import hashlib
import hmac
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.config import get_settings
from app.database import get_db
from app.models import ApiKey

security_scheme = HTTPBearer(auto_error=False)


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


def hash_api_key(raw_key: str) -> str:
    secret = get_settings().jwt_secret.encode("utf-8")
    return hmac.new(secret, raw_key.encode("utf-8"), hashlib.sha256).hexdigest()


def verify_api_key_hash(raw_key: str, stored_hash: str) -> bool:
    if hmac.compare_digest(hash_api_key(raw_key), stored_hash):
        return True
    return hmac.compare_digest(_legacy_hash_api_key(raw_key), stored_hash)


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:
    rows = db.scalars(select(ApiKey).where(ApiKey.is_active.is_(True))).all()
    for row in rows:
        if verify_api_key_hash(raw_key, row.key_hash):
            return True
    return False


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