import React, { useState, useRef } from 'react';
import { Send, Search, Loader2 } from 'lucide-react';
import { useStore } from '../store/useStore.js';

export default function MentionInput({ onSend, sending }) {
  const { models, webSearchEnabled, toggleWebSearch } = useStore();
  const [value, setValue] = useState('');
  const [mentionState, setMentionState] = useState(null);
  const textareaRef = useRef(null);

  const filteredModels = mentionState
    ? models.filter(m => m.tag.toLowerCase().startsWith(mentionState.query.toLowerCase()))
    : [];

  const handleChange = (e) => {
    const text = e.target.value;
    setValue(text);
    const pos = e.target.selectionStart;
    const before = text.slice(0, pos);
    const match = before.match(/@(\w*)$/);
    if (match) {
      setMentionState({ start: match.index, query: match[1] });
    } else {
      setMentionState(null);
    }
  };

  const insertMention = (tag) => {
    if (!mentionState) return;
    const before = value.slice(0, mentionState.start);
    const after = value.slice(mentionState.start + 1 + mentionState.query.length);
    const newVal = `${before}@${tag} ${after}`;
    setValue(newVal);
    setMentionState(null);
    textareaRef.current?.focus();
  };

  const handleKeyDown = (e) => {
    if (mentionState && filteredModels.length > 0 && e.key === 'Enter') {
      e.preventDefault();
      insertMention(filteredModels[0].tag);
      return;
    }
    if (mentionState && e.key === 'Escape') { setMentionState(null); return; }
    if (e.key === 'Enter' && !e.shiftKey) { e.preventDefault(); submit(); }
  };

  const submit = () => {
    const text = value.trim();
    if (!text || sending) return;
    setValue('');
    setMentionState(null);
    onSend(text);
  };

  const activeTags = models.filter(m => new RegExp(`@${m.tag}\\b`, 'i').test(value));

  return (
    <div className="relative">
      {/* Mention dropdown */}
      {mentionState && filteredModels.length > 0 && (
        <div className="absolute bottom-full mb-2 left-0 bg-surface-2 border border-grape/30 rounded-2xl shadow-2xl overflow-hidden z-50 min-w-[220px] animate-slide-up glow-grape">
          <div className="px-3 py-2 text-xs text-apricot/30 border-b border-grape/15 font-medium">
            Tag a model
          </div>
          {filteredModels.map((model) => (
            <button
              key={model.id}
              onMouseDown={(e) => { e.preventDefault(); insertMention(model.tag); }}
              className="flex items-center gap-3 w-full px-3 py-3 hover:bg-grape/15 transition-colors text-left"
            >
              <span className="text-xl">{model.avatar}</span>
              <div className="flex-1">
                <div className="text-sm text-apricot/90 font-medium">@{model.tag}</div>
                <div className="text-xs text-apricot/40">{model.displayName}</div>
              </div>
              <div className="w-2 h-2 rounded-full flex-shrink-0" style={{ background: model.color }} />
            </button>
          ))}
        </div>
      )}

      {/* Input container */}
      <div className="bg-surface-2 border border-grape/25 rounded-2xl overflow-hidden focus-within:border-grape/50 transition-all focus-within:glow-grape">
        {/* Active model chips */}
        {activeTags.length > 0 && (
          <div className="flex flex-wrap gap-1.5 px-4 pt-3">
            {activeTags.map(m => (
              <span
                key={m.id}
                className="flex items-center gap-1 text-xs px-2 py-0.5 rounded-full border font-medium font-display"
                style={{ color: m.color, background: `${m.color}18`, borderColor: `${m.color}35` }}
              >
                {m.avatar} @{m.tag}
              </span>
            ))}
          </div>
        )}

        <textarea
          ref={textareaRef}
          value={value}
          onChange={handleChange}
          onKeyDown={handleKeyDown}
          placeholder="Message… (type @ to mention a model · Shift+Enter for newline)"
          className="w-full bg-transparent px-4 pt-3 pb-2 text-sm text-apricot/85 placeholder-apricot/20 resize-none outline-none leading-relaxed"
          rows={1}
          disabled={sending}
        />

        <div className="flex items-center justify-between px-3 pb-3 pt-1">
          <button
            onClick={toggleWebSearch}
            title="Toggle web search (injects DuckDuckGo results as context)"
            className={`flex items-center gap-1.5 text-xs px-3 py-1.5 rounded-xl border transition-all ${
              webSearchEnabled
                ? 'bg-tangerine/20 border-tangerine/40 text-tangerine'
                : 'border-grape/20 text-apricot/30 hover:text-apricot/60 hover:border-grape/40'
            }`}
          >
            <Search size={12} />
            Web Search
            {webSearchEnabled && <span className="w-1.5 h-1.5 rounded-full bg-tangerine animate-pulse" />}
          </button>

          <button
            onClick={submit}
            disabled={!value.trim() || sending}
            className="flex items-center gap-2 text-midnight text-sm px-4 py-1.5 rounded-xl transition-all font-semibold font-display disabled:opacity-40 disabled:cursor-not-allowed"
            style={{
              background: value.trim() && !sending
                ? 'linear-gradient(90deg, #da627d, #9a348e)'
                : '#9a348e40'
            }}
          >
            {sending ? <Loader2 size={14} className="animate-spin" /> : <Send size={14} />}
            Send
          </button>
        </div>
      </div>
    </div>
  );
}