#!/usr/bin/env python3
import common

import argparse
import sys
from gitlab import Gitlab, GitlabGetError
from gitlab.v4.objects import Project
from get_merge_requests import get_merge_requests


def create_merge_request(project: Project, source_branch, target_branch):
    """Create a merge request"""
    # Check if merge request already exists
    mrs = get_merge_requests(
        project,
        source_branch=source_branch,
        target_branch=target_branch,
        state="opened",
    )
    if mrs:
        return mrs[0], False

    # Check if branches exist
    try:
        sb = project.branches.get(source_branch, retry_transient_errors=True)
    except GitlabGetError:
        sys.exit("ERROR: source branch '%s' does not exist." % source_branch)
    try:
        project.branches.get(target_branch, retry_transient_errors=True)
    except GitlabGetError:
        sys.exit("ERROR: target branch '%s' does not exist." % target_branch)

    # Get commit of source branch
    commit = project.commits.get(sb.attributes["commit"]["id"])

    # Create new merge request
    mr = project.mergerequests.create(
        {
            "source_branch": source_branch,
            "target_branch": target_branch,
            "remove_source_branch": True,
            "title": commit.attributes["title"],
            "description": common.extract_message_body(commit.attributes["message"]),
        }
    )

    return mr, True


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument(
        "--gitlab-url",
        help="""URL to the GitLab instance""",
        dest="gitlab_url",
        required=True,
    )
    parser.add_argument(
        "--token",
        help="""GitLab REST API private access token""",
        dest="token",
        required=True,
    )
    parser.add_argument(
        "--project",
        help="""name of the GitLab project""",
        dest="project",
        required=True,
    )
    parser.add_argument(
        "--source-branch",
        help="""source branch of the merge request""",
        dest="source_branch",
        required=True,
    )
    parser.add_argument(
        "--target-branch",
        help="""target branch of the merge request""",
        dest="target_branch",
        required=True,
    )

    args, _ = parser.parse_known_args()

    gitlab = Gitlab(args.gitlab_url, private_token=args.token)
    project = common.get_project(gitlab, args.project)

    create_merge_request(
        project,
        source_branch=args.source_branch,
        target_branch=args.target_branch,
    )


if __name__ == "__main__":
    main()