from git import Repo, Remote

from app.config import GitConfig, get_settings


class GitService:
  def __init__(self):
    self._settings = get_settings()
    self._repo = self._check_preconditions(self._settings.git)
    if self._repo.head.ref.name != self._settings.git.branch:
      self._repo.git.checkout(self._settings.git.branch)
    self._origin: Remote = self._repo.remotes.origin


  def get_modified_compose(self) -> str | None:
    self._update()
    return self._diff()

  @staticmethod
  def _check_preconditions(config: GitConfig) -> Repo:
    def clone():
      return Repo.clone_from(config.url, config.path, branch=config.branch)
    import os
    if not config.path.exists():
      return clone()
    if not (config.path / ".git").exists():
      os.rmdir(config.path)
      return clone()
    return Repo(config.path)

  def _update(self):
    self._origin.pull()

  def _diff(self) -> str | None:
    diff = self._repo.head.commit.diff("HEAD~1")
    composes = [f for f in diff if f.a_path.endswith("docker-compose.yml")]
    match len(composes):
      case 0:
        return None
      case 1:
        return composes[0].a_path
      case _:
        raise Exception("Multiple compose files modified")