from datetime import timedelta, datetime
from typing import Annotated
from fastapi import APIRouter, Depends, HTTPException
from pydantic import BaseModel
from passlib.context import CryptContext
from sqlalchemy.orm import Session
from starlette import status
from fastapi.security import OAuth2PasswordRequestForm, OAuth2PasswordBearer
from jose import jwt, JWTError

from models import User
from database import SessionLocal

router = APIRouter()

SECRET_KEY = '3b004eeae34b43bd05226f210d9bdc2ad99abdd3c52bf32802906085b762ff55'
ALGORITHM = 'HS256'

bcrypt_context = CryptContext(schemes=['bcrypt'], deprecated='auto')
oauth2_bearer = OAuth2PasswordBearer(tokenUrl='validate')


def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()


db_dependency = Annotated[Session, Depends(get_db)]


def authenticate_user(username: str, password: str, db):
    user = db.query(User).filter(User.username == username).first()
    if not user:
        return False
    if not bcrypt_context.verify(password, user.password):
        return False
    return user


def create_access_token(username: str, user_id: int, expires_delta: timedelta):
    encode = {'sub': username, 'id': user_id}
    expire = datetime.now() + expires_delta
    encode.update({'exp': expire})

    return jwt.encode(encode, SECRET_KEY, ALGORITHM)


class CreateUser(BaseModel):
    username: str
    email: str
    password: str


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


async def get_current_user(token: Annotated[str, Depends(oauth2_bearer)]):
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        username: str = payload.get('sub')
        user_id: int = payload.get('id')
        if username is None or user_id is None:
            raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Could not validate credentials")

        return {'username': username, 'user_id': user_id}
    except JWTError:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Could not validate credentials")


@router.post('/auth/create', status_code=status.HTTP_201_CREATED)
async def create_user(db: db_dependency, data: CreateUser):
    create_user_model = User(
        username=data.username,
        email=data.email,
        password=bcrypt_context.hash(data.password),
        role='admin'
    )

    db.add(create_user_model)
    db.commit()


@router.post('/auth/token', status_code=status.HTTP_200_OK, response_model=Token)
async def get_token(
        form_data: Annotated[OAuth2PasswordRequestForm, Depends()],
        db: db_dependency
):
    user = authenticate_user(form_data.username, form_data.password, db)
    if not user:
        return "authentication failed"

    token = create_access_token(user.username, user.id, timedelta(minutes=20))
    return {'access_token': token, 'token_type': 'bearer'}