from datetime import datetime, timedelta
from schemas.user import User, UserInDB
from schemas.token import Token, TokenData
from services.main import OpenDBMSessionContext
from config.db import get_db
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from fastapi import Depends, HTTPException, status
from passlib.context import CryptContext
from jose import JWTError, jwt
from typing import Union
import os
from dotenv import load_dotenv

load_dotenv()


oauth2_scheme = OAuth2PasswordBearer(tokenUrl="odbm/v1/login")
SECRET_KEY = os.getenv('JWT_SECRET', 'DUMMY_SECRET')
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = int(os.getenv('TOKEN_EXPIRE', 30))

pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
db = get_db()

def get_user(username: str):
    if username in db:
        user_dict = db[username]
        return UserInDB(**user_dict)

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 authenticate_user(username: str, password: str):
    user = get_user(username)
    if not user:
        return False
    if not verify_password(password, user.hashed_password):
        return False
    return user

def create_access_token(data: dict, expires_delta: Union[timedelta, None] = 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

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, SECRET_KEY, algorithms=[ALGORITHM])
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
        token_data = TokenData(username=username)
    except JWTError:
        raise credentials_exception
    user = get_user(username=token_data.username)
    if user is None:
        raise credentials_exception
    return user

async def get_current_active_user(current_user: User = Depends(get_current_user)):
    if current_user.disabled:
        raise HTTPException(status_code=400, detail="Inactive user")
    return current_user

def login(form_data: OAuth2PasswordRequestForm):
    hashed_pwd = get_password_hash(form_data.password)
    user = authenticate_user(form_data.username, form_data.password)
    if not user:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Bearer"},
        )
    access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
    access_token = create_access_token(
        data={"sub": user.username}, expires_delta=access_token_expires
    )
    token = Token(access_token=access_token, token_type="bearer")
    return token