from datetime import datetime, timedelta
from typing import Optional
from jose import JWTError, jwt
from passlib.context import CryptContext
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from sqlalchemy.orm import Session
from config.settings import settings
from config.database import get_db
from models.user import User
from schemas.user import TokenData

pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/auth/login")

def verify_password(plain_password: str, hashed_password: str) -> bool:
    """Verify a plain password against a hashed password."""
    return pwd_context.verify(plain_password, hashed_password)

def get_password_hash(password: str) -> str:
    """Generate a password hash."""
    return pwd_context.hash(password)

def create_access_token(data: dict, expires_delta: Optional[timedelta] = None) -> str:
    """Create a JWT access token."""
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=settings.JWT_EXPIRATION_MINUTES)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, settings.JWT_SECRET_KEY, algorithm=settings.JWT_ALGORITHM)
    return encoded_jwt

def verify_token(token: str, credentials_exception) -> TokenData:
    """Verify a JWT token and return the token data."""
    try:
        payload = jwt.decode(token, settings.JWT_SECRET_KEY, algorithms=[settings.JWT_ALGORITHM])
        user_id: int = payload.get("sub")
        email: str = payload.get("email")
        if user_id is None:
            raise credentials_exception
        token_data = TokenData(user_id=user_id, email=email)
        return token_data
    except JWTError:
        raise credentials_exception

async def get_current_user(token: str = Depends(oauth2_scheme), db: Session = Depends(get_db)) -> User:
    """Get the current authenticated user."""
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    token_data = verify_token(token, credentials_exception)
    user = db.query(User).filter(User.id == token_data.user_id).first()
    if user is None:
        raise credentials_exception
    return user

async def get_current_active_user(current_user: User = Depends(get_current_user)) -> User:
    """Get the current active user."""
    if not current_user.is_active:
        raise HTTPException(status_code=400, detail="Inactive user")
    return current_user

async def get_admin_user(current_user: User = Depends(get_current_active_user)) -> User:
    """Get the current admin user."""
    if not current_user.is_admin:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Not enough permissions"
        )
    return current_user
