"""
FastAPI dependencies for authentication and database access
"""
from fastapi import Depends, HTTPException, status
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
from sqlalchemy.orm import Session
from app.database import get_db
from app.models import User
from app.services.auth_service import decode_access_token

# Security scheme
security = HTTPBearer()


async def get_current_user(
    credentials: HTTPAuthorizationCredentials = Depends(security),
    db: Session = Depends(get_db)
) -> User:
    """
    Dependency to get the current authenticated user from JWT token
    
    Raises:
        HTTPException 401: If token is invalid or user not found
    """
    token = credentials.credentials
    
    # Decode token
    payload = decode_access_token(token)
    if payload is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid or expired token",
            headers={"WWW-Authenticate": "Bearer"}
        )
    
    # Get user ID from token
    user_id = payload.get("sub")
    if user_id is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid token payload",
            headers={"WWW-Authenticate": "Bearer"}
        )
    
    # Fetch user from database
    user = db.query(User).filter(User.id == user_id).first()
    if user is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="User not found",
            headers={"WWW-Authenticate": "Bearer"}
        )
    
    return user