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 app.core.config import settings
from app.core.database import get_db

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


def verify_password(plain_password: str, hashed_password: str) -> bool:
    return pwd_context.verify(plain_password, hashed_password)


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


def create_access_token(data: dict, expires_delta: Optional[timedelta] = None) -> str:
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)
    return encoded_jwt


def decode_token(token: str) -> Optional[dict]:
    try:
        payload = jwt.decode(token, settings.SECRET_KEY, algorithms=[settings.ALGORITHM])
        return payload
    except JWTError:
        return None


async def get_current_user(
    token: str = Depends(oauth2_scheme),
    db: Session = Depends(get_db)
):
    from app.models.models import User
    
    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
    
    user_id: int = payload.get("sub")
    if user_id is None:
        raise credentials_exception
    
    user = db.query(User).filter(User.id == user_id).first()
    if user is None:
        raise credentials_exception
    
    if not user.is_active:
        raise HTTPException(status_code=400, detail="Inactive user")
    
    return user


async def get_current_admin_user(
    current_user = Depends(get_current_user)
):
    if current_user.role != "admin":
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Not enough permissions"
        )
    return current_user