<?php namespace App\Util\Blurhash; use InvalidArgumentException; class Base83 { private const ALPHABET = [ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '#', '$', '%', '*', '+', ',', '-', '.', ':', ';', '=', '?', '@', '[', ']', '^', '_', '{', '|', '}', '~' ]; private const BASE = 83; public static function encode(int $value, int $length): string { if (floor($value / (self::BASE ** $length)) != 0) { throw new InvalidArgumentException('Specified length is too short to encode given value.'); } $result = ''; for ($i = 1; $i <= $length; $i++) { $digit = floor($value / (self::BASE ** ($length - $i))) % self::BASE; $result .= self::ALPHABET[$digit]; } return $result; } public static function decode(string $hash): int { $result = 0; foreach (str_split($hash) as $char) { $result = $result * self::BASE + (int) array_search($char, self::ALPHABET, true); } return (int) $result; } }