<?php

/**
 * NTICompass' crappy base32 library for PHP
 * 
 * http://labs.nticompassinc.com
 */
class Base32 {

    var $encode, $decode, $type;

    // Supports RFC 4648 (default) or Crockford (http://www.crockford.com/wrmg/base32.html)
    function __construct($alphabet = 'rfc4648') 
    {
        $alphabet = strtolower($alphabet);
        $this->type = $alphabet;
        // Crockford's alphabet removes I,L,O, and U
        $crockfordABC = range('A', 'Z');
        unset($crockfordABC[8], $crockfordABC[11], $crockfordABC[14], $crockfordABC[20]);
        $crockfordABC = array_values($crockfordABC);

        $alphabets = array(
            'rfc4648' => array_merge(range('A', 'Z'), range(2, 7), array('=')),
            'crockford' => array_merge(range(0, 9), $crockfordABC, array('='))
        );
        $this->encode = $alphabets[$alphabet];
        $this->decode = array_flip($this->encode);
        // Add extra letters for Crockford's alphabet
        if ($alphabet === 'crockford') {
            $this->decode['O'] = 0;
            $this->decode['I'] = 1;
            $this->decode['L'] = 1;
        }
    }

    private function bin_chunk($binaryString, $bits) 
    {
        $binaryString = chunk_split($binaryString, $bits, ' ');
        if ($this->endsWith($binaryString, ' ')) {
            $binaryString = substr($binaryString, 0, strlen($binaryString) - 1);
        }
        return explode(' ', $binaryString);
    }

    // String <-> Binary conversion
    // Based off: http://psoug.org/snippet/PHP-Binary-to-Text-Text-to-Binary_380.htm

    private function bin2str($binaryString) 
    {
        // Make sure binary string is in 8-bit chunks
        $binaryArray = $this->bin_chunk($binaryString, 8);
        $string = '';
        foreach ($binaryArray as $bin) {
            // Pad each value to 8 bits
            $bin = str_pad($bin, 8, 0, STR_PAD_RIGHT);
            // Convert binary strings to ascii
            $string .= chr(bindec($bin));
        }
        return $string;
    }

    private function str2bin($input) 
    {
        $bin = '';
        foreach (str_split($input) as $s) {
            // Return each character as an 8-bit binary string
            $s = decbin(ord($s));
            $bin .= str_pad($s, 8, 0, STR_PAD_LEFT);
        }
        return $bin;
    }

    // starts/endsWith from:
    // http://stackoverflow.com/questions/834303/php-startswith-and-endswith-functions/834355#834355

    private function startsWith($haystack, $needle) 
    {
        $length = strlen($needle);
        return substr($haystack, 0, $length) === $needle;
    }

    private function endsWith($haystack, $needle) 
    {
        $length = strlen($needle);
        return substr($haystack, -$length) === $needle;
    }

    // base32 info from: http://www.garykessler.net/library/base64.html
    // base32_encode
    public function base32_encode($string) 
    {
        // Convert string to binary
        $binaryString = $this->str2bin($string);

        // Break into 5-bit chunks, then break that into an array
        $binaryArray = $this->bin_chunk($binaryString, 5);

        // Pad array to be divisible by 8
        while (count($binaryArray) % 8 !== 0) {
            $binaryArray[] = null;
        }

        $base32String = '';

        // Encode in base32
        foreach ($binaryArray as $bin) {
            $char = 32;
            if (!is_null($bin)) {
                // Pad the binary strings
                $bin = str_pad($bin, 5, 0, STR_PAD_RIGHT);
                $char = bindec($bin);
            }
            // Base32 character
            $base32String .= $this->encode[$char];
        }

        return $base32String;
    }

    // base32_decode
    public function base32_decode($base32String) 
    {
        $base32Array = str_split(str_replace('-', '', strtoupper($base32String)));
        $binaryArray = array();
        $string = '';
        foreach ($base32Array as $str) {
            $char = $this->decode[$str];
            if ($char !== 32) {
                $char = decbin($char);
                $string .= str_pad($char, 5, 0, STR_PAD_LEFT);
            }
        }
        while (strlen($string) % 8 !== 0) {
            $string = substr($string, 0, strlen($string) - 1);
        }
        return $this->bin2str($string);
    }

}

?>