from __future__ import annotations

import secrets
from typing import Optional

from fastapi import Depends, Header, HTTPException, Request
from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer

from backend import config, db

_bearer = HTTPBearer(auto_error=False)

_RATE_LIMIT = 5
_RATE_WINDOW = 600  # 10 minutes

_SIGNAL_RATE_LIMIT = 10
_SIGNAL_RATE_WINDOW = 60  # 1 minute

_AUTH_REGISTER_RATE_LIMIT = 3
_AUTH_REGISTER_RATE_WINDOW = 600  # 10 minutes


def _get_client_ip(request: Request) -> str:
    return (
        request.headers.get("X-Real-IP")
        or request.headers.get("X-Forwarded-For", "").split(",")[0].strip()
        or (request.client.host if request.client else "unknown")
    )


async def verify_webhook_secret(
    x_telegram_bot_api_secret_token: str = Header(default=""),
) -> None:
    if not secrets.compare_digest(
        x_telegram_bot_api_secret_token, config.WEBHOOK_SECRET
    ):
        raise HTTPException(status_code=403, detail="Forbidden")


async def verify_admin_token(
    credentials: Optional[HTTPAuthorizationCredentials] = Depends(_bearer),
) -> None:
    if credentials is None or not secrets.compare_digest(
        credentials.credentials, config.ADMIN_TOKEN
    ):
        raise HTTPException(status_code=401, detail="Unauthorized")


async def rate_limit_register(request: Request) -> None:
    key = f"reg:{_get_client_ip(request)}"
    count = await db.rate_limit_increment(key, _RATE_WINDOW)
    if count > _RATE_LIMIT:
        raise HTTPException(status_code=429, detail="Too Many Requests")


async def rate_limit_signal(request: Request) -> None:
    key = f"sig:{_get_client_ip(request)}"
    count = await db.rate_limit_increment(key, _SIGNAL_RATE_WINDOW)
    if count > _SIGNAL_RATE_LIMIT:
        raise HTTPException(status_code=429, detail="Too Many Requests")


async def rate_limit_auth_register(request: Request) -> None:
    key = f"authreg:{_get_client_ip(request)}"
    count = await db.rate_limit_increment(key, _AUTH_REGISTER_RATE_WINDOW)
    if count > _AUTH_REGISTER_RATE_LIMIT:
        raise HTTPException(status_code=429, detail="Too Many Requests")