import hashlib
import secrets

from fastapi import Depends, HTTPException, Security
from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
from sqlalchemy import select
from sqlalchemy.orm import Session

from app.database import get_db
from app.models import ApiKey

security_scheme = HTTPBearer(auto_error=False)


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


def generate_api_key() -> tuple[str, str, str]:
    """Returns (full_key, prefix, hash)."""
    raw = f"sac_{secrets.token_urlsafe(32)}"
    prefix = raw[:12]
    return raw, prefix, hash_api_key(raw)


def verify_api_key(db: Session, raw_key: str) -> bool:
    key_hash = hash_api_key(raw_key)
    row = db.scalar(select(ApiKey).where(ApiKey.key_hash == key_hash, ApiKey.is_active.is_(True)))
    return row is not None


def get_api_key_auth(
    credentials: HTTPAuthorizationCredentials | None = Security(security_scheme),
    db: Session = Depends(get_db),
) -> str:
    if credentials is None or credentials.scheme.lower() != "bearer":
        raise HTTPException(status_code=401, detail="Missing or invalid Authorization header")
    if not verify_api_key(db, credentials.credentials):
        raise HTTPException(status_code=401, detail="Invalid API key")
    return credentials.credentials