<?php
/**
 * @package AKSRT
 */

namespace AKSRT\Sms;

defined('ABSPATH') || exit;

class SMS {

    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_send_sms_code', [$this, 'ajax_send_code']);
        add_action('wp_ajax_nopriv_aksrt_send_sms_code', [$this, 'ajax_send_code']);
        add_action('wp_ajax_aksrt_sms_test', [$this, 'ajax_test_provider']);
        add_action('wp_ajax_aksrt_sms_status', [$this, 'ajax_provider_status']);
    }

    /**
     * 获取短信供应商配置
     */
    public function get_provider_config(): array {
        if (class_exists('\AKSRT\Settings\Settings')) {
            return \AKSRT\Settings\Settings::get_sms_settings();
        }
        return ['sms_enabled' => false, 'sms_provider' => ''];
    }

    /**
     * 获取当前 provider adapter
     */
    public function get_provider(): ?ProviderInterface {
        $config = $this->get_provider_config();
        $key    = sanitize_key((string) ($config['sms_provider'] ?? ''));
        return SMSProviderFactory::get($key);
    }

    /**
     * 发送短信验证码
     *
     * @param string $phone 手机号
     * @return array{success: bool, message: string, remaining_time?: int}
     */
    public function send_code(string $phone): array {
        $config = $this->get_provider_config();

        if (empty($config['sms_enabled'])) {
            return ['success' => false, 'message' => __('短信服务未启用', 'aksrt')];
        }

        $provider_key = sanitize_key((string) ($config['sms_provider'] ?? ''));
        if ($provider_key === '') {
            return ['success' => false, 'message' => __('未配置短信供应商', 'aksrt')];
        }

        $provider = SMSProviderFactory::get($provider_key);
        if ($provider === null) {
            return ['success' => false, 'message' => sprintf(__('短信供应商 "%s" 不可用', 'aksrt'), $provider_key)];
        }

        // 校验配置完整性
        $missing = $provider->validate_config($config);
        if (!empty($missing)) {
            return ['success' => false, 'message' => sprintf(__('短信配置不完整，缺少: %s', 'aksrt'), implode(', ', $missing))];
        }

        // 频率限制：间隔限制（对齐 legacy 60 秒冷却 + 返回剩余时间）
        $rate_limit = max(10, (int) ($config['sms_rate_limit'] ?? 60));
        $rate_key   = 'aksrt_sms_rate_' . md5($phone);
        $rate_set   = get_transient($rate_key);
        if ($rate_set !== false) {
            // 计算剩余等待时间
            $rate_ts_key = 'aksrt_sms_rate_ts_' . md5($phone);
            $sent_time   = (int) get_transient($rate_ts_key);
            $elapsed     = $sent_time > 0 ? time() - $sent_time : $rate_limit;
            $remaining   = max(1, $rate_limit - $elapsed);
            return [
                'success'         => false,
                'message'         => sprintf(__('请 %d 秒后再试', 'aksrt'), $remaining),
                'remaining_time'  => $remaining,
            ];
        }

        // 每日限制
        $daily_limit = max(1, (int) ($config['sms_daily_limit'] ?? 10));
        $daily_key   = 'aksrt_sms_daily_' . md5($phone) . '_' . date('Ymd');
        $daily_count = (int) get_transient($daily_key);
        if ($daily_count >= $daily_limit) {
            return ['success' => false, 'message' => __('今日发送次数已达上限', 'aksrt')];
        }

        $code_length = max(4, min(8, (int) ($config['sms_code_length'] ?? 6)));
        $code        = $this->generate_code($code_length);
        $ttl         = max(60, min(600, (int) ($config['sms_code_expire'] ?? 300)));

        // 存储验证码（绑定手机号）
        set_transient('aksrt_sms_code_' . md5($phone), $code, $ttl);
        set_transient('aksrt_sms_phone_' . md5($phone), $phone, $ttl);
        set_transient($rate_key, '1', $rate_limit);
        set_transient('aksrt_sms_rate_ts_' . md5($phone), time(), $rate_limit);
        set_transient($daily_key, $daily_count + 1, DAY_IN_SECONDS);

        // 委托 provider 发送
        $result = $provider->send_code($phone, $code, $config);

        if (!empty($result['success'])) {
            return [
                'success'        => true,
                'message'        => $result['message'] ?? __('验证码已发送', 'aksrt'),
                'remaining_time' => $rate_limit,
            ];
        }

        // 发送失败：删除已存储的验证码，避免无效等待
        delete_transient('aksrt_sms_code_' . md5($phone));
        delete_transient('aksrt_sms_phone_' . md5($phone));
        return ['success' => false, 'message' => $result['message'] ?? __('发送失败，请稍后重试', 'aksrt')];
    }

    /**
     * 验证短信验证码（对齐 legacy：同时校验验证码和目标手机号）
     *
     * @param string $phone 手机号
     * @param string $code  验证码
     * @return array{success: bool, message: string}
     */
    public function verify_code(string $phone, string $code): array {
        // 错误频率限制检查
        $error_check = $this->check_error_frequency('sms_verify_' . md5($phone));
        if (!$error_check['allowed']) {
            return [
                'success'        => false,
                'message'        => sprintf(__('验证失败次数过多，请 %d 秒后再试', 'aksrt'), $error_check['remaining']),
                'remaining_time' => $error_check['remaining'],
            ];
        }

        $code_key  = 'aksrt_sms_code_' . md5($phone);
        $phone_key = 'aksrt_sms_phone_' . md5($phone);

        $stored_code  = get_transient($code_key);
        $stored_phone = get_transient($phone_key);

        // 验证码不存在或已过期
        if ($stored_code === false) {
            $this->record_error('sms_verify_' . md5($phone));
            return ['success' => false, 'message' => __('验证码已过期或不存在', 'aksrt')];
        }

        // 验证码不匹配
        if (!hash_equals((string) $stored_code, $code)) {
            $this->record_error('sms_verify_' . md5($phone));
            return ['success' => false, 'message' => __('验证码不正确', 'aksrt')];
        }

        // 目标手机号绑定校验
        if ($stored_phone !== false && (string) $stored_phone !== $phone) {
            $this->record_error('sms_verify_' . md5($phone));
            return ['success' => false, 'message' => __('手机号不匹配', 'aksrt')];
        }

        // 验证成功：清除验证码和错误计数
        delete_transient($code_key);
        delete_transient($phone_key);
        $this->reset_error_frequency('sms_verify_' . md5($phone));

        return ['success' => true, 'message' => __('验证成功', 'aksrt')];
    }

    /**
     * 兼容旧接口：verify_code 返回 bool
     */
    public function verify_code_bool(string $phone, string $code): bool {
        $result = $this->verify_code($phone, $code);
        return !empty($result['success']);
    }

    /**
     * 生成验证码
     */
    private function generate_code(int $length = 6): string {
        $max = (int) str_pad('9', $length, '9');
        return str_pad((string) random_int(0, $max), $length, '0', STR_PAD_LEFT);
    }

    /* ------------------------------------------------------------------
     * 错误频率限制（对齐 legacy 的 error_frequency_limit）
     * ----------------------------------------------------------------*/

    /**
     * 检查是否被频率限制
     *
     * @return array{allowed: bool, remaining: int}
     */
    private function check_error_frequency(string $key): array {
        $count_key = 'aksrt_sms_err_' . $key;
        $time_key  = 'aksrt_sms_err_ts_' . $key;

        $count = (int) get_transient($count_key);
        $last  = (int) get_transient($time_key);

        if ($count <= 0) {
            return ['allowed' => true, 'remaining' => 0];
        }

        // 超过 10 次错误：3 分钟冷却
        if ($count >= 10) {
            $cooldown = 180;
            $elapsed  = time() - $last;
            if ($elapsed < $cooldown) {
                return ['allowed' => false, 'remaining' => $cooldown - $elapsed];
            }
            // 冷却结束，重置
            $this->reset_error_frequency($key);
            return ['allowed' => true, 'remaining' => 0];
        }

        // 超过 5 次错误：30 秒冷却
        if ($count >= 5) {
            $cooldown = 30;
            $elapsed  = time() - $last;
            if ($elapsed < $cooldown) {
                return ['allowed' => false, 'remaining' => $cooldown - $elapsed];
            }
        }

        return ['allowed' => true, 'remaining' => 0];
    }

    /**
     * 记录一次错误
     */
    private function record_error(string $key): void {
        $count_key = 'aksrt_sms_err_' . $key;
        $time_key  = 'aksrt_sms_err_ts_' . $key;

        $count = (int) get_transient($count_key);
        set_transient($count_key, $count + 1, HOUR_IN_SECONDS);
        set_transient($time_key, time(), HOUR_IN_SECONDS);
    }

    /**
     * 重置错误计数
     */
    private function reset_error_frequency(string $key): void {
        delete_transient('aksrt_sms_err_' . $key);
        delete_transient('aksrt_sms_err_ts_' . $key);
    }

    /* ------------------------------------------------------------------
     * AJAX Handlers
     * ----------------------------------------------------------------*/

    /**
     * 手机号格式校验（对齐 legacy：支持中国号和国际号）
     */
    private function validate_phone(string $phone): bool {
        $config = $this->get_provider_config();
        $limit_ch = !isset($config['sms_number_limit_ch']) || !empty($config['sms_number_limit_ch']);

        if ($limit_ch) {
            // 仅中国大陆手机号
            return (bool) preg_match('/^1[3-9]\d{9}$/', $phone);
        }

        // 国际手机号：5 位以上数字，可选 + 前缀
        return (bool) preg_match('/^(?:\d{5,}|\+\d{6,})$/', $phone);
    }

    /**
     * AJAX 发送验证码
     */
    public function ajax_send_code(): void {
        check_ajax_referer('aksrt_sms', '_nonce');

        $phone = sanitize_text_field((string) ($_POST['phone'] ?? ''));
        if (!$this->validate_phone($phone)) {
            wp_send_json_error(['message' => __('手机号格式不正确', 'aksrt')]);
        }

        $scene = sanitize_key((string) ($_POST['scene'] ?? 'register'));
        if (!array_key_exists($scene, function_exists('aksrt_captcha_scenes') ? aksrt_captcha_scenes() : [])) {
            $scene = 'register';
        }
        if (function_exists('aksrt_require_captcha')) {
            $captcha_result = aksrt_require_captcha($scene, wp_unslash($_POST));
            if ($captcha_result !== true) {
                wp_send_json_error(['message' => $captcha_result ?: __('人机验证失败', 'aksrt')]);
            }
        }

        $result = $this->send_code($phone);

        if ($result['success']) {
            wp_send_json_success([
                'message'        => $result['message'],
                'remaining_time' => $result['remaining_time'] ?? 60,
            ]);
        }

        $error_data = ['message' => $result['message']];
        if (isset($result['remaining_time'])) {
            $error_data['remaining_time'] = $result['remaining_time'];
        }
        wp_send_json_error($error_data);
    }

    /**
     * AJAX: Test SMS provider (admin only).
     */
    public function ajax_test_provider(): void {
        if (!current_user_can('manage_options')) {
            wp_send_json_error(['message' => __('权限不足', 'aksrt')]);
        }

        $phone = sanitize_text_field((string) ($_POST['phone'] ?? ''));
        if (!preg_match('/^1[3-9]\d{9}$/', $phone)) {
            wp_send_json_error(['message' => __('手机号格式不正确', 'aksrt')]);
        }

        $result = $this->test_provider($phone);
        wp_send_json($result);
    }

    /**
     * AJAX: Get SMS provider status (admin only).
     */
    public function ajax_provider_status(): void {
        if (!current_user_can('manage_options')) {
            wp_send_json_error(['message' => __('权限不足', 'aksrt')]);
        }

        wp_send_json_success($this->get_provider_status());
    }

    /**
     * 获取 provider 真实运行时状态
     */
    public function get_provider_status(): array {
        $config       = $this->get_provider_config();
        $provider_key = sanitize_key((string) ($config['sms_provider'] ?? ''));

        $status = [
            'enabled'        => !empty($config['sms_enabled']),
            'provider'       => $provider_key ?: 'none',
            'configured'     => false,
            'available'      => false,
            'verified'       => false,
            'transport'      => '',
            'missing_fields' => [],
            'code_length'    => max(4, min(8, (int) ($config['sms_code_length'] ?? 6))),
            'code_expire'    => max(60, min(600, (int) ($config['sms_code_expire'] ?? 300))),
            'rate_limit'     => max(10, (int) ($config['sms_rate_limit'] ?? 60)),
            'daily_limit'    => max(1, (int) ($config['sms_daily_limit'] ?? 10)),
            'notify_bind'    => !empty($config['sms_notify_bind']),
            'notify_login'   => !empty($config['sms_notify_login']),
        ];

        $provider = SMSProviderFactory::get($provider_key);
        if ($provider !== null) {
            $provider_status           = $provider->get_status($config);
            $status['configured']      = !empty($provider_status['configured']);
            $status['available']       = !empty($provider_status['available']);
            $status['verified']        = !empty($provider_status['verified']);
            $status['transport']       = (string) ($provider_status['transport'] ?? '');
            $status['missing_fields']  = (array) ($provider_status['missing_fields'] ?? []);
        }

        return $status;
    }

    /**
     * Test provider connectivity (admin only).
     */
    public function test_provider(string $phone): array {
        $config = $this->get_provider_config();
        if (empty($config['sms_enabled'])) {
            return ['success' => false, 'message' => __('短信服务未启用', 'aksrt')];
        }

        $provider_key = sanitize_key((string) ($config['sms_provider'] ?? ''));
        if ($provider_key === '') {
            return ['success' => false, 'message' => __('未配置短信供应商', 'aksrt')];
        }

        $provider = SMSProviderFactory::get($provider_key);
        if ($provider === null) {
            return ['success' => false, 'message' => sprintf(__('短信供应商 "%s" 不可用', 'aksrt'), $provider_key)];
        }

        $missing = $provider->validate_config($config);
        if (!empty($missing)) {
            return ['success' => false, 'message' => sprintf(__('缺少配置项: %s', 'aksrt'), implode(', ', $missing))];
        }

        return $this->send_code($phone);
    }
}