import hashlib

from fastapi import HTTPException, status
from redis.exceptions import RedisError

from app.config.settings import settings
from app.utils.redis_client import get_redis_client


def _hash_text(text: str) -> str:
    return hashlib.sha256(text.encode("utf-8")).hexdigest()


async def enforce_message_spam_policy(*, user_id: int, chat_id: int, text: str | None) -> None:
    redis = get_redis_client()
    rate_key = f"spam:msg_rate:{user_id}:{chat_id}"
    try:
        count = await redis.incr(rate_key)
        if count == 1:
            await redis.expire(rate_key, 60)
        if count > settings.message_rate_limit_per_minute:
            raise HTTPException(
                status_code=status.HTTP_429_TOO_MANY_REQUESTS,
                detail="Message rate limit exceeded for this chat.",
            )

        normalized = (text or "").strip()
        if normalized:
            dup_key = f"spam:dup:{user_id}:{chat_id}:{_hash_text(normalized)}"
            if await redis.exists(dup_key):
                raise HTTPException(
                    status_code=status.HTTP_429_TOO_MANY_REQUESTS,
                    detail="Duplicate message cooldown is active.",
                )
            await redis.set(dup_key, "1", ex=settings.duplicate_message_cooldown_seconds)
    except RedisError:
        return