package com.wordpress.alankent.livescribe.support;

import java.io.IOException;

import javax.microedition.media.Manager;
import javax.microedition.media.MediaException;
import javax.microedition.media.Player;
import javax.microedition.media.control.MIDIControl;

/**
* Helper class designed for accessing the
* LiveScribe pen internal MIDI interface.
* This class uses JSR135, so should work with
* other MIDI devices but may not make all the
* the functionality of those devices visible.
*/
public class Midi {
    private Player midiPlayer;
    private MIDIControl midiControl;

    /**
     * A suggested channel number to use if only
     * going to play one note at a time.
     */
    public static final int DEFAULT_CHANNEL = 0;

    /**
     * The number of concurrent channels that can
     * play at once.
     * Channels are numbered 0 to 15.
     */
    public static final int NUM_CHANNELS = 16;

    /**
     * The maximum velocity that can be used when
     * playing a note.
     */
    public static final int MAX_VELOCITY = 127;
    /**
     * The MIDI note number for middle C.
     */
    public static final int NOTE_MIDDLE_C = 60;
    /**
     * Program number for a piano sound. See
     * http://en.wikipedia.org/wiki/General_MIDI
     * for a long list of program numbers. The
     * LiveScribe pen is not a high quality MIDI
     * device, so does not necessarily make
     * sounds like the instruments listed.
     */
    public static final int PROGRAM_ACCOUSTIC_GRAND_PIANO = 0;

    /**
     * Constructor. Connects to the MIDI
     * subsystem and prepares to play sounds.
     *
     * @throws MediaException
     * @throws IOException
     */
    public Midi()
            throws MediaException, IOException {
        midiPlayer = Manager.createPlayer(
                        Manager.MIDI_DEVICE_LOCATOR);
        midiPlayer.prefetch();
        midiPlayer.start();
        midiControl = (MIDIControl)
                midiPlayer.getControl("MIDIControl");
    }

    /**
     * Play a note on the specified channel at
     * the specified velocity.
     *
     * @param channel
     *            The channel to play the note on.
     * @param midiNote
     *            The note to play.
     * @param velocity
     *            The velocity of the note to play.
     */
    public void playNote(int channel,
                         int midiNote,
                         int velocity) {
        midiControl.shortMidiEvent(
                        MIDIControl.NOTE_ON | channel,
                        midiNote,
                        velocity);
    }

    /**
     * Silence a channel (stop playing any sound).
     *
     * @param channel
     *            The channel to silence.
     */
    public void turnSoundOff(int channel) {
        final int CONTROL_ALL_SOUND_OFF = 0x78;
        midiControl.shortMidiEvent(
                MIDIControl.CONTROL_CHANGE | channel,
                CONTROL_ALL_SOUND_OFF, 0);
    }

    /**
     * Silence the MIDI device completely (all
     * channels).
     */
    public void turnAllSoundOff() {
        for (int channel = 0;
                        channel < NUM_CHANNELS;
                        channel++ ) {
            turnSoundOff(channel);
        }
    }

    /**
     * Change the "program" (instrument sound) to
     * be used by the specified channel.
     *
     * @param channel
     *            The channel to use.
     * @param program
     *            The program from the bank to use.
     */
    public void setProgram(int channel, int program) {
        midiControl.setProgram(channel, 0, program);
    }
}