import base64
import binascii

import casbin

from fastapi import FastAPI
from starlette.authentication import AuthenticationBackend, AuthenticationError, SimpleUser, AuthCredentials
from starlette.middleware.authentication import AuthenticationMiddleware

from fastapi_casbin_auth import CasbinMiddleware

app = FastAPI()


class BasicAuth(AuthenticationBackend):
    async def authenticate(self, request):
        if "Authorization" not in request.headers:
            return None

        auth = request.headers["Authorization"]
        try:
            scheme, credentials = auth.split()
            decoded = base64.b64decode(credentials).decode("ascii")
        except (ValueError, UnicodeDecodeError, binascii.Error):
            raise AuthenticationError("Invalid basic auth credentials")

        username, _, password = decoded.partition(":")
        return AuthCredentials(["authenticated"]), SimpleUser(username)


enforcer = casbin.Enforcer('../examples/rbac_model.conf', '../examples/rbac_policy.csv')

app.add_middleware(CasbinMiddleware, enforcer=enforcer)
app.add_middleware(AuthenticationMiddleware, backend=BasicAuth())


@app.get('/')
async def index():
    return "If you see this, you have been authenticated."


@app.get('/dataset1/protected')
async def auth_test():
    return "You must be alice to see this."