from dataclasses import dataclass
import click
import os
import subprocess

INPUT_FILE_EXTS_OPUSENC = [
    ".flac",
    ".wav",
    ".aiff",
]
INPUT_FILE_EXTS_COPY = [
    ".opus",
    ".ogg",  # this can also contain FLAC (fry about it)
    ".mp3",
    ".m4a",
]


def get_opusenc_args(
    input_path: str,
    output_path: str,
    bitrate: int = 192,
) -> list[str]:
    return [
        "opusenc",
        "--bitrate",
        str(bitrate),
        "--music",
        input_path,
        output_path,
    ]


@dataclass
class InputFile:
    filepath: str
    relpath: str
    relpath_noext: str
    transcode: bool


@click.option(
    "--input-dir",
    "-i",
    type=click.Path(exists=True, dir_okay=True, file_okay=False, resolve_path=True),
)
@click.option(
    "--output-dir",
    "-o",
    type=click.Path(
        exists=False, dir_okay=True, file_okay=False, writable=True, resolve_path=True
    ),
)
@click.command()
def music_transcoder(input_dir, output_dir):
    input_files: list[InputFile] = []

    for dirpath, _, filenames in os.walk(input_dir):
        for filename in filenames:
            _, ext = os.path.splitext(filename)

            transcode: bool
            if ext in INPUT_FILE_EXTS_OPUSENC:
                transcode = True
            elif ext in INPUT_FILE_EXTS_COPY:
                transcode = False
            else:
                print("[WARN] rejecting file:", dirpath, filename)
                continue

            filepath = os.path.join(dirpath, filename)
            relpath = os.path.relpath(filepath, input_dir)
            relpath_noext, _ = os.path.splitext(relpath)
            input_files.append(
                InputFile(
                    filepath=filepath,
                    relpath=relpath,
                    relpath_noext=relpath_noext,
                    transcode=transcode,
                )
            )

    for input_file in input_files:
        if input_file.transcode:
            output_path = os.path.join(output_dir, input_file.relpath_noext + ".opus")
        else:
            output_path = os.path.join(output_dir, input_file.relpath)

        if os.path.exists(output_path):
            print("[WARN] skipping existing file", output_path)
            continue

        output_path_dir, _ = os.path.split(output_path)
        os.makedirs(output_path_dir, exist_ok=True)

        if not input_file.transcode:
            print("[INFO] hardlinking lossy file →", output_path)
            os.link(input_file.filepath, output_path)
            continue

        print("[INFO] transcoding lossless file →", output_path)
        opusenc_args = get_opusenc_args(input_file.filepath, output_path)
        subprocess.run(opusenc_args, check=True)


if __name__ == "__main__":
    music_transcoder()