<?php
/**
 * AKSRT Charge Card — 充值卡系统
 *
 * 管理充值卡的创建、使用和查询。
 *
 * @package AKSRT
 */

defined('ABSPATH') || exit;

class AKSRT_Charge_Card {

    private static $instance = null;

    const STATUS_ACTIVE   = 'active';
    const STATUS_USED     = 'used';
    const STATUS_EXPIRED  = 'expired';
    const STATUS_DISABLED = 'disabled';

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

    private function table(): string {
        return AKSRT_DB_Migrator::table('charge_card');
    }

    /**
     * 创建充值卡
     */
    public function create(array $data): int {
        global $wpdb;

        $code   = sanitize_text_field((string) ($data['code'] ?? ''));
        $amount = (float) ($data['amount'] ?? 0);
        $expires_at = sanitize_text_field((string) ($data['expires_at'] ?? ''));
        $note   = sanitize_textarea_field((string) ($data['note'] ?? ''));

        if ($code === '' || $amount <= 0) {
            return 0;
        }

        // 检查 code 唯一性
        $exists = $wpdb->get_var($wpdb->prepare(
            "SELECT id FROM {$this->table()} WHERE code = %s",
            $code
        ));
        if ($exists) return 0;

        $result = $wpdb->insert($this->table(), [
            'code'       => $code,
            'amount'     => $amount,
            'balance'    => $amount,
            'status'     => self::STATUS_ACTIVE,
            'expires_at' => $expires_at !== '' ? $expires_at : null,
            'created_at' => current_time('mysql'),
            'note'       => $note,
        ]);

        return $result ? (int) $wpdb->insert_id : 0;
    }

    /**
     * 批量生成充值卡
     */
    public function batch_create(float $amount, int $count, int $length = 16, string $prefix = ''): array {
        $codes = [];
        for ($i = 0; $i < $count; $i++) {
            $code = $prefix . strtoupper(wp_generate_password($length, false));
            $id = $this->create([
                'code'   => $code,
                'amount' => $amount,
            ]);
            if ($id > 0) {
                $codes[] = $code;
            }
        }
        return $codes;
    }

    /**
     * 使用充值卡
     */
    public function redeem(string $code, int $user_id): array {
        global $wpdb;

        $code = sanitize_text_field($code);
        $card = $wpdb->get_row($wpdb->prepare(
            "SELECT * FROM {$this->table()} WHERE code = %s",
            $code
        ), ARRAY_A);

        if (!$card) {
            return ['success' => false, 'message' => '充值卡不存在'];
        }

        if ($card['status'] !== self::STATUS_ACTIVE) {
            return ['success' => false, 'message' => '充值卡已使用或已失效'];
        }

        if ($card['expires_at'] && strtotime($card['expires_at']) < time()) {
            // 标记过期
            $wpdb->update($this->table(), ['status' => self::STATUS_EXPIRED], ['id' => (int) $card['id']]);
            return ['success' => false, 'message' => '充值卡已过期'];
        }

        $amount = (float) $card['balance'];

        // 更新卡状态
        $wpdb->update($this->table(), [
            'status'  => self::STATUS_USED,
            'used_by' => $user_id,
            'used_at' => current_time('mysql'),
            'balance' => 0,
        ], ['id' => (int) $card['id']]);

        // 增加用户余额
        if (class_exists('AKSRT_Credits')) {
            AKSRT_Credits::add($user_id, (int) $amount, 'charge_card', [
                'ref_type' => 'charge_card',
                'ref_id'   => (int) $card['id'],
            ]);
        }

        return [
            'success' => true,
            'message' => sprintf('充值成功，已到账 %s 元', number_format($amount, 2)),
            'amount'  => $amount,
        ];
    }

    /**
     * 获取充值卡列表
     */
    public function get_list(array $args = []): array {
        global $wpdb;

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

        $where = [];
        $params = [];

        if ($status !== '') {
            $where[] = 'status = %s';
            $params[] = $status;
        }

        $where_sql = $where ? 'WHERE ' . implode(' AND ', $where) : '';

        $count_sql = "SELECT COUNT(*) FROM {$this->table()} {$where_sql}";
        $total = $params ? (int) $wpdb->get_var($wpdb->prepare($count_sql, $params)) : (int) $wpdb->get_var($count_sql);

        $sql = "SELECT * FROM {$this->table()} {$where_sql} ORDER BY created_at DESC LIMIT %d OFFSET %d";
        $params[] = $limit;
        $params[] = $offset;

        $items = $wpdb->get_results($wpdb->prepare($sql, $params), ARRAY_A);

        return [
            'items'     => $items ?: [],
            'total'     => $total,
            'page'      => floor($offset / $limit) + 1,
            'max_pages' => ceil($total / $limit),
        ];
    }

    /**
     * 禁用充值卡
     */
    public function disable(int $id): bool {
        global $wpdb;
        return (bool) $wpdb->update($this->table(), [
            'status' => self::STATUS_DISABLED,
        ], ['id' => $id]);
    }

    /**
     * 获取统计
     */
    public function get_stats(): array {
        global $wpdb;
        $table = $this->table();

        $row = $wpdb->get_row(
            "SELECT
                COUNT(*) as total,
                SUM(CASE WHEN status = 'active' THEN 1 ELSE 0 END) as active,
                SUM(CASE WHEN status = 'used' THEN 1 ELSE 0 END) as used,
                SUM(amount) as total_amount,
                SUM(CASE WHEN status = 'used' THEN amount ELSE 0 END) as used_amount
            FROM {$table}",
            ARRAY_A
        );

        return [
            'total'        => (int) ($row['total'] ?? 0),
            'active'       => (int) ($row['active'] ?? 0),
            'used'         => (int) ($row['used'] ?? 0),
            'total_amount' => (float) ($row['total_amount'] ?? 0),
            'used_amount'  => (float) ($row['used_amount'] ?? 0),
        ];
    }
}