<?php
/**
 * AKSRT Email Rollback
 *
 * 用户修改邮箱后会写入两条 user_meta：
 *   - aksrt_email_previous   旧邮箱
 *   - aksrt_email_changed_at 时间戳
 *
 * 14 天内管理员可执行回滚：把账号邮箱改回旧值并清除回滚 meta。
 *
 * 入口：
 *   - 后台用户列表新增"邮箱回滚"行操作
 *   - REST: GET /aksrt/v1/email-rollback/users      列出窗口内可回滚的用户
 *   - REST: POST /aksrt/v1/email-rollback/users/{id}/rollback 执行回滚
 *
 * @package AKSRT
 */

defined('ABSPATH') || exit;

class AKSRT_Email_Rollback {

    const META_PREVIOUS   = 'aksrt_email_previous';
    const META_CHANGED_AT = 'aksrt_email_changed_at';
    const WINDOW_SECONDS  = 1209600; // 14 days

    private static $instance = null;

    private function __construct() {}

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

    public function init(): void {
        add_filter('user_row_actions', [$this, 'add_row_action'], 20, 2);
        add_action('admin_post_aksrt_email_rollback', [$this, 'handle_admin_rollback']);
        // cron 清理过期 meta
        add_action('aksrt_email_rollback_cleanup', [self::class, 'cron_cleanup']);
        add_action('wp', [self::class, 'maybe_schedule_cleanup']);
    }

    public static function maybe_schedule_cleanup(): void {
        if (!wp_next_scheduled('aksrt_email_rollback_cleanup')) {
            wp_schedule_event(time() + DAY_IN_SECONDS, 'daily', 'aksrt_email_rollback_cleanup');
        }
    }

    public static function cron_cleanup(): void {
        global $wpdb;
        $cutoff = time() - self::WINDOW_SECONDS;
        $rows = $wpdb->get_col($wpdb->prepare(
            "SELECT user_id FROM {$wpdb->usermeta} WHERE meta_key = %s AND CAST(meta_value AS UNSIGNED) < %d",
            self::META_CHANGED_AT,
            $cutoff
        ));
        if (empty($rows)) return;
        foreach ($rows as $uid) {
            delete_user_meta((int) $uid, self::META_PREVIOUS);
            delete_user_meta((int) $uid, self::META_CHANGED_AT);
        }
    }

    /**
     * 在 14 天窗口内？
     */
    public static function is_within_window(int $user_id): bool {
        $changed_at = (int) get_user_meta($user_id, self::META_CHANGED_AT, true);
        if ($changed_at <= 0) return false;
        return (time() - $changed_at) <= self::WINDOW_SECONDS;
    }

    /**
     * 列出窗口内可回滚的用户。
     */
    public static function list_pending(int $page = 1, int $per_page = 20): array {
        global $wpdb;
        $page     = max(1, $page);
        $per_page = min(100, max(1, $per_page));
        $offset   = ($page - 1) * $per_page;
        $cutoff   = time() - self::WINDOW_SECONDS;

        $sql_count = $wpdb->prepare(
            "SELECT COUNT(DISTINCT um1.user_id)
             FROM {$wpdb->usermeta} um1
             INNER JOIN {$wpdb->usermeta} um2 ON um2.user_id = um1.user_id AND um2.meta_key = %s
             WHERE um1.meta_key = %s AND CAST(um1.meta_value AS UNSIGNED) >= %d",
            self::META_PREVIOUS,
            self::META_CHANGED_AT,
            $cutoff
        );
        $total = (int) $wpdb->get_var($sql_count);

        $sql = $wpdb->prepare(
            "SELECT um1.user_id, um1.meta_value AS changed_at, um2.meta_value AS previous_email
             FROM {$wpdb->usermeta} um1
             INNER JOIN {$wpdb->usermeta} um2 ON um2.user_id = um1.user_id AND um2.meta_key = %s
             WHERE um1.meta_key = %s AND CAST(um1.meta_value AS UNSIGNED) >= %d
             ORDER BY CAST(um1.meta_value AS UNSIGNED) DESC
             LIMIT %d OFFSET %d",
            self::META_PREVIOUS,
            self::META_CHANGED_AT,
            $cutoff,
            $per_page,
            $offset
        );
        $rows = $wpdb->get_results($sql, ARRAY_A);

        $items = [];
        foreach ((array) $rows as $r) {
            $uid = (int) $r['user_id'];
            $u = get_userdata($uid);
            if (!$u) continue;
            $items[] = [
                'user_id'        => $uid,
                'login'          => $u->user_login,
                'display_name'   => $u->display_name,
                'current_email'  => $u->user_email,
                'previous_email' => (string) $r['previous_email'],
                'changed_at'     => (int) $r['changed_at'],
                'expires_in'     => max(0, (int) $r['changed_at'] + self::WINDOW_SECONDS - time()),
            ];
        }

        return [
            'items'    => $items,
            'total'    => $total,
            'page'     => $page,
            'per_page' => $per_page,
        ];
    }

    /**
     * 执行回滚。
     *
     * @return array{success:bool, message?:string, error?:string}
     */
    public static function rollback(int $user_id, int $by_admin_id = 0): array {
        if ($user_id <= 0 || !current_user_can('edit_user', $user_id)) {
            return ['success' => false, 'error' => __('权限不足', 'aksrt')];
        }
        if (!self::is_within_window($user_id)) {
            return ['success' => false, 'error' => __('回滚窗口已过期或当前账号未发起过邮箱变更', 'aksrt')];
        }

        $previous = (string) get_user_meta($user_id, self::META_PREVIOUS, true);
        if ($previous === '' || !is_email($previous)) {
            return ['success' => false, 'error' => __('旧邮箱无效', 'aksrt')];
        }

        // 检查旧邮箱是否被其他用户占用（理论上极少见）
        $occupier = email_exists($previous);
        if ($occupier && (int) $occupier !== $user_id) {
            return ['success' => false, 'error' => __('旧邮箱已被其他账号占用，无法回滚', 'aksrt')];
        }

        $update = wp_update_user([
            'ID'         => $user_id,
            'user_email' => $previous,
        ]);
        if (is_wp_error($update)) {
            return ['success' => false, 'error' => $update->get_error_message()];
        }

        // 清空回滚 meta（一次性）
        delete_user_meta($user_id, self::META_PREVIOUS);
        delete_user_meta($user_id, self::META_CHANGED_AT);

        // 记录管理员操作日志
        $log = get_user_meta($user_id, 'aksrt_email_verification_admin_log', true);
        if (!is_array($log)) $log = [];
        $log[] = [
            't'      => time(),
            'action' => 'email_rollback',
            'by'     => $by_admin_id ?: get_current_user_id(),
        ];
        if (count($log) > 10) $log = array_slice($log, -10);
        update_user_meta($user_id, 'aksrt_email_verification_admin_log', $log);

        if (class_exists('AKSRT_Auth_Service')) {
            AKSRT_Auth_Service::log_event('admin.email_rollback', [
                'uid' => $user_id,
                'by'  => $by_admin_id ?: get_current_user_id(),
            ]);
        }

        return [
            'success' => true,
            'message' => sprintf(__('已将用户邮箱回滚为 %s', 'aksrt'), $previous),
        ];
    }

    /**
     * 在用户列表行操作中加入"回滚邮箱"。
     */
    public function add_row_action(array $actions, WP_User $user): array {
        if (!current_user_can('edit_user', $user->ID)) return $actions;
        if (!self::is_within_window((int) $user->ID)) return $actions;

        $url = wp_nonce_url(
            admin_url('admin-post.php?action=aksrt_email_rollback&user_id=' . (int) $user->ID),
            'aksrt_email_rollback_' . (int) $user->ID
        );
        $actions['aksrt_email_rollback'] = sprintf(
            '<a href="%s">%s</a>',
            esc_url($url),
            esc_html__('回滚邮箱', 'aksrt')
        );
        return $actions;
    }

    public function handle_admin_rollback(): void {
        $user_id = isset($_GET['user_id']) ? absint($_GET['user_id']) : 0;
        if ($user_id <= 0 || !current_user_can('edit_user', $user_id)) {
            wp_die(esc_html__('权限不足', 'aksrt'));
        }
        check_admin_referer('aksrt_email_rollback_' . $user_id);

        $r    = self::rollback($user_id, get_current_user_id());
        $type = !empty($r['success']) ? 'success' : 'error';
        $msg  = $r['message'] ?? $r['error'] ?? '';
        set_transient('aksrt_admin_notice_' . get_current_user_id(), [['type' => $type, 'msg' => $msg]], 30);

        wp_safe_redirect(wp_get_referer() ?: admin_url('users.php'));
        exit;
    }
}