#!/usr/bin/env python3
"""Commit the given paths and push to the default branch.

Pushing to main triggers `publish`. Needs the repository secrets
TANGLED_CI_SSH_KEY and TANGLED_PUSH_URL. If main moved while the job ran, the
commit is rebased onto it and the push retried.

    commit_and_push.py -m 'actions: sync' modpacks
"""

import argparse
import os
import shlex
import subprocess
import sys
import tempfile
from pathlib import Path

PUSH_ATTEMPTS = 3


def git(*args: str, env: dict[str, str] | None = None, check: bool = True) -> subprocess.CompletedProcess:
    return subprocess.run(["git", *args], env=env, check=check)


def commit_and_push(message: str, paths: list[str]) -> int:
    for name in ("TANGLED_CI_SSH_KEY", "TANGLED_PUSH_URL"):
        if not os.environ.get(name):
            print(f"{name} is not set; configure this Tangled repository secret", file=sys.stderr)
            return 1

    git("config", "user.name", "tangled-ci[bot]")
    git("config", "user.email", "tangled-ci@noreply.invalid")
    git("add", "--", *paths)
    if git("diff", "--cached", "--quiet", check=False).returncode == 0:
        print("nothing to commit")
        return 0
    git("commit", "-m", message)

    branch = os.environ.get("TANGLED_REPO_DEFAULT_BRANCH", "main")
    url = os.environ["TANGLED_PUSH_URL"]
    with tempfile.TemporaryDirectory(prefix="tangled-ci-") as tmp:
        key = Path(tmp) / "id_ed25519"
        key.touch(mode=0o600)
        key.write_text(os.environ["TANGLED_CI_SSH_KEY"].rstrip("\n") + "\n")
        ssh_opts = "-o IdentitiesOnly=yes -o StrictHostKeyChecking=accept-new"
        env = {
            **os.environ,
            "GIT_SSH_COMMAND": f"ssh -i {shlex.quote(str(key))} {ssh_opts}",
        }
        for attempt in range(1, PUSH_ATTEMPTS + 1):
            if git("push", url, f"HEAD:refs/heads/{branch}", env=env, check=False).returncode == 0:
                return 0
            if attempt == PUSH_ATTEMPTS:
                break
            print(f"push rejected (attempt {attempt}/{PUSH_ATTEMPTS}); rebasing onto {branch}", file=sys.stderr)
            git("pull", "--rebase", url, branch, env=env)
    print("push failed", file=sys.stderr)
    return 1


def main() -> int:
    parser = argparse.ArgumentParser(description=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter)
    parser.add_argument("-m", "--message", default=os.environ.get("TANGLED_COMMIT_MESSAGE"))
    parser.add_argument("paths", nargs="+")
    args = parser.parse_args()
    if not args.message:
        parser.error("a commit message is required (-m or TANGLED_COMMIT_MESSAGE)")
    return commit_and_push(args.message, args.paths)


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