$this->api_handler = new WA_Attr_Api_Handler();

        // Initialize inbox REST API
        new WA_Attr_Inbox_Api();

        // Initialize upload handler
        new WA_Attr_Inbox_Upload();
    }

    /**
     * Initialize attribution module.
     */
    private function init_attribution() {
        $this->attribution_engine = new WA_Attr_Attribution_Engine();

        // Register welcome message handler
        add_action('wa_attribution_conversation_started', [$this, 'maybe_send_welcome_message'], 10, 3);
    }

    /**
     * Send welcome message or start chatbot flow if enabled.
     *
     * @param int    $conversation_id Conversation ID.
     * @param string $phone           Phone number.
     * @param array  $attribution     Attribution data.
     */
    public function maybe_send_welcome_message($conversation_id, $phone, $attribution) {
        // Check if chatbot flow is enabled (takes priority over welcome message)
        $flow_engine = new WA_Attr_Core_Flow_Engine();
        if ($flow_engine->is_enabled()) {
            $this->logger->info('Starting chatbot flow instead of welcome message', [
                'conversation_id' => $conversation_id,
                'phone'           => $phone,
            ]);

            $delay = (int) $this->settings->get('welcome_message_delay', 3);

            if ($delay > 0) {
                wp_schedule_single_event(
                    time() + $delay,
                    'wa_attribution_send_welcome_message',
                    [$conversation_id, $phone, '__chatbot_flow__']
                );
            } else {
                $flow_engine->start_flow($conversation_id, $phone);
            }
            return;
        }

        // Check if welcome message is enabled
        if (!$this->settings->get('welcome_message_enabled', false)) {
            return;
        }

        $message_text = $this->settings->get('welcome_message_text', '');
        if (empty($message_text)) {
            return;
        }

        $delay = (int) $this->settings->get('welcome_message_delay', 3);

        $this->logger->info('Scheduling welcome message', [
            'conversation_id' => $conversation_id,
            'phone'           => $phone,
            'delay'           => $delay,
        ]);

        // Schedule the message sending with delay
        if ($delay > 0) {
            wp_schedule_single_event(
                time() + $delay,
                'wa_attribution_send_welcome_message',
                [$conversation_id, $phone, $message_text]
            );
        } else {
            // Send immediately
            $this->send_welcome_message($conversation_id, $phone, $message_text);
        }
    }

    /**
     * Actually send the welcome message (or start chatbot flow).
     *
     * @param int    $conversation_id Conversation ID.
     * @param string $phone           Phone number.
     * @param string $message_text    Message text or '__chatbot_flow__' to start flow.
     */
    public function send_welcome_message($conversation_id, $phone, $message_text) {
        // Handle chatbot flow trigger
        if ($message_text === '__chatbot_flow__') {
            $this->logger->info('Starting chatbot flow (delayed)', [
                'conversation_id' => $conversation_id,
                'phone'           => $phone,
            ]);
            $flow_engine = new WA_Attr_Core_Flow_Engine();
            $flow_engine->start_flow($conversation_id, $phone);
            return;
        }

        $this->logger->info('Sending welcome message', [
            'conversation_id' => $conversation_id,
            'phone'           => $phone,
        ]);

        // Send the message
        $result = WA_Attr_Inbox_Sender::send_text($phone, $message_text);

        if ($result['success']) {
            // Store the message in database
            $message_id = $result['message_id'] ?? null;

            $this->database->insert_message([
                'conversation_id' => $conversation_id,
                'wa_message_id'   => $message_id,
                'direction'       => 'outbound',
                'message_type'    => 'text',
                'content'         => $message_text,
                'status'          => 'sent',
                'sent_by'         => 0, // System/automated
                'created_at'      => current_time('mysql'),
            ]);

            $this->logger->info('Welcome message sent successfully', [
                'conversation_id' => $conversation_id,
                'message_id'      => $message_id,
            ]);
        } else {
            $this->logger->error('Failed to send welcome message', [
                'conversation_id' => $conversation_id,
                'error'           => $result['error'] ?? 'Unknown error',
            ]);
        }
    }

    /**
     * Initialize integrations (WooCommerce, Sage, Pipedrive, etc).
     */
    private function init_integrations() {
        // WooCommerce integration
        new WA_Attr_Integrations_Woocommerce();

        // Sage theme integration
        new WA_Attr_Integrations_Sage();

        // Pipedrive CRM integration
        if (!class_exists('WA_Attr_Integrations_Pipedrive')) {
            require_once WA_ATTR_PLUGIN_DIR . 'includes/integrations/class-pipedrive.php';
        }

        if (class_exists('WA_Attr_Integrations_Pipedrive')) {
            new WA_Attr_Integrations_Pipedrive();
        } elseif ($this->logger) {
            $this->logger->error('Pipedrive integration class not found');
        }

        // Access Database Export API
        new WA_Attr_Integrations_Access_Export();
    }

    /**
     * Handler for init action.
     */
    public function on_init() {
        // Run database migrations if needed
        $this->run_migrations();

        // Additional initialization if needed
        do_action('wa_attr_init');
    }

    /**
     * Run database migrations for plugin updates.
     */
    private function run_migrations() {
        global $wpdb;

        $table_conversations = $wpdb->prefix . 'wa_attribution_conversations';

        // Migration: Add contact_name column for WhatsApp profile name
        $column_exists = $wpdb->get_results("SHOW COLUMNS FROM {$table_conversations} LIKE 'contact_name'");
        if (empty($column_exists)) {
            $wpdb->query("ALTER TABLE {$table_conversations} ADD COLUMN contact_name VARCHAR(255) DEFAULT NULL AFTER phone_hash");
            $this->logger->info('Migration: Added contact_name column to conversations table');
        }
    }

    /**
     * Handler for rest_api_init action.
     */
    public function on_rest_api_init() {
        // REST API initialization if needed
        do_action('wa_attr_rest_api_init');
    }

    /**
     * Prevent cloning of the instance.
     */
    private function __clone() {}

    /**
     * Prevent unserializing of the instance.
     */
    public function __wakeup() {
        throw new Exception('Cannot unserialize singleton');
    }
}