"""
Dépendances FastAPI — authentification par API Key + vérification de scopes.

Usage dans les routers :
    client = Depends(get_current_client)
    _     = Depends(require_scope("images:read"))
"""
import hashlib
import logging
from typing import Callable

from fastapi import Depends, Header, HTTPException, Request, status
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.database import get_db
from app.models.client import APIClient

logger = logging.getLogger(__name__)


def hash_api_key(api_key: str) -> str:
    """Hash SHA-256 d'une clé API — fonction utilitaire réutilisable."""
    return hashlib.sha256(api_key.encode("utf-8")).hexdigest()


async def verify_api_key(
    request: Request,
    authorization: str = Header(
        ...,
        alias="Authorization",
        description="Clé API au format 'Bearer <key>'",
    ),
    db: AsyncSession = Depends(get_db),
) -> APIClient:
    """
    Vérifie la clé API fournie dans le header Authorization.
    Injecte client_id et client_plan dans request.state pour le rate limiter.

    Raises:
        HTTPException 401: clé absente, invalide ou client inactif.
    """
    # ── Extraction du token ───────────────────────────────────
    if not authorization.startswith("Bearer "):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Authentification requise",
            headers={"WWW-Authenticate": "Bearer"},
        )

    raw_key = authorization[7:]  # strip "Bearer "
    if not raw_key:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Authentification requise",
            headers={"WWW-Authenticate": "Bearer"},
        )

    # ── Lookup par hash ───────────────────────────────────────
    key_hash = hash_api_key(raw_key)
    result = await db.execute(
        select(APIClient).where(APIClient.api_key_hash == key_hash)
    )
    client = result.scalar_one_or_none()

    if client is None:
        logger.warning("Tentative d'authentification avec une clé invalide")
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Authentification requise",
            headers={"WWW-Authenticate": "Bearer"},
        )

    if not client.is_active:
        logger.warning("Tentative d'authentification avec un client inactif: %s", client.id)
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Authentification requise",
            headers={"WWW-Authenticate": "Bearer"},
        )

    # Injecter dans request.state pour le rate limiter
    request.state.client_id = client.id
    request.state.client_plan = client.plan.value if client.plan else "free"

    return client


# Alias pratique pour injection dans les routers
get_current_client = verify_api_key


def require_scope(scope: str) -> Callable:
    """
    Factory qui retourne une dépendance FastAPI vérifiant qu'un scope est accordé.

    Usage:
        @router.get("/...", dependencies=[Depends(require_scope("images:read"))])
    """

    async def _check_scope(
        client: APIClient = Depends(get_current_client),
    ) -> APIClient:
        if not client.has_scope(scope):
            logger.warning(
                "Client %s (%s) a tenté d'accéder au scope '%s' sans autorisation",
                client.id, client.name, scope,
            )
            raise HTTPException(
                status_code=status.HTTP_403_FORBIDDEN,
                detail="Permission insuffisante",
            )
        return client

    return _check_scope