<?php

declare(strict_types=1);

namespace app\miniapi\protection;

use app\miniapi\exception\ApiException;
use support\Log;

/** Transport-independent quota policy. Identities must come from the verified session. */
final class TrafficGuard
{
    private static int $lastFailureLog = 0;

    public function check(string $scope, string $identity, string $endpoint, int $listCost, string $requestId, bool $listOnly = false): void
    {
        if (!config('mini_protection.enabled', false)) {
            return;
        }
        if (!in_array($scope, ['ip', 'account'], true)) {
            throw new \LogicException('Unknown protection scope');
        }
        $subject = hash('sha256', $identity);
        $buckets = $listOnly ? [] : [
            $this->bucket($scope . '_requests', $subject, 1),
            $this->bucket($scope . '_endpoint', $subject . ':' . hash('sha256', $endpoint), 1),
        ];
        if ($listCost > 0) {
            $buckets[] = $this->bucket($scope . '_list_rows', $subject, $listCost);
        }
        try {
            [$blocked, $retry, $notice] = (new RedisQuota())->consume($buckets);
        } catch (\Throwable $error) {
            // Do not log connection strings, request data or exception messages.
            if (time() - self::$lastFailureLog >= 60) {
                self::$lastFailureLog = time();
                Log::channel('mini_protection')->error('mini_api.protection_unavailable', [
                    'request_id' => $requestId,
                    'exception_type' => get_class($error),
                ]);
            }
            throw new ApiException(50303, '访问保护服务暂时不可用，请稍后重试', 503, ['retry_after' => 5]);
        }
        if (!$blocked) {
            return;
        }
        if ($notice) {
            Log::channel('mini_protection')->warning('mini_api.quota_exceeded', [
                'request_id' => $requestId,
                'scope' => $scope,
                'subject_hash' => $subject,
                'endpoint' => $endpoint,
                'rule' => $buckets[$blocked - 1]['rule'],
                'retry_after' => $retry,
            ]);
        }

        throw new ApiException(42902, '访问过于频繁，请在' . $retry . '秒后重试', 429, ['retry_after' => $retry]);
    }

    private function bucket(string $rule, string $subject, int $cost): array
    {
        [$limit, $seconds] = config('mini_protection.limits.' . $rule);

        return [
            'key' => config('mini_protection.prefix') . $rule . ':' . $subject,
            'limit' => (int) $limit,
            'seconds' => (int) $seconds,
            'cost' => $cost,
            'rule' => $rule,
        ];
    }
}