from datetime import datetime, timedelta
from typing import Optional
from jose import JWTError, jwt
from passlib.context import CryptContext
from fastapi.security import OAuth2PasswordBearer
from fastapi import Depends, HTTPException, status
from sqlalchemy.orm import Session
from . import crud, models, schemas
from .dependencies import get_db

SECRET_KEY = "YOUR_SECRET_KEY_HERE_PLEASE_CHANGE_IN_PROD"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30

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

def verify_password(plain_password, hashed_password):
    return pwd_context.verify(plain_password, hashed_password)

def get_password_hash(password):
    return pwd_context.hash(password)

def create_access_token(data: dict, expires_delta: Optional[timedelta] = None):
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=15)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt

def get_current_user(token: str = Depends(oauth2_scheme), db: Session = Depends(get_db)):
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
        token_data = schemas.TokenData(username=username)
    except JWTError:
        raise credentials_exception
    user = crud.get_user_by_username(db, username=token_data.username)
    if user is None:
        raise credentials_exception
    return user

def get_current_active_user(current_user: models.User = Depends(get_current_user)):
    return current_user

def get_current_admin_user(current_user: models.User = Depends(get_current_user)):
    if current_user.role != models.UserRole.admin:
        raise HTTPException(status_code=400, detail="Not enough permissions")
    return current_user