#!/usr/bin/env python3
import sys
import time
import rtmidi

# MIDI port name. The first port that contains this string will be used.
port_name = 'Launchpad X MIDI 1'

### Helper functions

def get_midi_port(midi, name):
    '''Returns rtmidi port index for a given port name'''
    for idx, port in enumerate(midi.get_ports()):
        if port_name in port: return idx

### MIDI messages

midi_colors = {
    'green': 21
}

midi_syx_prefix = [0xf0, 0x00, 0x20, 0x29, 0x02, 0x0c]


def midi_daw_mode(mode):
    '''Set DAW mode, mode=0 to enable, mode=1 to disable.'''
    return midi_syx_prefix + [0x10, mode, 0xf7]

def midi_select_layout(layout):
    '''Select layout: session (0), note (1), custom (4-7), faders (13), programmer (127)'''
    return midi_syx_prefix + [0x00, layout, 0xf7]

def midi_setup_faders(orientation, polarity, cc, color):
    '''Setup fader mode.
    orientation=0 for vertical, orientation=1 for horizontal
    polarity=0 for unipolar, polarity=1 for bipolar (single value or 8-element list)
    cc is control change to send (single start value or 8-element list)
    color is the color (single value or 8-element list)
    '''
    if not hasattr(polarity, '__iter__'): polarity = [polarity] * 8
    if not hasattr(cc, '__iter__'):       cc = range(cc, cc + 8)
    if not hasattr(color, '__iter__'):    color = [color] * 8

    faders = zip(range(0,8), polarity, cc, color)
    faders = [y for x in faders for y in x] # flatten

    return midi_syx_prefix + [0x01, 0x00, orientation] + faders + [0xf7]

def midi_fader_mode():
    return midi_syx_prefix + [0x00, 0x0d, 0xf7]

### MIDI in callback

current_mode = 'session'

def midiin_callback(event, midiout):
    global current_mode
    
    message, dt = event

    # handle mode selection
    if message == [0xb0, 0x5f, 127]: # session button
        if current_mode == 'session':
            # switch to fader mode is done by software
            midiout.send_message(midi_select_layout(13))
            current_mode = 'fader'
        else:
            current_mode = 'session'
    elif message == [0xb0, 0x60, 127]: # note button
        current_mode = 'note'
    elif message == [0xb0, 0x61, 127]: # custom button
        current_mode = 'custom'

    # handle other buttons when in a specific mode
    elif current_mode == 'fader':
        pass # @todo multiple fader banks

### Main

def main():
    midiout = rtmidi.MidiOut()
    midiout_idx = get_midi_port(midiout, port_name)
    if not midiout_idx:
        sys.stderr.write("Device not found (output port)\n")
        sys.exit(1)
    midiout.open_port(midiout_idx, name='Launchpad X Helper')

    midiin = rtmidi.MidiIn()
    midiin_idx = get_midi_port(midiin, port_name)
    if not midiin_idx:
        sys.stderr.write("Device not found (input port)\n")
        sys.exit(1)
    midiin.open_port(midiin_idx, name='Launchpad X Helper')
    midiin.set_callback(midiin_callback, midiout)

    # Enable session mode, enter session mode, setup faders
    midiout.send_message(midi_daw_mode(1))
    midiout.send_message(midi_select_layout(0))
    midiout.send_message(midi_setup_faders(0, 0, 100, midi_colors['green']))

    print("Entering main loop. Press Control-C to exit.")
    try:
        while True: time.sleep(1)         
    except KeyboardInterrupt:
        print('')
    finally:
        print("Exit.")
        midiin.close_port()
        midiout.send_message(midi_daw_mode(0))
        midiout.close_port()

if __name__ == '__main__':
    main()