"""Supplement Gitea native protection when review identity is not expressible."""
from __future__ import annotations

from dataclasses import dataclass
from typing import Any, Mapping, Sequence


class MergeGateDenied(RuntimeError):
    pass


@dataclass(frozen=True)
class MergeGateDecision:
    allowed: bool
    owner_review_id: int
    required_contexts: tuple[str, ...]


def validate_protected_merge(
    pull_request: Mapping[str, Any],
    reviews: Sequence[Mapping[str, Any]],
    statuses: Mapping[str, str],
    *,
    required_contexts: Sequence[str],
    unresolved_conversations: int,
    owner_login: str = "owner",
    owner_id: int = 2,
) -> MergeGateDecision:
    if pull_request.get("state") != "open" or pull_request.get("mergeable") is not True:
        raise MergeGateDenied("pull_request_not_mergeable")
    author = (pull_request.get("user") or {}).get("login")
    owner_review = None
    for review in reviews:
        user = review.get("user") or {}
        if review.get("state") == "APPROVED" and user.get("login") == owner_login and user.get("id") == owner_id:
            if author == owner_login or (pull_request.get("author_id") == owner_id):
                raise MergeGateDenied("pr_author_self_approval_denied")
            owner_review = review
    if owner_review is None:
        raise MergeGateDenied("owner_review_required")
    if unresolved_conversations != 0:
        raise MergeGateDenied("unresolved_conversations_block_merge")
    missing = [context for context in required_contexts if statuses.get(context) != "success"]
    if missing:
        raise MergeGateDenied("required_checks_missing:" + ",".join(missing))
    return MergeGateDecision(True, int(owner_review.get("id", 0)), tuple(required_contexts))