from typing import Annotated
from uuid import UUID
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select

from app.core.database import get_db
from app.core.security import decode_token
from app.models.user import User

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/v1/auth/login")


async def get_current_user(
    db: Annotated[AsyncSession, Depends(get_db)],
    token: Annotated[str, Depends(oauth2_scheme)]
) -> User:
    """Get current authenticated user from JWT token."""
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )

    payload = decode_token(token)
    if payload is None:
        raise credentials_exception

    token_type = payload.get("type")
    if token_type != "access":
        raise credentials_exception

    user_id: str = payload.get("sub")
    if user_id is None:
        raise credentials_exception

    try:
        user_uuid = UUID(user_id)
    except ValueError:
        raise credentials_exception

    result = await db.execute(select(User).where(User.id == user_uuid))
    user = result.scalar_one_or_none()

    if user is None:
        raise credentials_exception

    return user


async def get_current_active_user(
    current_user: Annotated[User, Depends(get_current_user)]
) -> User:
    """Ensure user is active (not disabled)."""
    # For now, all users are considered active
    # Add logic here if you add an is_active field to User
    return current_user


async def require_admin(
    current_user: Annotated[User, Depends(get_current_active_user)]
) -> User:
    """Require admin role."""
    if current_user.role != "admin":
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Admin access required"
        )
    return current_user


async def require_engineer_or_admin(
    current_user: Annotated[User, Depends(get_current_active_user)]
) -> User:
    """Require engineer or admin role."""
    if current_user.role not in ("admin", "engineer"):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Engineer or admin access required"
        )
    return current_user