commit b64397dcd36c130f01a0f202cb4585fd787be506
Author: Malin <malin@cloudhost.es>
Date:   Tue Feb 17 09:59:53 2026 +0100

    feat: WooCommerce Business Central integration plugin
    
    Native PHP plugin (no Composer) that syncs:
    - Product stock and pricing from BC to WooCommerce (scheduled cron)
    - Orders from WooCommerce to BC (on payment received)
    - Auto-creates customers in BC from WooCommerce billing data
    
    Product matching: WooCommerce SKU → BC Item Number, fallback to GTIN (EAN).
    OAuth2 client credentials auth with encrypted secret storage.
    Admin settings page with connection test, manual sync, and log viewer.
    
    Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

diff --git a/woo-business-central/admin/class-wbc-admin.php b/woo-business-central/admin/class-wbc-admin.php
new file mode 100644
index 0000000..3df3c4c
--- /dev/null
+++ b/woo-business-central/admin/class-wbc-admin.php
@@ -0,0 +1,332 @@
+<?php
+/**
+ * Admin Settings for WooCommerce Business Central Integration
+ *
+ * @package WooBusinessCentral
+ */
+
+// Prevent direct access
+if ( ! defined( 'ABSPATH' ) ) {
+    exit;
+}
+
+/**
+ * Class WBC_Admin
+ *
+ * Handles admin settings page and AJAX actions.
+ */
+class WBC_Admin {
+
+    /**
+     * Settings page slug
+     */
+    const PAGE_SLUG = 'wbc-settings';
+
+    /**
+     * Add admin menu
+     */
+    public function add_admin_menu() {
+        add_submenu_page(
+            'woocommerce',
+            __( 'Business Central', 'woo-business-central' ),
+            __( 'Business Central', 'woo-business-central' ),
+            'manage_woocommerce',
+            self::PAGE_SLUG,
+            array( $this, 'render_settings_page' )
+        );
+    }
+
+    /**
+     * Register settings
+     */
+    public function register_settings() {
+        // Connection settings
+        register_setting( 'wbc_settings', 'wbc_tenant_id', array(
+            'sanitize_callback' => 'sanitize_text_field',
+        ) );
+        register_setting( 'wbc_settings', 'wbc_client_id', array(
+            'sanitize_callback' => 'sanitize_text_field',
+        ) );
+        register_setting( 'wbc_settings', 'wbc_client_secret', array(
+            'sanitize_callback' => array( $this, 'sanitize_client_secret' ),
+        ) );
+        register_setting( 'wbc_settings', 'wbc_environment', array(
+            'sanitize_callback' => 'sanitize_text_field',
+        ) );
+        register_setting( 'wbc_settings', 'wbc_company_id', array(
+            'sanitize_callback' => 'sanitize_text_field',
+        ) );
+
+        // Sync settings
+        register_setting( 'wbc_settings', 'wbc_sync_frequency', array(
+            'sanitize_callback' => array( $this, 'sanitize_frequency' ),
+        ) );
+        register_setting( 'wbc_settings', 'wbc_enable_stock_sync', array(
+            'sanitize_callback' => array( $this, 'sanitize_checkbox' ),
+        ) );
+        register_setting( 'wbc_settings', 'wbc_enable_price_sync', array(
+            'sanitize_callback' => array( $this, 'sanitize_checkbox' ),
+        ) );
+
+        // Order settings
+        register_setting( 'wbc_settings', 'wbc_enable_order_sync', array(
+            'sanitize_callback' => array( $this, 'sanitize_checkbox' ),
+        ) );
+        register_setting( 'wbc_settings', 'wbc_default_payment_terms_id', array(
+            'sanitize_callback' => 'sanitize_text_field',
+        ) );
+        register_setting( 'wbc_settings', 'wbc_default_shipment_method_id', array(
+            'sanitize_callback' => 'sanitize_text_field',
+        ) );
+        register_setting( 'wbc_settings', 'wbc_shipping_item_number', array(
+            'sanitize_callback' => 'sanitize_text_field',
+        ) );
+    }
+
+    /**
+     * Sanitize client secret
+     *
+     * @param string $value Input value.
+     * @return string Sanitized value.
+     */
+    public function sanitize_client_secret( $value ) {
+        if ( empty( $value ) ) {
+            // Keep existing value if empty (masked field)
+            return get_option( 'wbc_client_secret', '' );
+        }
+
+        // If it looks like a masked value, keep existing
+        if ( strpos( $value, '***' ) !== false ) {
+            return get_option( 'wbc_client_secret', '' );
+        }
+
+        // Encrypt new value
+        return WBC_OAuth::encrypt( sanitize_text_field( $value ) );
+    }
+
+    /**
+     * Sanitize frequency
+     *
+     * @param string $value Input value.
+     * @return string Sanitized value.
+     */
+    public function sanitize_frequency( $value ) {
+        $allowed = array( 'hourly', 'twice_daily', 'daily' );
+        $value = sanitize_text_field( $value );
+
+        if ( ! in_array( $value, $allowed, true ) ) {
+            return 'daily';
+        }
+
+        // Reschedule cron if frequency changed
+        $old_frequency = get_option( 'wbc_sync_frequency', 'daily' );
+        if ( $value !== $old_frequency ) {
+            WBC_Cron::reschedule_sync( $value );
+        }
+
+        return $value;
+    }
+
+    /**
+     * Sanitize checkbox
+     *
+     * @param string $value Input value.
+     * @return string Sanitized value.
+     */
+    public function sanitize_checkbox( $value ) {
+        return $value === 'yes' ? 'yes' : 'no';
+    }
+
+    /**
+     * Enqueue admin scripts
+     *
+     * @param string $hook Current admin page hook.
+     */
+    public function enqueue_scripts( $hook ) {
+        if ( strpos( $hook, self::PAGE_SLUG ) === false ) {
+            return;
+        }
+
+        wp_enqueue_style(
+            'wbc-admin-style',
+            WBC_PLUGIN_URL . 'admin/css/wbc-admin.css',
+            array(),
+            WBC_VERSION
+        );
+
+        wp_enqueue_script(
+            'wbc-admin-script',
+            WBC_PLUGIN_URL . 'admin/js/wbc-admin.js',
+            array( 'jquery' ),
+            WBC_VERSION,
+            true
+        );
+
+        wp_localize_script( 'wbc-admin-script', 'wbc_admin', array(
+            'ajax_url' => admin_url( 'admin-ajax.php' ),
+            'nonce'    => wp_create_nonce( 'wbc_admin_nonce' ),
+            'strings'  => array(
+                'testing'      => __( 'Testing connection...', 'woo-business-central' ),
+                'syncing'      => __( 'Syncing products...', 'woo-business-central' ),
+                'clearing'     => __( 'Clearing logs...', 'woo-business-central' ),
+                'loading'      => __( 'Loading...', 'woo-business-central' ),
+                'confirm_clear' => __( 'Are you sure you want to clear all logs?', 'woo-business-central' ),
+            ),
+        ) );
+    }
+
+    /**
+     * Add settings link to plugin list
+     *
+     * @param array $links Existing links.
+     * @return array Modified links.
+     */
+    public function add_settings_link( $links ) {
+        $settings_link = sprintf(
+            '<a href="%s">%s</a>',
+            admin_url( 'admin.php?page=' . self::PAGE_SLUG ),
+            __( 'Settings', 'woo-business-central' )
+        );
+
+        array_unshift( $links, $settings_link );
+
+        return $links;
+    }
+
+    /**
+     * Render settings page
+     */
+    public function render_settings_page() {
+        // Check user capabilities
+        if ( ! current_user_can( 'manage_woocommerce' ) ) {
+            wp_die( __( 'You do not have sufficient permissions to access this page.', 'woo-business-central' ) );
+        }
+
+        // Handle tab
+        $current_tab = isset( $_GET['tab'] ) ? sanitize_text_field( wp_unslash( $_GET['tab'] ) ) : 'connection';
+
+        include WBC_PLUGIN_DIR . 'admin/partials/wbc-admin-display.php';
+    }
+
+    /**
+     * AJAX: Test connection
+     */
+    public function ajax_test_connection() {
+        check_ajax_referer( 'wbc_admin_nonce', 'nonce' );
+
+        if ( ! current_user_can( 'manage_woocommerce' ) ) {
+            wp_send_json_error( array( 'message' => __( 'Permission denied.', 'woo-business-central' ) ) );
+        }
+
+        $result = WBC_OAuth::test_connection();
+
+        if ( is_wp_error( $result ) ) {
+            wp_send_json_error( array( 'message' => $result->get_error_message() ) );
+        }
+
+        wp_send_json_success( $result );
+    }
+
+    /**
+     * AJAX: Manual sync
+     */
+    public function ajax_manual_sync() {
+        check_ajax_referer( 'wbc_admin_nonce', 'nonce' );
+
+        if ( ! current_user_can( 'manage_woocommerce' ) ) {
+            wp_send_json_error( array( 'message' => __( 'Permission denied.', 'woo-business-central' ) ) );
+        }
+
+        $result = WBC_Cron::run_sync_now();
+
+        if ( isset( $result['success'] ) && $result['success'] ) {
+            wp_send_json_success( $result );
+        } else {
+            wp_send_json_error( $result );
+        }
+    }
+
+    /**
+     * AJAX: Clear logs
+     */
+    public function ajax_clear_logs() {
+        check_ajax_referer( 'wbc_admin_nonce', 'nonce' );
+
+        if ( ! current_user_can( 'manage_woocommerce' ) ) {
+            wp_send_json_error( array( 'message' => __( 'Permission denied.', 'woo-business-central' ) ) );
+        }
+
+        WBC_Logger::clear_logs();
+
+        wp_send_json_success( array( 'message' => __( 'Logs cleared successfully.', 'woo-business-central' ) ) );
+    }
+
+    /**
+     * AJAX: Get companies
+     */
+    public function ajax_get_companies() {
+        check_ajax_referer( 'wbc_admin_nonce', 'nonce' );
+
+        if ( ! current_user_can( 'manage_woocommerce' ) ) {
+            wp_send_json_error( array( 'message' => __( 'Permission denied.', 'woo-business-central' ) ) );
+        }
+
+        $result = WBC_API_Client::get_companies();
+
+        if ( is_wp_error( $result ) ) {
+            wp_send_json_error( array( 'message' => $result->get_error_message() ) );
+        }
+
+        $companies = isset( $result['value'] ) ? $result['value'] : array();
+
+        wp_send_json_success( array( 'companies' => $companies ) );
+    }
+
+    /**
+     * Handle CSV export of logs
+     */
+    public function handle_csv_export() {
+        if ( ! isset( $_GET['wbc_export_logs'] ) || $_GET['wbc_export_logs'] !== '1' ) {
+            return;
+        }
+
+        if ( ! isset( $_GET['_wpnonce'] ) || ! wp_verify_nonce( sanitize_text_field( wp_unslash( $_GET['_wpnonce'] ) ), 'wbc_export_logs' ) ) {
+            wp_die( esc_html__( 'Security check failed.', 'woo-business-central' ) );
+        }
+
+        if ( ! current_user_can( 'manage_woocommerce' ) ) {
+            wp_die( esc_html__( 'Permission denied.', 'woo-business-central' ) );
+        }
+
+        $csv = WBC_Logger::export_to_csv();
+
+        header( 'Content-Type: text/csv; charset=utf-8' );
+        header( 'Content-Disposition: attachment; filename=wbc-logs-' . gmdate( 'Y-m-d' ) . '.csv' );
+        header( 'Pragma: no-cache' );
+        header( 'Expires: 0' );
+
+        echo $csv; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped -- CSV output
+        exit;
+    }
+
+    /**
+     * Get logs for display
+     *
+     * @param array $args Query arguments.
+     * @return array Logs data.
+     */
+    public static function get_logs_for_display( $args = array() ) {
+        $defaults = array(
+            'limit'  => 50,
+            'offset' => 0,
+            'level'  => '',
+        );
+
+        $args = wp_parse_args( $args, $defaults );
+
+        return array(
+            'logs'  => WBC_Logger::get_logs( $args ),
+            'total' => WBC_Logger::get_log_count( $args ),
+        );
+    }
+}
diff --git a/woo-business-central/admin/css/wbc-admin.css b/woo-business-central/admin/css/wbc-admin.css
new file mode 100644
index 0000000..19e2fc8
--- /dev/null
+++ b/woo-business-central/admin/css/wbc-admin.css
@@ -0,0 +1,233 @@
+/**
+ * WooCommerce Business Central - Admin Styles
+ */
+
+/* General Layout */
+.wbc-admin-wrap {
+    max-width: 1200px;
+}
+
+.wbc-nav-tabs {
+    margin-bottom: 0;
+}
+
+/* Cards */
+.wbc-card {
+    background: #fff;
+    border: 1px solid #c3c4c7;
+    border-radius: 4px;
+    padding: 20px;
+    margin-top: 20px;
+    box-shadow: 0 1px 1px rgba(0, 0, 0, 0.04);
+}
+
+.wbc-card h2 {
+    margin-top: 0;
+    padding-bottom: 10px;
+    border-bottom: 1px solid #eee;
+    font-size: 1.3em;
+}
+
+.wbc-card h2:first-child {
+    margin-top: 0;
+}
+
+/* Status Messages */
+.wbc-status {
+    display: inline-block;
+    margin-left: 10px;
+    font-weight: 500;
+}
+
+.wbc-status.success {
+    color: #00a32a;
+}
+
+.wbc-status.error {
+    color: #d63638;
+}
+
+.wbc-status.loading {
+    color: #2271b1;
+}
+
+/* Status Table */
+.wbc-status-table {
+    margin-bottom: 15px;
+}
+
+.wbc-status-table th {
+    text-align: left;
+    padding: 8px 20px 8px 0;
+    font-weight: 600;
+}
+
+.wbc-status-table td {
+    padding: 8px 0;
+}
+
+/* Logs Table */
+.wbc-logs-table {
+    margin-top: 15px;
+}
+
+.wbc-logs-table .column-timestamp {
+    width: 160px;
+}
+
+.wbc-logs-table .column-level {
+    width: 90px;
+}
+
+.wbc-logs-table .column-context {
+    width: 130px;
+}
+
+.wbc-logs-table .column-message {
+    min-width: 300px;
+}
+
+/* Log Level Badges */
+.wbc-log-badge {
+    display: inline-block;
+    padding: 3px 8px;
+    border-radius: 3px;
+    font-size: 11px;
+    font-weight: 600;
+    text-transform: uppercase;
+}
+
+.wbc-log-badge-debug {
+    background: #f0f0f1;
+    color: #50575e;
+}
+
+.wbc-log-badge-info {
+    background: #d1e4f6;
+    color: #0a4b78;
+}
+
+.wbc-log-badge-warning {
+    background: #fcf9e8;
+    color: #bd8600;
+}
+
+.wbc-log-badge-error {
+    background: #facfd2;
+    color: #8a1f1f;
+}
+
+/* Log Row Colors */
+.wbc-log-level-error {
+    background-color: #fff5f5 !important;
+}
+
+.wbc-log-level-warning {
+    background-color: #fffbe8 !important;
+}
+
+/* Log Data Display */
+.wbc-log-data {
+    background: #f6f7f7;
+    padding: 10px;
+    margin-top: 10px;
+    font-size: 12px;
+    max-height: 200px;
+    overflow: auto;
+    border: 1px solid #ddd;
+    border-radius: 3px;
+    white-space: pre-wrap;
+    word-break: break-word;
+}
+
+/* Log Filters */
+.wbc-log-filters {
+    margin-bottom: 15px;
+    padding: 10px;
+    background: #f6f7f7;
+    border-radius: 3px;
+}
+
+.wbc-log-filters label {
+    font-weight: 500;
+    margin-right: 10px;
+}
+
+/* Toggle Data Link */
+.wbc-toggle-data {
+    margin-left: 10px;
+    font-size: 12px;
+}
+
+/* Form Improvements */
+.wbc-settings-form .form-table th {
+    padding-left: 0;
+}
+
+.wbc-settings-form .description {
+    color: #646970;
+    font-style: normal;
+    margin-top: 5px;
+}
+
+/* Button Spacing */
+.wbc-card .button + .button,
+.wbc-card .button-primary + .button {
+    margin-left: 10px;
+}
+
+/* Connection Status */
+#wbc-connection-status {
+    vertical-align: middle;
+}
+
+/* Companies List */
+#wbc-companies-list {
+    margin-top: 10px;
+    padding: 10px;
+    background: #f6f7f7;
+    border-radius: 3px;
+}
+
+#wbc-company-select {
+    min-width: 300px;
+}
+
+/* Responsive Adjustments */
+@media screen and (max-width: 782px) {
+    .wbc-logs-table .column-timestamp,
+    .wbc-logs-table .column-context {
+        display: none;
+    }
+
+    .wbc-logs-table .column-level {
+        width: 70px;
+    }
+
+    #wbc-company-select {
+        min-width: 100%;
+    }
+}
+
+/* Loading State */
+.wbc-loading {
+    opacity: 0.5;
+    pointer-events: none;
+}
+
+/* Pagination */
+.wbc-logs-table + .tablenav {
+    margin-top: 15px;
+}
+
+.tablenav-pages .pagination-links {
+    display: flex;
+    align-items: center;
+    gap: 5px;
+}
+
+.tablenav-pages .button {
+    padding: 0 8px;
+    min-height: 28px;
+    line-height: 26px;
+}
diff --git a/woo-business-central/admin/js/wbc-admin.js b/woo-business-central/admin/js/wbc-admin.js
new file mode 100644
index 0000000..c5d6afe
--- /dev/null
+++ b/woo-business-central/admin/js/wbc-admin.js
@@ -0,0 +1,239 @@
+/**
+ * WooCommerce Business Central - Admin JavaScript
+ */
+
+(function($) {
+    'use strict';
+
+    var WBC_Admin = {
+        /**
+         * Initialize
+         */
+        init: function() {
+            this.bindEvents();
+        },
+
+        /**
+         * Bind event handlers
+         */
+        bindEvents: function() {
+            // Test connection
+            $('#wbc-test-connection').on('click', this.testConnection);
+
+            // Manual sync
+            $('#wbc-manual-sync').on('click', this.manualSync);
+
+            // Clear logs
+            $('#wbc-clear-logs').on('click', this.clearLogs);
+
+            // Load companies
+            $('#wbc-load-companies').on('click', this.loadCompanies);
+
+            // Select company
+            $('#wbc-company-select').on('change', this.selectCompany);
+
+            // Toggle log data
+            $(document).on('click', '.wbc-toggle-data', this.toggleLogData);
+        },
+
+        /**
+         * Test connection to Business Central
+         */
+        testConnection: function(e) {
+            e.preventDefault();
+
+            var $btn = $(this);
+            var $status = $('#wbc-connection-status');
+
+            $btn.prop('disabled', true);
+            $status.removeClass('success error').addClass('loading').text(wbc_admin.strings.testing);
+
+            $.ajax({
+                url: wbc_admin.ajax_url,
+                type: 'POST',
+                data: {
+                    action: 'wbc_test_connection',
+                    nonce: wbc_admin.nonce
+                },
+                success: function(response) {
+                    $btn.prop('disabled', false);
+                    $status.removeClass('loading');
+
+                    if (response.success) {
+                        $status.addClass('success').text(response.data.message);
+                    } else {
+                        $status.addClass('error').text(response.data.message || 'Connection failed');
+                    }
+                },
+                error: function(xhr, status, error) {
+                    $btn.prop('disabled', false);
+                    $status.removeClass('loading').addClass('error').text('Request failed: ' + error);
+                }
+            });
+        },
+
+        /**
+         * Run manual sync
+         */
+        manualSync: function(e) {
+            e.preventDefault();
+
+            var $btn = $(this);
+            var $status = $('#wbc-sync-status');
+
+            $btn.prop('disabled', true);
+            $status.removeClass('success error').addClass('loading').text(wbc_admin.strings.syncing);
+
+            $.ajax({
+                url: wbc_admin.ajax_url,
+                type: 'POST',
+                data: {
+                    action: 'wbc_manual_sync',
+                    nonce: wbc_admin.nonce
+                },
+                success: function(response) {
+                    $btn.prop('disabled', false);
+                    $status.removeClass('loading');
+
+                    if (response.success) {
+                        $status.addClass('success').text(response.data.message);
+                    } else {
+                        $status.addClass('error').text(response.data.message || 'Sync failed');
+                    }
+                },
+                error: function(xhr, status, error) {
+                    $btn.prop('disabled', false);
+                    $status.removeClass('loading').addClass('error').text('Request failed: ' + error);
+                }
+            });
+        },
+
+        /**
+         * Clear all logs
+         */
+        clearLogs: function(e) {
+            e.preventDefault();
+
+            if (!confirm(wbc_admin.strings.confirm_clear)) {
+                return;
+            }
+
+            var $btn = $(this);
+            var originalText = $btn.text();
+
+            $btn.prop('disabled', true).text(wbc_admin.strings.clearing);
+
+            $.ajax({
+                url: wbc_admin.ajax_url,
+                type: 'POST',
+                data: {
+                    action: 'wbc_clear_logs',
+                    nonce: wbc_admin.nonce
+                },
+                success: function(response) {
+                    if (response.success) {
+                        // Reload the page to show empty logs
+                        location.reload();
+                    } else {
+                        alert(response.data.message || 'Failed to clear logs');
+                        $btn.prop('disabled', false).text(originalText);
+                    }
+                },
+                error: function(xhr, status, error) {
+                    alert('Request failed: ' + error);
+                    $btn.prop('disabled', false).text(originalText);
+                }
+            });
+        },
+
+        /**
+         * Load companies from Business Central
+         */
+        loadCompanies: function(e) {
+            e.preventDefault();
+
+            var $btn = $(this);
+            var $select = $('#wbc-company-select');
+            var $list = $('#wbc-companies-list');
+            var originalText = $btn.text();
+
+            $btn.prop('disabled', true).text(wbc_admin.strings.loading);
+
+            $.ajax({
+                url: wbc_admin.ajax_url,
+                type: 'POST',
+                data: {
+                    action: 'wbc_get_companies',
+                    nonce: wbc_admin.nonce
+                },
+                success: function(response) {
+                    $btn.prop('disabled', false).text(originalText);
+
+                    if (response.success && response.data.companies) {
+                        // Clear existing options except the first one
+                        $select.find('option:not(:first)').remove();
+
+                        // Add companies
+                        $.each(response.data.companies, function(i, company) {
+                            $select.append(
+                                $('<option>', {
+                                    value: company.id,
+                                    text: company.displayName + ' (' + company.id.substring(0, 8) + '...)'
+                                })
+                            );
+                        });
+
+                        // Show the select
+                        $list.slideDown();
+
+                        // Pre-select current company if set
+                        var currentCompany = $('#wbc_company_id').val();
+                        if (currentCompany) {
+                            $select.val(currentCompany);
+                        }
+                    } else {
+                        alert(response.data.message || 'Failed to load companies. Make sure credentials are saved and correct.');
+                    }
+                },
+                error: function(xhr, status, error) {
+                    $btn.prop('disabled', false).text(originalText);
+                    alert('Request failed: ' + error);
+                }
+            });
+        },
+
+        /**
+         * Select company from dropdown
+         */
+        selectCompany: function() {
+            var companyId = $(this).val();
+            if (companyId) {
+                $('#wbc_company_id').val(companyId);
+            }
+        },
+
+        /**
+         * Toggle log data visibility
+         */
+        toggleLogData: function(e) {
+            e.preventDefault();
+
+            var $btn = $(this);
+            var $data = $btn.siblings('.wbc-log-data');
+
+            $data.slideToggle(200, function() {
+                if ($data.is(':visible')) {
+                    $btn.text($btn.data('hide-text') || 'Hide data');
+                } else {
+                    $btn.text($btn.data('show-text') || 'Show data');
+                }
+            });
+        }
+    };
+
+    // Initialize on document ready
+    $(document).ready(function() {
+        WBC_Admin.init();
+    });
+
+})(jQuery);
diff --git a/woo-business-central/admin/partials/wbc-admin-display.php b/woo-business-central/admin/partials/wbc-admin-display.php
new file mode 100644
index 0000000..7903375
--- /dev/null
+++ b/woo-business-central/admin/partials/wbc-admin-display.php
@@ -0,0 +1,399 @@
+<?php
+/**
+ * Admin settings page template
+ *
+ * @package WooBusinessCentral
+ */
+
+// Prevent direct access
+if ( ! defined( 'ABSPATH' ) ) {
+    exit;
+}
+
+$tabs = array(
+    'connection' => __( 'Connection', 'woo-business-central' ),
+    'sync'       => __( 'Sync Settings', 'woo-business-central' ),
+    'orders'     => __( 'Order Settings', 'woo-business-central' ),
+    'logs'       => __( 'Logs', 'woo-business-central' ),
+);
+?>
+
+<div class="wrap wbc-admin-wrap">
+    <h1><?php echo esc_html( get_admin_page_title() ); ?></h1>
+
+    <nav class="nav-tab-wrapper wbc-nav-tabs">
+        <?php foreach ( $tabs as $tab_id => $tab_name ) : ?>
+            <a href="<?php echo esc_url( add_query_arg( 'tab', $tab_id ) ); ?>"
+               class="nav-tab <?php echo $current_tab === $tab_id ? 'nav-tab-active' : ''; ?>">
+                <?php echo esc_html( $tab_name ); ?>
+            </a>
+        <?php endforeach; ?>
+    </nav>
+
+    <div class="wbc-admin-content">
+        <?php if ( $current_tab === 'connection' ) : ?>
+            <!-- Connection Settings -->
+            <form method="post" action="options.php" class="wbc-settings-form">
+                <?php settings_fields( 'wbc_settings' ); ?>
+
+                <div class="wbc-card">
+                    <h2><?php esc_html_e( 'Microsoft Azure AD Credentials', 'woo-business-central' ); ?></h2>
+                    <p class="description">
+                        <?php esc_html_e( 'Enter your Azure AD application credentials to connect to Business Central.', 'woo-business-central' ); ?>
+                    </p>
+
+                    <table class="form-table">
+                        <tr>
+                            <th scope="row">
+                                <label for="wbc_tenant_id"><?php esc_html_e( 'Tenant ID', 'woo-business-central' ); ?></label>
+                            </th>
+                            <td>
+                                <input type="text" id="wbc_tenant_id" name="wbc_tenant_id"
+                                       value="<?php echo esc_attr( get_option( 'wbc_tenant_id', '' ) ); ?>"
+                                       class="regular-text" />
+                                <p class="description">
+                                    <?php esc_html_e( 'Your Azure AD tenant ID (GUID format).', 'woo-business-central' ); ?>
+                                </p>
+                            </td>
+                        </tr>
+                        <tr>
+                            <th scope="row">
+                                <label for="wbc_client_id"><?php esc_html_e( 'Client ID', 'woo-business-central' ); ?></label>
+                            </th>
+                            <td>
+                                <input type="text" id="wbc_client_id" name="wbc_client_id"
+                                       value="<?php echo esc_attr( get_option( 'wbc_client_id', '' ) ); ?>"
+                                       class="regular-text" />
+                                <p class="description">
+                                    <?php esc_html_e( 'Application (client) ID from Azure AD.', 'woo-business-central' ); ?>
+                                </p>
+                            </td>
+                        </tr>
+                        <tr>
+                            <th scope="row">
+                                <label for="wbc_client_secret"><?php esc_html_e( 'Client Secret', 'woo-business-central' ); ?></label>
+                            </th>
+                            <td>
+                                <?php
+                                $has_secret = ! empty( WBC_OAuth::get_client_secret() );
+                                $placeholder = $has_secret ? '********' : '';
+                                ?>
+                                <input type="password" id="wbc_client_secret" name="wbc_client_secret"
+                                       value="" placeholder="<?php echo esc_attr( $placeholder ); ?>"
+                                       class="regular-text" autocomplete="new-password" />
+                                <p class="description">
+                                    <?php if ( $has_secret ) : ?>
+                                        <?php esc_html_e( 'Leave blank to keep existing secret. Enter a new value to update.', 'woo-business-central' ); ?>
+                                    <?php else : ?>
+                                        <?php esc_html_e( 'Client secret from Azure AD application.', 'woo-business-central' ); ?>
+                                    <?php endif; ?>
+                                </p>
+                            </td>
+                        </tr>
+                        <tr>
+                            <th scope="row">
+                                <label for="wbc_environment"><?php esc_html_e( 'Environment', 'woo-business-central' ); ?></label>
+                            </th>
+                            <td>
+                                <select id="wbc_environment" name="wbc_environment">
+                                    <option value="production" <?php selected( get_option( 'wbc_environment', 'production' ), 'production' ); ?>>
+                                        <?php esc_html_e( 'Production', 'woo-business-central' ); ?>
+                                    </option>
+                                    <option value="sandbox" <?php selected( get_option( 'wbc_environment' ), 'sandbox' ); ?>>
+                                        <?php esc_html_e( 'Sandbox', 'woo-business-central' ); ?>
+                                    </option>
+                                </select>
+                            </td>
+                        </tr>
+                        <tr>
+                            <th scope="row">
+                                <label for="wbc_company_id"><?php esc_html_e( 'Company ID', 'woo-business-central' ); ?></label>
+                            </th>
+                            <td>
+                                <input type="text" id="wbc_company_id" name="wbc_company_id"
+                                       value="<?php echo esc_attr( get_option( 'wbc_company_id', '' ) ); ?>"
+                                       class="regular-text" />
+                                <button type="button" id="wbc-load-companies" class="button">
+                                    <?php esc_html_e( 'Load Companies', 'woo-business-central' ); ?>
+                                </button>
+                                <p class="description">
+                                    <?php esc_html_e( 'Business Central company ID (GUID). Click "Load Companies" after saving credentials.', 'woo-business-central' ); ?>
+                                </p>
+                                <div id="wbc-companies-list" style="display: none; margin-top: 10px;">
+                                    <select id="wbc-company-select">
+                                        <option value=""><?php esc_html_e( 'Select a company...', 'woo-business-central' ); ?></option>
+                                    </select>
+                                </div>
+                            </td>
+                        </tr>
+                    </table>
+
+                    <p class="submit">
+                        <?php submit_button( __( 'Save Settings', 'woo-business-central' ), 'primary', 'submit', false ); ?>
+                        <button type="button" id="wbc-test-connection" class="button button-secondary">
+                            <?php esc_html_e( 'Test Connection', 'woo-business-central' ); ?>
+                        </button>
+                        <span id="wbc-connection-status" class="wbc-status"></span>
+                    </p>
+                </div>
+            </form>
+
+        <?php elseif ( $current_tab === 'sync' ) : ?>
+            <!-- Sync Settings -->
+            <form method="post" action="options.php" class="wbc-settings-form">
+                <?php settings_fields( 'wbc_settings' ); ?>
+
+                <div class="wbc-card">
+                    <h2><?php esc_html_e( 'Product Sync Settings', 'woo-business-central' ); ?></h2>
+
+                    <table class="form-table">
+                        <tr>
+                            <th scope="row">
+                                <label for="wbc_sync_frequency"><?php esc_html_e( 'Sync Frequency', 'woo-business-central' ); ?></label>
+                            </th>
+                            <td>
+                                <select id="wbc_sync_frequency" name="wbc_sync_frequency">
+                                    <option value="hourly" <?php selected( get_option( 'wbc_sync_frequency', 'daily' ), 'hourly' ); ?>>
+                                        <?php esc_html_e( 'Hourly', 'woo-business-central' ); ?>
+                                    </option>
+                                    <option value="twice_daily" <?php selected( get_option( 'wbc_sync_frequency' ), 'twice_daily' ); ?>>
+                                        <?php esc_html_e( 'Twice Daily', 'woo-business-central' ); ?>
+                                    </option>
+                                    <option value="daily" <?php selected( get_option( 'wbc_sync_frequency' ), 'daily' ); ?>>
+                                        <?php esc_html_e( 'Daily', 'woo-business-central' ); ?>
+                                    </option>
+                                </select>
+                            </td>
+                        </tr>
+                        <tr>
+                            <th scope="row"><?php esc_html_e( 'Enable Stock Sync', 'woo-business-central' ); ?></th>
+                            <td>
+                                <label>
+                                    <input type="checkbox" name="wbc_enable_stock_sync" value="yes"
+                                        <?php checked( get_option( 'wbc_enable_stock_sync', 'yes' ), 'yes' ); ?> />
+                                    <?php esc_html_e( 'Sync stock levels from Business Central to WooCommerce', 'woo-business-central' ); ?>
+                                </label>
+                            </td>
+                        </tr>
+                        <tr>
+                            <th scope="row"><?php esc_html_e( 'Enable Price Sync', 'woo-business-central' ); ?></th>
+                            <td>
+                                <label>
+                                    <input type="checkbox" name="wbc_enable_price_sync" value="yes"
+                                        <?php checked( get_option( 'wbc_enable_price_sync', 'yes' ), 'yes' ); ?> />
+                                    <?php esc_html_e( 'Sync prices from Business Central to WooCommerce', 'woo-business-central' ); ?>
+                                </label>
+                            </td>
+                        </tr>
+                    </table>
+
+                    <p class="submit">
+                        <?php submit_button( __( 'Save Settings', 'woo-business-central' ), 'primary', 'submit', false ); ?>
+                    </p>
+                </div>
+
+                <div class="wbc-card">
+                    <h2><?php esc_html_e( 'Sync Status', 'woo-business-central' ); ?></h2>
+
+                    <table class="wbc-status-table">
+                        <tr>
+                            <th><?php esc_html_e( 'Last Sync:', 'woo-business-central' ); ?></th>
+                            <td><?php echo esc_html( WBC_Cron::get_last_sync_formatted() ); ?></td>
+                        </tr>
+                        <tr>
+                            <th><?php esc_html_e( 'Next Scheduled Sync:', 'woo-business-central' ); ?></th>
+                            <td><?php echo esc_html( WBC_Cron::get_next_sync_formatted() ); ?></td>
+                        </tr>
+                    </table>
+
+                    <p>
+                        <button type="button" id="wbc-manual-sync" class="button button-primary">
+                            <?php esc_html_e( 'Sync Now', 'woo-business-central' ); ?>
+                        </button>
+                        <span id="wbc-sync-status" class="wbc-status"></span>
+                    </p>
+                </div>
+            </form>
+
+        <?php elseif ( $current_tab === 'orders' ) : ?>
+            <!-- Order Settings -->
+            <form method="post" action="options.php" class="wbc-settings-form">
+                <?php settings_fields( 'wbc_settings' ); ?>
+
+                <div class="wbc-card">
+                    <h2><?php esc_html_e( 'Order Sync Settings', 'woo-business-central' ); ?></h2>
+
+                    <table class="form-table">
+                        <tr>
+                            <th scope="row"><?php esc_html_e( 'Enable Order Sync', 'woo-business-central' ); ?></th>
+                            <td>
+                                <label>
+                                    <input type="checkbox" name="wbc_enable_order_sync" value="yes"
+                                        <?php checked( get_option( 'wbc_enable_order_sync', 'yes' ), 'yes' ); ?> />
+                                    <?php esc_html_e( 'Sync orders to Business Central when payment is received', 'woo-business-central' ); ?>
+                                </label>
+                            </td>
+                        </tr>
+                        <tr>
+                            <th scope="row">
+                                <label for="wbc_default_payment_terms_id"><?php esc_html_e( 'Default Payment Terms ID', 'woo-business-central' ); ?></label>
+                            </th>
+                            <td>
+                                <input type="text" id="wbc_default_payment_terms_id" name="wbc_default_payment_terms_id"
+                                       value="<?php echo esc_attr( get_option( 'wbc_default_payment_terms_id', '' ) ); ?>"
+                                       class="regular-text" />
+                                <p class="description">
+                                    <?php esc_html_e( 'Optional. Business Central payment terms ID to use for new orders.', 'woo-business-central' ); ?>
+                                </p>
+                            </td>
+                        </tr>
+                        <tr>
+                            <th scope="row">
+                                <label for="wbc_default_shipment_method_id"><?php esc_html_e( 'Default Shipment Method ID', 'woo-business-central' ); ?></label>
+                            </th>
+                            <td>
+                                <input type="text" id="wbc_default_shipment_method_id" name="wbc_default_shipment_method_id"
+                                       value="<?php echo esc_attr( get_option( 'wbc_default_shipment_method_id', '' ) ); ?>"
+                                       class="regular-text" />
+                                <p class="description">
+                                    <?php esc_html_e( 'Optional. Business Central shipment method ID to use for new orders.', 'woo-business-central' ); ?>
+                                </p>
+                            </td>
+                        </tr>
+                        <tr>
+                            <th scope="row">
+                                <label for="wbc_shipping_item_number"><?php esc_html_e( 'Shipping Item Number', 'woo-business-central' ); ?></label>
+                            </th>
+                            <td>
+                                <input type="text" id="wbc_shipping_item_number" name="wbc_shipping_item_number"
+                                       value="<?php echo esc_attr( get_option( 'wbc_shipping_item_number', '' ) ); ?>"
+                                       class="regular-text" />
+                                <p class="description">
+                                    <?php esc_html_e( 'Optional. Business Central item number to use for shipping charges.', 'woo-business-central' ); ?>
+                                </p>
+                            </td>
+                        </tr>
+                    </table>
+
+                    <p class="submit">
+                        <?php submit_button( __( 'Save Settings', 'woo-business-central' ), 'primary', 'submit', false ); ?>
+                    </p>
+                </div>
+            </form>
+
+        <?php elseif ( $current_tab === 'logs' ) : ?>
+            <!-- Logs -->
+            <div class="wbc-card">
+                <h2><?php esc_html_e( 'Sync Logs', 'woo-business-central' ); ?></h2>
+
+                <p>
+                    <button type="button" id="wbc-clear-logs" class="button">
+                        <?php esc_html_e( 'Clear All Logs', 'woo-business-central' ); ?>
+                    </button>
+                    <a href="<?php echo esc_url( add_query_arg( array( 'wbc_export_logs' => '1', '_wpnonce' => wp_create_nonce( 'wbc_export_logs' ) ) ) ); ?>"
+                       class="button">
+                        <?php esc_html_e( 'Download CSV', 'woo-business-central' ); ?>
+                    </a>
+                </p>
+
+                <?php
+                $log_level = isset( $_GET['log_level'] ) ? sanitize_text_field( wp_unslash( $_GET['log_level'] ) ) : '';
+                $page_num = isset( $_GET['log_page'] ) ? max( 1, absint( $_GET['log_page'] ) ) : 1;
+                $per_page = 50;
+
+                $logs_data = WBC_Admin::get_logs_for_display( array(
+                    'level'  => $log_level,
+                    'limit'  => $per_page,
+                    'offset' => ( $page_num - 1 ) * $per_page,
+                ) );
+
+                $logs = $logs_data['logs'];
+                $total = $logs_data['total'];
+                $total_pages = ceil( $total / $per_page );
+                ?>
+
+                <div class="wbc-log-filters">
+                    <label for="wbc-log-level-filter"><?php esc_html_e( 'Filter by level:', 'woo-business-central' ); ?></label>
+                    <select id="wbc-log-level-filter" onchange="location = this.value;">
+                        <option value="<?php echo esc_url( remove_query_arg( 'log_level' ) ); ?>"><?php esc_html_e( 'All', 'woo-business-central' ); ?></option>
+                        <?php foreach ( array( 'DEBUG', 'INFO', 'WARNING', 'ERROR' ) as $level ) : ?>
+                            <option value="<?php echo esc_url( add_query_arg( 'log_level', $level ) ); ?>" <?php selected( $log_level, $level ); ?>>
+                                <?php echo esc_html( $level ); ?>
+                            </option>
+                        <?php endforeach; ?>
+                    </select>
+                </div>
+
+                <table class="wp-list-table widefat fixed striped wbc-logs-table">
+                    <thead>
+                        <tr>
+                            <th class="column-timestamp"><?php esc_html_e( 'Timestamp', 'woo-business-central' ); ?></th>
+                            <th class="column-level"><?php esc_html_e( 'Level', 'woo-business-central' ); ?></th>
+                            <th class="column-context"><?php esc_html_e( 'Context', 'woo-business-central' ); ?></th>
+                            <th class="column-message"><?php esc_html_e( 'Message', 'woo-business-central' ); ?></th>
+                        </tr>
+                    </thead>
+                    <tbody>
+                        <?php if ( empty( $logs ) ) : ?>
+                            <tr>
+                                <td colspan="4"><?php esc_html_e( 'No logs found.', 'woo-business-central' ); ?></td>
+                            </tr>
+                        <?php else : ?>
+                            <?php foreach ( $logs as $log ) : ?>
+                                <tr class="wbc-log-level-<?php echo esc_attr( strtolower( $log['level'] ) ); ?>">
+                                    <td class="column-timestamp">
+                                        <?php echo esc_html( wp_date( 'Y-m-d H:i:s', strtotime( $log['timestamp'] ) ) ); ?>
+                                    </td>
+                                    <td class="column-level">
+                                        <span class="wbc-log-badge wbc-log-badge-<?php echo esc_attr( strtolower( $log['level'] ) ); ?>">
+                                            <?php echo esc_html( $log['level'] ); ?>
+                                        </span>
+                                    </td>
+                                    <td class="column-context"><?php echo esc_html( $log['context'] ); ?></td>
+                                    <td class="column-message">
+                                        <?php echo esc_html( $log['message'] ); ?>
+                                        <?php if ( ! empty( $log['data'] ) ) : ?>
+                                            <button type="button" class="button-link wbc-toggle-data"
+                                                    data-show-text="<?php esc_attr_e( 'Show data', 'woo-business-central' ); ?>"
+                                                    data-hide-text="<?php esc_attr_e( 'Hide data', 'woo-business-central' ); ?>">
+                                                <?php esc_html_e( 'Show data', 'woo-business-central' ); ?>
+                                            </button>
+                                            <pre class="wbc-log-data" style="display: none;"><?php echo esc_html( $log['data'] ); ?></pre>
+                                        <?php endif; ?>
+                                    </td>
+                                </tr>
+                            <?php endforeach; ?>
+                        <?php endif; ?>
+                    </tbody>
+                </table>
+
+                <?php if ( $total_pages > 1 ) : ?>
+                    <div class="tablenav bottom">
+                        <div class="tablenav-pages">
+                            <span class="displaying-num">
+                                <?php printf( esc_html__( '%d items', 'woo-business-central' ), $total ); ?>
+                            </span>
+                            <span class="pagination-links">
+                                <?php if ( $page_num > 1 ) : ?>
+                                    <a class="prev-page button" href="<?php echo esc_url( add_query_arg( 'log_page', $page_num - 1 ) ); ?>">
+                                        &lsaquo;
+                                    </a>
+                                <?php endif; ?>
+                                <span class="paging-input">
+                                    <?php echo esc_html( $page_num ); ?> / <?php echo esc_html( $total_pages ); ?>
+                                </span>
+                                <?php if ( $page_num < $total_pages ) : ?>
+                                    <a class="next-page button" href="<?php echo esc_url( add_query_arg( 'log_page', $page_num + 1 ) ); ?>">
+                                        &rsaquo;
+                                    </a>
+                                <?php endif; ?>
+                            </span>
+                        </div>
+                    </div>
+                <?php endif; ?>
+            </div>
+
+        <?php endif; ?>
+    </div>
+</div>
+
diff --git a/woo-business-central/includes/class-wbc-api-client.php b/woo-business-central/includes/class-wbc-api-client.php
new file mode 100644
index 0000000..7ed0de3
--- /dev/null
+++ b/woo-business-central/includes/class-wbc-api-client.php
@@ -0,0 +1,381 @@
+<?php
+/**
+ * Business Central API Client
+ *
+ * @package WooBusinessCentral
+ */
+
+// Prevent direct access
+if ( ! defined( 'ABSPATH' ) ) {
+    exit;
+}
+
+/**
+ * Class WBC_API_Client
+ *
+ * HTTP client for Business Central API using native cURL.
+ */
+class WBC_API_Client {
+
+    /**
+     * Base API URL template
+     */
+    const BASE_URL = 'https://api.businesscentral.dynamics.com/v2.0/%s/api/v2.0';
+
+    /**
+     * Maximum retry attempts
+     */
+    const MAX_RETRIES = 3;
+
+    /**
+     * Retry delay in seconds
+     */
+    const RETRY_DELAY = 2;
+
+    /**
+     * Request timeout in seconds
+     */
+    const TIMEOUT = 30;
+
+    /**
+     * Get the base API URL
+     *
+     * @return string
+     */
+    private static function get_base_url() {
+        $environment = WBC_OAuth::get_environment();
+        return sprintf( self::BASE_URL, $environment );
+    }
+
+    /**
+     * Get company ID for URL
+     *
+     * @return string
+     */
+    private static function get_company_id() {
+        return WBC_OAuth::get_company_id();
+    }
+
+    /**
+     * Build full endpoint URL
+     *
+     * @param string $endpoint The API endpoint.
+     * @param bool   $include_company Whether to include company ID in URL.
+     * @return string Full URL.
+     */
+    private static function build_url( $endpoint, $include_company = true ) {
+        $base_url = self::get_base_url();
+
+        if ( $include_company ) {
+            $company_id = self::get_company_id();
+            return $base_url . '/companies(' . $company_id . ')' . $endpoint;
+        }
+
+        return $base_url . $endpoint;
+    }
+
+    /**
+     * Make an HTTP request to the Business Central API
+     *
+     * @param string $method      HTTP method (GET, POST, PATCH, DELETE).
+     * @param string $endpoint    API endpoint.
+     * @param array  $params      Query parameters (for GET) or body data (for POST/PATCH).
+     * @param bool   $include_company Whether to include company ID in URL.
+     * @param int    $retry_count Current retry attempt.
+     * @return array|WP_Error Response data or error.
+     */
+    private static function request( $method, $endpoint, $params = array(), $include_company = true, $retry_count = 0 ) {
+        // Get access token
+        $token = WBC_OAuth::get_access_token();
+
+        if ( is_wp_error( $token ) ) {
+            return $token;
+        }
+
+        // Build URL
+        $url = self::build_url( $endpoint, $include_company );
+
+        // Add query parameters for GET requests
+        if ( $method === 'GET' && ! empty( $params ) ) {
+            $url .= '?' . http_build_query( $params );
+        }
+
+        WBC_Logger::debug( 'API', "Making $method request", array(
+            'url'    => $url,
+            'method' => $method,
+        ) );
+
+        // Initialize cURL
+        $ch = curl_init();
+
+        // Set base options
+        $curl_options = array(
+            CURLOPT_URL            => $url,
+            CURLOPT_RETURNTRANSFER => true,
+            CURLOPT_TIMEOUT        => self::TIMEOUT,
+            CURLOPT_HTTPHEADER     => array(
+                'Authorization: Bearer ' . $token,
+                'Content-Type: application/json',
+                'Accept: application/json',
+            ),
+        );
+
+        // Set method-specific options
+        switch ( $method ) {
+            case 'POST':
+                $curl_options[ CURLOPT_POST ] = true;
+                if ( ! empty( $params ) ) {
+                    $curl_options[ CURLOPT_POSTFIELDS ] = wp_json_encode( $params );
+                }
+                break;
+
+            case 'PATCH':
+                $curl_options[ CURLOPT_CUSTOMREQUEST ] = 'PATCH';
+                if ( ! empty( $params ) ) {
+                    $curl_options[ CURLOPT_POSTFIELDS ] = wp_json_encode( $params );
+                }
+                // Add If-Match header for PATCH requests
+                $curl_options[ CURLOPT_HTTPHEADER ][] = 'If-Match: *';
+                break;
+
+            case 'DELETE':
+                $curl_options[ CURLOPT_CUSTOMREQUEST ] = 'DELETE';
+                break;
+
+            default: // GET
+                $curl_options[ CURLOPT_HTTPGET ] = true;
+                break;
+        }
+
+        curl_setopt_array( $ch, $curl_options );
+
+        // Execute request
+        $response = curl_exec( $ch );
+        $http_code = curl_getinfo( $ch, CURLINFO_HTTP_CODE );
+        $curl_error = curl_error( $ch );
+
+        curl_close( $ch );
+
+        // Handle cURL errors
+        if ( $response === false ) {
+            WBC_Logger::error( 'API', 'cURL error', array(
+                'error' => $curl_error,
+                'url'   => $url,
+            ) );
+            return new WP_Error( 'wbc_curl_error', $curl_error );
+        }
+
+        // Parse response
+        $data = json_decode( $response, true );
+
+        // Handle 401 (unauthorized) - token might be expired
+        if ( $http_code === 401 && $retry_count < self::MAX_RETRIES ) {
+            WBC_Logger::warning( 'API', 'Received 401, refreshing token and retrying', array(
+                'retry_count' => $retry_count + 1,
+            ) );
+
+            // Clear token cache and retry
+            WBC_OAuth::clear_token_cache();
+            sleep( self::RETRY_DELAY );
+
+            return self::request( $method, $endpoint, $params, $include_company, $retry_count + 1 );
+        }
+
+        // Handle rate limiting (429)
+        if ( $http_code === 429 && $retry_count < self::MAX_RETRIES ) {
+            $retry_after = isset( $data['error']['retryAfterSeconds'] ) ? (int) $data['error']['retryAfterSeconds'] : self::RETRY_DELAY * ( $retry_count + 1 );
+
+            WBC_Logger::warning( 'API', 'Rate limited, retrying after delay', array(
+                'retry_after'  => $retry_after,
+                'retry_count'  => $retry_count + 1,
+            ) );
+
+            sleep( $retry_after );
+
+            return self::request( $method, $endpoint, $params, $include_company, $retry_count + 1 );
+        }
+
+        // Handle server errors (5xx)
+        if ( $http_code >= 500 && $retry_count < self::MAX_RETRIES ) {
+            WBC_Logger::warning( 'API', 'Server error, retrying', array(
+                'http_code'   => $http_code,
+                'retry_count' => $retry_count + 1,
+            ) );
+
+            sleep( self::RETRY_DELAY * ( $retry_count + 1 ) );
+
+            return self::request( $method, $endpoint, $params, $include_company, $retry_count + 1 );
+        }
+
+        // Handle other errors
+        if ( $http_code >= 400 ) {
+            $error_message = isset( $data['error']['message'] ) ? $data['error']['message'] : __( 'API request failed', 'woo-business-central' );
+
+            WBC_Logger::error( 'API', 'Request failed', array(
+                'http_code' => $http_code,
+                'error'     => $data['error'] ?? null,
+                'url'       => $url,
+            ) );
+
+            return new WP_Error( 'wbc_api_error', $error_message, array(
+                'status' => $http_code,
+                'error'  => $data['error'] ?? null,
+            ) );
+        }
+
+        WBC_Logger::debug( 'API', 'Request successful', array(
+            'http_code' => $http_code,
+            'url'       => $url,
+        ) );
+
+        return $data;
+    }
+
+    /**
+     * GET request
+     *
+     * @param string $endpoint API endpoint.
+     * @param array  $params   Query parameters.
+     * @param bool   $include_company Whether to include company ID.
+     * @return array|WP_Error Response data or error.
+     */
+    public static function get( $endpoint, $params = array(), $include_company = true ) {
+        return self::request( 'GET', $endpoint, $params, $include_company );
+    }
+
+    /**
+     * POST request
+     *
+     * @param string $endpoint API endpoint.
+     * @param array  $data     Request body data.
+     * @param bool   $include_company Whether to include company ID.
+     * @return array|WP_Error Response data or error.
+     */
+    public static function post( $endpoint, $data = array(), $include_company = true ) {
+        return self::request( 'POST', $endpoint, $data, $include_company );
+    }
+
+    /**
+     * PATCH request
+     *
+     * @param string $endpoint API endpoint.
+     * @param array  $data     Request body data.
+     * @param bool   $include_company Whether to include company ID.
+     * @return array|WP_Error Response data or error.
+     */
+    public static function patch( $endpoint, $data = array(), $include_company = true ) {
+        return self::request( 'PATCH', $endpoint, $data, $include_company );
+    }
+
+    /**
+     * DELETE request
+     *
+     * @param string $endpoint API endpoint.
+     * @param bool   $include_company Whether to include company ID.
+     * @return array|WP_Error Response data or error.
+     */
+    public static function delete( $endpoint, $include_company = true ) {
+        return self::request( 'DELETE', $endpoint, array(), $include_company );
+    }
+
+    /**
+     * Get all companies
+     *
+     * @return array|WP_Error Array of companies or error.
+     */
+    public static function get_companies() {
+        return self::get( '/companies', array(), false );
+    }
+
+    /**
+     * Get items with pagination support
+     *
+     * @param int    $top  Number of items to fetch.
+     * @param int    $skip Number of items to skip.
+     * @param string $select Fields to select.
+     * @return array|WP_Error Response data or error.
+     */
+    public static function get_items( $top = 100, $skip = 0, $select = '' ) {
+        $params = array(
+            '$top'  => $top,
+            '$skip' => $skip,
+        );
+
+        if ( ! empty( $select ) ) {
+            $params['$select'] = $select;
+        }
+
+        return self::get( '/items', $params );
+    }
+
+    /**
+     * Get customers with optional filter
+     *
+     * @param string $filter OData filter expression.
+     * @return array|WP_Error Response data or error.
+     */
+    public static function get_customers( $filter = '' ) {
+        $params = array();
+
+        if ( ! empty( $filter ) ) {
+            $params['$filter'] = $filter;
+        }
+
+        return self::get( '/customers', $params );
+    }
+
+    /**
+     * Create a customer
+     *
+     * @param array $data Customer data.
+     * @return array|WP_Error Response data or error.
+     */
+    public static function create_customer( $data ) {
+        return self::post( '/customers', $data );
+    }
+
+    /**
+     * Create a sales order
+     *
+     * @param array $data Sales order data.
+     * @return array|WP_Error Response data or error.
+     */
+    public static function create_sales_order( $data ) {
+        return self::post( '/salesOrders', $data );
+    }
+
+    /**
+     * Create a sales order line
+     *
+     * @param string $order_id Sales order ID.
+     * @param array  $data     Sales order line data.
+     * @return array|WP_Error Response data or error.
+     */
+    public static function create_sales_order_line( $order_id, $data ) {
+        return self::post( '/salesOrders(' . $order_id . ')/salesOrderLines', $data );
+    }
+
+    /**
+     * Escape a string value for use in OData filter expressions
+     *
+     * @param string $value The value to escape.
+     * @return string Escaped value safe for OData filters.
+     */
+    public static function escape_odata_string( $value ) {
+        return str_replace( "'", "''", $value );
+    }
+
+    /**
+     * Get a specific item by number
+     *
+     * @param string $item_number Item number.
+     * @return array|WP_Error Response data or error.
+     */
+    public static function get_item_by_number( $item_number ) {
+        $params = array(
+            '$filter' => "number eq '" . self::escape_odata_string( $item_number ) . "'",
+        );
+
+        return self::get( '/items', $params );
+    }
+}
diff --git a/woo-business-central/includes/class-wbc-cron.php b/woo-business-central/includes/class-wbc-cron.php
new file mode 100644
index 0000000..bccd296
--- /dev/null
+++ b/woo-business-central/includes/class-wbc-cron.php
@@ -0,0 +1,173 @@
+<?php
+/**
+ * Cron Scheduler for WooCommerce Business Central Integration
+ *
+ * @package WooBusinessCentral
+ */
+
+// Prevent direct access
+if ( ! defined( 'ABSPATH' ) ) {
+    exit;
+}
+
+/**
+ * Class WBC_Cron
+ *
+ * Handles scheduled tasks for syncing with Business Central.
+ */
+class WBC_Cron {
+
+    /**
+     * Cron event name
+     */
+    const SYNC_EVENT = 'wbc_product_sync_event';
+
+    /**
+     * Cleanup event name
+     */
+    const CLEANUP_EVENT = 'wbc_log_cleanup_event';
+
+    /**
+     * Constructor
+     */
+    public function __construct() {
+        // Register cleanup cron if not scheduled
+        if ( ! wp_next_scheduled( self::CLEANUP_EVENT ) ) {
+            wp_schedule_event( time(), 'daily', self::CLEANUP_EVENT );
+        }
+
+        // Hook the cleanup handler
+        add_action( self::CLEANUP_EVENT, array( $this, 'run_log_cleanup' ) );
+    }
+
+    /**
+     * Run scheduled product sync
+     */
+    public function run_scheduled_sync() {
+        WBC_Logger::info( 'Cron', 'Starting scheduled product sync' );
+
+        $product_sync = new WBC_Product_Sync();
+        $result = $product_sync->run_sync();
+
+        if ( isset( $result['success'] ) && $result['success'] ) {
+            WBC_Logger::info( 'Cron', 'Scheduled product sync completed', $result );
+        } else {
+            WBC_Logger::error( 'Cron', 'Scheduled product sync failed', $result );
+        }
+    }
+
+    /**
+     * Run log cleanup
+     */
+    public function run_log_cleanup() {
+        $deleted = WBC_Logger::cleanup_old_logs( 30 );
+        WBC_Logger::info( 'Cron', 'Log cleanup completed', array( 'deleted_count' => $deleted ) );
+    }
+
+    /**
+     * Reschedule the sync event with a new frequency
+     *
+     * @param string $frequency New frequency (hourly, twice_daily, daily).
+     */
+    public static function reschedule_sync( $frequency ) {
+        // Clear existing schedule
+        $timestamp = wp_next_scheduled( self::SYNC_EVENT );
+        if ( $timestamp ) {
+            wp_unschedule_event( $timestamp, self::SYNC_EVENT );
+        }
+
+        // Schedule with new frequency
+        wp_schedule_event( time(), $frequency, self::SYNC_EVENT );
+
+        WBC_Logger::info( 'Cron', 'Sync schedule updated', array( 'frequency' => $frequency ) );
+    }
+
+    /**
+     * Get next scheduled sync time
+     *
+     * @return int|false Timestamp of next scheduled sync or false if not scheduled.
+     */
+    public static function get_next_sync_time() {
+        return wp_next_scheduled( self::SYNC_EVENT );
+    }
+
+    /**
+     * Get next scheduled sync time formatted
+     *
+     * @return string Formatted date/time string or 'Not scheduled'.
+     */
+    public static function get_next_sync_formatted() {
+        $next = self::get_next_sync_time();
+
+        if ( ! $next ) {
+            return __( 'Not scheduled', 'woo-business-central' );
+        }
+
+        return wp_date( get_option( 'date_format' ) . ' ' . get_option( 'time_format' ), $next );
+    }
+
+    /**
+     * Get last sync time
+     *
+     * @return string|false Last sync time or false if never synced.
+     */
+    public static function get_last_sync_time() {
+        return get_option( 'wbc_last_sync_time', false );
+    }
+
+    /**
+     * Get last sync time formatted
+     *
+     * @return string Formatted date/time string or 'Never'.
+     */
+    public static function get_last_sync_formatted() {
+        $last = self::get_last_sync_time();
+
+        if ( ! $last ) {
+            return __( 'Never', 'woo-business-central' );
+        }
+
+        return wp_date( get_option( 'date_format' ) . ' ' . get_option( 'time_format' ), strtotime( $last ) );
+    }
+
+    /**
+     * Update last sync time
+     */
+    public static function update_last_sync_time() {
+        update_option( 'wbc_last_sync_time', current_time( 'mysql' ) );
+    }
+
+    /**
+     * Run sync now (manual trigger)
+     *
+     * @return array Sync result.
+     */
+    public static function run_sync_now() {
+        WBC_Logger::info( 'Cron', 'Manual sync triggered' );
+
+        $product_sync = new WBC_Product_Sync();
+        $result = $product_sync->run_sync();
+
+        // Update last sync time
+        self::update_last_sync_time();
+
+        return $result;
+    }
+
+    /**
+     * Clear all scheduled events
+     */
+    public static function clear_all_schedules() {
+        // Clear sync event
+        $sync_timestamp = wp_next_scheduled( self::SYNC_EVENT );
+        if ( $sync_timestamp ) {
+            wp_unschedule_event( $sync_timestamp, self::SYNC_EVENT );
+        }
+
+        // Clear cleanup event
+        $cleanup_timestamp = wp_next_scheduled( self::CLEANUP_EVENT );
+        if ( $cleanup_timestamp ) {
+            wp_unschedule_event( $cleanup_timestamp, self::CLEANUP_EVENT );
+        }
+    }
+}
diff --git a/woo-business-central/includes/class-wbc-customer-sync.php b/woo-business-central/includes/class-wbc-customer-sync.php
new file mode 100644
index 0000000..b8eb660
--- /dev/null
+++ b/woo-business-central/includes/class-wbc-customer-sync.php
@@ -0,0 +1,270 @@
+<?php
+/**
+ * Customer Sync to Business Central
+ *
+ * @package WooBusinessCentral
+ */
+
+// Prevent direct access
+if ( ! defined( 'ABSPATH' ) ) {
+    exit;
+}
+
+/**
+ * Class WBC_Customer_Sync
+ *
+ * Handles syncing customers from WooCommerce to Business Central.
+ */
+class WBC_Customer_Sync {
+
+    /**
+     * Get or create a customer in Business Central
+     *
+     * @param WC_Order $order WooCommerce order.
+     * @return string|WP_Error BC customer number or error.
+     */
+    public function get_or_create_customer( $order ) {
+        $email = $order->get_billing_email();
+
+        if ( empty( $email ) ) {
+            return new WP_Error( 'wbc_no_email', __( 'Order has no billing email.', 'woo-business-central' ) );
+        }
+
+        WBC_Logger::debug( 'CustomerSync', 'Getting or creating customer', array( 'email' => $email ) );
+
+        // Check if we have a cached BC customer ID for this user
+        $user_id = $order->get_user_id();
+        if ( $user_id ) {
+            $cached_customer_number = get_user_meta( $user_id, '_wbc_bc_customer_number', true );
+            if ( ! empty( $cached_customer_number ) ) {
+                // Verify the customer still exists in BC
+                $exists = $this->verify_customer_exists( $cached_customer_number );
+                if ( $exists ) {
+                    WBC_Logger::debug( 'CustomerSync', 'Using cached BC customer', array(
+                        'customer_number' => $cached_customer_number,
+                    ) );
+                    return $cached_customer_number;
+                }
+            }
+        }
+
+        // Try to find existing customer in BC by email
+        $existing = $this->find_customer_by_email( $email );
+
+        if ( is_wp_error( $existing ) ) {
+            return $existing;
+        }
+
+        if ( $existing ) {
+            $customer_number = $existing['number'];
+
+            // Cache the customer number for this user
+            if ( $user_id ) {
+                update_user_meta( $user_id, '_wbc_bc_customer_id', $existing['id'] );
+                update_user_meta( $user_id, '_wbc_bc_customer_number', $customer_number );
+            }
+
+            WBC_Logger::info( 'CustomerSync', 'Found existing BC customer', array(
+                'email'           => $email,
+                'customer_number' => $customer_number,
+            ) );
+
+            return $customer_number;
+        }
+
+        // Create new customer in BC
+        $new_customer = $this->create_customer( $order );
+
+        if ( is_wp_error( $new_customer ) ) {
+            return $new_customer;
+        }
+
+        $customer_number = $new_customer['number'];
+
+        // Cache the customer number for this user
+        if ( $user_id ) {
+            update_user_meta( $user_id, '_wbc_bc_customer_id', $new_customer['id'] );
+            update_user_meta( $user_id, '_wbc_bc_customer_number', $customer_number );
+        }
+
+        WBC_Logger::info( 'CustomerSync', 'Created new BC customer', array(
+            'email'           => $email,
+            'customer_number' => $customer_number,
+        ) );
+
+        return $customer_number;
+    }
+
+    /**
+     * Find customer in BC by email
+     *
+     * @param string $email Customer email.
+     * @return array|false|WP_Error Customer data, false if not found, or error.
+     */
+    private function find_customer_by_email( $email ) {
+        $filter = "email eq '" . WBC_API_Client::escape_odata_string( $email ) . "'";
+        $result = WBC_API_Client::get_customers( $filter );
+
+        if ( is_wp_error( $result ) ) {
+            return $result;
+        }
+
+        $customers = isset( $result['value'] ) ? $result['value'] : array();
+
+        if ( empty( $customers ) ) {
+            return false;
+        }
+
+        return $customers[0];
+    }
+
+    /**
+     * Verify a customer exists in BC
+     *
+     * @param string $customer_number BC customer number.
+     * @return bool Whether the customer exists.
+     */
+    private function verify_customer_exists( $customer_number ) {
+        $filter = "number eq '" . WBC_API_Client::escape_odata_string( $customer_number ) . "'";
+        $result = WBC_API_Client::get_customers( $filter );
+
+        if ( is_wp_error( $result ) ) {
+            return false;
+        }
+
+        $customers = isset( $result['value'] ) ? $result['value'] : array();
+
+        return ! empty( $customers );
+    }
+
+    /**
+     * Create a new customer in BC
+     *
+     * @param WC_Order $order WooCommerce order.
+     * @return array|WP_Error Created customer data or error.
+     */
+    private function create_customer( $order ) {
+        // Build customer data from order
+        $customer_data = $this->build_customer_data( $order );
+
+        WBC_Logger::debug( 'CustomerSync', 'Creating new customer in BC', array(
+            'data' => $customer_data,
+        ) );
+
+        $result = WBC_API_Client::create_customer( $customer_data );
+
+        if ( is_wp_error( $result ) ) {
+            WBC_Logger::error( 'CustomerSync', 'Failed to create customer in BC', array(
+                'error' => $result->get_error_message(),
+                'data'  => $customer_data,
+            ) );
+            return $result;
+        }
+
+        return $result;
+    }
+
+    /**
+     * Build customer data from WC order
+     *
+     * @param WC_Order $order WooCommerce order.
+     * @return array Customer data for BC API.
+     */
+    private function build_customer_data( $order ) {
+        // Get billing info
+        $first_name = $order->get_billing_first_name();
+        $last_name = $order->get_billing_last_name();
+        $company = $order->get_billing_company();
+
+        // Determine display name and type
+        if ( ! empty( $company ) ) {
+            $display_name = $company;
+            $type = 'Company';
+        } else {
+            $display_name = trim( $first_name . ' ' . $last_name );
+            $type = 'Person';
+        }
+
+        // Build address
+        $address_line1 = $order->get_billing_address_1();
+        $address_line2 = $order->get_billing_address_2();
+
+        if ( ! empty( $address_line2 ) ) {
+            $address_line1 .= ', ' . $address_line2;
+        }
+
+        // Map country code
+        $country = $order->get_billing_country();
+
+        // Build customer payload
+        $customer_data = array(
+            'displayName'  => substr( $display_name, 0, 100 ), // BC has max length
+            'type'         => $type,
+            'email'        => $order->get_billing_email(),
+        );
+
+        // Add optional fields if present
+        $phone = $order->get_billing_phone();
+        if ( ! empty( $phone ) ) {
+            $customer_data['phoneNumber'] = substr( $phone, 0, 30 );
+        }
+
+        if ( ! empty( $address_line1 ) ) {
+            $customer_data['addressLine1'] = substr( $address_line1, 0, 100 );
+        }
+
+        $city = $order->get_billing_city();
+        if ( ! empty( $city ) ) {
+            $customer_data['city'] = substr( $city, 0, 30 );
+        }
+
+        $state = $order->get_billing_state();
+        if ( ! empty( $state ) ) {
+            $customer_data['state'] = substr( $state, 0, 30 );
+        }
+
+        $postcode = $order->get_billing_postcode();
+        if ( ! empty( $postcode ) ) {
+            $customer_data['postalCode'] = substr( $postcode, 0, 20 );
+        }
+
+        if ( ! empty( $country ) ) {
+            $customer_data['country'] = $country;
+        }
+
+        // Add currency if available
+        $currency = $order->get_currency();
+        if ( ! empty( $currency ) ) {
+            $customer_data['currencyCode'] = $currency;
+        }
+
+        return $customer_data;
+    }
+
+    /**
+     * Update customer in BC with WC order data
+     *
+     * @param string   $customer_id BC customer ID.
+     * @param WC_Order $order       WooCommerce order.
+     * @return array|WP_Error Updated customer data or error.
+     */
+    public function update_customer( $customer_id, $order ) {
+        $customer_data = $this->build_customer_data( $order );
+
+        WBC_Logger::debug( 'CustomerSync', 'Updating customer in BC', array(
+            'customer_id' => $customer_id,
+            'data'        => $customer_data,
+        ) );
+
+        $result = WBC_API_Client::patch( '/customers(' . $customer_id . ')', $customer_data );
+
+        if ( is_wp_error( $result ) ) {
+            WBC_Logger::error( 'CustomerSync', 'Failed to update customer in BC', array(
+                'error'       => $result->get_error_message(),
+                'customer_id' => $customer_id,
+            ) );
+        }
+
+        return $result;
+    }
+}
diff --git a/woo-business-central/includes/class-wbc-loader.php b/woo-business-central/includes/class-wbc-loader.php
new file mode 100644
index 0000000..907e9b5
--- /dev/null
+++ b/woo-business-central/includes/class-wbc-loader.php
@@ -0,0 +1,140 @@
+<?php
+/**
+ * Register all actions and filters for the plugin
+ *
+ * @package WooBusinessCentral
+ */
+
+// Prevent direct access
+if ( ! defined( 'ABSPATH' ) ) {
+    exit;
+}
+
+/**
+ * Class WBC_Loader
+ *
+ * Maintains lists of all hooks registered throughout the plugin
+ * and registers them with WordPress.
+ */
+class WBC_Loader {
+
+    /**
+     * Array of actions registered with WordPress
+     *
+     * @var array
+     */
+    protected $actions = array();
+
+    /**
+     * Array of filters registered with WordPress
+     *
+     * @var array
+     */
+    protected $filters = array();
+
+    /**
+     * Initialize the loader
+     */
+    public function __construct() {
+        $this->actions = array();
+        $this->filters = array();
+    }
+
+    /**
+     * Add a new action to the collection
+     *
+     * @param string $hook          The name of the WordPress action.
+     * @param object $component     A reference to the instance of the object on which the action is defined.
+     * @param string $callback      The name of the function definition on the $component.
+     * @param int    $priority      Optional. The priority at which the function should be fired. Default 10.
+     * @param int    $accepted_args Optional. The number of arguments that should be passed to the callback. Default 1.
+     */
+    public function add_action( $hook, $component, $callback, $priority = 10, $accepted_args = 1 ) {
+        $this->actions = $this->add( $this->actions, $hook, $component, $callback, $priority, $accepted_args );
+    }
+
+    /**
+     * Add a new filter to the collection
+     *
+     * @param string $hook          The name of the WordPress filter.
+     * @param object $component     A reference to the instance of the object on which the filter is defined.
+     * @param string $callback      The name of the function definition on the $component.
+     * @param int    $priority      Optional. The priority at which the function should be fired. Default 10.
+     * @param int    $accepted_args Optional. The number of arguments that should be passed to the callback. Default 1.
+     */
+    public function add_filter( $hook, $component, $callback, $priority = 10, $accepted_args = 1 ) {
+        $this->filters = $this->add( $this->filters, $hook, $component, $callback, $priority, $accepted_args );
+    }
+
+    /**
+     * A utility function for registering hooks into a single collection
+     *
+     * @param array  $hooks         The collection of hooks being registered.
+     * @param string $hook          The name of the WordPress filter being registered.
+     * @param object $component     A reference to the instance of the object on which the filter is defined.
+     * @param string $callback      The name of the function definition on the $component.
+     * @param int    $priority      The priority at which the function should be fired.
+     * @param int    $accepted_args The number of arguments that should be passed to the callback.
+     * @return array The collection of actions and filters registered with WordPress.
+     */
+    private function add( $hooks, $hook, $component, $callback, $priority, $accepted_args ) {
+        $hooks[] = array(
+            'hook'          => $hook,
+            'component'     => $component,
+            'callback'      => $callback,
+            'priority'      => $priority,
+            'accepted_args' => $accepted_args,
+        );
+        return $hooks;
+    }
+
+    /**
+     * Register the filters and actions with WordPress
+     */
+    public function run() {
+        // Register cron handler
+        $cron = new WBC_Cron();
+        $this->add_action( 'wbc_product_sync_event', $cron, 'run_scheduled_sync' );
+
+        // Register order sync handler
+        $order_sync = new WBC_Order_Sync();
+        $this->add_action( 'woocommerce_order_status_processing', $order_sync, 'sync_order', 10, 1 );
+        $this->add_action( 'woocommerce_payment_complete', $order_sync, 'sync_order', 10, 1 );
+
+        // Register admin handler
+        if ( is_admin() ) {
+            $admin = new WBC_Admin();
+            $this->add_action( 'admin_menu', $admin, 'add_admin_menu' );
+            $this->add_action( 'admin_init', $admin, 'register_settings' );
+            $this->add_action( 'admin_enqueue_scripts', $admin, 'enqueue_scripts' );
+            $this->add_action( 'wp_ajax_wbc_test_connection', $admin, 'ajax_test_connection' );
+            $this->add_action( 'wp_ajax_wbc_manual_sync', $admin, 'ajax_manual_sync' );
+            $this->add_action( 'wp_ajax_wbc_clear_logs', $admin, 'ajax_clear_logs' );
+            $this->add_action( 'wp_ajax_wbc_get_companies', $admin, 'ajax_get_companies' );
+            $this->add_action( 'admin_init', $admin, 'handle_csv_export' );
+
+            // Add settings link to plugins page
+            $this->add_filter( 'plugin_action_links_' . WBC_PLUGIN_BASENAME, $admin, 'add_settings_link' );
+        }
+
+        // Register all actions
+        foreach ( $this->actions as $hook ) {
+            add_action(
+                $hook['hook'],
+                array( $hook['component'], $hook['callback'] ),
+                $hook['priority'],
+                $hook['accepted_args']
+            );
+        }
+
+        // Register all filters
+        foreach ( $this->filters as $hook ) {
+            add_filter(
+                $hook['hook'],
+                array( $hook['component'], $hook['callback'] ),
+                $hook['priority'],
+                $hook['accepted_args']
+            );
+        }
+    }
+}
diff --git a/woo-business-central/includes/class-wbc-logger.php b/woo-business-central/includes/class-wbc-logger.php
new file mode 100644
index 0000000..182e5b3
--- /dev/null
+++ b/woo-business-central/includes/class-wbc-logger.php
@@ -0,0 +1,325 @@
+<?php
+/**
+ * Logger class for WooCommerce Business Central Integration
+ *
+ * @package WooBusinessCentral
+ */
+
+// Prevent direct access
+if ( ! defined( 'ABSPATH' ) ) {
+    exit;
+}
+
+/**
+ * Class WBC_Logger
+ *
+ * Handles logging to database with different severity levels.
+ */
+class WBC_Logger {
+
+    /**
+     * Log level constants
+     */
+    const DEBUG   = 'DEBUG';
+    const INFO    = 'INFO';
+    const WARNING = 'WARNING';
+    const ERROR   = 'ERROR';
+
+    /**
+     * Database table name
+     *
+     * @var string
+     */
+    private static $table_name = null;
+
+    /**
+     * Create the logs database table
+     */
+    public static function create_table() {
+        global $wpdb;
+
+        $table_name = $wpdb->prefix . 'wbc_logs';
+        $charset_collate = $wpdb->get_charset_collate();
+
+        $sql = "CREATE TABLE IF NOT EXISTS $table_name (
+            id bigint(20) NOT NULL AUTO_INCREMENT,
+            timestamp datetime DEFAULT CURRENT_TIMESTAMP NOT NULL,
+            level varchar(20) NOT NULL,
+            context varchar(100) NOT NULL,
+            message text NOT NULL,
+            data longtext,
+            PRIMARY KEY (id),
+            KEY level (level),
+            KEY context (context),
+            KEY timestamp (timestamp)
+        ) $charset_collate;";
+
+        require_once ABSPATH . 'wp-admin/includes/upgrade.php';
+        dbDelta( $sql );
+    }
+
+    /**
+     * Get the table name
+     *
+     * @return string
+     */
+    private static function get_table_name() {
+        if ( self::$table_name === null ) {
+            global $wpdb;
+            self::$table_name = $wpdb->prefix . 'wbc_logs';
+        }
+        return self::$table_name;
+    }
+
+    /**
+     * Log a debug message
+     *
+     * @param string $context The context/source of the log.
+     * @param string $message The log message.
+     * @param mixed  $data    Optional. Additional data to log.
+     */
+    public static function debug( $context, $message, $data = null ) {
+        self::log( self::DEBUG, $context, $message, $data );
+    }
+
+    /**
+     * Log an info message
+     *
+     * @param string $context The context/source of the log.
+     * @param string $message The log message.
+     * @param mixed  $data    Optional. Additional data to log.
+     */
+    public static function info( $context, $message, $data = null ) {
+        self::log( self::INFO, $context, $message, $data );
+    }
+
+    /**
+     * Log a warning message
+     *
+     * @param string $context The context/source of the log.
+     * @param string $message The log message.
+     * @param mixed  $data    Optional. Additional data to log.
+     */
+    public static function warning( $context, $message, $data = null ) {
+        self::log( self::WARNING, $context, $message, $data );
+    }
+
+    /**
+     * Log an error message
+     *
+     * @param string $context The context/source of the log.
+     * @param string $message The log message.
+     * @param mixed  $data    Optional. Additional data to log.
+     */
+    public static function error( $context, $message, $data = null ) {
+        self::log( self::ERROR, $context, $message, $data );
+    }
+
+    /**
+     * Log a message to the database
+     *
+     * @param string $level   The log level.
+     * @param string $context The context/source of the log.
+     * @param string $message The log message.
+     * @param mixed  $data    Optional. Additional data to log.
+     */
+    private static function log( $level, $context, $message, $data = null ) {
+        global $wpdb;
+
+        $table_name = self::get_table_name();
+
+        // Prepare data for storage
+        $data_json = null;
+        if ( $data !== null ) {
+            $data_json = wp_json_encode( $data, JSON_PRETTY_PRINT );
+        }
+
+        // Insert log entry
+        $wpdb->insert(
+            $table_name,
+            array(
+                'timestamp' => current_time( 'mysql' ),
+                'level'     => $level,
+                'context'   => sanitize_text_field( $context ),
+                'message'   => sanitize_textarea_field( $message ),
+                'data'      => $data_json,
+            ),
+            array( '%s', '%s', '%s', '%s', '%s' )
+        );
+
+        // Also log to WooCommerce logger if available
+        if ( function_exists( 'wc_get_logger' ) ) {
+            $wc_logger = wc_get_logger();
+            $log_level = strtolower( $level );
+            if ( method_exists( $wc_logger, $log_level ) ) {
+                $wc_message = "[$context] $message";
+                if ( $data !== null ) {
+                    $wc_message .= ' | Data: ' . wp_json_encode( $data );
+                }
+                $wc_logger->$log_level( $wc_message, array( 'source' => 'woo-business-central' ) );
+            }
+        }
+    }
+
+    /**
+     * Get log entries
+     *
+     * @param array $args Query arguments.
+     * @return array Array of log entries.
+     */
+    public static function get_logs( $args = array() ) {
+        global $wpdb;
+
+        $defaults = array(
+            'level'    => '',
+            'context'  => '',
+            'limit'    => 100,
+            'offset'   => 0,
+            'orderby'  => 'timestamp',
+            'order'    => 'DESC',
+        );
+
+        $args = wp_parse_args( $args, $defaults );
+        $table_name = self::get_table_name();
+
+        // Build WHERE clause
+        $where = array( '1=1' );
+        $values = array();
+
+        if ( ! empty( $args['level'] ) ) {
+            $where[] = 'level = %s';
+            $values[] = $args['level'];
+        }
+
+        if ( ! empty( $args['context'] ) ) {
+            $where[] = 'context = %s';
+            $values[] = $args['context'];
+        }
+
+        $where_clause = implode( ' AND ', $where );
+
+        // Sanitize orderby and order
+        $allowed_orderby = array( 'id', 'timestamp', 'level', 'context' );
+        $orderby = in_array( $args['orderby'], $allowed_orderby, true ) ? $args['orderby'] : 'timestamp';
+        $order = strtoupper( $args['order'] ) === 'ASC' ? 'ASC' : 'DESC';
+
+        // Build query
+        $limit = absint( $args['limit'] );
+        $offset = absint( $args['offset'] );
+
+        $sql = "SELECT * FROM $table_name WHERE $where_clause ORDER BY $orderby $order LIMIT $limit OFFSET $offset";
+
+        if ( ! empty( $values ) ) {
+            $sql = $wpdb->prepare( $sql, $values );
+        }
+
+        return $wpdb->get_results( $sql, ARRAY_A );
+    }
+
+    /**
+     * Get total log count
+     *
+     * @param array $args Query arguments.
+     * @return int Total count.
+     */
+    public static function get_log_count( $args = array() ) {
+        global $wpdb;
+
+        $table_name = self::get_table_name();
+
+        // Build WHERE clause
+        $where = array( '1=1' );
+        $values = array();
+
+        if ( ! empty( $args['level'] ) ) {
+            $where[] = 'level = %s';
+            $values[] = $args['level'];
+        }
+
+        if ( ! empty( $args['context'] ) ) {
+            $where[] = 'context = %s';
+            $values[] = $args['context'];
+        }
+
+        $where_clause = implode( ' AND ', $where );
+
+        $sql = "SELECT COUNT(*) FROM $table_name WHERE $where_clause";
+
+        if ( ! empty( $values ) ) {
+            $sql = $wpdb->prepare( $sql, $values );
+        }
+
+        return (int) $wpdb->get_var( $sql );
+    }
+
+    /**
+     * Clear all logs
+     *
+     * @return bool|int Number of rows deleted or false on error.
+     */
+    public static function clear_logs() {
+        global $wpdb;
+        $table_name = self::get_table_name();
+        return $wpdb->query( "TRUNCATE TABLE $table_name" );
+    }
+
+    /**
+     * Delete old logs
+     *
+     * @param int $days Number of days to keep logs.
+     * @return int Number of rows deleted.
+     */
+    public static function cleanup_old_logs( $days = 30 ) {
+        global $wpdb;
+
+        $table_name = self::get_table_name();
+        $cutoff_date = gmdate( 'Y-m-d H:i:s', strtotime( "-{$days} days" ) );
+
+        return $wpdb->query(
+            $wpdb->prepare(
+                "DELETE FROM $table_name WHERE timestamp < %s",
+                $cutoff_date
+            )
+        );
+    }
+
+    /**
+     * Export logs to CSV format
+     *
+     * @param array $args Query arguments.
+     * @return string CSV content.
+     */
+    public static function export_to_csv( $args = array() ) {
+        $logs = self::get_logs( array_merge( $args, array( 'limit' => 10000 ) ) );
+
+        $output = "ID,Timestamp,Level,Context,Message,Data\n";
+
+        foreach ( $logs as $log ) {
+            $row = array(
+                $log['id'],
+                $log['timestamp'],
+                $log['level'],
+                self::sanitize_csv_field( $log['context'] ),
+                self::sanitize_csv_field( $log['message'] ),
+                self::sanitize_csv_field( $log['data'] ?? '' ),
+            );
+            $output .= implode( ',', $row ) . "\n";
+        }
+
+        return $output;
+    }
+
+    /**
+     * Sanitize a field value for CSV export to prevent formula injection
+     *
+     * @param string $value The value to sanitize.
+     * @return string Sanitized and quoted CSV value.
+     */
+    private static function sanitize_csv_field( $value ) {
+        // Prevent formula injection by prefixing dangerous characters with a single quote
+        if ( preg_match( '/^[=+\-@\t\r]/', $value ) ) {
+            $value = "'" . $value;
+        }
+        return '"' . str_replace( '"', '""', $value ) . '"';
+    }
+}
diff --git a/woo-business-central/includes/class-wbc-oauth.php b/woo-business-central/includes/class-wbc-oauth.php
new file mode 100644
index 0000000..2462e22
--- /dev/null
+++ b/woo-business-central/includes/class-wbc-oauth.php
@@ -0,0 +1,338 @@
+<?php
+/**
+ * OAuth2 Authentication for Business Central API
+ *
+ * @package WooBusinessCentral
+ */
+
+// Prevent direct access
+if ( ! defined( 'ABSPATH' ) ) {
+    exit;
+}
+
+/**
+ * Class WBC_OAuth
+ *
+ * Handles OAuth2 token management for Microsoft Business Central API.
+ */
+class WBC_OAuth {
+
+    /**
+     * Token endpoint URL template
+     */
+    const TOKEN_ENDPOINT = 'https://login.microsoftonline.com/%s/oauth2/v2.0/token';
+
+    /**
+     * API scope
+     */
+    const API_SCOPE = 'https://api.businesscentral.dynamics.com/.default';
+
+    /**
+     * Token transient name
+     */
+    const TOKEN_TRANSIENT = 'wbc_access_token';
+
+    /**
+     * Token expiry buffer (refresh 5 minutes before expiry)
+     */
+    const EXPIRY_BUFFER = 300;
+
+    /**
+     * Encryption key option name
+     */
+    const ENCRYPTION_KEY_OPTION = 'wbc_encryption_key';
+
+    /**
+     * Get the encryption key
+     *
+     * @return string
+     */
+    private static function get_encryption_key() {
+        $key = get_option( self::ENCRYPTION_KEY_OPTION );
+
+        if ( empty( $key ) ) {
+            // Generate a new key if one doesn't exist
+            $key = wp_generate_password( 32, true, true );
+            update_option( self::ENCRYPTION_KEY_OPTION, $key );
+        }
+
+        return $key;
+    }
+
+    /**
+     * Encrypt a value
+     *
+     * @param string $value The value to encrypt.
+     * @return string Encrypted value.
+     */
+    public static function encrypt( $value ) {
+        if ( empty( $value ) ) {
+            return '';
+        }
+
+        $key = self::get_encryption_key();
+
+        // Use WordPress salt for additional entropy
+        $salt = wp_salt( 'auth' );
+        $key = hash( 'sha256', $key . $salt, true );
+
+        // Generate random IV
+        $iv_length = openssl_cipher_iv_length( 'aes-256-cbc' );
+        $iv = openssl_random_pseudo_bytes( $iv_length );
+
+        // Encrypt (OPENSSL_RAW_DATA ensures raw binary output)
+        $encrypted = openssl_encrypt( $value, 'aes-256-cbc', $key, OPENSSL_RAW_DATA, $iv );
+
+        if ( $encrypted === false ) {
+            return '';
+        }
+
+        // Combine IV and encrypted data, then base64 encode
+        return base64_encode( $iv . $encrypted );
+    }
+
+    /**
+     * Decrypt a value
+     *
+     * @param string $encrypted The encrypted value.
+     * @return string Decrypted value.
+     */
+    public static function decrypt( $encrypted ) {
+        if ( empty( $encrypted ) ) {
+            return '';
+        }
+
+        $key = self::get_encryption_key();
+
+        // Use WordPress salt for additional entropy
+        $salt = wp_salt( 'auth' );
+        $key = hash( 'sha256', $key . $salt, true );
+
+        // Decode
+        $data = base64_decode( $encrypted );
+        if ( $data === false ) {
+            return '';
+        }
+
+        // Extract IV and encrypted data
+        $iv_length = openssl_cipher_iv_length( 'aes-256-cbc' );
+        $iv = substr( $data, 0, $iv_length );
+        $encrypted_data = substr( $data, $iv_length );
+
+        // Decrypt (OPENSSL_RAW_DATA matches the encrypt flag)
+        $decrypted = openssl_decrypt( $encrypted_data, 'aes-256-cbc', $key, OPENSSL_RAW_DATA, $iv );
+
+        return $decrypted !== false ? $decrypted : '';
+    }
+
+    /**
+     * Get stored tenant ID
+     *
+     * @return string
+     */
+    public static function get_tenant_id() {
+        return get_option( 'wbc_tenant_id', '' );
+    }
+
+    /**
+     * Get stored client ID
+     *
+     * @return string
+     */
+    public static function get_client_id() {
+        return get_option( 'wbc_client_id', '' );
+    }
+
+    /**
+     * Get stored client secret (decrypted)
+     *
+     * @return string
+     */
+    public static function get_client_secret() {
+        $encrypted = get_option( 'wbc_client_secret', '' );
+        return self::decrypt( $encrypted );
+    }
+
+    /**
+     * Save client secret (encrypted)
+     *
+     * @param string $secret The client secret to save.
+     */
+    public static function save_client_secret( $secret ) {
+        $encrypted = self::encrypt( $secret );
+        update_option( 'wbc_client_secret', $encrypted );
+    }
+
+    /**
+     * Get environment (production/sandbox)
+     *
+     * @return string
+     */
+    public static function get_environment() {
+        return get_option( 'wbc_environment', 'production' );
+    }
+
+    /**
+     * Get company ID
+     *
+     * @return string
+     */
+    public static function get_company_id() {
+        return get_option( 'wbc_company_id', '' );
+    }
+
+    /**
+     * Check if credentials are configured
+     *
+     * @return bool
+     */
+    public static function is_configured() {
+        return ! empty( self::get_tenant_id() )
+            && ! empty( self::get_client_id() )
+            && ! empty( self::get_client_secret() )
+            && ! empty( self::get_company_id() );
+    }
+
+    /**
+     * Get access token
+     *
+     * @param bool $force_refresh Force refresh even if cached token exists.
+     * @return string|WP_Error Access token or error.
+     */
+    public static function get_access_token( $force_refresh = false ) {
+        // Check for cached token
+        if ( ! $force_refresh ) {
+            $cached_token = get_transient( self::TOKEN_TRANSIENT );
+            if ( $cached_token !== false ) {
+                return $cached_token;
+            }
+        }
+
+        // Request new token
+        return self::request_token();
+    }
+
+    /**
+     * Request a new access token from Microsoft
+     *
+     * @return string|WP_Error Access token or error.
+     */
+    private static function request_token() {
+        $tenant_id = self::get_tenant_id();
+        $client_id = self::get_client_id();
+        $client_secret = self::get_client_secret();
+
+        // Validate credentials
+        if ( empty( $tenant_id ) || empty( $client_id ) || empty( $client_secret ) ) {
+            $error = new WP_Error( 'wbc_missing_credentials', __( 'Business Central API credentials are not configured.', 'woo-business-central' ) );
+            WBC_Logger::error( 'OAuth', 'Missing API credentials' );
+            return $error;
+        }
+
+        // Build token endpoint URL
+        $token_url = sprintf( self::TOKEN_ENDPOINT, $tenant_id );
+
+        // Prepare request body
+        $body = array(
+            'grant_type'    => 'client_credentials',
+            'client_id'     => $client_id,
+            'client_secret' => $client_secret,
+            'scope'         => self::API_SCOPE,
+        );
+
+        WBC_Logger::debug( 'OAuth', 'Requesting new access token', array( 'tenant_id' => $tenant_id ) );
+
+        // Make the request using cURL
+        $ch = curl_init();
+
+        curl_setopt_array( $ch, array(
+            CURLOPT_URL            => $token_url,
+            CURLOPT_POST           => true,
+            CURLOPT_POSTFIELDS     => http_build_query( $body ),
+            CURLOPT_RETURNTRANSFER => true,
+            CURLOPT_TIMEOUT        => 30,
+            CURLOPT_HTTPHEADER     => array(
+                'Content-Type: application/x-www-form-urlencoded',
+            ),
+        ) );
+
+        $response = curl_exec( $ch );
+        $http_code = curl_getinfo( $ch, CURLINFO_HTTP_CODE );
+        $curl_error = curl_error( $ch );
+
+        curl_close( $ch );
+
+        // Check for cURL errors
+        if ( $response === false ) {
+            $error = new WP_Error( 'wbc_curl_error', sprintf( __( 'cURL error: %s', 'woo-business-central' ), $curl_error ) );
+            WBC_Logger::error( 'OAuth', 'cURL error during token request', array( 'error' => $curl_error ) );
+            return $error;
+        }
+
+        // Parse response
+        $data = json_decode( $response, true );
+
+        // Check for HTTP errors
+        if ( $http_code !== 200 ) {
+            $error_message = isset( $data['error_description'] ) ? $data['error_description'] : __( 'Unknown error', 'woo-business-central' );
+            $error = new WP_Error( 'wbc_token_error', $error_message, array( 'status' => $http_code ) );
+            WBC_Logger::error( 'OAuth', 'Token request failed', array(
+                'http_code' => $http_code,
+                'error'     => $data['error'] ?? 'unknown',
+                'message'   => $error_message,
+            ) );
+            return $error;
+        }
+
+        // Extract token
+        if ( ! isset( $data['access_token'] ) ) {
+            $error = new WP_Error( 'wbc_invalid_response', __( 'Invalid token response from Microsoft.', 'woo-business-central' ) );
+            WBC_Logger::error( 'OAuth', 'Invalid token response', array( 'response' => $data ) );
+            return $error;
+        }
+
+        $access_token = $data['access_token'];
+        $expires_in = isset( $data['expires_in'] ) ? (int) $data['expires_in'] : 3600;
+
+        // Cache the token (with buffer for expiry)
+        $cache_duration = max( 60, $expires_in - self::EXPIRY_BUFFER );
+        set_transient( self::TOKEN_TRANSIENT, $access_token, $cache_duration );
+
+        WBC_Logger::info( 'OAuth', 'Successfully obtained access token', array(
+            'expires_in' => $expires_in,
+            'cached_for' => $cache_duration,
+        ) );
+
+        return $access_token;
+    }
+
+    /**
+     * Clear cached token
+     */
+    public static function clear_token_cache() {
+        delete_transient( self::TOKEN_TRANSIENT );
+        WBC_Logger::debug( 'OAuth', 'Token cache cleared' );
+    }
+
+    /**
+     * Test the connection to Business Central
+     *
+     * @return array|WP_Error Array with success status or WP_Error.
+     */
+    public static function test_connection() {
+        // Clear any cached token
+        self::clear_token_cache();
+
+        // Try to get a new token
+        $token = self::get_access_token( true );
+
+        if ( is_wp_error( $token ) ) {
+            return $token;
+        }
+
+        return array(
+            'success' => true,
+            'message' => __( 'Successfully connected to Business Central.', 'woo-business-central' ),
+        );
+    }
+}
diff --git a/woo-business-central/includes/class-wbc-order-sync.php b/woo-business-central/includes/class-wbc-order-sync.php
new file mode 100644
index 0000000..5cafa85
--- /dev/null
+++ b/woo-business-central/includes/class-wbc-order-sync.php
@@ -0,0 +1,333 @@
+<?php
+/**
+ * Order Sync to Business Central
+ *
+ * @package WooBusinessCentral
+ */
+
+// Prevent direct access
+if ( ! defined( 'ABSPATH' ) ) {
+    exit;
+}
+
+/**
+ * Class WBC_Order_Sync
+ *
+ * Handles syncing orders from WooCommerce to Business Central.
+ */
+class WBC_Order_Sync {
+
+    /**
+     * Customer sync instance
+     *
+     * @var WBC_Customer_Sync
+     */
+    private $customer_sync;
+
+    /**
+     * Constructor
+     */
+    public function __construct() {
+        $this->customer_sync = new WBC_Customer_Sync();
+    }
+
+    /**
+     * Sync an order to Business Central
+     *
+     * @param int $order_id WooCommerce order ID.
+     * @return array|WP_Error Sync result or error.
+     */
+    public function sync_order( $order_id ) {
+        // Check if order sync is enabled
+        if ( get_option( 'wbc_enable_order_sync', 'yes' ) !== 'yes' ) {
+            return array(
+                'success' => false,
+                'message' => __( 'Order sync is disabled.', 'woo-business-central' ),
+            );
+        }
+
+        // Check if credentials are configured
+        if ( ! WBC_OAuth::is_configured() ) {
+            WBC_Logger::error( 'OrderSync', 'Order sync failed - API credentials not configured', array(
+                'order_id' => $order_id,
+            ) );
+            return new WP_Error( 'wbc_not_configured', __( 'API credentials not configured.', 'woo-business-central' ) );
+        }
+
+        // Get the order
+        $order = wc_get_order( $order_id );
+
+        if ( ! $order ) {
+            return new WP_Error( 'wbc_order_not_found', __( 'Order not found.', 'woo-business-central' ) );
+        }
+
+        // Check if order is already synced
+        $bc_order_id = $order->get_meta( '_wbc_bc_order_id' );
+        if ( ! empty( $bc_order_id ) ) {
+            WBC_Logger::debug( 'OrderSync', 'Order already synced', array(
+                'order_id'    => $order_id,
+                'bc_order_id' => $bc_order_id,
+            ) );
+            return array(
+                'success' => true,
+                'message' => __( 'Order already synced to Business Central.', 'woo-business-central' ),
+                'bc_order_id' => $bc_order_id,
+            );
+        }
+
+        // Acquire a lock to prevent duplicate syncs from concurrent hooks
+        $lock_key = 'wbc_syncing_order_' . $order_id;
+        if ( get_transient( $lock_key ) ) {
+            WBC_Logger::debug( 'OrderSync', 'Order sync already in progress', array( 'order_id' => $order_id ) );
+            return array(
+                'success' => true,
+                'message' => __( 'Order sync already in progress.', 'woo-business-central' ),
+            );
+        }
+        set_transient( $lock_key, true, 120 );
+
+        WBC_Logger::info( 'OrderSync', 'Starting order sync', array( 'order_id' => $order_id ) );
+
+        // Step 1: Get or create customer in BC
+        $customer_number = $this->customer_sync->get_or_create_customer( $order );
+
+        if ( is_wp_error( $customer_number ) ) {
+            $this->add_order_note( $order, sprintf(
+                __( 'Failed to sync customer to Business Central: %s', 'woo-business-central' ),
+                $customer_number->get_error_message()
+            ) );
+            return $customer_number;
+        }
+
+        // Step 2: Create sales order in BC
+        $sales_order = $this->create_sales_order( $order, $customer_number );
+
+        if ( is_wp_error( $sales_order ) ) {
+            $this->add_order_note( $order, sprintf(
+                __( 'Failed to create sales order in Business Central: %s', 'woo-business-central' ),
+                $sales_order->get_error_message()
+            ) );
+            return $sales_order;
+        }
+
+        $bc_order_id = $sales_order['id'];
+        $bc_order_number = $sales_order['number'] ?? '';
+
+        // Step 3: Add sales order lines
+        $lines_result = $this->create_sales_order_lines( $order, $bc_order_id );
+
+        if ( is_wp_error( $lines_result ) ) {
+            // Log the error but don't fail completely
+            WBC_Logger::warning( 'OrderSync', 'Some order lines failed to sync', array(
+                'order_id'    => $order_id,
+                'bc_order_id' => $bc_order_id,
+                'error'       => $lines_result->get_error_message(),
+            ) );
+        }
+
+        // Step 4: Save BC order ID to WC order meta
+        $order->update_meta_data( '_wbc_bc_order_id', $bc_order_id );
+        $order->update_meta_data( '_wbc_bc_order_number', $bc_order_number );
+        $order->update_meta_data( '_wbc_synced_at', current_time( 'mysql' ) );
+        $order->save();
+
+        // Add order note
+        $this->add_order_note( $order, sprintf(
+            __( 'Order synced to Business Central. BC Order Number: %s', 'woo-business-central' ),
+            $bc_order_number
+        ) );
+
+        // Release the sync lock
+        delete_transient( 'wbc_syncing_order_' . $order_id );
+
+        WBC_Logger::info( 'OrderSync', 'Order sync completed', array(
+            'order_id'        => $order_id,
+            'bc_order_id'     => $bc_order_id,
+            'bc_order_number' => $bc_order_number,
+        ) );
+
+        return array(
+            'success'         => true,
+            'message'         => __( 'Order synced to Business Central.', 'woo-business-central' ),
+            'bc_order_id'     => $bc_order_id,
+            'bc_order_number' => $bc_order_number,
+        );
+    }
+
+    /**
+     * Create sales order in BC
+     *
+     * @param WC_Order $order           WooCommerce order.
+     * @param string   $customer_number BC customer number.
+     * @return array|WP_Error Created sales order or error.
+     */
+    private function create_sales_order( $order, $customer_number ) {
+        $order_data = array(
+            'customerNumber'         => $customer_number,
+            'orderDate'              => $order->get_date_created()->format( 'Y-m-d' ),
+            'externalDocumentNumber' => $order->get_order_number(),
+            'currencyCode'           => $order->get_currency(),
+        );
+
+        // Add payment terms if configured
+        $payment_terms_id = get_option( 'wbc_default_payment_terms_id', '' );
+        if ( ! empty( $payment_terms_id ) ) {
+            $order_data['paymentTermsId'] = $payment_terms_id;
+        }
+
+        // Add shipment method if configured
+        $shipment_method_id = get_option( 'wbc_default_shipment_method_id', '' );
+        if ( ! empty( $shipment_method_id ) ) {
+            $order_data['shipmentMethodId'] = $shipment_method_id;
+        }
+
+        // Add shipping address if different from billing
+        $shipping_address_1 = $order->get_shipping_address_1();
+        if ( ! empty( $shipping_address_1 ) ) {
+            $order_data['shipToName'] = trim( $order->get_shipping_first_name() . ' ' . $order->get_shipping_last_name() );
+            $order_data['shipToAddressLine1'] = $shipping_address_1;
+            $order_data['shipToCity'] = $order->get_shipping_city();
+            $order_data['shipToState'] = $order->get_shipping_state();
+            $order_data['shipToPostCode'] = $order->get_shipping_postcode();
+            $order_data['shipToCountry'] = $order->get_shipping_country();
+        }
+
+        WBC_Logger::debug( 'OrderSync', 'Creating sales order in BC', array(
+            'order_id' => $order->get_id(),
+            'data'     => $order_data,
+        ) );
+
+        return WBC_API_Client::create_sales_order( $order_data );
+    }
+
+    /**
+     * Create sales order lines in BC
+     *
+     * @param WC_Order $order       WooCommerce order.
+     * @param string   $bc_order_id BC sales order ID.
+     * @return true|WP_Error True on success or error.
+     */
+    private function create_sales_order_lines( $order, $bc_order_id ) {
+        $errors = array();
+        $items = $order->get_items();
+
+        foreach ( $items as $item_id => $item ) {
+            $product = $item->get_product();
+
+            if ( ! $product ) {
+                WBC_Logger::warning( 'OrderSync', 'Skipping order line - product not found', array(
+                    'order_id' => $order->get_id(),
+                    'item_id'  => $item_id,
+                ) );
+                continue;
+            }
+
+            // Get the BC item number (use SKU)
+            $bc_item_number = $product->get_sku();
+
+            if ( empty( $bc_item_number ) ) {
+                WBC_Logger::warning( 'OrderSync', 'Skipping order line - product has no SKU', array(
+                    'order_id'   => $order->get_id(),
+                    'product_id' => $product->get_id(),
+                ) );
+                $errors[] = sprintf( 'Product "%s" has no SKU', $product->get_name() );
+                continue;
+            }
+
+            // Build line data
+            $line_data = array(
+                'lineType'         => 'Item',
+                'lineObjectNumber' => $bc_item_number,
+                'quantity'         => $item->get_quantity(),
+                'unitPrice'        => (float) $order->get_item_total( $item, false, false ),
+            );
+
+            // Add description if different from product name
+            $line_description = $item->get_name();
+            if ( ! empty( $line_description ) ) {
+                $line_data['description'] = substr( $line_description, 0, 100 );
+            }
+
+            WBC_Logger::debug( 'OrderSync', 'Creating sales order line', array(
+                'bc_order_id' => $bc_order_id,
+                'data'        => $line_data,
+            ) );
+
+            $result = WBC_API_Client::create_sales_order_line( $bc_order_id, $line_data );
+
+            if ( is_wp_error( $result ) ) {
+                WBC_Logger::error( 'OrderSync', 'Failed to create sales order line', array(
+                    'bc_order_id'    => $bc_order_id,
+                    'bc_item_number' => $bc_item_number,
+                    'error'          => $result->get_error_message(),
+                ) );
+                $errors[] = sprintf( 'Item %s: %s', $bc_item_number, $result->get_error_message() );
+            }
+        }
+
+        // Handle shipping as a line item if there's shipping cost
+        $shipping_total = (float) $order->get_shipping_total();
+        if ( $shipping_total > 0 ) {
+            $shipping_item_number = get_option( 'wbc_shipping_item_number', '' );
+
+            if ( ! empty( $shipping_item_number ) ) {
+                $shipping_line = array(
+                    'lineType'         => 'Item',
+                    'lineObjectNumber' => $shipping_item_number,
+                    'quantity'         => 1,
+                    'unitPrice'        => $shipping_total,
+                    'description'      => __( 'Shipping', 'woo-business-central' ),
+                );
+
+                $result = WBC_API_Client::create_sales_order_line( $bc_order_id, $shipping_line );
+
+                if ( is_wp_error( $result ) ) {
+                    WBC_Logger::warning( 'OrderSync', 'Failed to add shipping line', array(
+                        'bc_order_id' => $bc_order_id,
+                        'error'       => $result->get_error_message(),
+                    ) );
+                }
+            }
+        }
+
+        if ( ! empty( $errors ) ) {
+            return new WP_Error( 'wbc_line_errors', implode( '; ', $errors ) );
+        }
+
+        return true;
+    }
+
+    /**
+     * Add order note
+     *
+     * @param WC_Order $order   WooCommerce order.
+     * @param string   $message Note message.
+     */
+    private function add_order_note( $order, $message ) {
+        $order->add_order_note( '[WBC] ' . $message );
+    }
+
+    /**
+     * Manual sync for an order (callable from admin)
+     *
+     * @param int $order_id WooCommerce order ID.
+     * @return array Sync result.
+     */
+    public function manual_sync( $order_id ) {
+        $order = wc_get_order( $order_id );
+
+        if ( ! $order ) {
+            return array(
+                'success' => false,
+                'message' => __( 'Order not found.', 'woo-business-central' ),
+            );
+        }
+
+        // Clear existing sync data to force re-sync
+        $order->delete_meta_data( '_wbc_bc_order_id' );
+        $order->delete_meta_data( '_wbc_bc_order_number' );
+        $order->save();
+
+        return $this->sync_order( $order_id );
+    }
+}
diff --git a/woo-business-central/includes/class-wbc-product-sync.php b/woo-business-central/includes/class-wbc-product-sync.php
new file mode 100644
index 0000000..f7490c7
--- /dev/null
+++ b/woo-business-central/includes/class-wbc-product-sync.php
@@ -0,0 +1,360 @@
+<?php
+/**
+ * Product Sync from Business Central to WooCommerce
+ *
+ * @package WooBusinessCentral
+ */
+
+// Prevent direct access
+if ( ! defined( 'ABSPATH' ) ) {
+    exit;
+}
+
+/**
+ * Class WBC_Product_Sync
+ *
+ * Handles syncing stock and pricing from Business Central to WooCommerce.
+ */
+class WBC_Product_Sync {
+
+    /**
+     * Items per page for BC API pagination
+     */
+    const ITEMS_PER_PAGE = 100;
+
+    /**
+     * Fields to select from BC items
+     */
+    const SELECT_FIELDS = 'id,number,gtin,displayName,unitPrice,inventory';
+
+    /**
+     * Sync results
+     *
+     * @var array
+     */
+    private $results = array(
+        'success'  => 0,
+        'failed'   => 0,
+        'skipped'  => 0,
+        'total'    => 0,
+        'errors'   => array(),
+    );
+
+    /**
+     * Run the product sync
+     *
+     * @return array Sync results.
+     */
+    public function run_sync() {
+        // Check if sync is enabled
+        if ( get_option( 'wbc_enable_stock_sync', 'yes' ) !== 'yes' && get_option( 'wbc_enable_price_sync', 'yes' ) !== 'yes' ) {
+            WBC_Logger::info( 'ProductSync', 'Sync skipped - both stock and price sync are disabled' );
+            return array(
+                'success' => true,
+                'message' => __( 'Sync skipped - both stock and price sync are disabled.', 'woo-business-central' ),
+            );
+        }
+
+        // Check if credentials are configured
+        if ( ! WBC_OAuth::is_configured() ) {
+            WBC_Logger::error( 'ProductSync', 'Sync failed - API credentials not configured' );
+            return array(
+                'success' => false,
+                'message' => __( 'Sync failed - API credentials not configured.', 'woo-business-central' ),
+            );
+        }
+
+        WBC_Logger::info( 'ProductSync', 'Starting product sync' );
+
+        $start_time = microtime( true );
+        $skip = 0;
+        $has_more = true;
+
+        // Fetch all items from BC with pagination
+        while ( $has_more ) {
+            $items = $this->fetch_items( $skip );
+
+            if ( is_wp_error( $items ) ) {
+                $this->results['errors'][] = $items->get_error_message();
+                WBC_Logger::error( 'ProductSync', 'Failed to fetch items from BC', array(
+                    'error' => $items->get_error_message(),
+                    'skip'  => $skip,
+                ) );
+                break;
+            }
+
+            // Check if we have items
+            $item_list = isset( $items['value'] ) ? $items['value'] : array();
+
+            if ( empty( $item_list ) ) {
+                $has_more = false;
+                break;
+            }
+
+            // Process each item
+            foreach ( $item_list as $item ) {
+                $this->process_item( $item );
+            }
+
+            // Check for more pages
+            $skip += self::ITEMS_PER_PAGE;
+            $has_more = count( $item_list ) >= self::ITEMS_PER_PAGE;
+
+            // Add a small delay to avoid rate limiting
+            if ( $has_more ) {
+                usleep( 100000 ); // 100ms
+            }
+        }
+
+        $duration = round( microtime( true ) - $start_time, 2 );
+
+        WBC_Logger::info( 'ProductSync', 'Product sync completed', array(
+            'duration_seconds' => $duration,
+            'total'            => $this->results['total'],
+            'success'          => $this->results['success'],
+            'failed'           => $this->results['failed'],
+            'skipped'          => $this->results['skipped'],
+        ) );
+
+        return array(
+            'success'  => empty( $this->results['errors'] ),
+            'message'  => sprintf(
+                __( 'Sync completed in %s seconds. Success: %d, Failed: %d, Skipped: %d', 'woo-business-central' ),
+                $duration,
+                $this->results['success'],
+                $this->results['failed'],
+                $this->results['skipped']
+            ),
+            'results'  => $this->results,
+        );
+    }
+
+    /**
+     * Fetch items from Business Central
+     *
+     * @param int $skip Number of items to skip.
+     * @return array|WP_Error Items data or error.
+     */
+    private function fetch_items( $skip = 0 ) {
+        return WBC_API_Client::get_items( self::ITEMS_PER_PAGE, $skip, self::SELECT_FIELDS );
+    }
+
+    /**
+     * Process a single BC item
+     *
+     * @param array $item BC item data.
+     */
+    private function process_item( $item ) {
+        $this->results['total']++;
+
+        // Get item number and GTIN
+        $item_number = isset( $item['number'] ) ? $item['number'] : '';
+        $gtin = isset( $item['gtin'] ) ? $item['gtin'] : '';
+
+        if ( empty( $item_number ) && empty( $gtin ) ) {
+            $this->results['skipped']++;
+            WBC_Logger::debug( 'ProductSync', 'Skipping item without number or GTIN', array( 'item' => $item ) );
+            return;
+        }
+
+        // Try to find WooCommerce product
+        $product_id = $this->find_wc_product( $item_number, $gtin );
+
+        if ( ! $product_id ) {
+            $this->results['skipped']++;
+            WBC_Logger::debug( 'ProductSync', 'No matching WC product found', array(
+                'item_number' => $item_number,
+                'gtin'        => $gtin,
+            ) );
+            return;
+        }
+
+        // Get the product
+        $product = wc_get_product( $product_id );
+
+        if ( ! $product ) {
+            $this->results['skipped']++;
+            WBC_Logger::warning( 'ProductSync', 'Product ID found but product not loaded', array(
+                'product_id' => $product_id,
+            ) );
+            return;
+        }
+
+        // Update the product
+        $updated = $this->update_product( $product, $item );
+
+        if ( $updated ) {
+            $this->results['success']++;
+        } else {
+            $this->results['failed']++;
+        }
+    }
+
+    /**
+     * Find WooCommerce product by SKU (item number or GTIN)
+     *
+     * @param string $item_number BC item number.
+     * @param string $gtin        BC GTIN/EAN.
+     * @return int|false Product ID or false if not found.
+     */
+    private function find_wc_product( $item_number, $gtin ) {
+        // First try to match by item number (SKU)
+        if ( ! empty( $item_number ) ) {
+            $product_id = wc_get_product_id_by_sku( $item_number );
+            if ( $product_id ) {
+                return $product_id;
+            }
+        }
+
+        // Fall back to GTIN match
+        if ( ! empty( $gtin ) ) {
+            $product_id = wc_get_product_id_by_sku( $gtin );
+            if ( $product_id ) {
+                return $product_id;
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * Update WooCommerce product with BC data
+     *
+     * @param WC_Product $product WooCommerce product.
+     * @param array      $item    BC item data.
+     * @return bool Whether the product was updated.
+     */
+    private function update_product( $product, $item ) {
+        $product_id = $product->get_id();
+        $updated = false;
+
+        try {
+            // Update stock if enabled
+            if ( get_option( 'wbc_enable_stock_sync', 'yes' ) === 'yes' ) {
+                $stock = isset( $item['inventory'] ) ? (float) $item['inventory'] : 0;
+                $current_stock = (float) $product->get_stock_quantity();
+
+                if ( $stock !== $current_stock ) {
+                    // Enable stock management if not already enabled
+                    if ( ! $product->get_manage_stock() ) {
+                        $product->set_manage_stock( true );
+                    }
+
+                    wc_update_product_stock( $product, $stock );
+                    $updated = true;
+
+                    WBC_Logger::debug( 'ProductSync', 'Updated stock', array(
+                        'product_id' => $product_id,
+                        'old_stock'  => $current_stock,
+                        'new_stock'  => $stock,
+                    ) );
+                }
+            }
+
+            // Update price if enabled
+            if ( get_option( 'wbc_enable_price_sync', 'yes' ) === 'yes' ) {
+                $price = isset( $item['unitPrice'] ) ? (float) $item['unitPrice'] : 0;
+                $current_price = (float) $product->get_regular_price();
+
+                if ( $price > 0 && $price !== $current_price ) {
+                    $product->set_regular_price( $price );
+
+                    // Also update sale price if it's higher than the new regular price
+                    $sale_price = (float) $product->get_sale_price();
+                    if ( $sale_price > 0 && $sale_price >= $price ) {
+                        $product->set_sale_price( '' );
+                    }
+
+                    $product->save();
+                    $updated = true;
+
+                    WBC_Logger::debug( 'ProductSync', 'Updated price', array(
+                        'product_id' => $product_id,
+                        'old_price'  => $current_price,
+                        'new_price'  => $price,
+                    ) );
+                }
+            }
+
+            // Store BC item info in meta via WooCommerce CRUD
+            $product->update_meta_data( '_wbc_bc_item_id', $item['id'] ?? '' );
+            $product->update_meta_data( '_wbc_bc_item_number', $item['number'] ?? '' );
+            $product->update_meta_data( '_wbc_last_sync', current_time( 'mysql' ) );
+            $product->save();
+
+            return true;
+
+        } catch ( Exception $e ) {
+            WBC_Logger::error( 'ProductSync', 'Failed to update product', array(
+                'product_id' => $product_id,
+                'error'      => $e->getMessage(),
+            ) );
+            $this->results['errors'][] = sprintf( 'Product %d: %s', $product_id, $e->getMessage() );
+            return false;
+        }
+    }
+
+    /**
+     * Get sync results
+     *
+     * @return array
+     */
+    public function get_results() {
+        return $this->results;
+    }
+
+    /**
+     * Sync a single product by WooCommerce product ID
+     *
+     * @param int $product_id WooCommerce product ID.
+     * @return array Sync result.
+     */
+    public function sync_single_product( $product_id ) {
+        $product = wc_get_product( $product_id );
+
+        if ( ! $product ) {
+            return array(
+                'success' => false,
+                'message' => __( 'Product not found.', 'woo-business-central' ),
+            );
+        }
+
+        $sku = $product->get_sku();
+
+        if ( empty( $sku ) ) {
+            return array(
+                'success' => false,
+                'message' => __( 'Product has no SKU.', 'woo-business-central' ),
+            );
+        }
+
+        // Fetch item from BC
+        $result = WBC_API_Client::get_item_by_number( $sku );
+
+        if ( is_wp_error( $result ) ) {
+            return array(
+                'success' => false,
+                'message' => $result->get_error_message(),
+            );
+        }
+
+        $items = isset( $result['value'] ) ? $result['value'] : array();
+
+        if ( empty( $items ) ) {
+            return array(
+                'success' => false,
+                'message' => __( 'Item not found in Business Central.', 'woo-business-central' ),
+            );
+        }
+
+        $item = $items[0];
+        $updated = $this->update_product( $product, $item );
+
+        return array(
+            'success' => true,
+            'message' => $updated
+                ? __( 'Product updated successfully.', 'woo-business-central' )
+                : __( 'Product is already up to date.', 'woo-business-central' ),
+        );
+    }
+}
diff --git a/woo-business-central/languages/.gitkeep b/woo-business-central/languages/.gitkeep
new file mode 100644
index 0000000..e69de29
diff --git a/woo-business-central/uninstall.php b/woo-business-central/uninstall.php
new file mode 100644
index 0000000..9698e3e
--- /dev/null
+++ b/woo-business-central/uninstall.php
@@ -0,0 +1,75 @@
+<?php
+/**
+ * Uninstall WooCommerce Business Central Integration
+ *
+ * @package WooBusinessCentral
+ */
+
+// Exit if uninstall not called from WordPress
+if ( ! defined( 'WP_UNINSTALL_PLUGIN' ) ) {
+    exit;
+}
+
+// Check if user wants to delete data (optional, could be a setting)
+$delete_data = get_option( 'wbc_delete_data_on_uninstall', 'no' );
+
+// Always delete these options
+$options_to_delete = array(
+    'wbc_tenant_id',
+    'wbc_client_id',
+    'wbc_client_secret',
+    'wbc_environment',
+    'wbc_company_id',
+    'wbc_sync_frequency',
+    'wbc_enable_stock_sync',
+    'wbc_enable_price_sync',
+    'wbc_enable_order_sync',
+    'wbc_default_payment_terms_id',
+    'wbc_default_shipment_method_id',
+    'wbc_shipping_item_number',
+    'wbc_last_sync_time',
+    'wbc_encryption_key',
+    'wbc_delete_data_on_uninstall',
+);
+
+foreach ( $options_to_delete as $option ) {
+    delete_option( $option );
+}
+
+// Delete transients
+delete_transient( 'wbc_access_token' );
+
+// Clear scheduled events
+$sync_timestamp = wp_next_scheduled( 'wbc_product_sync_event' );
+if ( $sync_timestamp ) {
+    wp_unschedule_event( $sync_timestamp, 'wbc_product_sync_event' );
+}
+
+$cleanup_timestamp = wp_next_scheduled( 'wbc_log_cleanup_event' );
+if ( $cleanup_timestamp ) {
+    wp_unschedule_event( $cleanup_timestamp, 'wbc_log_cleanup_event' );
+}
+
+// Drop logs table
+global $wpdb;
+$table_name = $wpdb->prefix . 'wbc_logs';
+$wpdb->query( "DROP TABLE IF EXISTS $table_name" );
+
+// Delete user meta (BC customer IDs)
+$wpdb->query( "DELETE FROM {$wpdb->usermeta} WHERE meta_key IN ('_wbc_bc_customer_id', '_wbc_bc_customer_number')" );
+
+// Delete post meta (BC item info, order sync info)
+$wpdb->query( "DELETE FROM {$wpdb->postmeta} WHERE meta_key LIKE '_wbc_%'" );
+
+// Delete order meta for HPOS (if using custom order tables)
+if ( class_exists( 'Automattic\WooCommerce\Utilities\OrderUtil' ) ) {
+    if ( Automattic\WooCommerce\Utilities\OrderUtil::custom_orders_table_usage_is_enabled() ) {
+        $orders_table = $wpdb->prefix . 'wc_orders_meta';
+        if ( $wpdb->get_var( "SHOW TABLES LIKE '$orders_table'" ) === $orders_table ) {
+            $wpdb->query( "DELETE FROM $orders_table WHERE meta_key LIKE '_wbc_%'" );
+        }
+    }
+}
+
+// Clear any cached data
+wp_cache_flush();
diff --git a/woo-business-central/woo-business-central.php b/woo-business-central/woo-business-central.php
new file mode 100644
index 0000000..535d22c
--- /dev/null
+++ b/woo-business-central/woo-business-central.php
@@ -0,0 +1,168 @@
+<?php
+/**
+ * Plugin Name: WooCommerce Business Central Integration
+ * Plugin URI: https://example.com/woo-business-central
+ * Description: Syncs stock, pricing, orders, and customers between WooCommerce and Microsoft Dynamics 365 Business Central.
+ * Version: 1.0.0
+ * Author: Your Name
+ * Author URI: https://example.com
+ * License: GPL-2.0+
+ * License URI: http://www.gnu.org/licenses/gpl-2.0.txt
+ * Text Domain: woo-business-central
+ * Domain Path: /languages
+ * Requires at least: 5.8
+ * Requires PHP: 7.4
+ * WC requires at least: 5.0
+ * WC tested up to: 8.0
+ */
+
+// Prevent direct access
+if ( ! defined( 'ABSPATH' ) ) {
+    exit;
+}
+
+// Plugin constants
+define( 'WBC_VERSION', '1.0.0' );
+define( 'WBC_PLUGIN_DIR', plugin_dir_path( __FILE__ ) );
+define( 'WBC_PLUGIN_URL', plugin_dir_url( __FILE__ ) );
+define( 'WBC_PLUGIN_BASENAME', plugin_basename( __FILE__ ) );
+
+/**
+ * Check if WooCommerce is active
+ */
+function wbc_check_woocommerce() {
+    if ( ! class_exists( 'WooCommerce' ) ) {
+        add_action( 'admin_notices', 'wbc_woocommerce_missing_notice' );
+        return false;
+    }
+    return true;
+}
+
+/**
+ * Admin notice for missing WooCommerce
+ */
+function wbc_woocommerce_missing_notice() {
+    ?>
+    <div class="notice notice-error">
+        <p><?php esc_html_e( 'WooCommerce Business Central Integration requires WooCommerce to be installed and active.', 'woo-business-central' ); ?></p>
+    </div>
+    <?php
+}
+
+/**
+ * Plugin activation hook
+ */
+function wbc_activate() {
+    // Check WooCommerce dependency
+    if ( ! class_exists( 'WooCommerce' ) ) {
+        deactivate_plugins( plugin_basename( __FILE__ ) );
+        wp_die(
+            esc_html__( 'WooCommerce Business Central Integration requires WooCommerce to be installed and active.', 'woo-business-central' ),
+            'Plugin dependency check',
+            array( 'back_link' => true )
+        );
+    }
+
+    // Create logs table
+    require_once WBC_PLUGIN_DIR . 'includes/class-wbc-logger.php';
+    WBC_Logger::create_table();
+
+    // Set default options
+    $defaults = array(
+        'wbc_sync_frequency' => 'daily',
+        'wbc_enable_stock_sync' => 'yes',
+        'wbc_enable_price_sync' => 'yes',
+        'wbc_enable_order_sync' => 'yes',
+        'wbc_environment' => 'production',
+    );
+
+    foreach ( $defaults as $option => $value ) {
+        if ( get_option( $option ) === false ) {
+            add_option( $option, $value );
+        }
+    }
+
+    // Schedule cron event
+    if ( ! wp_next_scheduled( 'wbc_product_sync_event' ) ) {
+        $frequency = get_option( 'wbc_sync_frequency', 'daily' );
+        wp_schedule_event( time(), $frequency, 'wbc_product_sync_event' );
+    }
+
+    // Flush rewrite rules
+    flush_rewrite_rules();
+}
+register_activation_hook( __FILE__, 'wbc_activate' );
+
+/**
+ * Plugin deactivation hook
+ */
+function wbc_deactivate() {
+    // Clear scheduled cron events
+    $timestamp = wp_next_scheduled( 'wbc_product_sync_event' );
+    if ( $timestamp ) {
+        wp_unschedule_event( $timestamp, 'wbc_product_sync_event' );
+    }
+
+    // Flush rewrite rules
+    flush_rewrite_rules();
+}
+register_deactivation_hook( __FILE__, 'wbc_deactivate' );
+
+/**
+ * Load plugin text domain
+ */
+function wbc_load_textdomain() {
+    load_plugin_textdomain( 'woo-business-central', false, dirname( WBC_PLUGIN_BASENAME ) . '/languages' );
+}
+add_action( 'plugins_loaded', 'wbc_load_textdomain' );
+
+/**
+ * Initialize the plugin
+ */
+function wbc_init() {
+    // Check WooCommerce dependency
+    if ( ! wbc_check_woocommerce() ) {
+        return;
+    }
+
+    // Load required files
+    require_once WBC_PLUGIN_DIR . 'includes/class-wbc-loader.php';
+    require_once WBC_PLUGIN_DIR . 'includes/class-wbc-logger.php';
+    require_once WBC_PLUGIN_DIR . 'includes/class-wbc-oauth.php';
+    require_once WBC_PLUGIN_DIR . 'includes/class-wbc-api-client.php';
+    require_once WBC_PLUGIN_DIR . 'includes/class-wbc-product-sync.php';
+    require_once WBC_PLUGIN_DIR . 'includes/class-wbc-customer-sync.php';
+    require_once WBC_PLUGIN_DIR . 'includes/class-wbc-order-sync.php';
+    require_once WBC_PLUGIN_DIR . 'includes/class-wbc-cron.php';
+
+    // Load admin files
+    if ( is_admin() ) {
+        require_once WBC_PLUGIN_DIR . 'admin/class-wbc-admin.php';
+    }
+
+    // Initialize the loader
+    $loader = new WBC_Loader();
+    $loader->run();
+}
+add_action( 'plugins_loaded', 'wbc_init', 20 );
+
+/**
+ * Add custom cron schedules
+ */
+function wbc_cron_schedules( $schedules ) {
+    $schedules['twice_daily'] = array(
+        'interval' => 12 * HOUR_IN_SECONDS,
+        'display'  => __( 'Twice Daily', 'woo-business-central' ),
+    );
+    return $schedules;
+}
+add_filter( 'cron_schedules', 'wbc_cron_schedules' );
+
+/**
+ * HPOS compatibility declaration
+ */
+add_action( 'before_woocommerce_init', function() {
+    if ( class_exists( \Automattic\WooCommerce\Utilities\FeaturesUtil::class ) ) {
+        \Automattic\WooCommerce\Utilities\FeaturesUtil::declare_compatibility( 'custom_order_tables', __FILE__, true );
+    }
+} );