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

Submits a review (APPROVE, COMMENT, REQUEST_CHANGES). CLI merge is disabled:
the `--merge` flag is retained only for compatibility and fails closed without
making any API call. Merge is handled solely by the gated `gitea_merge_pr` MCP
workflow (#16), which enforces identity/profile/eligibility, explicit
confirmation, expected head SHA checking, and self-merge protection.

Usage (review only):
    review_pr.py --pr-number 12 --event APPROVE --body "Approved and signed off"
"""
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="DISABLED — fails closed with no API call. CLI merge is not "
                             "supported; use the gated gitea_merge_pr MCP workflow (#16).")
    parser.add_argument("--merge-method", choices=["merge", "squash", "rebase"], default="merge",
                        help="Ignored — CLI merge is disabled (see --merge).")
    args = parser.parse_args(argv)

    # Fail closed: direct CLI merge is disabled (#16). LLM automations were
    # using this flag as an ungated merge bypass. Merge is only available via
    # the gated `gitea_merge_pr` MCP workflow, which enforces
    # identity/profile/eligibility, explicit confirmation, expected head SHA,
    # and self-merge protection. No API call is made here.
    if args.merge:
        print(
            "Direct CLI merge is disabled. Merge is only available through the "
            "gated #16 workflow (MCP tool 'gitea_merge_pr'), which enforces "
            "identity/profile/eligibility, explicit confirmation, expected head "
            "SHA checking, and self-merge protection. Re-run without --merge to "
            "submit a review only.",
            file=sys.stderr,
        )
        return 2

    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

    # Merge is intentionally not performed here — see the fail-closed guard
    # above. Use the gated `gitea_merge_pr` MCP workflow (#16) to merge.
    return 0


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