<?php
/**
 * Class PHPMP3
 *
 * @license LGPL
 */
class PHPMP3
{

    /**
     * The full mp3 file
     *
     * @var string
     */
    private $str;

    /**
     * The time length of the current file
     *
     * @var
     */
    private $time;

    /**
     * The amount of frames in the current file
     *
     * @var
     */
    private $frames;

    /**
     * Translate ascii characters to binary
     *
     * @var array
     */
    private $binaryTable;

    /**
     * Construct a new instance
     *
     * @param string $path Path to an mp3 file
     */
    public function __construct($path = '')
    {
        $this->binaryTable = array();
        for ($i = 0; $i < 256; $i ++) {
            $this->binaryTable[chr($i)] = sprintf('%08b', $i);
        }

        if ($path != '') {
            $this->str = file_get_contents($path);
        }
    }

    /**
     * Set the mp3 data
     *
     * @param string $str Mp3 file
     * @return void
     */
    private function setStr($str)
    {
        $this->str = $str;
    }

    /**
     * Get the start of audio data
     *
     * @return bool|int|void
     */
    public function getStart()
    {
        $currentStrPos = - 1;
        while (true) {
            $currentStrPos = strpos($this->str, chr(255), $currentStrPos + 1);
            if ($currentStrPos === false) {
                return 0;
            }

            $str    = substr($this->str, $currentStrPos, 4);
            $strlen = strlen($str);
            $parts  = array();
            for ($i = 0; $i < $strlen; $i ++) {
                $parts[] = $this->binaryTable[$str[$i]];
            }

            if ($this->doFrameStuff($parts) === false) {
                continue;
            }

            return $currentStrPos;
        }
    }

    /**
     * Manually count the frames and time of the file
     *
     * @return bool
     */
    public function setFileInfoExact()
    {
        $maxStrLen     = strlen($this->str);
        $currentStrPos = $this->getStart();

        $framesCount = 0;
        $time        = 0;
        while ($currentStrPos < $maxStrLen) {
            $str    = substr($this->str, $currentStrPos, 4);
            $strlen = strlen($str);
            $parts  = array();
            for ($i = 0; $i < $strlen; $i ++) {
                $parts[] = $this->binaryTable[$str[$i]];
            }

            if ($parts[0] != '11111111') {
                if (($maxStrLen - 128) > $currentStrPos) {
                    return false;
                } else {
                    $this->time   = $time;
                    $this->frames = $framesCount;
                    return true;
                }
            }
            $a = $this->doFrameStuff($parts);
            $currentStrPos += $a[0];
            $time += $a[1];
            $framesCount ++;
        }
        $this->time   = $time;
        $this->frames = $framesCount;
        return true;
    }

    /**
     * Extract a portion of an mp3
     *
     * @param int $start Time in seconds to extract from
     * @param int $length Time in seconds to extract
     * @return static
     */
    public function extract($start, $length)
    {
        $maxStrLen     = strlen($this->str);
        $currentStrPos = $this->getStart();
        $framesCount   = 0;
        $time          = 0;
        $startCount    = - 1;
        $endCount      = - 1;
        while ($currentStrPos < $maxStrLen) {
            if ($startCount == - 1 && $time >= $start) {
                $startCount = $currentStrPos;
            }
            if ($endCount == - 1 && $time >= ($start + $length)) {
                $endCount = $currentStrPos - $startCount;
            }
            $str    = substr($this->str, $currentStrPos, 4);
            $strlen = strlen($str);
            $parts  = array();
            for ($i = 0; $i < $strlen; $i ++) {
                $parts[] = $this->binaryTable[$str[$i]];
            }
            if ($parts[0] == '11111111') {
                $a = $this->doFrameStuff($parts);
                $currentStrPos += $a[0];
                $time += $a[1];
                $framesCount ++;
            } else {
                break;
            }
        }
        $mp3 = new static();
        if ($endCount == - 1) {
            $endCount = $maxStrLen - $startCount;
        }
        if ($startCount != - 1 && $endCount != - 1) {
            $mp3->setStr(substr($this->str, $startCount, $endCount));
        }
        return $mp3;
    }

    /**
     * Get the length of a frame in bytes and seconds
     *
     * @param string[] $parts A frame with bytes converted to binary
     * @return array|bool
     */
    private function doFrameStuff($parts)
    {
        //Get Audio Version
        $seconds = 0;
        $errors  = array();
        switch (substr($parts[1], 3, 2)) {
            case '01':
                $errors[] = 'Reserved audio version';
                $audio = 0;
                break;
            case '00':
                $audio = 2.5;
                break;
            case '10':
                $audio = 2;
                break;
            case '11':
                $audio = 1;
                break;
        }
        //Get Layer
        switch (substr($parts[1], 5, 2)) {
            case '01':
                $layer = 3;
                break;
            case '00':
                $errors[] = 'Reserved layer';
                $layer = 0;
                break;
            case '10':
                $layer = 2;
                break;
            case '11':
                $layer = 1;
                break;
        }
        //Get Bitrate
        $bitFlag  = substr($parts[2], 0, 4);
        $bitArray = array(
            '0000' => array(0, 0, 0, 0, 0),
            '0001' => array(32, 32, 32, 32, 8),
            '0010' => array(64, 48, 40, 48, 16),
            '0011' => array(96, 56, 48, 56, 24),
            '0100' => array(128, 64, 56, 64, 32),
            '0101' => array(160, 80, 64, 80, 40),
            '0110' => array(192, 96, 80, 96, 48),
            '0111' => array(224, 112, 96, 112, 56),
            '1000' => array(256, 128, 112, 128, 64),
            '1001' => array(288, 160, 128, 144, 80),
            '1010' => array(320, 192, 160, 160, 96),
            '1011' => array(352, 224, 192, 176, 112),
            '1100' => array(384, 256, 224, 192, 128),
            '1101' => array(416, 320, 256, 224, 144),
            '1110' => array(448, 384, 320, 256, 160),
            '1111' => array(- 1, - 1, - 1, - 1, - 1)
        );
        $bitPart  = $bitArray[$bitFlag];
        $bitArrayNumber = null;
        if ($audio == 1) {
            switch ($layer) {
                case 1:
                    $bitArrayNumber = 0;
                    break;
                case 2:
                    $bitArrayNumber = 1;
                    break;
                case 3:
                    $bitArrayNumber = 2;
                    break;
            }
        } else {
            switch ($layer) {
                case 1:
                    $bitArrayNumber = 3;
                    break;
                case 2:
                    $bitArrayNumber = 4;
                    break;
                case 3:
                    $bitArrayNumber = 4;
                    break;
            }
        }

        if( !$bitArrayNumber || !$audio ){
        	return false;
        }

        $bitRate = $bitPart[$bitArrayNumber];
        if ($bitRate <= 0) {
            return false;
        }
        //Get Frequency
        $frequencies = array(
            1   => array(
                '00' => 44100,
                '01' => 48000,
                '10' => 32000,
                '11' => 'reserved'
            ),
            2   => array(
                '00' => 44100,
                '01' => 48000,
                '10' => 32000,
                '11' => 'reserved'
            ),
            2.5 => array(
                '00' => 44100,
                '01' => 48000,
                '10' => 32000,
                '11' => 'reserved'
            )
        );
        $freq        = $frequencies[$audio][substr($parts[2], 4, 2)];
        $frameLength = 0;
        //IsPadded?
        $padding = substr($parts[2], 6, 1);
        if ($layer == 3 || $layer == 2) {
            $frameLength = 144 * $bitRate * 1000 / $freq + $padding;
        }
        $frameLength = floor($frameLength);
        if ($frameLength == 0) {
            return false;
        }
        $seconds += $frameLength * 8 / ($bitRate * 1000);
        return array($frameLength, $seconds);
    }

    /**
     * Set ID3 data
     *
     * @param string $track
     * @param string $title
     * @param string $artist
     * @param string $album
     * @param string $year
     * @param string $genre
     * @param string $comments
     * @param string $composer
     * @param string $origArtist
     * @param string $copyright
     * @param string $url
     * @param string $encodedBy
     * @return void
     */
    public function setIdv3_2(
        $track,
        $title,
        $artist,
        $album,
        $year,
        $genre,
        $comments,
        $composer,
        $origArtist,
        $copyright,
        $url,
        $encodedBy
    ) {
        $urlLength        = (int) (strlen($url) + 2);
        $copyrightLength  = (int) (strlen($copyright) + 1);
        $origArtistLength = (int) (strlen($origArtist) + 1);
        $composerLength   = (int) (strlen($composer) + 1);
        $commentsLength   = (int) (strlen($comments) + 5);
        $titleLength      = (int) (strlen($title) + 1);
        $artistLength     = (int) (strlen($artist) + 1);
        $albumLength      = (int) (strlen($album) + 1);
        $genreLength      = (int) (strlen($genre) + 1);
        $encodedByLength  = (int) (strlen($encodedBy) + 1);
        $trackLength      = (int) (strlen($track) + 1);
        $yearLength       = (int) (strlen($year) + 1);

        $str = "ID3\x03\0\0\0\0\x085TRCK\0\0\0{$trackLength}\0\0\0{$track}TENC\0\0\0{$encodedByLength}@\0\0{$encodedBy}WXXX\0\0\0{$urlLength}\0\0\0\0{$url}TCOP\0\0\0{$copyrightLength}\0\0\0{$copyright}TOPE\0\0\0{$origArtistLength}\0\0\0{$origArtist}TCOM\0\0\0{$composerLength}\0\0\0{$composer}COMM\0\0\0{$commentsLength}\0\0\0\0\x09\0\0{$comments}TCON\0\0\0{$genreLength}\0\0\0{$genre}TYER\0\0\0{$yearLength}\0\0\0{$year}TALB\0\0\0{$albumLength}\0\0\0{$album}TPE1\0\0\0{$artistLength}\0\0\0{$artist}TIT2\0\0\0{$titleLength}\0\0\0{$title}";
        $this->str = $str . $this->str;
    }

    /**
     * Append another mp3 file to the end of this file
     *
     * @param self $mp3
     * @return void
     */
    public function mergeBehind(self $mp3)
    {
        $this->str .= $mp3->str;
    }

    /**
     * Prepend another mp3 to the start of this file
     *
     * @param self $mp3
     * @return void
     */
    public function mergeInfront(self $mp3)
    {
        $this->str = $mp3->str . $this->str;
    }

    /**
     * Get the end string of the ID3 data
     *
     * @return bool|string
     */
    private function getIdvEnd()
    {
        $strlen = strlen($this->str);
        $str    = substr($this->str, ($strlen - 128));
        $str1   = substr($str, 0, 3);
        if (strtolower($str1) == strtolower('TAG')) {
            return $str;
        } else {
            return false;
        }
    }

    /**
     * Remove ID3 data from the file
     *
     * @return bool
     */
    public function striptags()
    {
        //Remove start stuff...
        $s = $start = $this->getStart();
        if ($s === false) {
            return false;
        } else {
            $this->str = substr($this->str, $start);
        }
        //Remove end tag stuff
        $end = $this->getIdvEnd();
        if ($end !== false) {
            $this->str = substr($this->str, 0, (strlen($this->str) - 129));
        }
    }

    /**
     * Write an mp3 file
     *
     * @param string $path Path to write file to
     * @return bool
     */
    public function save($path)
    {
        $fp           = fopen($path, 'w');
        $bytesWritten = fwrite($fp, $this->str);
        fclose($fp);
        return $bytesWritten == strlen($this->str);
    }

    /**
     * Join multiple mp3 files into one file
     *
     * @param string $newpath
     * @param array $array
     * @return void
     */
    public function multiJoin($newpath, $array)
    {
        foreach ($array as $path) {
            $mp3 = new static($path);
            $mp3->striptags();
            $mp3_1 = new static($newpath);
            $mp3->mergeBehind($mp3_1);
            $mp3->save($newpath);
        }
    }
}