#!/usr/bin/env python3
"""
This script downloads issues from a given Gitea repository and produces a pull request for each issue.
It assumes that the default branch (default "main") exists and that you have a valid API token if authentication is required.
"""

import argparse
import requests
import sys

def get_default_branch_sha(gitea_url, owner, repo, branch, token):
    """Retrieve the commit SHA of the default branch."""
    headers = {"Authorization": f"token {token}"} if token else {}
    url = f"{gitea_url}/repos/{owner}/{repo}/branches/{branch}"
    response = requests.get(url, headers=headers)
    response.raise_for_status()
    data = response.json()
    return data['commit']['sha']

def create_branch(gitea_url, owner, repo, new_branch, sha, token):
    """Create a new branch from the provided SHA."""
    headers = {"Authorization": f"token {token}", "Content-Type": "application/json"} if token else {"Content-Type": "application/json"}
    url = f"{gitea_url}/repos/{owner}/{repo}/git/refs"
    json_data = {"ref": f"refs/heads/{new_branch}", "sha": sha}
    response = requests.post(url, headers=headers, json=json_data)
    if response.status_code == 422:
        print(f"Branch {new_branch} already exists.")
        return False
    response.raise_for_status()
    return True

def get_issues(gitea_url, owner, repo, token):
    """Download issues from the specified repository."""
    headers = {"Authorization": f"token {token}"} if token else {}
    url = f"{gitea_url}/repos/{owner}/{repo}/issues"
    response = requests.get(url, headers=headers)
    response.raise_for_status()
    return response.json()

def create_pull_request(gitea_url, owner, repo, title, head, base, body, token):
    """Create a pull request for the given branch."""
    headers = {"Authorization": f"token {token}", "Content-Type": "application/json"} if token else {"Content-Type": "application/json"}
    url = f"{gitea_url}/repos/{owner}/{repo}/pulls"
    json_data = {"title": title, "head": head, "base": base, "body": body}
    response = requests.post(url, headers=headers, json=json_data)
    response.raise_for_status()
    return response.json()

def main():
    parser = argparse.ArgumentParser(description="Download issues and create pull requests for a Gitea repository.")
    parser.add_argument("--gitea-url", required=True, help="Base URL for the Gitea instance, e.g., https://gitfub.space/api/v1")
    parser.add_argument("--owner", required=True, help="Owner of the repository")
    parser.add_argument("--repo", required=True, help="Repository name")
    parser.add_argument("--base-branch", default="main", help="Base branch to use for new branches (default: main)")
    parser.add_argument("--token", default="", help="Authentication token if required")
    args = parser.parse_args()

    try:
        issues = get_issues(args.gitea_url, args.owner, args.repo, args.token)
    except Exception as e:
        sys.exit(f"Failed to retrieve issues: {e}")

    if not issues:
        print("No issues found.")
        return

    try:
        base_sha = get_default_branch_sha(args.gitea_url, args.owner, args.repo, args.base_branch, args.token)
    except Exception as e:
        sys.exit(f"Failed to retrieve base branch SHA: {e}")

    for issue in issues:
        issue_number = issue.get("number")
        title = issue.get("title", f"Issue {issue_number}")
        branch_name = f"issue-{issue_number}"
        try:
            created = create_branch(args.gitea_url, args.owner, args.repo, branch_name, base_sha, args.token)
            if created:
                print(f"Created branch {branch_name} for issue {issue_number}.")
        except Exception as e:
            print(f"Error creating branch {branch_name}: {e}")
        body = f"Automatically generated pull request for issue: {issue.get('html_url', 'unknown')}"
        try:
            pr = create_pull_request(args.gitea_url, args.owner, args.repo, f"[Issue {issue_number}] {title}", branch_name, args.base_branch, body, args.token)
            print(f"Created pull request: {pr.get('html_url', 'unknown')} for issue {issue_number}.")
        except Exception as e:
            print(f"Error creating pull request for branch {branch_name}: {e}")

if __name__ == "__main__":
    main()