import music21
import subprocess
import sys
import os


MSCORE="mscore"
REMOVE_MID_FILES=False


def get_elements(stream, classe):
    elements = []
    for el in stream[classe]:
        offset = el.activeSite.getOffsetBySite(stream.parts[0]) + el.getOffsetBySite(el.activeSite)
        elements.append((offset, el))
    return elements


def add_elements(stream, elements):
    st_elements = [(offset, el.number) for (offset, el) in get_elements(stream, 'MetronomeMark')]
    #print(st_elements)
    for offset, el in elements:
        if (offset, el.number) not in st_elements:
            stream.insert(offset, el)
            #print(f"Inserting {el}@{offset}")

    return stream

def separate_instruments(input_midi_path, output_folder):
    # Load MIDI file
    stream = music21.converter.parse(input_midi_path)
    outputs = []

    elements = get_elements(stream, 'MetronomeMark')
    #print(elements)

    # Extract each part (music21.instrument) and create a separate MIDI file for each
    for i, part in enumerate(stream.parts):
        part.makeRests(fillGaps=True, inPlace=True)
        part.makeMeasures(inPlace=True)
        part.makeTies(inPlace=True)

        # Create a new music21.stream for each part
        instrument_stream = music21.stream.Score()
        instrument_stream.append(part)

        instrument_stream = add_elements(instrument_stream, elements)

        # Create a new MIDI file for each music21.instrument
        output_path = f"{output_folder}/instrument_{i + 1}.mid"
        instrument_stream.write('midi', fp=output_path)
        outputs.append(output_path)
    return outputs


def change_instrument(input, output):
    s = music21.converter.parse(input)

    for el in s.recurse():
        if 'Instrument' in el.classes: # or 'Piano'
            el.activeSite.replace(el, music21.instrument.Piano())

    s.write('midi', output)

def basename(name):
    return '.'.join(name.split('/')[-1].split('.')[:-1])

def create_audios(files, dest="out"):
    if len(files) == 0:
        return

    for el in files:
        subprocess.call(["mscore", el, "-o", os.path.join(dest, basename(el))+".mp3"])
        print(f"Converted {basename(el)}.mp3")


def __main__():
    SCORE=sys.argv[1]
    OUT=sys.argv[2]
    os.makedirs(OUT, exist_ok=True)

    # Create midi file
    subprocess.call([MSCORE, SCORE, "-o", f"{OUT}/{basename(SCORE)}.mid"])

    midi_files = separate_instruments(f"{OUT}/{basename(SCORE)}.mid", OUT)

    for file in midi_files:
        change_instrument(file, file)

    print("=== Creating audios ===")
    #create_audios(midi_files, OUT)

    if REMOVE_MID_FILES:
        os.remove(f"{OUT}/{basename(SCORE)}.mid")
        for file in midi_files:
            os.remove(file)


if __name__ == "__main__":
    __main__()