from datetime import datetime, timedelta, timezone

from fastapi import Depends, HTTPException, status
from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
from jose import JWTError, jwt

from app.config import get_settings

bearer_scheme = HTTPBearer(auto_error=False)


def create_access_token(subject: str) -> str:
    settings = get_settings()
    expire = datetime.now(timezone.utc) + timedelta(minutes=settings.jwt_expire_minutes)
    payload = {"sub": subject, "exp": expire}
    return jwt.encode(payload, settings.jwt_secret, algorithm=settings.jwt_algorithm)


def _decode_username(token: str) -> str:
    settings = get_settings()
    try:
        payload = jwt.decode(
            token,
            settings.jwt_secret,
            algorithms=[settings.jwt_algorithm],
        )
        username = payload.get("sub")
        if not username:
            raise HTTPException(status_code=401, detail="Invalid token")
        return str(username)
    except JWTError as exc:
        raise HTTPException(status_code=401, detail="Invalid token") from exc


def verify_access_token(token: str) -> str:
    """Проверка JWT (в т.ч. query-параметр для SSE)."""
    return _decode_username(token)


def get_current_user(
    credentials: HTTPAuthorizationCredentials | None = Depends(bearer_scheme),
) -> str:
    if credentials is None or credentials.scheme.lower() != "bearer":
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Not authenticated",
        )
    return _decode_username(credentials.credentials)