#!/usr/bin/env python3
"""Create an idempotent Gitea pull request or conflict issue."""

from __future__ import annotations

import json
import os
import sys
import urllib.error
import urllib.parse
import urllib.request


BASE_URL = os.environ['GITEA_URL'].rstrip('/') + '/api/v1'
REPOSITORY = os.environ['CUSTOM_REPOSITORY']
TOKEN = os.environ['GITEA_TOKEN']
TARGET = os.environ['INTEGRATION_BRANCH']
HEAD = os.environ['UPDATE_BRANCH']


def request(method: str, path: str, payload: dict | None = None):
    data = json.dumps(payload).encode() if payload is not None else None
    req = urllib.request.Request(
        f'{BASE_URL}{path}', data=data, method=method,
        headers={
            'Authorization': f'token {TOKEN}',
            'Accept': 'application/json',
            'Content-Type': 'application/json',
        })
    try:
        with urllib.request.urlopen(req, timeout=30) as response:
            return json.load(response)
    except urllib.error.HTTPError as exc:
        detail = exc.read().decode(errors='replace')
        raise RuntimeError(f'Gitea API returned {exc.code}: {detail}') from exc
    except urllib.error.URLError as exc:
        raise RuntimeError(f'Could not reach the Gitea API: {exc.reason}') from exc


def open_pulls():
    query = urllib.parse.urlencode({'state': 'open', 'limit': 50})
    return request('GET', f'/repos/{REPOSITORY}/pulls?{query}')


def ensure_pull_request(upstream_sha: str) -> None:
    for pull in open_pulls():
        if pull['head']['ref'] == HEAD and pull['base']['ref'] == TARGET:
            print(f"Using existing pull request: {pull['html_url']}")
            return
    pull = request('POST', f'/repos/{REPOSITORY}/pulls', {
        'title': f'Upstream Tryton 8.0 update ({upstream_sha[:12]})',
        'head': HEAD,
        'base': TARGET,
        'body': (
            'Automated proposal from the private official mirror.\n\n'
            'Review the upstream changes and wait for all required checks. '
            'This pull request must be merged manually.'),
    })
    print(f"Created pull request: {pull['html_url']}")


def ensure_conflict_issue(conflicts: str) -> None:
    title = 'Upstream Tryton 8.0 synchronization conflict'
    query = urllib.parse.urlencode({'state': 'open', 'type': 'issues', 'limit': 50})
    for issue in request('GET', f'/repos/{REPOSITORY}/issues?{query}'):
        if issue['title'] == title:
            print(f"Conflict issue already open: {issue['html_url']}")
            return
    issue = request('POST', f'/repos/{REPOSITORY}/issues', {
        'title': title,
        'body': (
            'The scheduled synchronization could not merge the latest '
            'official 8.0 changes. No branch was overwritten.\n\n'
            f'Conflicting paths:\n```\n{conflicts or "unknown"}\n```'),
    })
    print(f"Created conflict issue: {issue['html_url']}")


def main() -> None:
    if len(sys.argv) != 3:
        raise SystemExit('usage: upstream_pr.py pull-request SHA | conflict PATHS')
    if sys.argv[1] == 'pull-request':
        ensure_pull_request(sys.argv[2])
    elif sys.argv[1] == 'conflict':
        ensure_conflict_issue(sys.argv[2])
    else:
        raise SystemExit('usage: upstream_pr.py pull-request SHA | conflict PATHS')


if __name__ == '__main__':
    main()