<?php

namespace extend\ba;

class Random
{
    /**
     * 获取全球唯一标识
     * @return string
     */
    public static function uuid(): string
    {
        return sprintf(
                '%04x%04x-%04x-%04x-%04x-',
                mt_rand(0, 0xffff),
                mt_rand(0, 0xffff),
                mt_rand(0, 0xffff),
                mt_rand(0, 0x0fff) | 0x4000,
                mt_rand(0, 0x3fff) | 0x8000
            ) . substr(md5(uniqid(mt_rand(), true)), 0, 12);
    }

    /**
     * 随机字符生成
     * @param string $type 类型 alpha/alnum/numeric/noZero/unique/md5/encrypt/sha1
     * @param int    $len  长度
     * @return string
     */
    public static function build(string $type = 'alnum', int $len = 8): string
    {
        switch ($type) {
            case 'alpha':
            case 'alnum':
            case 'numeric':
            case 'noZero':
                $pool = match ($type) {
                    'alpha' => 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ',
                    'alnum' => '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ',
                    'numeric' => '0123456789',
                    'noZero' => '123456789',
                    default => '',
                };
                return substr(str_shuffle(str_repeat($pool, ceil($len / strlen($pool)))), 0, $len);
            case 'unique':
            case 'md5':
                return md5(uniqid(mt_rand()));
            case 'encrypt':
            case 'sha1':
                return sha1(uniqid(mt_rand(), true));
        }
        return '';
    }


    /**
     * 生成带随机前缀的唯一ID
     * @param int $length ID总长度
     * @return string 唯一ID
     */
    public static function generateRandomPrefixedId(int $length = 16): string {
        $length = min($length, 18);
        $prefixLength = 4;
        $timestamp = floor(microtime(true) * 1000); // 毫秒级时间戳
        $randomPart = '';

        // 生成随机前缀
        for ($i = 0; $i < $prefixLength; $i++) {
            $randomPart .= random_int(0, 9);
        }

        // 计算剩余长度用于时间戳
        $timestampLength = $length - $prefixLength;
        $timestampStr = (string) $timestamp;

        // 截取或补零时间戳部分
        if (strlen($timestampStr) > $timestampLength) {
            $timestampStr = substr($timestampStr, -$timestampLength);
        } else {
            $timestampStr = str_pad($timestampStr, $timestampLength, '0', STR_PAD_LEFT);
        }

        return $randomPart . $timestampStr;
    }


}