// All MIDI global variables & global MIDI functions are in this tab.
import javax.sound.midi.* ;  // Get everything in the Java MIDI (Musical Instrument Digital Interface) package.


// MIDI VARIABLES, see http://faculty.kutztown.edu/parson/spring2017/MidiKBSpring2016Parson.txt
final int midiDeviceIndex = 0 ;  // setup() checks for number of devices. Use one for output.
// NOTE: A final variable is in fact a constant that cannot be changed.
MidiDevice.Info[] midiDeviceInfo = null ;
// See javax.sound.midi.MidiSystem and javax.sound.midi.MidiDevice
MidiDevice device = null ;
// See javax.sound.midi.MidiSystem and javax.sound.midi.MidiDevice
Receiver receiver = null ;
// javax.sound.midi.Receiver receives your OUTPUT MIDI messages (counterintuitive?)
// SEE https://www.midi.org/specifications/item/gm-level-1-sound-set but start at 0, not 1
int patch = 98 ; // tonal percussion per above link, change with up & down arrow keys
int lastnote = -1 ; // most recent midi note in the range 0..127
int lastvelocity = -1 ; // most recent midi note in the range 0..127
int interval = 64 ; // for sending out a harmonic interval
int controller = 1 ;  // start with modwheel, let user adjust
int controllerDegree = 0 ; // initially no audio effect amount

void initMIDI() {
  // MIDI:
  // 1. FIND OUT WHAT MIDI DEVICES ARE AVAILABLE FOR VARIABLE midiDeviceIndex.
  midiDeviceInfo = MidiSystem.getMidiDeviceInfo();
  for (int i = 0 ; i < midiDeviceInfo.length ; i++) {
    println("MIDI DEVICE NUMBER " + i + " Name: " + midiDeviceInfo[i].getName()
      + ", Vendor: " + midiDeviceInfo[i].getVendor()
      + ", Description: " + midiDeviceInfo[i].getDescription());
  }
  // 2. OPEN ONE OF THE MIDI DEVICES UP FOR OUTPUT.
  try {
    device = MidiSystem.getMidiDevice(midiDeviceInfo[midiDeviceIndex]);
    device.open();  // Make sure to close it before this sketch terminates!!!
    // There should be a way to schedule a method when Processing closes this
    // sketch, so we can close the device there, but it is not documented for Processing 3.
    receiver = device.getReceiver();
    // NOTE: Either of the above method calls can throw MidiUnavailableException
    // if there is no available device or if it does not have a Receiver to
    // which we can send messages. The catch clause intercepts those error messages.
    // See https://www.midi.org/specifications/item/gm-level-1-sound-set, use patch variable
    ShortMessage noteMessage1 = new ShortMessage() ;
    noteMessage1.setMessage(ShortMessage.PROGRAM_CHANGE, 0, patch, 0); // to channel 0
    receiver.send(noteMessage1, -1L);  // send it now
    ShortMessage noteMessage2 = new ShortMessage() ;
    noteMessage2.setMessage(ShortMessage.PROGRAM_CHANGE, 1, (patch+32)%128, 0); // to channel 1
    receiver.send(noteMessage2, -1L);  // send it now
  } catch (MidiUnavailableException mx) {
    System.err.println("MIDI UNAVAILABLE"); // Error messages go here.
    device = null ;
    receiver = null ; // Do not try to use them.
  } catch (InvalidMidiDataException dx) {
    System.err.println("MIDI ERROR: " + dx.getMessage()); // Error messages go here.
  }
}
 
void sendMIDI(int command, int channel, int data1, int data2) {
  // Construct & send a ShortMessage with these parameters.
  try {
    ShortMessage message = new ShortMessage(command, channel, data1, data2);
    receiver.send(message, -1L);  // -1L means send it now, not queued for later.
  } catch (InvalidMidiDataException ix) {
    System.err.println("InvalidMidiDataException: " + ix.getMessage());
  }
}