<?php

// Do not allow the file to be called directly.
if (!defined('ABSPATH')) {
	exit;
}

/**
 * Encode in Base32 based on RFC 4648.
 * Requires 20% more space than base64  
 * Great for case-insensitive filesystems like Windows and URL's  (except for = char which can be excluded using the pad option for urls)
 *
 * @package default
 * @author Bryan Ruiz
 **/
class Base32Static
{
	private static $map = array(
		'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', //  7
		'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', // 15
		'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', // 23
		'Y', 'Z', '2', '3', '4', '5', '6', '7', // 31
		'='  // padding character
	);
		
	 private static $flippedMap = array(
		'A'=>'0', 'B'=>'1', 'C'=>'2', 'D'=>'3', 'E'=>'4', 'F'=>'5', 'G'=>'6', 'H'=>'7',
		'I'=>'8', 'J'=>'9', 'K'=>'10', 'L'=>'11', 'M'=>'12', 'N'=>'13', 'O'=>'14', 'P'=>'15',
		'Q'=>'16', 'R'=>'17', 'S'=>'18', 'T'=>'19', 'U'=>'20', 'V'=>'21', 'W'=>'22', 'X'=>'23',
		'Y'=>'24', 'Z'=>'25', '2'=>'26', '3'=>'27', '4'=>'28', '5'=>'29', '6'=>'30', '7'=>'31'
	);
		
	/**
	 * Use padding false when encoding for urls
	 *
	 * @return base32 encoded string
	 * @author Bryan Ruiz
	 **/
	public static function encode($input, $padding = true)
	{
		if (empty($input)) {
			return '';
		}
		
		$input = str_split($input);
		$binaryString = '';
		
		for($i = 0; $i < count($input); $i++) {
			$binaryString .= str_pad(base_convert(ord($input[$i]), 10, 2), 8, '0', STR_PAD_LEFT);
		}
		
		$fiveBitBinaryArray = str_split($binaryString, 5);
		$base32 = '';
		$i = 0;
		
		while ($i < count($fiveBitBinaryArray)) {    
			$base32 .= self::$map[base_convert(str_pad($fiveBitBinaryArray[$i], 5, '0'), 2, 10)];
			$i++;
		}
		
		if ($padding && ($x = strlen($binaryString) % 40) != 0) {
			if ($x == 8) {
				$base32 .= str_repeat(self::$map[32], 6);
			} elseif ($x == 16) {
				$base32 .= str_repeat(self::$map[32], 4);
			} elseif ($x == 24) {
				$base32 .= str_repeat(self::$map[32], 3);
			} elseif ($x == 32) {
				$base32 .= self::$map[32];
			}
		}
		
		return $base32;
	}
	
	public static function decode($input)
	{
		if (empty($input)) {
			return;
		}
		
		$paddingCharCount = substr_count($input, self::$map[32]);
		$allowedValues = array(6,4,3,1,0);
		
		if (!in_array($paddingCharCount, $allowedValues)) {
			return false;
		}
		
		for ($i=0; $i<4; $i++) { 
			if ($paddingCharCount == $allowedValues[$i] && substr($input, -($allowedValues[$i])) != str_repeat(self::$map[32], $allowedValues[$i])) {
				return false;
			}
		}
		
		$input = str_replace('=', '', $input);
		$input = str_split($input);
		$binaryString = '';
		
		for ($i = 0; $i < count($input); $i = $i+8) {
			$x = '';
			
			if (!in_array($input[$i], self::$map)) {
				return false;
			}
			
			for ($j = 0; $j < 8; $j++) {
				$x .= str_pad(base_convert(@self::$flippedMap[@$input[$i + $j]], 10, 2), 5, '0', STR_PAD_LEFT);
			}
			
			$eightBits = str_split($x, 8);
			
			for ($z = 0; $z < count($eightBits); $z++) {
				$binaryString .= (($y = chr(base_convert($eightBits[$z], 2, 10))) || ord($y) == 48) ? $y : '';
			}
		}
		
		return $binaryString;
	}
}