<?php
/**
 * AKSRT Coupon — 优惠券系统
 *
 * 使用专用表 {prefix}aksrt_coupon 存储优惠券。
 * 支持：创建、列表、验证、核销。
 *
 * @package AKSRT
 */

defined('ABSPATH') || exit;

class AKSRT_Coupon {

    const TYPE_PERCENT = 'percent';
    const TYPE_FIXED   = 'fixed';

    private static $instance = null;

    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('coupon');
    }

    /**
     * 创建优惠券
     */
    public function create(array $data): int {
        global $wpdb;

        $code = sanitize_text_field((string) ($data['code'] ?? ''));
        if ($code === '') return 0;

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

        $type = sanitize_key((string) ($data['type'] ?? self::TYPE_FIXED));
        if (!in_array($type, [self::TYPE_PERCENT, self::TYPE_FIXED], true)) {
            $type = self::TYPE_FIXED;
        }

        $wpdb->insert($this->table(), [
            'code'           => $code,
            'type'           => $type,
            'value'          => (float) ($data['value'] ?? 0),
            'min_amount'     => (float) ($data['min_amount'] ?? 0),
            'usage_limit'    => (int) ($data['usage_limit'] ?? 0),
            'used_count'     => 0,
            'expires_at'     => sanitize_text_field((string) ($data['expires_at'] ?? '')),
            'per_user_limit' => (int) ($data['per_user_limit'] ?? 0),
            'product_scope'  => wp_json_encode($data['product_scope'] ?? [], JSON_UNESCAPED_UNICODE),
            'max_discount'   => (float) ($data['max_discount'] ?? 0),
            'status'         => 'active',
            'created_at'     => current_time('mysql'),
        ], ['%s', '%s', '%f', '%f', '%d', '%d', '%s', '%d', '%s', '%f', '%s', '%s']);

        return (int) $wpdb->insert_id;
    }

    /**
     * 获取优惠券列表
     */
    public function get_list(array $args = []): array {
        global $wpdb;

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

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

        $search = sanitize_text_field((string) ($args['search'] ?? ''));
        if ($search !== '') {
            $where[] = 'code LIKE %s';
            $params[] = '%' . $wpdb->esc_like($search) . '%';
        }

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

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

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

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

        return [
            'items'       => array_map([$this, 'normalize_row'], (array) $rows),
            'total'       => $total,
            'page'        => max(1, (int) ceil($offset / $limit) + 1),
            'total_pages' => max(1, (int) ceil($total / $limit)),
        ];
    }

    /**
     * 验证优惠券是否可用
     *
     * @return array{valid: bool, coupon?: array, message?: string}
     */
    public function validate(string $code, float $order_amount = 0, array $args = []): array {
        global $wpdb;

        $code = sanitize_text_field($code);
        if ($code === '') {
            return ['valid' => false, 'message' => '请输入优惠码'];
        }

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

        if (!$coupon) {
            return ['valid' => false, 'message' => '优惠码不存在'];
        }

        $coupon = $this->normalize_row($coupon);

        if ($coupon['status'] !== 'active') {
            return ['valid' => false, 'message' => '优惠码已失效'];
        }

        if (!empty($coupon['expires_at']) && strtotime($coupon['expires_at']) < time()) {
            return ['valid' => false, 'message' => '优惠码已过期'];
        }

        if ($coupon['usage_limit'] > 0 && $coupon['used_count'] >= $coupon['usage_limit']) {
            return ['valid' => false, 'message' => '优惠码已用完'];
        }

        if ($coupon['min_amount'] > 0 && $order_amount < $coupon['min_amount']) {
            return ['valid' => false, 'message' => '订单金额不满足最低消费要求'];
        }

        // Per-user limit check
        $user_id = (int) ($args['user_id'] ?? 0);
        if ($coupon['per_user_limit'] > 0 && $user_id > 0) {
            $user_used = $this->get_user_usage_count($coupon['id'], $user_id);
            if ($user_used >= $coupon['per_user_limit']) {
                return ['valid' => false, 'message' => '您已使用该优惠码达到上限'];
            }
        }

        // Product / content scope check.
        // Supports shop product cats and content post cats.
        if (!empty($coupon['product_scope']) && !empty($args['product_ids'])) {
            $scope = is_array($coupon['product_scope']) ? $coupon['product_scope'] : json_decode($coupon['product_scope'], true);
            if (is_array($scope) && !empty($scope)) {
                $scope_type = sanitize_key((string) ($scope['type'] ?? ''));
                $scope_ids  = array_map('intval', (array) ($scope['ids'] ?? []));
                $product_ids = array_map('intval', (array) $args['product_ids']);
                $taxonomies = array_values(array_filter(array_map('sanitize_key', (array) ($scope['taxonomies'] ?? []))));
                if ($taxonomies === []) {
                    // content context prefers category; shop admin may pass aksrt_product_cat.
                    $context = sanitize_key((string) ($args['context'] ?? ''));
                    $taxonomies = ($context === 'content')
                        ? ['category']
                        : ['aksrt_product_cat', 'category'];
                }

                if ($scope_type === 'include' && empty(array_intersect($product_ids, $scope_ids))) {
                    return ['valid' => false, 'message' => __('该优惠码不适用于当前商品', 'aksrt')];
                }
                if ($scope_type === 'exclude' && !empty(array_intersect($product_ids, $scope_ids))) {
                    return ['valid' => false, 'message' => __('该优惠码不适用于当前商品', 'aksrt')];
                }
                if (in_array($scope_type, ['category', 'content_category', 'post_category'], true)) {
                    $matched = false;
                    foreach ($product_ids as $pid) {
                        foreach ($taxonomies as $tax) {
                            $cats = wp_get_post_terms($pid, $tax, ['fields' => 'ids']);
                            if (!is_wp_error($cats) && !empty(array_intersect(array_map('intval', (array) $cats), $scope_ids))) {
                                $matched = true;
                                break 2;
                            }
                        }
                    }
                    if (!$matched) {
                        return ['valid' => false, 'message' => __('该优惠码不适用于当前分类', 'aksrt')];
                    }
                }
            }
        }

        // Calculate discount
        $discount = 0;
        if ($coupon['type'] === self::TYPE_PERCENT) {
            $discount = $order_amount * ($coupon['value'] / 100);
        } else {
            $discount = min($coupon['value'], $order_amount);
        }

        // Max discount cap
        if ($coupon['max_discount'] > 0 && $discount > $coupon['max_discount']) {
            $discount = $coupon['max_discount'];
        }

        return [
            'valid'    => true,
            'coupon'   => $coupon,
            'discount' => round($discount, 2),
        ];
    }

    /**
     * 核销优惠券
     */
    public function use_coupon(string $code): bool {
        global $wpdb;

        $code = sanitize_text_field($code);
        $result = $wpdb->query($wpdb->prepare(
            "UPDATE {$this->table()} SET used_count = used_count + 1 WHERE code = %s",
            $code
        ));

        return $result !== false;
    }

    /**
     * 禁用优惠券
     */
    public function disable(int $id): bool {
        global $wpdb;
        return $wpdb->update($this->table(), ['status' => 'disabled'], ['id' => $id], ['%s'], ['%d']) !== false;
    }

    public function enable(int $id): bool {
        global $wpdb;
        return $wpdb->update($this->table(), ['status' => 'active'], ['id' => $id], ['%s'], ['%d']) !== false;
    }

    /**
     * Batch-create coupons with auto-generated codes.
     *
     * @return array{created:int,codes:array<int,string>}
     */
    public function batch_create(array $data, int $count = 1, int $length = 10, string $prefix = ''): array {
        $count  = max(1, min(100, $count));
        $length = max(6, min(24, $length));
        $prefix = sanitize_text_field($prefix);
        $codes  = [];
        $created = 0;

        for ($i = 0; $i < $count; $i++) {
            $code = $prefix !== ''
                ? $prefix . strtoupper(wp_generate_password($length, false, false))
                : strtoupper(wp_generate_password($length, false, false));
            $payload = $data;
            $payload['code'] = $code;
            $id = $this->create($payload);
            if ($id > 0) {
                $created++;
                $codes[] = $code;
            }
        }

        return [
            'created' => $created,
            'codes'   => $codes,
        ];
    }

    /**
     * Count how many times a user has used a specific coupon.
     */
    public function get_user_usage_count(int $coupon_id, int $user_id): int {
        global $wpdb;
        $table = AKSRT_DB_Migrator::table('coupon_usage');
        return (int) $wpdb->get_var($wpdb->prepare(
            "SELECT COUNT(*) FROM {$table} WHERE coupon_id = %d AND user_id = %d",
            $coupon_id, $user_id
        ));
    }

    /**
     * Log a coupon usage record.
     */
    public function log_usage(int $coupon_id, int $user_id, string $order_number, float $discount): void {
        global $wpdb;
        $table = AKSRT_DB_Migrator::table('coupon_usage');
        $wpdb->insert($table, [
            'coupon_id'    => $coupon_id,
            'user_id'      => $user_id,
            'order_number' => $order_number,
            'discount'     => $discount,
            'created_at'   => current_time('mysql'),
        ], ['%d', '%d', '%s', '%f', '%s']);
    }

    private function normalize_row(array $row): array {
        $row['id'] = (int) $row['id'];
        $row['value'] = (float) $row['value'];
        $row['min_amount'] = (float) $row['min_amount'];
        $row['usage_limit'] = (int) $row['usage_limit'];
        $row['used_count'] = (int) $row['used_count'];
        $row['per_user_limit'] = (int) ($row['per_user_limit'] ?? 0);
        $row['max_discount'] = (float) ($row['max_discount'] ?? 0);
        if (!empty($row['product_scope']) && is_string($row['product_scope'])) {
            $row['product_scope'] = json_decode($row['product_scope'], true) ?: [];
        }
        return $row;
    }
}