#!/usr/bin/env python3
"""Review and sign-off on a Gitea pull request.

Supports submitting a review (APPROVE, COMMENT, REQUEST_CHANGES) and optionally
merging the pull request in one command.

Usage:
    review_pr.py --pr-number 12 --event APPROVE --body "Approved and signed off" --merge
"""
import os
import sys
import json
import base64
import argparse
import urllib.request
import urllib.error

# Auto-execute using the project's local virtual environment Python
PROJECT_ROOT = os.path.dirname(os.path.abspath(__file__))
venv_python = os.path.join(PROJECT_ROOT, "venv", "bin", "python3")
if os.path.exists(venv_python) and sys.executable != venv_python:
    os.execv(venv_python, [venv_python] + sys.argv)

from gitea_auth import get_auth_header, resolve_remote, add_remote_args, api_request, repo_api_url


def main(argv=None):
    parser = argparse.ArgumentParser(description="Review and sign-off on a Gitea pull request.")
    add_remote_args(parser)
    parser.add_argument("--pr-number", type=int, required=True, help="PR number/index to review.")
    parser.add_argument("--event", choices=["APPROVE", "COMMENT", "REQUEST_CHANGES"], default="APPROVE",
                        help="Review event/action type (default: APPROVE).")
    parser.add_argument("--body", default="", help="Review body/comment text.")
    parser.add_argument("--body-file", help="Read review body from this file ('-' for stdin).")
    parser.add_argument("--merge", action="store_true", help="Automatically merge the PR if approved.")
    parser.add_argument("--merge-method", choices=["merge", "squash", "rebase"], default="merge",
                        help="Merge method/style to use if merging (default: merge).")
    args = parser.parse_args(argv)

    host, org, repo = resolve_remote(args)

    body = args.body
    if args.body_file:
        if args.body_file == "-":
            body = sys.stdin.read()
        else:
            with open(args.body_file, "r", encoding="utf-8") as fh:
                body = fh.read()

    auth = get_auth_header(host)
    if not auth:
        print(f"Could not get credentials or token for {host}.", file=sys.stderr)
        return 1

    # 1. Fetch PR to get the latest head commit SHA (required for review validation)
    pr_url = f"{repo_api_url(host, org, repo)}/pulls/{args.pr_number}"
    try:
        pr_data = api_request("GET", pr_url, auth)
    except Exception as e:
        print(f"Error fetching PR #{args.pr_number}: {e}", file=sys.stderr)
        return 1

    commit_sha = pr_data.get("head", {}).get("sha")
    if not commit_sha:
        print(f"Could not find head commit SHA for PR #{args.pr_number}.", file=sys.stderr)
        return 1

    # 2. Submit the PR review
    review_url = f"{repo_api_url(host, org, repo)}/pulls/{args.pr_number}/reviews"
    payload = {
        "body": body,
        "event": args.event,
        "commit_id": commit_sha
    }
    
    try:
        api_request("POST", review_url, auth, payload)
        print(f"Successfully submitted review for PR #{args.pr_number}: event={args.event}")
    except Exception as e:
        print(f"Error submitting review: {e}", file=sys.stderr)
        return 1

    # 3. Merge PR if --merge is requested and event is APPROVE
    if args.merge:
        if args.event != "APPROVE":
            print("Warning: Skipping merge because review event is not 'APPROVE'.", file=sys.stderr)
            return 0

        merge_url = f"{repo_api_url(host, org, repo)}/pulls/{args.pr_number}/merge"
        merge_payload = {
            "Do": args.merge_method,
            "force_merge": False
        }
        
        try:
            api_request("POST", merge_url, auth, merge_payload)
            print(f"Successfully merged PR #{args.pr_number} using '{args.merge_method}' method.")
        except Exception as e:
            print(f"Error merging PR: {e}", file=sys.stderr)
            return 1

    return 0


if __name__ == "__main__":
    sys.exit(main())