"""Git helpers via subprocess (ADR-001)."""

from __future__ import annotations

import subprocess
from pathlib import Path


class GitError(RuntimeError):
    pass


def _run(repo: Path, *args: str, check: bool = True) -> subprocess.CompletedProcess[str]:
    proc = subprocess.run(
        ["git", *args],
        cwd=repo,
        capture_output=True,
        text=True,
        check=False,
    )
    if check and proc.returncode != 0:
        raise GitError(proc.stderr.strip() or proc.stdout.strip() or f"git {' '.join(args)} failed")
    return proc


def head_sha(repo: Path) -> str | None:
    proc = _run(repo, "rev-parse", "HEAD", check=False)
    if proc.returncode != 0:
        return None
    return proc.stdout.strip() or None


def is_git_repo(repo: Path) -> bool:
    return (repo / ".git").exists() or _run(repo, "rev-parse", "--git-dir", check=False).returncode == 0


def commit_paths(
    repo: Path,
    paths: list[str],
    message: str,
    *,
    author_name: str = "repo-manager",
    author_email: str = "repo-manager@local",
) -> str:
    """Stage paths and commit. Returns new HEAD sha."""
    env_author = [
        "-c",
        f"user.name={author_name}",
        "-c",
        f"user.email={author_email}",
    ]
    for path in paths:
        _run(repo, "add", "--", path)
    proc = subprocess.run(
        ["git", *env_author, "commit", "-m", message],
        cwd=repo,
        capture_output=True,
        text=True,
        check=False,
    )
    if proc.returncode != 0:
        raise GitError(proc.stderr.strip() or proc.stdout.strip() or "git commit failed")
    sha = head_sha(repo)
    if not sha:
        raise GitError("commit succeeded but HEAD missing")
    return sha


def push_ff(repo: Path) -> tuple[bool, str]:
    """Best-effort push (push-seal compatible). Never force-pushes."""
    try:
        proc = subprocess.run(
            ["git", "push"],
            cwd=repo,
            capture_output=True,
            text=True,
            timeout=60,
            check=False,
        )
        if proc.returncode == 0:
            return True, (proc.stdout.strip() or "pushed")
        return False, (proc.stderr.strip() or proc.stdout.strip() or "push failed")
    except Exception as exc:  # noqa: BLE001
        return False, str(exc)