from datetime import datetime, timedelta, timezone
from typing import Union

from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from jose import JWTError, jwt
from passlib.context import CryptContext
from pydantic import BaseModel

# to get a string like this run:
# openssl rand -hex 32
SECRET_KEY = "09d25e094faa6ca2556c818166b7a9563b93f7099f6f0f4caa6cf63b88e8d3e7"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30


fake_users_db = {
 "johndoe": {
 "username": "johndoe",
 "full_name": "John Doe",
 "email": "johndoe@example.com",
 "hashed_password": "2ドルb12ドル$EixZaYVK1fsbw1ZfbX3OXePaWxn96p36WQoeG6Lruj3vjPGga31lW",
 "disabled": False,
 }
}


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


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


class User(BaseModel):
 username: str
 email: Union[str, None] = None
 full_name: Union[str, None] = None
 disabled: Union[bool, None] = None


class UserInDB(User):
 hashed_password: str


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

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")

app = FastAPI()


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


def authenticate_user(fake_db, username: str, password: str):
 user = get_user(fake_db, 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.now(timezone.utc) + expires_delta
 else:
 expire = datetime.now(timezone.utc) + 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(fake_users_db, 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


@app.post("/token")
async def login_for_access_token(
 form_data: OAuth2PasswordRequestForm = Depends(),
) -> Token:
 user = authenticate_user(fake_users_db, 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
 )
 return Token(access_token=access_token, token_type="bearer")


@app.get("/users/me/", response_model=User)
async def read_users_me(current_user: User = Depends(get_current_active_user)):
 return current_user


@app.get("/users/me/items/")
async def read_own_items(current_user: User = Depends(get_current_active_user)):
 return [{"item_id": "Foo", "owner": current_user.username}]