#!/usr/bin/env python3
"""Generate a LetterBomb tree directly in Dolphin's virtual SD folder."""

from __future__ import annotations

import argparse
import hashlib
import hmac
import shutil
import zipfile
from datetime import datetime, timedelta
from pathlib import Path, PurePosixPath


REPO_ROOT = Path(__file__).resolve().parents[1]
DEFAULT_SOURCE = REPO_ROOT / ".starlet_check" / "letterbomb-web" / "public"


def parse_mac(text: str) -> bytes:
    compact = text.replace(":", "").replace("-", "")
    if len(compact) != 12:
        raise argparse.ArgumentTypeError("MAC must contain exactly 12 hexadecimal digits")
    try:
        return bytes.fromhex(compact)
    except ValueError as error:
        raise argparse.ArgumentTypeError("MAC contains a non-hexadecimal character") from error


def safe_extract(archive: zipfile.ZipFile, destination: Path) -> None:
    for member in archive.infolist():
        relative = PurePosixPath(member.filename)
        if relative.is_absolute() or ".." in relative.parts:
            raise RuntimeError(f"Unsafe archive member: {member.filename!r}")
        target = destination.joinpath(*relative.parts)
        if member.is_dir():
            target.mkdir(parents=True, exist_ok=True)
            continue
        target.parent.mkdir(parents=True, exist_ok=True)
        with archive.open(member) as source, target.open("wb") as output:
            shutil.copyfileobj(source, output)


def generate(template: bytes, mac: bytes, message_time: datetime) -> tuple[bytes, Path]:
    payload = bytearray(template)
    key = hashlib.sha1(mac + b"uyy").digest()
    payload[8:16] = key[:8]
    payload[176:196] = bytes(20)

    epoch = datetime(2000, 1, 1)
    timestamp = int((message_time - epoch).total_seconds())
    payload[124:128] = timestamp.to_bytes(4, "big")
    payload[128:138] = f"{timestamp:010d}".encode("ascii")
    payload[176:196] = hmac.new(key[8:], payload, hashlib.sha1).digest()

    relative_path = Path(
        "private",
        "wii",
        "title",
        "HAEA",
        key[:4].hex().upper(),
        key[4:8].hex().upper(),
        f"{message_time.year:04d}",
        f"{message_time.month - 1:02d}",
        f"{message_time.day:02d}",
        f"{message_time.hour:02d}",
        f"{message_time.minute:02d}",
        "HABA_#1",
        "txt",
        f"{timestamp:08X}.000",
    )
    return bytes(payload), relative_path


def main() -> None:
    parser = argparse.ArgumentParser()
    parser.add_argument("--mac", required=True, type=parse_mac)
    parser.add_argument("--region", required=True, choices=("E", "U", "J", "K"))
    parser.add_argument("--output", required=True, type=Path)
    parser.add_argument("--source", type=Path, default=DEFAULT_SOURCE)
    parser.add_argument(
        "--date",
        help="message date as YYYY-MM-DD; defaults to yesterday in local Wii time",
    )
    args = parser.parse_args()

    source = args.source.resolve()
    output = args.output.resolve()
    template_path = source / f"template{args.region}.bin"
    bundle_path = source / "hackmii.zip"
    if not template_path.is_file() or not bundle_path.is_file():
        raise RuntimeError(f"LetterBomb assets are missing from {source}")

    if args.date:
        message_time = datetime.strptime(args.date, "%Y-%m-%d")
    else:
        message_time = datetime.now().replace(second=0, microsecond=0) - timedelta(days=1)

    payload, relative_path = generate(template_path.read_bytes(), args.mac, message_time)
    output.mkdir(parents=True, exist_ok=True)
    target = output / relative_path
    target.parent.mkdir(parents=True, exist_ok=True)
    target.write_bytes(payload)
    with zipfile.ZipFile(bundle_path) as archive:
        safe_extract(archive, output)

    mac_text = ":".join(f"{byte:02X}" for byte in args.mac)
    (output / "LETTERBOMB-INFO.txt").write_text(
        "LetterBomb virtual Wii test card\n"
        f"System Menu: 4.3{args.region}\n"
        f"Emulated Wi-Fi MAC: {mac_text}\n"
        f"Message date: {message_time:%Y-%m-%d %H:%M}\n"
        f"Message file: {relative_path.as_posix()}\n"
        "Close Dolphin before changing files in this folder.\n",
        encoding="utf-8",
    )
    print(f"LetterBomb generated at {target}")
    print(f"Bundled HackMii Installer extracted to {output}")


if __name__ == "__main__":
    main()