorker: {te}\n   Passed Args: [{', '.join(sorted(worker_init_args.keys()))}]\n{traceback.format_exc(limit=5)}"); self.cancellation_event.set(); break
            except RuntimeError: self.log_signal.emit("⚠️ Runtime error submitting task (pool likely shutting down)."); break
            except Exception as e: self.log_signal.emit(f"❌ Error submitting post {post_data_item.get('id','N/A')} to worker: {e}"); break

        if not self.cancellation_event.is_set(): self.log_signal.emit(f"   {len(self.active_futures)} post processing tasks submitted to pool.")
        else:
            self.finished_signal.emit(self.download_counter, self.skip_counter, True, self.all_kept_original_filenames)
            if self.thread_pool: self.thread_pool.shutdown(wait=False, cancel_futures=True); self.thread_pool = None

    def _handle_future_result(self, future: Future):
        self.processed_posts_count += 1
        downloaded_files_from_future, skipped_files_from_future = 0, 0
        kept_originals_from_future = []
        try:
            if future.cancelled(): self.log_signal.emit("   A post processing task was cancelled.")
            elif future.exception(): self.log_signal.emit(f"❌ Post processing worker error: {future.exception()}")
            else:
                downloaded_files_from_future, skipped_files_from_future, kept_originals_from_future = future.result()

            with self.downloaded_files_lock:
                self.download_counter += downloaded_files_from_future
                self.skip_counter += skipped_files_from_future

            if kept_originals_from_future:
                self.all_kept_original_filenames.extend(kept_originals_from_future)

            self.overall_progress_signal.emit(self.total_posts_to_process, self.processed_posts_count)
        except Exception as e: self.log_signal.emit(f"❌ Error in _handle_future_result callback: {e}\n{traceback.format_exc(limit=2)}")

        if self.total_posts_to_process > 0 and self.processed_posts_count >= self.total_posts_to_process:
            if all(f.done() for f in self.active_futures):
                QApplication.processEvents()
                self.log_signal.emit("🏁 All submitted post tasks have completed or failed.")
                self.finished_signal.emit(self.download_counter, self.skip_counter, self.cancellation_event.is_set(), self.all_kept_original_filenames)

    def set_ui_enabled(self, enabled):
        widgets_to_toggle = [ self.download_btn, self.link_input, self.radio_all, self.radio_images, self.radio_videos, self.radio_only_links,
            self.skip_zip_checkbox, self.skip_rar_checkbox, self.use_subfolders_checkbox, self.compress_images_checkbox,
            self.download_thumbnails_checkbox, self.use_multithreading_checkbox, self.skip_words_input, self.character_search_input,
            self.new_char_input, self.add_char_button, self.delete_char_button, 
            self.char_filter_scope_toggle_button, 
            self.start_page_input, self.end_page_input,
            self.page_range_label, self.to_label, self.character_input, self.custom_folder_input, self.custom_folder_label, self.remove_from_filename_input,
            self.reset_button, self.manga_mode_checkbox, self.manga_rename_toggle_button, self.multipart_toggle_button,
            self.skip_scope_toggle_button 
        ]
        
        for widget in widgets_to_toggle:
            if widget: widget.setEnabled(enabled)
        
        if enabled:
            self._handle_filter_mode_change(self.radio_group.checkedButton(), True)
        
        if self.external_links_checkbox:
            is_only_links = self.radio_only_links and self.radio_only_links.isChecked()
            self.external_links_checkbox.setEnabled(enabled and not is_only_links)

        if self.log_verbosity_button: self.log_verbosity_button.setEnabled(True)

        multithreading_currently_on = self.use_multithreading_checkbox.isChecked()
        self.thread_count_input.setEnabled(enabled and multithreading_currently_on)
        self.thread_count_label.setEnabled(enabled and multithreading_currently_on)

        subfolders_currently_on = self.use_subfolders_checkbox.isChecked()
        self.use_subfolder_per_post_checkbox.setEnabled(enabled)

        self.cancel_btn.setEnabled(not enabled)

        if enabled: # Ensure these are updated based on current (possibly reset) checkbox states
            self._handle_multithreading_toggle(multithreading_currently_on)
            self.update_ui_for_manga_mode(self.manga_mode_checkbox.isChecked() if self.manga_mode_checkbox else False)
            self.update_custom_folder_visibility(self.link_input.text())
            self.update_page_range_enabled_state()


    def _perform_soft_ui_reset(self, preserve_url=None, preserve_dir=None):
        """Resets UI elements and some state to app defaults, then applies preserved inputs."""
        self.log_signal.emit("🔄 Performing soft UI reset...")

        # 1. Reset UI fields to their visual defaults
        self.link_input.clear() # Will be set later if preserve_url is given
        self.dir_input.clear()  # Will be set later if preserve_dir is given
        self.custom_folder_input.clear(); self.character_input.clear();
        self.skip_words_input.clear(); self.start_page_input.clear(); self.end_page_input.clear(); self.new_char_input.clear();
        if hasattr(self, 'remove_from_filename_input'): self.remove_from_filename_input.clear()
        self.character_search_input.clear(); self.thread_count_input.setText("4"); self.radio_all.setChecked(True);
        self.skip_zip_checkbox.setChecked(True); self.skip_rar_checkbox.setChecked(True); self.download_thumbnails_checkbox.setChecked(False);
        self.compress_images_checkbox.setChecked(False); self.use_subfolders_checkbox.setChecked(True);
        self.use_subfolder_per_post_checkbox.setChecked(False); self.use_multithreading_checkbox.setChecked(True);
        self.external_links_checkbox.setChecked(False)
        if self.manga_mode_checkbox: self.manga_mode_checkbox.setChecked(False)

        # 2. Reset internal state for UI-managed settings to app defaults (not from QSettings)
        self.allow_multipart_download_setting = False # Default to OFF
        self._update_multipart_toggle_button_text()

        self.skip_words_scope = SKIP_SCOPE_POSTS # Default
        self._update_skip_scope_button_text()

        self.char_filter_scope = CHAR_SCOPE_TITLE # Default
        self._update_char_filter_scope_button_text()

        self.manga_filename_style = STYLE_POST_TITLE # Reset to app default
        self._update_manga_filename_style_button_text()

        # 3. Restore preserved URL and Directory
        if preserve_url is not None:
            self.link_input.setText(preserve_url)
        if preserve_dir is not None:
            self.dir_input.setText(preserve_dir)

        # 4. Reset operational state variables (but not session-based downloaded_files/hashes)
        self.external_link_queue.clear(); self.extracted_links_cache = []
        self._is_processing_external_link_queue = False; self._current_link_post_title = None
        self.total_posts_to_process = 0; self.processed_posts_count = 0
        self.download_counter = 0; self.skip_counter = 0
        self.all_kept_original_filenames = []

        # 5. Update UI based on new (default or preserved) states
        self._handle_filter_mode_change(self.radio_group.checkedButton(), True)
        self._handle_multithreading_toggle(self.use_multithreading_checkbox.isChecked())
        self.filter_character_list(self.character_search_input.text())

        self.set_ui_enabled(True) # This enables buttons and calls other UI update methods

        # Explicitly call these to ensure they reflect changes from preserved inputs
        self.update_custom_folder_visibility(self.link_input.text())
        self.update_page_range_enabled_state()
        # update_ui_for_manga_mode is called within set_ui_enabled

        self.log_signal.emit("✅ Soft UI reset complete. Preserved URL and Directory (if provided).")


    def cancel_download_button_action(self):
        if not self.cancel_btn.isEnabled() and not self.cancellation_event.is_set(): self.log_signal.emit("ℹ️ No active download to cancel or already cancelling."); return
        self.log_signal.emit("⚠️ Requesting cancellation of download process (soft reset)...")

        current_url = self.link_input.text()
        current_dir = self.dir_input.text()

        self.cancellation_event.set()
        if self.download_thread and self.download_thread.isRunning(): self.download_thread.requestInterruption(); self.log_signal.emit("   Signaled single download thread to interrupt.")
        if self.thread_pool:
            self.log_signal.emit("   Initiating non-blocking shutdown and cancellation of worker pool tasks...")
            self.thread_pool.shutdown(wait=False, cancel_futures=True)
            self.thread_pool = None # Allow recreation for next download
            self.active_futures = []

        self.external_link_queue.clear(); self._is_processing_external_link_queue = False; self._current_link_post_title = None

        self._perform_soft_ui_reset(preserve_url=current_url, preserve_dir=current_dir)

        self.progress_label.setText("Progress: Cancelled. Ready for new task.")
        self.file_progress_label.setText("")
        self.log_signal.emit("ℹ️ UI reset. Ready for new operation. Background tasks are being terminated.")

    def download_finished(self, total_downloaded, total_skipped, cancelled_by_user, kept_original_names_list=None):
        if kept_original_names_list is None:
            kept_original_names_list = self.all_kept_original_filenames if hasattr(self, 'all_kept_original_filenames') else []
        if kept_original_names_list is None:
            kept_original_names_list = []


        status_message = "Cancelled by user" if cancelled_by_user else "Finished"

        summary_log = "="*40
        summary_log += f"\n🏁 Download {status_message}!\n   Summary: Downloaded Files={total_downloaded}, Skipped Files={total_skipped}\n"
        summary_log += "="*40
        self.log_signal.emit(summary_log)

        if kept_original_names_list:
            intro_msg = (
                HTML_PREFIX +
                "<p>ℹ️ The following files from multi-file manga posts "
                "(after the first file) kept their <b>original names</b>:</p>"
            )
            self.log_signal.emit(intro_msg)

            html_list_items = "<ul>"
            for name in kept_original_names_list:
                html_list_items += f"<li><b>{name}</b></li>"
            html_list_items += "</ul>"

            self.log_signal.emit(HTML_PREFIX + html_list_items)
            self.log_signal.emit("="*40)


        self.progress_label.setText(f"{status_message}: {total_downloaded} downloaded, {total_skipped} skipped."); self.file_progress_label.setText("")
        if not cancelled_by_user: self._try_process_next_external_link()

        if self.download_thread:
            try:
                if hasattr(self.download_thread, 'progress_signal'): self.download_thread.progress_signal.disconnect(self.handle_main_log)
                if hasattr(self.download_thread, 'add_character_prompt_signal'): self.download_thread.add_character_prompt_signal.disconnect(self.add_character_prompt_signal)
                if hasattr(self.download_thread, 'finished_signal'): self.download_thread.finished_signal.disconnect(self.download_finished)
                if hasattr(self.download_thread, 'receive_add_character_result'): self.character_prompt_response_signal.disconnect(self.download_thread.receive_add_character_result)
                if hasattr(self.download_thread, 'external_link_signal'): self.download_thread.external_link_signal.disconnect(self.handle_external_link_signal)
                if hasattr(self.download_thread, 'file_progress_signal'): self.download_thread.file_progress_signal.disconnect(self.update_file_progress_display)
            except (TypeError, RuntimeError) as e: self.log_signal.emit(f"ℹ️ Note during single-thread signal disconnection: {e}")
            # Ensure these are cleared if the download_finished is for the single download thread
            if self.download_thread and not self.download_thread.isRunning(): # Check if it was this thread
                self.download_thread = None

        if self.thread_pool: self.log_signal.emit("   Ensuring worker thread pool is shut down..."); self.thread_pool.shutdown(wait=True, cancel_futures=True); self.thread_pool = None
        self.active_futures = []

        self.set_ui_enabled(True); self.cancel_btn.setEnabled(False)

    def toggle_log_verbosity(self):
        self.basic_log_mode = not self.basic_log_mode
        if self.basic_log_mode: self.log_verbosity_button.setText("Show Full Log"); self.log_signal.emit("="*20 + " Basic Log Mode Enabled " + "="*20)
        else: self.log_verbosity_button.setText("Show Basic Log"); self.log_signal.emit("="*20 + " Full Log Mode Enabled " + "="*20)

    def reset_application_state(self):
        if self._is_download_active(): QMessageBox.warning(self, "Reset Error", "Cannot reset while a download is in progress. Please cancel first."); return
        self.log_signal.emit("🔄 Resetting application state to defaults..."); self._reset_ui_to_defaults()
        self.main_log_output.clear(); self.external_log_output.clear()
        if self.show_external_links and not (self.radio_only_links and self.radio_only_links.isChecked()): self.external_log_output.append("🔗 External Links Found:")
        self.external_link_queue.clear(); self.extracted_links_cache = []; self._is_processing_external_link_queue = False; self._current_link_post_title = None
        self.progress_label.setText("Progress: Idle"); self.file_progress_label.setText("")

        with self.downloaded_files_lock: count = len(self.downloaded_files); self.downloaded_files.clear();
        if count > 0: self.log_signal.emit(f"   Cleared {count} downloaded filename(s) from session memory.")
        with self.downloaded_file_hashes_lock: count = len(self.downloaded_file_hashes); self.downloaded_file_hashes.clear();
        if count > 0: self.log_signal.emit(f"   Cleared {count} downloaded file hash(es) from session memory.")

        self.total_posts_to_process = 0; self.processed_posts_count = 0; self.download_counter = 0; self.skip_counter = 0
        self.all_kept_original_filenames = []
        self.cancellation_event.clear(); self.basic_log_mode = False
        if self.log_verbosity_button: self.log_verbosity_button.setText("Show Basic Log")

        self.manga_filename_style = STYLE_POST_TITLE
        self.settings.setValue(MANGA_FILENAME_STYLE_KEY, self.manga_filename_style)
        
        self.skip_words_scope = SKIP_SCOPE_POSTS
        self.settings.setValue(SKIP_WORDS_SCOPE_KEY, self.skip_words_scope)
        self._update_skip_scope_button_text()

        self.char_filter_scope = CHAR_SCOPE_TITLE 
        self.settings.setValue(CHAR_FILTER_SCOPE_KEY, self.char_filter_scope) 
        self._update_char_filter_scope_button_text() 

        self.duplicate_file_mode = DUPLICATE_MODE_DELETE # Reset to default (Delete)
        self.settings.setValue(DUPLICATE_FILE_MODE_KEY, self.duplicate_file_mode)
        self._update_duplicate_mode_button_text()

        self.settings.sync()
        self._update_manga_filename_style_button_text()
        self.update_ui_for_manga_mode(self.manga_mode_checkbox.isChecked() if self.manga_mode_checkbox else False)

        self.log_signal.emit("✅ Application reset complete.")

    def _reset_ui_to_defaults(self):
        self.link_input.clear(); self.dir_input.clear(); self.custom_folder_input.clear(); self.character_input.clear();
        self.skip_words_input.clear(); self.start_page_input.clear(); self.end_page_input.clear(); self.new_char_input.clear();
        if hasattr(self, 'remove_from_filename_input'): self.remove_from_filename_input.clear()
        self.character_search_input.clear(); self.thread_count_input.setText("4"); self.radio_all.setChecked(True);
        self.skip_zip_checkbox.setChecked(True); self.skip_rar_checkbox.setChecked(True); self.download_thumbnails_checkbox.setChecked(False);
        self.compress_images_checkbox.setChecked(False); self.use_subfolders_checkbox.setChecked(True);
        self.use_subfolder_per_post_checkbox.setChecked(False); self.use_multithreading_checkbox.setChecked(True);
        self.external_links_checkbox.setChecked(False)
        if self.manga_mode_checkbox: self.manga_mode_checkbox.setChecked(False)        
        self.allow_multipart_download_setting = False # Default to OFF
        self._update_multipart_toggle_button_text() # Update button text

        self.skip_words_scope = SKIP_SCOPE_POSTS
        self._update_skip_scope_button_text()
        self.char_filter_scope = CHAR_SCOPE_TITLE
        self._update_char_filter_scope_button_text() 
        self.duplicate_file_mode = DUPLICATE_MODE_DELETE # Default to DELETE
        self._update_duplicate_mode_button_text()


        self._handle_filter_mode_change(self.radio_all, True)
        self._handle_multithreading_toggle(self.use_multithreading_checkbox.isChecked())
        self.filter_character_list("")

        self.download_btn.setEnabled(True); self.cancel_btn.setEnabled(False)
        if self.reset_button: self.reset_button.setEnabled(True)
        if self.log_verbosity_button: self.log_verbosity_button.setText("Show Basic Log")

        self._update_manga_filename_style_button_text()
        self.update_ui_for_manga_mode(False)

    def prompt_add_character(self, character_name):
        global KNOWN_NAMES
        reply = QMessageBox.question(self, "Add Filter Name to Known List?", f"The name '{character_name}' was encountered or used as a filter.\nIt's not in your known names list (used for folder suggestions).\nAdd it now?", QMessageBox.Yes | QMessageBox.No, QMessageBox.Yes)
        result = (reply == QMessageBox.Yes)
        if result:
              self.new_char_input.setText(character_name)
              if self.add_new_character(): self.log_signal.emit(f"✅ Added '{character_name}' to known names via background prompt.")
              else: result = False; self.log_signal.emit(f"ℹ️ Adding '{character_name}' via background prompt was declined or failed.")
        self.character_prompt_response_signal.emit(result)

    def receive_add_character_result(self, result):
        with QMutexLocker(self.prompt_mutex): self._add_character_response = result
        self.log_signal.emit(f"   Main thread received character prompt response: {'Action resulted in addition/confirmation' if result else 'Action resulted in no addition/declined'}")

    def _update_multipart_toggle_button_text(self):
        if hasattr(self, 'multipart_toggle_button'):
            text = "Multi-part: ON" if self.allow_multipart_download_setting else "Multi-part: OFF"
            self.multipart_toggle_button.setText(text)

    def _toggle_multipart_mode(self):
        # If currently OFF, and user is trying to turn it ON
        if not self.allow_multipart_download_setting:
            msg_box = QMessageBox(self)
            msg_box.setIcon(QMessageBox.Warning)
            msg_box.setWindowTitle("Multi-part Download Advisory")
            msg_box.setText(
                "<b>Multi-part download advisory:</b><br><br>"
                "<ul>"
                "<li>Best suited for <b>large files</b> (e.g., single post videos).</li>"
                "<li>When downloading a full creator feed with many small files (like images):"
                "<ul><li>May not offer significant speed benefits.</li>"
                "<li>Could potentially make the UI feel <b>choppy</b>.</li>"
                "<li>May <b>spam the process log</b> with rapid, numerous small download messages.</li></ul></li>"
                "<li>Consider using the <b>'Videos' filter</b> if downloading a creator feed to primarily target large files for multi-part.</li>"
                "</ul><br>"
                "Do you want to enable multi-part download?"
            )
            proceed_button = msg_box.addButton("Proceed Anyway", QMessageBox.AcceptRole)
            cancel_button = msg_box.addButton("Cancel", QMessageBox.RejectRole)
            msg_box.setDefaultButton(proceed_button) # Default to Proceed
            msg_box.exec_()

            if msg_box.clickedButton() == cancel_button:
                # User cancelled, so don't change the setting (it's already False)
                self.log_signal.emit("ℹ️ Multi-part download enabling cancelled by user.")
                return # Exit without changing the state or button text
        
        self.allow_multipart_download_setting = not self.allow_multipart_download_setting # Toggle the actual setting
        self._update_multipart_toggle_button_text()
        self.settings.setValue(ALLOW_MULTIPART_DOWNLOAD_KEY, self.allow_multipart_download_setting)
        self.log_signal.emit(f"ℹ️ Multi-part download set to: {'Enabled' if self.allow_multipart_download_setting else 'Disabled'}")

    def _update_duplicate_mode_button_text(self):
        if hasattr(self, 'duplicate_mode_toggle_button'):
            if self.duplicate_file_mode == DUPLICATE_MODE_DELETE:
                self.duplicate_mode_toggle_button.setText("Duplicates: Delete")
            elif self.duplicate_file_mode == DUPLICATE_MODE_MOVE_TO_SUBFOLDER:
                self.duplicate_mode_toggle_button.setText("Duplicates: Move")
            else: # Should not happen
                self.duplicate_mode_toggle_button.setText("Duplicates: Move") # Default to Move if unknown

    def _cycle_duplicate_mode(self):
        if self.duplicate_file_mode == DUPLICATE_MODE_MOVE_TO_SUBFOLDER:
            self.duplicate_file_mode = DUPLICATE_MODE_DELETE
        else: # If it's DELETE or unknown, cycle back to MOVE
            self.duplicate_file_mode = DUPLICATE_MODE_MOVE_TO_SUBFOLDER
        self._update_duplicate_mode_button_text()
        self.settings.setValue(DUPLICATE_FILE_MODE_KEY, self.duplicate_file_mode)
        self.log_signal.emit(f"ℹ️ Duplicate file handling mode changed to: '{self.duplicate_file_mode.capitalize()}'")

if __name__ == '__main__':
    import traceback
    try:
        qt_app = QApplication(sys.argv)
        if getattr(sys, 'frozen', False): base_dir = sys._MEIPASS
        else: base_dir = os.path.dirname(os.path.abspath(__file__))
        icon_path = os.path.join(base_dir, 'Kemono.ico')
        if os.path.exists(icon_path): qt_app.setWindowIcon(QIcon(icon_path))
        else: print(f"Warning: Application icon 'Kemono.ico' not found at {icon_path}")

        downloader_app_instance = DownloaderApp()
        # Set a reasonable default size before showing
        downloader_app_instance.resize(1150, 780) # Adjusted default size
        downloader_app_instance.show()
        # Center the window on the screen after it's shown and sized
        downloader_app_instance._center_on_screen()

        if TourDialog:
            tour_settings = QSettings(TourDialog.CONFIG_ORGANIZATION_NAME, TourDialog.CONFIG_APP_NAME_TOUR)
            tour_settings.setValue(TourDialog.TOUR_SHOWN_KEY, False)
            tour_settings.sync()
            print("[Main] Forcing tour to be active for this session.")
            tour_result = TourDialog.run_tour_if_needed(downloader_app_instance)
            if tour_result == QDialog.Accepted: print("Tour completed by user.")
            elif tour_result == QDialog.Rejected: print("Tour skipped or was already shown.")

        exit_code = qt_app.exec_()
        print(f"Application finished with exit code: {exit_code}")
        sys.exit(exit_code)
    except SystemExit: pass
    except Exception as e:
        print("--- CRITICAL APPLICATION ERROR ---")
        print(f"An unhandled exception occurred: {e}")
        traceback.print_exc()
        print("--- END CRITICAL ERROR ---")
        sys.exit(1)