<?php
declare(strict_types=1);

namespace app\mcp\service;

use think\Request;

/**
 * AI 授权令牌：安全随机数生成，只保存 SHA-256；固定前缀便于密钥扫描。
 */
class TokenService
{
    public const PREFIX = 'zyt_ai_';

    public static function generate(): string
    {
        return self::PREFIX . bin2hex(random_bytes(32));
    }

    public static function hash(string $token): string
    {
        return hash('sha256', $token);
    }

    public static function displayPrefix(string $token): string
    {
        return substr($token, 0, 12);
    }

    /** 从 Authorization: Bearer 头取令牌；格式不对返回空字符串 */
    public static function fromRequest(Request $request): string
    {
        $header = (string) $request->header('authorization', '');
        if (!preg_match('/^\s*Bearer\s+(\S+)\s*$/i', $header, $m)) {
            return '';
        }
        $token = $m[1];
        return (str_starts_with($token, self::PREFIX) && strlen($token) === strlen(self::PREFIX) + 64) ? $token : '';
    }
}