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