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

namespace AKSRT\Credits;

defined('ABSPATH') || exit;

class Invite {

    const COOKIE_NAME = 'aksrt_invite';
    const COOKIE_TTL_DAYS = 30;
    const META_INVITE_CODE = 'aksrt_invite_code';
    const OPT_STANDALONE_CODES = 'aksrt_standalone_invite_codes';

    /**
     * 反向映射 option：code => user_id
     *
     * 注意：option 大小受限（默认非 autoload），10 万级用户没问题，
     * 百万级仍可走，性能瓶颈在 update_option 写入；此处采用懒写策略：
     * 仅在 get_or_create_code 生成新码时同步写入。
     */
    const OPT_REVERSE_MAP = 'aksrt_invite_code_map';

    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 {
        // 在请求最早期捕获邀请码
        add_action('init', [$this, 'capture_invite_cookie'], 1);
        // 注册时记录邀请关系
        add_action('user_register', [$this, 'on_user_register'], 20, 1);
        // 邮箱验证后兑现
        add_action('aksrt_email_verified', [$this, 'on_email_verified'], 10, 1);
        // 用户删除时清理邀请码映射
        add_action('delete_user', [$this, 'on_delete_user'], 10, 1);

        add_action('rest_api_init', [$this, 'register_routes']);
    }

    public function register_routes(): void {
        register_rest_route('aksrt/v1', '/invite/me', [
            'methods'             => 'GET',
            'callback'            => [$this, 'rest_me'],
            'permission_callback' => function () {
                return is_user_logged_in();
            },
        ]);
        register_rest_route('aksrt/v1', '/invite/list', [
            'methods'             => 'GET',
            'callback'            => [$this, 'rest_list'],
            'permission_callback' => function () {
                return is_user_logged_in();
            },
            'args'                => [
                'page'     => [
                    'type'    => 'integer',
                    'default' => 1,
                    'minimum' => 1,
                ],
                'per_page' => [
                    'type'    => 'integer',
                    'default' => 10,
                    'minimum' => 1,
                    'maximum' => 50,
                ],
            ],
        ]);
    }
    /** Capture the unified ?ref=XYZ referral parameter. */
    public function capture_invite_cookie(): void {
        if (is_admin()) return;
        $raw_code = $_GET['ref'] ?? '';
        if ($raw_code === '') return;
        // 邀请注册功能关闭时不处理
        if (class_exists('\AKSRT\Settings\Settings') && !\AKSRT\Settings\Settings::invite_registration_enabled()) return;

        $code = sanitize_key(wp_unslash((string) $raw_code));
        if ($code === '') return;

        // 校验邀请码是否对应真实用户
        $inviter_id = $this->resolve_code($code);
        if ($inviter_id <= 0) return;

        // 已登录用户不能用自己的邀请码
        if (is_user_logged_in() && $inviter_id === get_current_user_id()) return;

        // 不覆盖已存在的（防多次访问被覆盖）
        if (!empty($_COOKIE[self::COOKIE_NAME])) return;

        $expires = time() + DAY_IN_SECONDS * self::COOKIE_TTL_DAYS;
        // 不覆盖 secure 标记的检测
        $secure = is_ssl();
        // headers_sent 检查
        if (!headers_sent()) {
            setcookie(self::COOKIE_NAME, $code, [
                'expires'  => $expires,
                'path'     => COOKIEPATH ?: '/',
                'domain'   => COOKIE_DOMAIN,
                'secure'   => $secure,
                'httponly' => true,
                'samesite' => 'Lax',
            ]);
            $_COOKIE[self::COOKIE_NAME] = $code;
        }
    }

    /** 注册：写入 aksrt_invite 表 */
    public function on_user_register(int $invitee_id): void {
        // 邀请注册功能关闭时不记录邀请关系
        if (class_exists('\AKSRT\Settings\Settings') && !\AKSRT\Settings\Settings::invite_registration_enabled()) return;

        // 优先级 1：表单显式填写的邀请码（由 \AKSRT\Auth\Service 注入）
        $code       = '';
        $inviter_id = 0;
        if (class_exists('\AKSRT\Auth\Service')) {
            $ctx = \AKSRT\Auth\Service::take_pending_invite_context();
            if (!empty($ctx['inviter_id']) && $ctx['inviter_id'] !== $invitee_id) {
                $inviter_id = (int) $ctx['inviter_id'];
                $code       = (string) $ctx['code'];
            }
        }

        // 优先级 2：fallback 到 cookie
        if ($inviter_id <= 0) {
            if (empty($_COOKIE[self::COOKIE_NAME])) return;
            $code = sanitize_key((string) $_COOKIE[self::COOKIE_NAME]);
            if ($code === '') return;
            $inviter_id = $this->get_user_by_code($code);
        }

        if ($inviter_id <= 0 || $inviter_id === $invitee_id) return;

        $this->record_invite_registration($inviter_id, $invitee_id, $code, 'registered');

        // 清 cookie，避免再次触发
        if (!headers_sent()) {
            setcookie(self::COOKIE_NAME, '', time() - 3600, COOKIEPATH ?: '/', COOKIE_DOMAIN);
        }

        // 若配置不要求邮箱验证就立即兑现
        $invite_cfg = class_exists('\AKSRT\Settings\Settings')
            ? \AKSRT\Settings\Settings::get_invite_reward_settings()
            : [
                'require_verify' => true,
            ];
        if (empty($invite_cfg['require_verify'])) {
            $this->reward_pair($inviter_id, $invitee_id);
        }
    }

    /** 邮箱验证后兑现奖励（钩子由 \AKSRT\Auth\Service 触发，可后续接入） */
    public function on_email_verified(int $user_id): void {
        // 邀请注册功能关闭时不兑现奖励
        if (class_exists('\AKSRT\Settings\Settings') && !\AKSRT\Settings\Settings::invite_registration_enabled()) return;

        global $wpdb;
        $table = \AKSRT\Core\DBMigrator::table('invite');
        if (!$table) return;

        $row = $wpdb->get_row($wpdb->prepare(
            "SELECT * FROM {$table} WHERE invitee_id = %d AND status IN ('registered', 'verified') LIMIT 1",
            $user_id
        ), ARRAY_A);
        if (!$row) return;

        $wpdb->update(
            $table,
            ['status' => 'verified'],
            ['id' => (int) $row['id']],
            ['%s'],
            ['%d']
        );

        if ((int) $row['inviter_id'] <= 0) {
            return;
        }

        $this->reward_pair((int) $row['inviter_id'], $user_id);
    }

    /** 用户被删除时清理邀请码映射 */
    public function on_delete_user(int $user_id): void {
        $code = (string) get_user_meta($user_id, self::META_INVITE_CODE, true);
        if ($code === '') return;

        $map = $this->load_reverse_map();
        if (isset($map[$code]) && (int) $map[$code] === $user_id) {
            unset($map[$code]);
            update_option(self::OPT_REVERSE_MAP, $map, false);
        }
    }

    /** 双向发放奖励 */
    private function reward_pair(int $inviter_id, int $invitee_id): void {
        if (!class_exists('AKSRT\\Credits\\Credits') || !class_exists('\AKSRT\Settings\Settings')) return;

        global $wpdb;
        $table = \AKSRT\Core\DBMigrator::table('invite');
        if (!$table) return;
        $claimed = $wpdb->update(
            $table,
            ['status' => 'rewarding'],
            ['inviter_id' => $inviter_id, 'invitee_id' => $invitee_id, 'status' => 'verified'],
            ['%s'],
            ['%d', '%d', '%s']
        );
        if ($claimed !== 1) return;

        $invite_cfg = \AKSRT\Settings\Settings::get_invite_reward_settings();
        if (empty($invite_cfg['enabled']) || !$this->ip_daily_check($invite_cfg)) {
            $wpdb->update($table, ['status' => 'verified'], ['inviter_id' => $inviter_id, 'invitee_id' => $invitee_id], ['%s'], ['%d', '%d']);
            return;
        }

        $inviter_amount = (int) ($invite_cfg['inviter_amount'] ?? 0);
        $invitee_amount = (int) ($invite_cfg['invitee_amount'] ?? 0);
        $level_integral = max(0, (int) ($invite_cfg['invit_reward_level'] ?? 0));

        if ($inviter_amount > 0) {
            Credits::add($inviter_id, $inviter_amount, 'invite', ['type' => 'user', 'id' => $invitee_id]);
        }
        if ($invitee_amount > 0) {
            Credits::add($invitee_id, $invitee_amount, 'invitee', ['type' => 'user', 'id' => $inviter_id]);
        }
        if ($level_integral > 0 && class_exists('\AKSRT\User\Level')) {
            \AKSRT\User\Level::add($inviter_id, 'invitation', $level_integral, true);
        }

        // 标记 rewarded
        $wpdb->update(
                $table,
                [
                    'status'      => 'rewarded',
                    'rewarded_at' => current_time('mysql', true),
                ],
                [
                    'inviter_id' => $inviter_id,
                    'invitee_id' => $invitee_id,
                ],
            ['%s', '%s'],
            ['%d', '%d']
        );
    }

    /** 同 IP 当日邀请兑现次数限制 */
    private function ip_daily_check(array $invite_cfg): bool {
        $cap = (int) ($invite_cfg['ip_daily_cap'] ?? 3);
        if ($cap <= 0) return true;

        $ip = function_exists('aksrt_get_client_ip') ? aksrt_get_client_ip() : '';
        if (!$ip) return true;

        global $wpdb;
        $log_table = \AKSRT\Core\DBMigrator::table('credit_log');
        if (!$log_table) return true;

        $today_utc = (new \DateTimeImmutable('today', wp_timezone()))->setTimezone(new \DateTimeZone('UTC'))->format('Y-m-d H:i:s');
        $count = (int) $wpdb->get_var($wpdb->prepare(
            "SELECT COUNT(*) FROM {$log_table} WHERE reason = 'invite' AND ip = %s AND created_at >= %s",
            $ip,
            $today_utc
        ));
        return $count < $cap;
    }

    /** 取或生成用户的邀请码 */
    public function get_or_create_code(int $user_id): string {
        $code = (string) get_user_meta($user_id, self::META_INVITE_CODE, true);

        // 邀请码长度（后台可配置，4-12，默认 6）
        $code_length = class_exists('\AKSRT\Settings\Settings')
            ? \AKSRT\Settings\Settings::invite_code_length()
            : max(4, min(12, (int) aksrt_get_setting('invite_code_length', 6)));

        // 兼容配置变更：已有码只要长度合理就复用
        if ($code !== '' && strlen($code) <= $code_length + 2) return $code;

        // 生成唯一码
        $alphabet = 'abcdefghjkmnpqrstuvwxyz23456789';
        $map = $this->load_reverse_map();
        for ($i = 0; $i < 5; $i++) {
            $code = '';
            for ($j = 0; $j < $code_length; $j++) {
                $code .= $alphabet[random_int(0, strlen($alphabet) - 1)];
            }
            if (!isset($map[$code]) && !$this->code_exists_legacy($code)) break;
        }
        update_user_meta($user_id, self::META_INVITE_CODE, $code);

        // 同步反向映射
        $map[$code] = $user_id;
        update_option(self::OPT_REVERSE_MAP, $map, false);

        return $code;
    }

    /**
     * 公开 API：根据邀请码反查邀请人 user_id（不存在返回 0）。
     * 给注册流程在 wp_create_user 之前做"邀请码是否合法"的预校验用。
     */
    /**
     * Resolve affiliate / invite referrer for a buyer (zibll-style).
     *
     * Priority:
     * 1. Logged-in: inviter_id from aksrt_invite table for this invitee
     * 2. Cookie invite code → resolve_code
     *
     * Respects pay_rebate_self_s when available (via affiliate settings).
     */
    public function get_referrer(int $user_id = 0): int {
        $uid = $user_id > 0 ? $user_id : get_current_user_id();
        $referrer_id = 0;

        if ($uid > 0) {
            global $wpdb;
            $table = \AKSRT\Core\DBMigrator::table('invite');
            if ($table) {
                $referrer_id = (int) $wpdb->get_var($wpdb->prepare(
                    "SELECT inviter_id FROM {$table} WHERE invitee_id = %d AND inviter_id > 0 ORDER BY id DESC LIMIT 1",
                    $uid
                ));
            }
        }

        if ($referrer_id <= 0) {
            $code = '';
            if (!empty($_COOKIE[self::COOKIE_NAME])) {
                $code = sanitize_key((string) $_COOKIE[self::COOKIE_NAME]);
            }
            if ($code !== '') {
                $referrer_id = $this->resolve_code($code);
            }
        }

        if ($referrer_id <= 0) {
            return 0;
        }

        // Self-purchase rebate gate (default allow, matching pay_rebate_self_s default true).
        $allow_self = true;
        if (class_exists('\AKSRT\Settings\Settings') && method_exists('\AKSRT\Settings\Settings', 'get_payment_affiliate_settings')) {
            $aff = \AKSRT\Settings\Settings::get_payment_affiliate_settings();
            $allow_self = !isset($aff['self_s']) || !empty($aff['self_s']);
        }
        if ($uid > 0 && $referrer_id === $uid && !$allow_self) {
            return 0;
        }

        return $referrer_id;
    }

    public function resolve_code(string $code): int {
        $code = sanitize_key($code);
        if ($code === '') return 0;
        return $this->get_user_by_code($code);
    }

    /**
     * 校验邀请码是否合法。
     *
     * 用户邀请码与后台批量生成的独立邀请码都视为有效。
     */
    public function validate_code(string $code): bool {
        $code = sanitize_key($code);
        if ($code === '') {
            return false;
        }

        if ($this->get_user_by_code($code) > 0) {
            return true;
        }

        return $this->find_standalone_code_index($code) >= 0;
    }

    /**
     * 注册完成后处理邀请码。
     *
     * - 用户邀请码：沿用 inviter/invitee canonical 关系
     * - 独立邀请码：记录使用人并标记为已消耗，不参与奖励
     */
    public function handle_registration_invite(int $invitee_id, string $invite_code): void {
        $invitee_id  = (int) $invitee_id;
        $invite_code = sanitize_key($invite_code);

        if ($invitee_id <= 0 || $invite_code === '') {
            return;
        }

        if (class_exists('\AKSRT\Settings\Settings') && !\AKSRT\Settings\Settings::invite_registration_enabled()) {
            return;
        }

        $inviter_id = $this->get_user_by_code($invite_code);
        if ($inviter_id > 0) {
            if ($inviter_id === $invitee_id) {
                return;
            }

            $this->record_invite_registration($inviter_id, $invitee_id, $invite_code, 'registered');
            return;
        }

        $index = $this->find_standalone_code_index($invite_code);
        if ($index < 0) {
            return;
        }

        $requires_verify = class_exists('\AKSRT\Settings\Settings') && \AKSRT\Settings\Settings::registration_requires_email_verification();
        $status          = $requires_verify ? 'registered' : 'verified';

        if ($this->record_invite_registration(0, $invitee_id, $invite_code, $status)) {
            $this->mark_standalone_code_used($invite_code, $invitee_id);
        }
    }

    /** 反查邀请码对应的用户（O(1) option 查表，回退 user_meta 扫描） */
    private function get_user_by_code(string $code): int {
        if ($code === '') return 0;

        $map = $this->load_reverse_map();
        if (isset($map[$code])) {
            $uid = (int) $map[$code];
            if ($uid > 0) {
                // 校验：确保该用户的 meta 仍然指向该 code（用户可能已被删除或 meta 被清空）
                $meta_code = (string) get_user_meta($uid, self::META_INVITE_CODE, true);
                if ($meta_code === $code) {
                    return $uid;
                }
                // 失配 → 修正映射
                unset($map[$code]);
                update_option(self::OPT_REVERSE_MAP, $map, false);
            }
        }

        // 回退 + 自愈：扫描 user_meta（应只在迁移期或映射损坏时触发）
        $uid = $this->code_exists_legacy($code);
        if ($uid > 0) {
            $map[$code] = $uid;
            update_option(self::OPT_REVERSE_MAP, $map, false);
        }
        return $uid;
    }

    private function load_reverse_map(): array {
        $map = get_option(self::OPT_REVERSE_MAP, []);
        return is_array($map) ? $map : [];
    }

    /**
     * 写入邀请关系记录。
     */
    private function record_invite_registration(int $inviter_id, int $invitee_id, string $code, string $status = 'registered'): bool {
        global $wpdb;

        $table = \AKSRT\Core\DBMigrator::table('invite');
        if (!$table || $invitee_id <= 0 || $code === '') {
            return false;
        }

        $existing_code = $wpdb->get_var($wpdb->prepare(
            "SELECT id FROM {$table} WHERE invite_code = %s LIMIT 1",
            $code
        ));
        if ($existing_code) {
            return false;
        }

        $existing_invitee = $wpdb->get_var($wpdb->prepare(
            "SELECT id FROM {$table} WHERE invitee_id = %d LIMIT 1",
            $invitee_id
        ));
        if ($existing_invitee) {
            return false;
        }

        $result = $wpdb->insert(
            $table,
            [
                'inviter_id'  => max(0, $inviter_id),
                'invitee_id'  => $invitee_id,
                'invite_code' => $code,
                'status'      => $status,
                'created_at'  => current_time('mysql', true),
            ],
            ['%d', '%d', '%s', '%s', '%s']
        );

        return (bool) $result;
    }

    private function load_standalone_codes(): array {
        $codes = get_option(self::OPT_STANDALONE_CODES, []);
        return is_array($codes) ? array_values($codes) : [];
    }

    private function save_standalone_codes(array $codes): void {
        update_option(self::OPT_STANDALONE_CODES, array_values($codes), false);
    }

    private function normalize_standalone_code(array $entry): array {
        $code    = sanitize_key((string) ($entry['code'] ?? ''));
        $used_by = (int) ($entry['used_by'] ?? 0);
        $used    = !empty($entry['used']) || $used_by > 0;

        return [
            'code'       => $code,
            'created_at' => sanitize_text_field((string) ($entry['created_at'] ?? '')),
            'used'       => $used,
            'used_by'    => $used_by,
            'used_at'    => sanitize_text_field((string) ($entry['used_at'] ?? '')),
            'disabled'   => !empty($entry['disabled']),
            'note'       => sanitize_textarea_field((string) ($entry['note'] ?? '')),
            'batch_id'   => sanitize_text_field((string) ($entry['batch_id'] ?? '')),
            'created_by' => (int) ($entry['created_by'] ?? 0),
        ];
    }

    private function find_standalone_code_index(string $code): int {
        $code  = sanitize_key($code);
        $codes = $this->load_standalone_codes();

        foreach ($codes as $index => $entry) {
            $normalized = $this->normalize_standalone_code((array) $entry);
            if ($normalized['code'] !== $code) {
                continue;
            }

            if ($normalized['disabled'] || $normalized['used']) {
                return -1;
            }

            return $index;
        }

        return -1;
    }

    private function mark_standalone_code_used(string $code, int $invitee_id): void {
        $code  = sanitize_key($code);
        $codes = $this->load_standalone_codes();

        foreach ($codes as $index => $entry) {
            $normalized = $this->normalize_standalone_code((array) $entry);
            if ($normalized['code'] !== $code) {
                continue;
            }

            $normalized['used']    = true;
            $normalized['used_by'] = $invitee_id;
            $normalized['used_at'] = current_time('mysql', true);
            $codes[$index]         = $normalized;
            $this->save_standalone_codes($codes);
            return;
        }
    }

    /** 旧路径：通过 user_meta 反查（保留作为自愈兜底） */
    private function code_exists_legacy(string $code): int {
        $users = get_users([
            'meta_key'   => self::META_INVITE_CODE,
            'meta_value' => $code,
            'number'     => 1,
            'fields'     => 'ID',
        ]);
        if (empty($users)) return 0;
        return (int) $users[0];
    }

    private function code_exists(string $code): bool {
        return $this->get_user_by_code($code) > 0;
    }

    // ---------- REST ----------

    public function rest_me(\WP_REST_Request $request) {
        if (class_exists('\AKSRT\Settings\Settings') && !\AKSRT\Settings\Settings::invite_registration_enabled()) {
            return new \WP_REST_Response(['code' => 'error', 'message' => '邀请注册功能已关闭'], 403);
        }

        $user_id = get_current_user_id();
        $code = $this->get_or_create_code($user_id);

        global $wpdb;
        $table = \AKSRT\Core\DBMigrator::table('invite');
        $stats = [
            'registered' => 0,
            'verified'   => 0,
            'rewarded'   => 0,
        ];
        if ($table) {
            $rows = $wpdb->get_results($wpdb->prepare(
                "SELECT status, COUNT(*) AS c FROM {$table} WHERE inviter_id = %d GROUP BY status",
                $user_id
            ), ARRAY_A);
            if (is_array($rows)) {
                foreach ($rows as $r) {
                    $status = (string) $r['status'];
                    $count  = (int) $r['c'];

                    // The stored status is terminal; dashboard stats are milestone totals.
                    if ($status === 'registered') {
                        $stats['registered'] += $count;
                    } elseif ($status === 'verified') {
                        $stats['registered'] += $count;
                        $stats['verified'] += $count;
                    } elseif ($status === 'rewarded') {
                        $stats['registered'] += $count;
                        $stats['verified'] += $count;
                        $stats['rewarded'] += $count;
                    }
                }
            }
        }

        $invite_url = add_query_arg('ref', $code, home_url('/'));

        return new \WP_REST_Response([
            'code'       => $code,
            'invite_url' => $invite_url,
            'stats'      => $stats,
        ], 200);
    }

    public function rest_list(\WP_REST_Request $request) {
        if (class_exists('\AKSRT\Settings\Settings') && !\AKSRT\Settings\Settings::invite_registration_enabled()) {
            return new \WP_REST_Response(['code' => 'error', 'message' => '邀请注册功能已关闭'], 403);
        }

        global $wpdb;
        $user_id = get_current_user_id();
        $page     = max(1, (int) $request->get_param('page'));
        $per_page = min(50, max(1, (int) $request->get_param('per_page') ?: 10));
        $table = \AKSRT\Core\DBMigrator::table('invite');
        if (!$table) {
            return new \WP_REST_Response(['items' => [], 'total' => 0], 200);
        }

        $total = (int) $wpdb->get_var($wpdb->prepare(
            "SELECT COUNT(*) FROM {$table} WHERE inviter_id = %d",
            $user_id
        ));
        $total_pages = max(1, (int) ceil($total / $per_page));
        $page = min($page, $total_pages);
        $offset = ($page - 1) * $per_page;
        $rows = $wpdb->get_results($wpdb->prepare(
            "SELECT * FROM {$table} WHERE inviter_id = %d ORDER BY created_at DESC LIMIT %d OFFSET %d",
            $user_id,
            $per_page,
            $offset
        ), ARRAY_A);

        $items = [];
        foreach ((array) $rows as $r) {
            $invitee = $r['invitee_id'] ? get_userdata((int) $r['invitee_id']) : null;
            $items[] = [
                'id'             => (int) $r['id'],
                'invitee_id'     => (int) $r['invitee_id'],
                'invitee_name'   => $invitee ? $invitee->display_name : '',
                'invitee_avatar' => $invitee ? get_avatar_url((int) $invitee->ID, ['size' => 64]) : '',
                'status'         => (string) $r['status'],
                'created_at'     => (string) $r['created_at'],
                'rewarded_at'    => (string) $r['rewarded_at'],
            ];
        }

        return new \WP_REST_Response([
            'items'    => $items,
            'total'    => $total,
            'page'     => $page,
            'per_page' => $per_page,
            'total_pages' => $total_pages,
        ], 200);
    }
}