from dataclasses import dataclass
from typing import List, Optional
import subprocess


class GitStatusError(Exception):
    pass


def _run_git_command(args: List[str], cwd: str = None) -> str:
    try:
        result = subprocess.run(
            ["git"] + args,
            cwd=cwd,
            capture_output=True,
            text=True,
            check=True,
        )
        return result.stdout.strip()
    except subprocess.CalledProcessError as e:
        raise GitStatusError(f"Git command failed: {e}")


def _get_current_branch(cwd: str = None) -> str:
    try:
        return _run_git_command(["rev-parse", "--abbrev-ref", "HEAD"], cwd)
    except GitStatusError:
        return "HEAD"


def _get_commit_hash(cwd: str = None) -> str:
    return _run_git_command(["rev-parse", "SHORT"], cwd)


def _is_detached(cwd: str = None) -> bool:
    branch = _get_current_branch(cwd)
    return branch == "HEAD"


def _get_staged_count(cwd: str = None) -> int:
    output = _run_git_command(["diff", "--staged", "--name-only"], cwd)
    return len(output.splitlines()) if output else 0


def _get_unstaged_count(cwd: str = None) -> int:
    output = _run_git_command(["diff", "--name-only"], cwd)
    return len(output.splitlines()) if output else 0


def _get_untracked_count(cwd: str = None) -> int:
    output = _run_git_command(["ls-files", "--others", "--exclude-standard"], cwd)
    return len(output.splitlines()) if output else 0


@dataclass
class GitStatus:
    branch: str
    commit: str
    staged: int = 0
    unstaged: int = 0
    untracked: int = 0
    ahead: int = 0
    behind: int = 0
    is_detached: bool = False
    is_clean: bool = True


def get_git_status(cwd: str = None) -> GitStatus:
    try:
        is_detached_head = _is_detached(cwd)
        branch = "(detached)" if is_detached_head else _get_current_branch(cwd)
        commit = _get_commit_hash(cwd)
        staged = _get_staged_count(cwd)
        unstaged = _get_unstaged_count(cwd)
        untracked = _get_untracked_count(cwd)
        is_clean = (staged == 0 and unstaged == 0 and untracked == 0)

        return GitStatus(
            branch=branch,
            commit=commit,
            staged=staged,
            unstaged=unstaged,
            untracked=untracked,
            is_detached=is_detached_head,
            is_clean=is_clean,
        )
    except GitStatusError:
        raise GitStatusError("Failed to get git status")


def is_git_repo(cwd: str = None) -> bool:
    try:
        _run_git_command(["rev-parse", "--git-dir"], cwd)
        return True
    except GitStatusError:
        return False