#!/usr/bin/env python3

# binary_to_midi.py
#
# Author: Intel A80486DX2-66
# License: Creative Commons Zero 1.0 Universal or Unlicense
# SPDX-License-Identifier: CC0-1.0 OR Unlicense

from decimal import Decimal
from midiutil import MIDIFile
from os import stat
from sys import argv

NOTE_TABLE = {i: 52 + i for i in range(8 * 2)}

is_prime = lambda n: n > 1 and all(n % i for i in range(2, n))

TEMPO = 110
TIME_SIGNATURE = (4, 4)
INSTRUMENT_SELECTED = 1
STEP_SIZE = 1
DURATION_CONSTANT = 32


def binary_to_midi(input_file, output_file):
	print("Reading file")
	with open(input_file, "rb") as f:
		byte_data = f.read()

	print("Initialization")
	pattern = MIDIFile(1, TIME_SIGNATURE, TEMPO)
	pattern.addTempo(0, 0, TEMPO)
	track = 0
	channel = 0
	time = 0

	chords = []
	current_chord = []

	previous_note = NOTE_TABLE[0]
	byte_step = (len(byte_data) // 2**6) + 1

	print("Converting")
	taking_chord = False
	for i, byte in enumerate(byte_data[::STEP_SIZE]):
		is_rest = False
		note = NOTE_TABLE[byte % len(NOTE_TABLE)]
		is_previous_note = i > 0 and note == previous_note

		if byte % 51 == 25:
			is_rest = True
		elif byte % 12 == 0:
			current_chord = [note]
			chords.append(current_chord)
			taking_chord = True
		elif taking_chord:
			current_chord.append(note)
			taking_chord = False

		duration = (Decimal('0.25') if is_prime(byte) or byte % 11 < 6 else \
		            Decimal('0.015')) * DURATION_CONSTANT

		if abs(previous_note - note) > 3 and not is_previous_note:
			current_chord.append(0)
			previous_note = note

	pattern.addProgramChange(0, 0, 0, INSTRUMENT_SELECTED)
	for chord in chords:
		for note in chord:
			if is_rest:
				pattern.addNote(track, channel, 0, time, duration, 0)
			else:
				pattern.addNote(track, channel, note, time, duration, 100)
		time += duration

	print("Writing out")
	with open(output_file, "wb") as file:
		pattern.writeFile(file)
	print(f"Saved, {stat(output_file).st_size} bytes")


if __name__ == "__main__":
	if len(argv) < 2:
		print("Fatal error: No file specified as argument.")
		exit(1)

	binary_to_midi(argv[1], "output.mid")