"""Generate a disposable, synthetic Serato library from the sample manifest."""

import argparse
import json
from pathlib import Path
from typing import Optional


SAMPLE_ROOT = Path(__file__).parent
SERATO_PATH_PREFIX = "Users/sample-user/OneDrive/Jukebox/"


def database_record(tag: bytes, payload: bytes) -> bytes:
    return tag + len(payload).to_bytes(4, "big") + payload


def load_manifest() -> dict:
    return json.loads((SAMPLE_ROOT / "manifest.json").read_text(encoding="utf-8"))


def build_sample(output: Optional[Path] = None) -> Path:
    root = output or SAMPLE_ROOT / "generated"
    manifest = load_manifest()
    music_root = root / "Music"
    serato_root = root / "Serato" / "_Serato_"

    for relative_path in manifest["tracks"]:
        track_path = music_root / relative_path
        track_path.parent.mkdir(parents=True, exist_ok=True)
        track_path.write_bytes(
            f"Synthetic Serato Doctor fixture: {relative_path}\n".encode("utf-8")
        )

    for crate in manifest["crates"]:
        is_smart = crate["type"] == "smart"
        folder_name = "SmartCrates" if is_smart else "Subcrates"
        crate_root = serato_root / folder_name
        crate_root.mkdir(parents=True, exist_ok=True)
        output_name = (
            Path(crate["name"]).with_suffix(".scrate").name
            if is_smart
            else crate["name"]
        )
        for other_folder in ("Subcrates", "Smartcrates", "SmartCrates"):
            for stale_name in (
                crate["name"],
                Path(crate["name"]).with_suffix(".scrate").name,
            ):
                stale_path = serato_root / other_folder / stale_name
                if stale_path.exists() and stale_path != crate_root / output_name:
                    stale_path.unlink()
        records = "".join(
            f"{SERATO_PATH_PREFIX}{relative_path}otrk"
            for relative_path in crate["references"]
        )
        (crate_root / output_name).write_bytes(records.encode("utf-16-le"))

    database_records = [
        database_record(b"vrsn", "2.0/Serato Doctor Fixture".encode("utf-16-be"))
    ]
    for relative_path in manifest["tracks"]:
        fields = database_record(
            b"pfil", str(music_root / relative_path).encode("utf-16-be")
        )
        database_records.append(database_record(b"otrk", fields))
    (serato_root / "database V2").write_bytes(b"".join(database_records))

    return root


def main() -> None:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--output", type=Path)
    args = parser.parse_args()
    root = build_sample(args.output)
    print(f"Generated synthetic library: {root}")


if __name__ == "__main__":
    main()