import gitlab
from typing import Optional, Tuple


class GitLabProvider:
    def __init__(self, merge_request_url: Optional[str] = None, personal_access_token: Optional[str] = None):
        self.gl = gitlab.Gitlab('https://your.gitlab.com', private_token=personal_access_token)
        self.project = None
        self.mr_iid = None
        self.mr = None
        if merge_request_url:
            self.set_merge_request(merge_request_url)

    def set_merge_request(self, merge_request_url: str):
        self.project, self.mr_iid = self._parse_merge_request_url(merge_request_url)
        self.mr = self._get_merge_request()

    def get_diff_files(self) -> list[FilePatchInfo]:
        diffs = self.mr.diffs.list()
        diff_files = []
        for diff in diffs:
            # GitLab doesn't provide base and head files. Only diffs are available.
            diff_files.append(FilePatchInfo("", "", diff['diff'], diff['new_path']))
        return diff_files

    def publish_comment(self, mr_comment: str):
        self.mr.notes.create({'body': mr_comment})

    def get_title(self):
        return self.mr.title

    def get_description(self):
        return self.mr.description

    def get_languages(self):
        # GitLab does not have a direct equivalent to get_languages().
        # An alternative could be to manually parse all the repository files and determine the language from the file extensions.
        raise NotImplementedError

    def get_main_pr_language(self) -> str:
        # Similar issue as get_languages().
        raise NotImplementedError

    def get_pr_branch(self):
        return self.mr.source_branch

    def get_notifications(self):
        # GitLab doesn't provide a notifications API similar to GitHub's.
        raise NotImplementedError

    @staticmethod
    def _parse_merge_request_url(merge_request_url: str) -> Tuple[str, int]:
        # This function will depend on your GitLab setup and URL structure
        raise NotImplementedError

    def _get_merge_request(self):
        return self.gl.projects.get(self.project).mergerequests.get(self.mr_iid)