from datetime import datetime, timedelta

import jwt
from fastapi import Depends, FastAPI, HTTPException
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from jwt import PyJWTError
from passlib.context import CryptContext
from starlette.status import HTTP_401_UNAUTHORIZED

from .models import Token, TokenData, TicketCollection, User, UserInDB, NewCollection, NewUser, TicketCollectionDB
from typing import List

# to get a string like this run:
# openssl rand -hex 32
SECRET_KEY = "da06994dd99d0c3a01df358c9e9bcec40db567378c3bbd47e10661d5fd8d7359"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30

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

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/token")

app = FastAPI(title="Ticket Backend",
              description="The backend for the ticket scanner application",
              redoc_url=None)


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)


async def get_user(username: str):
    try:
        return await UserInDB.objects.get(username=username)
    except:
        return None


async def authenticate_user(username: str, password: str):
    user = await 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: 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=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 PyJWTError:
        raise credentials_exception
    user = await 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


@app.post("/token", response_model=Token)
async def login_for_access_token(form_data: OAuth2PasswordRequestForm = Depends()):
    user = await authenticate_user(
        form_data.username, form_data.password)
    if not user:
        raise HTTPException(
            status_code=HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Bearer"},
        )
    access_token_expires = timedelta(minutes=30)
    access_token = create_access_token(
        data={"sub": user.username}, expires_delta=access_token_expires
    )
    return {"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}]


@app.post("/users/new", response_model=User)
async def add_new_user(them: NewUser):
    return await UserInDB.objects.create(username=them.username, hashed_password=get_password_hash(them.password), email=str(them.email), full_name=them.name)


@app.post("/collections/new", response_model=TicketCollection)
async def add_new_collection(collection: NewCollection, current_user: UserInDB = Depends(get_current_active_user)):
    return await TicketCollectionDB.objects.create(name=collection.name, user=current_user, price=int(collection.price*100), description=collection.description, requires_student=collection.requires_student)


@app.get("/collections", response_model=List[TicketCollection])
async def get_all_collections(current_user: User = Depends(get_current_active_user)):
    return await TicketCollectionDB.objects.filter(user=current_user).all()


@app.on_event("startup")
async def start():
    try:
        await UserInDB.objects.create(
            username="johndoe", hashed_password="$2b$12$EixZaYVK1fsbw1ZfbX3OXePaWxn96p36WQoeG6Lruj3vjPGga31lW", email="johndoe@example.com", full_name="John Doe")
    except:
        pass