from datetime import datetime, timedelta
from typing import Optional

from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from jose import JWTError, jwt
import bcrypt

from .schemas import TokenData
from .settings import settings
from .models import User
from .two_factor import verify_totp_code # Import verify_totp_code

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")

def verify_password(plain_password, hashed_password):
    password_bytes = plain_password[:72].encode('utf-8')
    hashed_bytes = hashed_password.encode('utf-8') if isinstance(hashed_password, str) else hashed_password
    return bcrypt.checkpw(password_bytes, hashed_bytes)

def get_password_hash(password):
    password_bytes = password[:72].encode('utf-8')
    return bcrypt.hashpw(password_bytes, bcrypt.gensalt()).decode('utf-8')

async def authenticate_user(username: str, password: str, two_factor_code: Optional[str] = None):
    user = await User.get_or_none(username=username)
    if not user:
        return None
    if not verify_password(password, user.hashed_password):
        return None

    if user.is_2fa_enabled:
        if not two_factor_code:
            return {"user": user, "2fa_required": True}
        if not verify_totp_code(user.two_factor_secret, two_factor_code):
            return None # 2FA code is incorrect
    return {"user": user, "2fa_required": False}

def create_access_token(data: dict, expires_delta: Optional[timedelta] = None, two_factor_verified: bool = False):
    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, "2fa_verified": two_factor_verified})
    encoded_jwt = jwt.encode(to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM)
    return encoded_jwt

async def get_current_user(token: str = Depends(oauth2_scheme)):
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, settings.SECRET_KEY, algorithms=[settings.ALGORITHM])
        username: str = payload.get("sub")
        two_factor_verified: bool = payload.get("2fa_verified", False)
        if username is None:
            raise credentials_exception
        token_data = TokenData(username=username, two_factor_verified=two_factor_verified)
    except JWTError:
        raise credentials_exception
    user = await User.get_or_none(username=token_data.username)
    if user is None:
        raise credentials_exception
    user.token_data = token_data # Attach token_data to user for easy access
    return user

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

async def get_current_verified_user(current_user: User = Depends(get_current_user)):
    if current_user.is_2fa_enabled and not current_user.token_data.two_factor_verified:
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="2FA required and not verified")
    return current_user

async def get_current_admin_user(current_user: User = Depends(get_current_verified_user)):
    if not current_user.is_superuser:
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Not enough permissions")
    return current_user