<?php

class RL_MailWarmer_DB_Helper {

    private static $conversation_table = 'rl_mailwarmer_conversation';
    private static $message_table = 'rl_mailwarmer_message';

    /**
     * Create necessary database tables.
     */
    public static function create_tables() {
        global $wpdb;

        $charset_collate = $wpdb->get_charset_collate();

        // Conversation table
        $conversation_sql = "CREATE TABLE IF NOT EXISTS `{$wpdb->prefix}" . self::$conversation_table . "` (
            id BIGINT(20) UNSIGNED NOT NULL AUTO_INCREMENT,
            campaign_id BIGINT(20) UNSIGNED NOT NULL,
            created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
            conversation_steps JSON NOT NULL,
            prompt TEXT NOT NULL,
            PRIMARY KEY (id),
            INDEX campaign_id_idx (campaign_id)
        ) $charset_collate;";

        // Message table
        $message_sql = "CREATE TABLE IF NOT EXISTS `{$wpdb->prefix}" . self::$message_table . "` (
            id BIGINT(20) UNSIGNED NOT NULL AUTO_INCREMENT,
            campaign_id BIGINT(20) UNSIGNED NOT NULL,
            conversation_id BIGINT(20) UNSIGNED NOT NULL,
            scheduled_for_timestamp DATETIME NOT NULL,
            status ENUM('pending', 'in_progress', 'sent', 'failed') NOT NULL DEFAULT 'pending',
            from_email VARCHAR(255) NOT NULL,
            to_email TEXT NOT NULL,
            cc TEXT NULL,
            subject VARCHAR(255) NOT NULL,
            body TEXT NOT NULL,
            PRIMARY KEY (id),
            INDEX scheduled_idx (scheduled_for_timestamp, status),
            INDEX conversation_id_idx (conversation_id),
            INDEX campaign_id_idx (campaign_id)
        ) $charset_collate;";

        require_once ABSPATH . 'wp-admin/includes/upgrade.php';
        dbDelta($conversation_sql);
        dbDelta($message_sql);
    }

    /**
     * Insert a conversation record.
     */
    public static function insert_conversation($campaign_id, $conversation_steps, $prompt) {
        global $wpdb;

        $wpdb->insert(
            "{$wpdb->prefix}" . self::$conversation_table,
            [
                'campaign_id' => $campaign_id,
                'conversation_steps' => json_encode($conversation_steps),
                'prompt' => $prompt,
            ],
            ['%d', '%s', '%s']
        );

        return $wpdb->insert_id;
    }

    /**
     * Insert a message record.
     */
    public static function insert_message($campaign_id, $conversation_id, $scheduled_for, $from_email, $to_email, $cc, $subject, $body) {
        global $wpdb;

        $wpdb->insert(
            "{$wpdb->prefix}" . self::$message_table,
            [
                'campaign_id' => $campaign_id,
                'conversation_id' => $conversation_id,
                'scheduled_for_timestamp' => $scheduled_for,
                'status' => 'pending',
                'from_email' => $from_email,
                'to_email' => $to_email,
                'cc' => $cc,
                'subject' => $subject,
                'body' => $body,
            ],
            ['%d', '%d', '%s', '%s', '%s', '%s', '%s', '%s']
        );

        return $wpdb->insert_id;
    }

    /**
     * Fetch pending messages.
     */
    public static function fetch_pending_messages($limit = 100) {
        global $wpdb;

        $sql = $wpdb->prepare(
            "SELECT * FROM `{$wpdb->prefix}" . self::$message_table . "`
             WHERE scheduled_for_timestamp <= %s AND status = 'pending'
             LIMIT %d",
            current_time('mysql'),
            $limit
        );

        return $wpdb->get_results($sql, ARRAY_A);
    }
}