<?php
	if (isset($_POST['submit']))
	{
		if (!empty($_POST['tempo']) && !empty($_POST['timesig_num']) && (!empty($_POST['c1_display']) || !empty($_POST['c2_display'])))
		{
			//create the midi file
			$filename = "a2600song_".date("Y-m-d_His").".mid"; //unique filename
			$filehandle = fopen("songs/".$filename,"wb");	//create the file, and open for writing
			
			//----------------------------------------------//
			$c1 = explode("\n",$_POST['c1_display']);
			$c2 = explode("\n",$_POST['c2_display']);
			$c1_data = array();
			$c2_data = array();
			
			for ($i = 0; $i < count($c1); $i++) //the -1 accounts for the last line, which just consists of a newline
				if (str_word_count($c1[$i],0,"#.0123456789") == 4)
					array_push($c1_data,explode(" ",$c1[$i]));	
					
			for ($i = 0; $i < count($c2); $i++) //the -1 accounts for the last line, which just consists of a newline
				if (str_word_count($c2[$i],0,"#.0123456789") == 4)
					array_push($c2_data,explode(" ",$c2[$i]));
				
			$track_arr = array(
				1 => array(0=>false,1=>false,2=>false,3=>false),
				2 => array(0=>false,1=>false,2=>false,3=>false));
				
			foreach ($c1_data as $i => $arr)
				if ($arr[1] != "x")
					$track_arr[1][$arr[1]] = true;
					
			foreach ($c2_data as $i => $arr)
				if ($arr[1] != "x")
					$track_arr[2][$arr[1]] = true;
					
			$numtracks = 1;
			foreach ($track_arr as $var => $arr)
				foreach ($arr as $val)
					if ($val)
						$numtracks++;
			//----------------------------------------------//
			
			//HEADER
			fwrite($filehandle,pack("I",77),1);
			fwrite($filehandle,pack("I",84),1);
			fwrite($filehandle,pack("I",104),1);
			fwrite($filehandle,pack("I",100),1);
			fwrite($filehandle,pack("I",0),1);
			fwrite($filehandle,pack("I",0),1);
			
			//Size of header
			fwrite($filehandle,pack("I",0),1);
			fwrite($filehandle,pack("I",6),1);
			
			//MIDI file format
			fwrite($filehandle,pack("I",0),1);
			fwrite($filehandle,pack("I",1),1);
			
			//# of tracks
			fwrite($filehandle,pack("I",0),1);
			fwrite($filehandle,pack("I",$numtracks),1); //one for each voice for each channel, plus the default one to declare time signatures, etc.
			
			//Time division
			fwrite($filehandle,pack("I",0),1);
			fwrite($filehandle,pack("I",240),1);
			//END HEADER
			
			//TRACK 1 DATA
			//Header
			fwrite($filehandle,pack("I",77),1);
			fwrite($filehandle,pack("I",84),1);
			fwrite($filehandle,pack("I",114),1);
			fwrite($filehandle,pack("I",107),1);
			
			//# of bytes in track data
			fwrite($filehandle,pack("I",0),1);
			fwrite($filehandle,pack("I",0),1);
			fwrite($filehandle,pack("I",0),1);
			fwrite($filehandle,pack("I",19),1);
			
			//Tempo
			$ms = round(60000000/$_POST['tempo']);
			$ms = str_pad(dechex($ms),6,"0",STR_PAD_LEFT);
			$byte1 = hexdec(substr($ms,0,2));
			$byte2 = hexdec(substr($ms,2,2));
			$byte3 = hexdec(substr($ms,4,2));			
			
			fwrite($filehandle,pack("I",0),1);
			fwrite($filehandle,pack("I",255),1);
			fwrite($filehandle,pack("I",81),1);
			fwrite($filehandle,pack("I",3),1);	
			fwrite($filehandle,pack("I",$byte1),1); 	//microseconds per beat (variable, depending on tempo)
			fwrite($filehandle,pack("I",$byte2),1); 	//microseconds per beat
			fwrite($filehandle,pack("I",$byte3),1); 	//microseconds per beat
			
			//Time signature
			fwrite($filehandle,pack("I",0),1);
			fwrite($filehandle,pack("I",255),1);
			fwrite($filehandle,pack("I",88),1);
			fwrite($filehandle,pack("I",4),1);
			fwrite($filehandle,pack("I",$_POST['timesig_num']),1);			//numerator (variable)
			fwrite($filehandle,pack("I",log($_POST['timesig_de'],2)),1);	//denominator^2 (variable)
			fwrite($filehandle,pack("I",24),1);										//Metronome
			fwrite($filehandle,pack("I",8),1);										//32nd notes per beat
			
			//End track
			fwrite($filehandle,pack("I",0),1);	
			fwrite($filehandle,pack("I",255),1);
			fwrite($filehandle,pack("I",47),1);
			fwrite($filehandle,pack("I",0),1);
			//END TRACK 1 DATA
				
			/*	Array Format
			*		$c1_data[note][0] = note name
			*		$c1_data[note][1] = distortion #
			*		$c1_data[note][2] = atari note index
			*		$c1_data[note][3] = note value (quarter, eighth, etc.)
			*/		
			
			if ($track_arr[1][0])	require("square_1.php");
			if ($track_arr[1][1])	require("lead_1.php");
			if ($track_arr[1][2])	require("saw_1.php");
			if ($track_arr[1][3])	require("bass_1.php");
			if ($track_arr[2][0])	require("square_2.php");
			if ($track_arr[2][1])	require("lead_2.php");
			if ($track_arr[2][2])	require("saw_2.php");
			if ($track_arr[2][3])	require("bass_2.php");
			
			fclose($filehandle);
			header("Content-type: audio/midi");
			header("Content-Disposition: attachment; filename=$filename");
			readfile("songs/$filename");
		}
		else
		{
			echo "<script>alert('not enough data! argh!');</script>";
		}
	}
?>