#!/usr/bin/env python3
# x-run: python3 % /mnt/windows/Users/user/Music/vgm/night-in-the-woods/2014-lost-constellation /tmp/lost-constellation.dfpwm

from tempfile import TemporaryDirectory
from subprocess import Popen, PIPE
from sys import argv
from pathlib import Path
from os.path import splitext
from math import ceil

DFPWM_ENCODER_EXECUTABLE = "aucmp"
FFMPEG_EXECUTABLE = "ffmpeg"

DFPWM_SAMPLE_RATE = 6000

TAPE_SIZES = [ 2, 4, 8, 16, 32, 64, 128 ]

input_folder = Path(argv[1])
output_file = Path(argv[2])

with TemporaryDirectory(prefix="tapedrive") as tmpdir_str:
    tmpdir = Path(tmpdir_str)

    filelist: list[Path] = []
    for i, name in enumerate(input_folder.rglob("*.mp3")):
        if i >= 48:
            print(f"more than 48 tracks, skipping {name}")
            continue
        encoded_file = tmpdir / (splitext(name.name)[0] + ".dfpwm")
        filelist.append(encoded_file)
        with encoded_file.open("wb") as fout:
            with Popen([ DFPWM_ENCODER_EXECUTABLE ], stdout=fout, stdin=PIPE) as dfpwm:
                with Popen([ FFMPEG_EXECUTABLE, "-i", name, "-f", "s8", "-ac", "1",
                            "-ar", "48k", "-" ], stdout=dfpwm.stdin) as ffmpeg:
                    ffmpeg.wait()

    offset: int = 6000
    titles: list[bytes] = []
    positions: list[tuple[int, int]] = []
    for file in filelist:
        titles.append(file.name.removesuffix(".dfpwm").encode("ascii", errors="replace"))
        size = ceil(file.stat().st_size / DFPWM_SAMPLE_RATE) * DFPWM_SAMPLE_RATE
        positions.append((offset, size))
        offset += size

    with output_file.open("wb") as fout:
        print("Writing header...")
        written_bytes: int = 0
        for i in range(48):
            name = (titles[i] if i < len(titles) else b"")[:117]
            pos = positions[i] if i < len(titles) else (0, 0)
            written_bytes += fout.write(pos[0].to_bytes(4, "little"))
            written_bytes += fout.write(pos[0].to_bytes(4, "little"))
            written_bytes += fout.write(name)
            written_bytes += fout.write(b"\x00" * (117 - len(name)))
        if written_bytes != 6000:
            print(f"!!! expected 6000 bytes to be written in header, but it's {written_bytes}")

        print("Writing files...")
        for i, (pos, file) in enumerate(zip(positions, filelist)):
            print(f"Writing {file.name}")
            if written_bytes != pos[0]:
                print(f"!!! expected to be at {pos[0]}, rn at {written_bytes}")
            with file.open("rb") as fin:
                file_size: int = 0
                while (chunk := fin.read(DFPWM_SAMPLE_RATE)):
                    file_size += fout.write(chunk)
                written_bytes += file_size
                padding_size = DFPWM_SAMPLE_RATE - (written_bytes % DFPWM_SAMPLE_RATE)
                written_bytes += fout.write(b"\x00" * padding_size)
        print("Use any of those tapes to store properly:")
        for size in filter(lambda sz: sz * DFPWM_SAMPLE_RATE * 60 >= written_bytes, TAPE_SIZES):
            print(f"{size} minutes ({size * DFPWM_SAMPLE_RATE * 60} bytes, {written_bytes * 100 / (size * DFPWM_SAMPLE_RATE * 60):7.3f}% used)")