<?php
/**
 * AKSRT Message — 站内通知系统
 *
 * 提供通知持久化（写入 aksrt_notification 表）、未读计数、标记已读。
 * 与 AKSRT_Private_Message 联动：私信发送时自动创建通知记录。
 *
 * @package AKSRT
 */

defined('ABSPATH') || exit;

class AKSRT_Message {

    private static $instance = null;

    public static function get_instance(): self {
        if (null === self::$instance) self::$instance = new self();
        return self::$instance;
    }

    public function init(): void {
        add_action('wp_ajax_aksrt_mark_message_read', [$this, 'ajax_mark_read']);
        add_action('wp_ajax_aksrt_get_unread_count', [$this, 'ajax_get_unread_count']);
    }

    /**
     * 获取用户未读消息数
     */
    public function get_unread_count(int $user_id): int {
        if ($user_id <= 0) return 0;

        // 优先从表中实时统计
        $table = $this->table();
        if ($table !== '') {
            global $wpdb;
            $count = (int) $wpdb->get_var($wpdb->prepare(
                "SELECT COUNT(*) FROM {$table} WHERE user_id = %d AND is_read = 0",
                $user_id
            ));
            // 同步到 user_meta 以兼容旧读取方
            update_user_meta($user_id, 'aksrt_unread_message_count', $count);
            return $count;
        }

        // 降级：从 user_meta 读取
        $count = (int) get_user_meta($user_id, 'aksrt_unread_message_count', true);
        return max(0, $count);
    }

    /**
     * 标记单条通知为已读
     */
    public function mark_read(int $user_id, string $message_id): bool {
        if ($user_id <= 0 || empty($message_id)) return false;

        $table = $this->table();
        if ($table !== '') {
            global $wpdb;
            $result = $wpdb->update(
                $table,
                ['is_read' => 1, 'read_at' => current_time('mysql')],
                ['id' => (int) $message_id, 'user_id' => $user_id, 'is_read' => 0],
                ['%d', '%s'],
                ['%d', '%d', '%d']
            );
            return $result !== false;
        }

        // 降级：仅更新计数
        $current = $this->get_unread_count($user_id);
        if ($current > 0) {
            update_user_meta($user_id, 'aksrt_unread_message_count', max(0, $current - 1));
        }
        return true;
    }

    /**
     * 标记用户所有通知为已读
     */
    public function mark_all_read(int $user_id): bool {
        if ($user_id <= 0) return false;

        $table = $this->table();
        if ($table !== '') {
            global $wpdb;
            $wpdb->update(
                $table,
                ['is_read' => 1, 'read_at' => current_time('mysql')],
                ['user_id' => $user_id, 'is_read' => 0],
                ['%d', '%s'],
                ['%d', '%d']
            );
        }

        update_user_meta($user_id, 'aksrt_unread_message_count', 0);
        return true;
    }

    /**
     * 发送站内通知（持久化到 aksrt_notification 表）
     *
     * @param int    $to_user_id 接收人 ID
     * @param string $type       通知类型 (comment_reply, download_ready, conversation, notice, ...)
     * @param string $content    通知内容摘要
     * @param array  $data       附加数据 (title, target_url, ...)
     * @return bool
     */
    public function send(int $to_user_id, string $type, string $content, array $data = []): bool {
        if ($to_user_id <= 0 || empty($content)) return false;

        $table = $this->table();
        if ($table !== '') {
            global $wpdb;
            $wpdb->insert($table, [
                'user_id'     => $to_user_id,
                'type'        => sanitize_key($type),
                'title'       => sanitize_text_field((string) ($data['title'] ?? $content)),
                'description' => sanitize_textarea_field($content),
                'target_url'  => esc_url_raw((string) ($data['target_url'] ?? '')),
                'is_read'     => 0,
                'created_at'  => current_time('mysql'),
            ], ['%d', '%s', '%s', '%s', '%s', '%d', '%s']);
        }

        // 同步更新 user_meta 未读计数
        $current = (int) get_user_meta($to_user_id, 'aksrt_unread_message_count', true);
        update_user_meta($to_user_id, 'aksrt_unread_message_count', max(0, $current) + 1);

        // 触发通知钩子
        do_action('aksrt_notification_sent', $to_user_id, $type, $data);

        return true;
    }

    /**
     * 获取用户通知列表
     */
    public function get_notifications(int $user_id, array $args = []): array {
        if ($user_id <= 0) return [];

        $table = $this->table();
        if ($table !== '') {
            global $wpdb;

            $where  = ['user_id = %d'];
            $params = [$user_id];

            $type = sanitize_key((string) ($args['type'] ?? ''));
            if ($type !== '' && $type !== 'all') {
                if ($type === 'unread') {
                    $where[] = 'is_read = 0';
                } else {
                    $where[] = 'type = %s';
                    $params[] = $type;
                }
            }

            $limit  = max(1, min(100, (int) ($args['limit'] ?? 20)));
            $offset = max(0, (int) ($args['offset'] ?? 0));

            $where_sql = implode(' AND ', $where);
            $sql = "SELECT * FROM {$table} WHERE {$where_sql} ORDER BY created_at DESC LIMIT %d OFFSET %d";
            $params[] = $limit;
            $params[] = $offset;

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

        return [];
    }

    /**
     * 获取通知收件箱完整视图（供 page-messages.php 使用）
     */
    public function get_all_notifications(int $user_id): array {
        return $this->get_notifications($user_id, ['limit' => 200]);
    }

    private function table(): string {
        if (class_exists('AKSRT_DB_Migrator')) {
            return AKSRT_DB_Migrator::table('notification');
        }
        return '';
    }

    /**
     * AJAX 标记已读
     */
    public function ajax_mark_read(): void {
        check_ajax_referer('aksrt_message', '_nonce');

        $user_id = get_current_user_id();
        if ($user_id <= 0) {
            wp_send_json_error(['message' => __('请先登录', 'aksrt')]);
        }

        $message_id = sanitize_text_field((string) ($_POST['message_id'] ?? ''));
        if ($this->mark_read($user_id, $message_id)) {
            wp_send_json_success(['unread' => $this->get_unread_count($user_id)]);
        }

        wp_send_json_error(['message' => __('操作失败', 'aksrt')]);
    }

    /**
     * AJAX 获取未读数
     */
    public function ajax_get_unread_count(): void {
        check_ajax_referer('aksrt_message', '_nonce');

        $user_id = get_current_user_id();
        if ($user_id <= 0) {
            wp_send_json_error(['message' => __('请先登录', 'aksrt')]);
        }

        wp_send_json_success(['unread' => $this->get_unread_count($user_id)]);
    }
}