/*
 * tests if using two sequencers can give the effect of continous playback
 * of several midi files
 */


import javax.sound.midi.*;
import java.io.File;

import java.io.IOException;


public class SeqSwapTest implements MetaEventListener {
    private Sequencer player1, player2;
    private Sequence seq1, seq2;
    private int beingPlayed;
    private boolean swapping = true;

    public SeqSwapTest(String file1, String file2) {
	// loading midifiles
	try {
	    seq1 = MidiSystem.getSequence(new File(file1));
	    seq2 = MidiSystem.getSequence(new File(file2));
	} catch (NullPointerException e) {
	    System.out.println("Error reading files: " + file1 + " " + file2);
	    System.exit(1);
	} catch (InvalidMidiDataException e) {
	    System.out.println("Midi error in files: " + file1 + " " + file2);
	    System.exit(1);
	} catch (IOException e) {
	    System.out.println("I/O error loading files: " + file1 + " " + file2);
	    System.exit(1);
	}
	// getting players
	try {
	  player1 = MidiSystem.getSequencer();
	  player2 = MidiSystem.getSequencer();
	  player1.open();
	  player2.open();
	  player1.addMetaEventListener(this);
	  player2.addMetaEventListener(this);
	} catch (MidiUnavailableException e) {
	    System.out.println("Error configuring players");
	    System.exit(1);
	}
	// setting sequences
	try {
	    player1.setSequence(seq1);
	    player2.setSequence(seq2);
	} catch (InvalidMidiDataException e) {
	    System.out.println("Error in midisequences");
	    System.exit(1);
	}
    }

    public void startPlayer() {
	if (swapping) System.out.println("Using swapping...");
	else System.out.println("No swapping...");
	player1.start();
	beingPlayed = 1;
    }


    /* metaeventlistener implementation, listens for "end of track",
       when reached ends playback, then starts the other player */
    public void meta(MetaMessage meta) {
	if (meta.getType() == 47) {  // 47 is end of track in SMF
	    if (swapping) {
		if (beingPlayed == 1) {
		    player2.start();
		    player1.stop();
		    beingPlayed = 2;
		} else if (beingPlayed == 2) {
		    player1.start();
		    player2.stop();
		    beingPlayed = 1;
		}
	    } else {
		if (beingPlayed == 1) {
		    try {
			player1.setSequence(seq2);
			beingPlayed = 2;
		    } catch (Exception ignored) {};
		    player1.start();
		} else if (beingPlayed == 2) {
		    try {
			player1.setSequence(seq1);
			beingPlayed = 1;
		    } catch (Exception ignored) {};
		    player1.start();
		}
	    }
	}
    }


    public static void main(String[] args) {
	//SeqSwapTest foo = new SeqSwapTest("drum01.mid", "drum02.mid");
	SeqSwapTest foo = new SeqSwapTest("complex01.mid", "complex01.mid");
	foo.startPlayer();
    }


}