<?php
/**
 * @author Daniel J. Summers <daniel@bitbadger.solutions>
 * @license MIT
 */

declare(strict_types=1);

namespace BitBadger\PDODocument;

use Random\RandomException;

/**
 * How automatic ID generation should be performed
 */
enum AutoId
{
    /** Do not automatically generate IDs */
    case None;

    /** New documents with a 0 ID should receive max ID plus one */
    case Number;

    /** New documents with a blank ID should receive a v4 UUID (Universally Unique Identifier) */
    case UUID;

    /** New documents with a blank ID should receive a random string (set `Configuration::$idStringLength`) */
    case RandomString;

    /**
     * Generate a v4 UUID
     *
     * @return string The v4 UUID
     * @throws RandomException If an appropriate source of randomness cannot be found
     */
    public static function generateUUID(): string
    {
        // hat tip: https://stackoverflow.com/a/15875555/276707
        $bytes = random_bytes(16);

        $bytes[6] = chr(ord($bytes[6]) & 0x0f | 0x40); // set version to 0100
        $bytes[8] = chr(ord($bytes[8]) & 0x3f | 0x80); // set bits 6-7 to 10

        return vsprintf('%s%s-%s-%s-%s-%s%s%s', str_split(bin2hex($bytes), 4));
    }

    /**
     * Generate a random string ID
     *
     * @param int|null $length The length of string to generate (optional; defaults to configured ID string length)
     * @return string A string filled with the hexadecimal representation of random bytes
     * @throws RandomException If an appropriate source of randomness cannot be found
     */
    public static function generateRandom(?int $length = null): string
    {
        return bin2hex(random_bytes(($length ?? Configuration::$idStringLength) / 2));
    }
}