import os
from app.config import *
from datetime import datetime, timedelta
from dotenv import load_dotenv
from typing import Optional
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from jose import JWTError, jwt
from passlib.context import CryptContext
from pydantic import BaseModel

# Based on https://fastapi.tiangolo.com/tutorial/security/oauth2-jwt
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30

pwd_context = CryptContext(schemes=["bcrypt"])
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")

users = [
    {
        "username": API_USERNAME,
        "hashed_password": API_PASSWORD,
        "disabled": False,
    }
]


class Token(BaseModel):
    access_token: str
    token_type: str


class TokenData(BaseModel):
    username: Optional[str] = None


class User(BaseModel):
    username: str
    email: Optional[str] = None
    disabled: Optional[bool] = None


class UserInDB(User):
    hashed_password: str


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


def get_user(username: str):
    user_dict = next((u for u in users if u["username"] == username), None)
    if user_dict:
        return UserInDB(**user_dict)


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: 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


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
