#!/usr/bin/python3

###
#
# midi4beep.py
# Author: Adrien MALINGREY <adrien@malingrey.fr>
#
# Play MIDI files with PC speaker using the beep command.
#
# Usage: python3 midi4beep.py <midi file> [channel]
#
# Dependencies:
# - Python 3
# - mido library (https://mido.readthedocs.io/)
# - beep command
#
###

import sys
import subprocess
import math
import mido


class PCSpeaker(mido.ports.BaseOutput):
    def __init__(self, channel=-1):
        super().__init__(self)
        self.channel = channel
        self.note_on = 0
        self.process = None

    def _send(self, message):
        if (message.type == "note_on" or message.type == "note_off") \
            and (message.channel == self.channel or (self.channel == -1 and message.channel != 9)):
            if message.type == "note_on" and message.velocity and message.note > self.note_on:
                self.process = subprocess.Popen(
                    [
                        "beep",
                        "-f",
                        str(int(440 * math.pow(2, (message.note - 69) / 12))),
                        "-l100000",
                    ]
                )
                self.note_on = message.note
                
            elif self.process and (message.type == "note_off" or (message.type == "note_on" and message.note == self.note_on)):
                self.process.terminate()
                self.process = None
                self.note_on = 0

    def reset(self):
        if self.process:
            self.process.terminate()
            self.process = None
            self.note_on = 0

    def panic(self):
        if self.process:
            self.process.kill()
            self.process = None
            self.note_on = 0

    def _close(self):
        self.reset()


if len(sys.argv) < 2:
    print("Usage: python3 midi4beep.py <midi file> [channel]")
    sys.exit(1)

path = sys.argv[1]
try:
    mid = mido.MidiFile(path)
except TypeError:
    mido.read_syx_file(path)

if len(sys.argv) > 2:
    channel = int(sys.argv[2])
else:
    channel = -1

with PCSpeaker(channel) as speaker:
    for msg in mid.play():
        speaker.send(msg)