<?php defined('SYSPATH') OR die('No direct access allowed.');

class Wave_Core {

	public $width = 1906;
	public $height = 100;
	public $foreground = "#cccccc";
	public $background = "";
	public $draw_flat = false;
	public $stereo = true;
	public $path = null;

	public $img = false;

	public $converted_wav = null;

	// how much detail we want. Larger number means less detail
	// (basically, how many bytes/frames to skip processing)
	// the lower the number means longer processing time
	public $detail = 5;

	public static function instance(){
		
		return new self;
	}

	/**
	* Input song data
	*
	* @path string image path
	* @stereo_support bool
	* 
	* @return instance
	*/
	public function input_file($path, $stereo_support){

		$this->path = $path;

		$this->stereo = $stereo_support;

		return $this;
	}

	/**
	* Convert MP3 file to Wav
	*
	* @return void
	*/ 
	public function convert(){
		$tmpname = "temp/".Helper::uuid1();

		//make file copy
		copy($this->path, $tmpname."_o.mp3");

		// convert mp3 to wav using lame decoder
		// First, resample the original mp3 using as mono (-m m), 16 bit (-b 16), and 8 KHz (--resample 8)
		// Secondly, convert that resampled mp3 into a wav
		// We don't necessarily need high quality audio to produce a waveform, doing this process reduces the WAV
		// to it's simplest form and makes processing significantly faster

		exec("lame {$tmpname}_o.mp3 -m m -S -f -b 16 --resample 8 {$tmpname}.mp3 && lame -S --decode {$tmpname}.mp3 {$tmpname}.wav");
		$this->converted_wav = "{$tmpname}.wav";

		// delete temporary files
		unlink("{$tmpname}_o.mp3");
		unlink("{$tmpname}.mp3");
	}

	/**
	* Convert file
	* 
	* @return instance
	*/
	public function generate_wave(){
		//convert to wav
		$this->convert();

		// generate foreground color
		list($r, $g, $b) = $this->html2rgb($this->foreground);

		/**
		* Below as posted by "zvoneM" on
		* http://forums.devshed.com/php-development-5/reading-16-bit-wav-file-318740.html
		* as findValues() defined above
		* Translated from Croation to English - July 11, 2011
		*/
		$handle = fopen($this->converted_wav, "r");
		// wav file header retrieval
		$heading[] = fread($handle, 4);
		$heading[] = bin2hex(fread($handle, 4));
		$heading[] = fread($handle, 4);
		$heading[] = fread($handle, 4);
		$heading[] = bin2hex(fread($handle, 4));
		$heading[] = bin2hex(fread($handle, 2));
		$heading[] = bin2hex(fread($handle, 2));
		$heading[] = bin2hex(fread($handle, 4));
		$heading[] = bin2hex(fread($handle, 4));
		$heading[] = bin2hex(fread($handle, 2));
		$heading[] = bin2hex(fread($handle, 2));
		$heading[] = fread($handle, 4);
		$heading[] = bin2hex(fread($handle, 4));
      
		// wav bitrate 
		$peek = hexdec(substr($heading[10], 0, 2));
		$byte = $peek / 8;

		// checking whether a mono or stereo wav
		$channel = hexdec(substr($heading[6], 0, 2));

		$ratio = ($channel == 2 ? 40 : 80);

		// start putting together the initial canvas
		// $data_size = (size_of_file - header_bytes_read) / skipped_bytes + 1
		$data_size = floor((filesize($this->converted_wav) - 44) / ($ratio + $byte) + 1);
		$data_point = 0;
      
		// now that we have the data_size for a single channel (they both will be the same)
		// we can initialize our image canvas
		if (!$this->img) {
			// create original image width based on amount of detail
			// each waveform to be processed with be $height high, but will be condensed
			// and resized later (if specified)
			$this->img = imagecreatetruecolor($data_size / $this->detail, $this->height * sizeof($this->converted_wav));

			// fill background of image
			if ($this->background == "") {
				// transparent background specified
				imagesavealpha($this->img, true);
				$transparentColor = imagecolorallocatealpha($this->img, 0, 0, 0, 127);
				imagefill($this->img, 0, 0, $transparentColor);
			} else {
				list($br, $bg, $bb) = $this->html2rgb($this->background);
				imagefilledrectangle($this->img, 0, 0, (int) ($data_size / $this->detail), $this->height * sizeof($this->converted_wav), imagecolorallocate($this->img, $br, $bg, $bb));
			}
		}

		imagesetthickness($this->img, 3);

		while(!feof($handle) && $data_point < $data_size){
			if ($data_point++ % $this->detail == 0) {
				$bytes = array();

				// get number of bytes depending on bitrate
				for ($i = 0; $i < $byte; $i++)
					$bytes[$i] = fgetc($handle);

				switch($byte){
					
					// get value for 8-bit wav
					case 1:
						$data = $this->findValues($bytes[0], $bytes[1]);
					break;

					// get value for 16-bit wav
					case 2:
						if(ord($bytes[1]) & 128)
							$temp = 0;
						else
							$temp = 128;

						$temp = chr((ord($bytes[1]) & 127) + $temp);
						$data = floor($this->findValues($bytes[0], $temp) / 256);
					break;
				}

				// skip bytes for memory optimization
				fseek($handle, $ratio, SEEK_CUR);

				// draw this data point
				// relative value based on height of image being generated
				// data values can range between 0 and 255
				$v = (int) ($data / 255 * $this->height);

				if($v < 20)
					$v = 20;

				// don't print flat values on the canvas if not necessary
				if (!($v / $this->height == 0.5 && !$this->draw_flat))
					// draw the line on the image using the $v value and centering it vertically on the canvas
					imageline(
						$this->img,
						// x1
						(int) ($data_point / $this->detail),
						// y1: height of the image minus $v as a percentage of the height for the wave amplitude
						$this->height - $v,
						// x2
						(int) ($data_point / $this->detail),
						// y2: same as y1, but from the bottom of the image
						$this->height,
						imagecolorallocate($this->img, 56, 56, 56)
					);         

			} else {
				// skip this one due to lack of detail
				fseek($handle, $ratio + $byte, SEEK_CUR);
			}
		}
      
		// close and cleanup
		fclose($handle);

		// delete the processed wav file
		unlink($this->converted_wav);

		return $this;
	}

	/**
	* Save wave file
	*
	* @return void
	*/
	public function save($path){
		// resample the image to the proportions defined in the form
		$rimg = imagecreatetruecolor($this->width, $this->height);

		// save alpha from original image
		imagesavealpha($rimg, true);
		imagealphablending($rimg, false);

		// copy to resized
		imagecopyresampled($rimg, $this->img, 0, 0, 0, 0, $this->width, $this->height, imagesx($this->img), imagesy($this->img));
		
		//save
		imagepng($rimg, $path);

		imagedestroy($rimg);

		imagedestroy($this->img);
	}

	/**
	* 
	*/
	private function findValues($byte1, $byte2){

		$byte1 = hexdec(bin2hex($byte1));
		$byte2 = hexdec(bin2hex($byte2));

		return ($byte1 + ($byte2*256));
	}

	/**
	* Convert HEX to RGB
	* 
	* @return array
	*/
	private function html2rgb($input) {
		$input=($input[0]=="#")?substr($input, 1,6):substr($input, 0,6);

		return array(
			hexdec(substr($input, 0, 2)),
			hexdec(substr($input, 2, 2)),
			hexdec(substr($input, 4, 2))
		);
	}
}