#!/usr/bin/env python3
import argparse
import json
import re
import sys
import urllib.request
from pathlib import Path

VERSION_RE = re.compile(r"[0-9]+(?:\.[0-9]+)*")


def fetch_latest_tag(repo: str) -> str:
    url = f"https://api.github.com/repos/{repo}/releases/latest"
    req = urllib.request.Request(
        url,
        headers={
            "Accept": "application/vnd.github+json",
            "User-Agent": "static-musl-builds-updater",
        },
    )
    with urllib.request.urlopen(req, timeout=30) as resp:
        data = json.load(resp)
    return data["tag_name"].strip()


def normalize_version(tag: str, strip_prefix: str) -> str:
    version = tag
    if strip_prefix and version.startswith(strip_prefix):
        version = version[len(strip_prefix):]
    version = version.strip()
    if not VERSION_RE.fullmatch(version):
        raise ValueError(f"Unexpected version format: {tag!r} -> {version!r}")
    return version


def main() -> int:
    parser = argparse.ArgumentParser()
    parser.add_argument("--repo", required=True, help="owner/repo on GitHub")
    parser.add_argument("--version-file", required=True, type=Path)
    parser.add_argument("--strip-prefix", default="v")
    parser.add_argument("--update-file", action="store_true")
    args = parser.parse_args()

    latest_tag = fetch_latest_tag(args.repo)
    latest = normalize_version(latest_tag, args.strip_prefix)
    current = args.version_file.read_text(encoding="utf-8").strip() if args.version_file.exists() else ""

    print(f"repo={args.repo}")
    print(f"current={current or '<missing>'}")
    print(f"latest={latest}")

    if current == latest:
        print("status=up-to-date")
        return 0

    print("status=update-available")
    if args.update_file:
        args.version_file.parent.mkdir(parents=True, exist_ok=True)
        args.version_file.write_text(latest + "\n", encoding="utf-8")
        print(f"updated_file={args.version_file}")
    return 0


if __name__ == "__main__":
    sys.exit(main())