# Copyright (c) 2019 Ultimaker B.V.
# Cura is released under the terms of the LGPLv3 or higher.
from datetime import datetime
import json
import random
from hashlib import sha512
from base64 import b64encode
from typing import Optional

import requests

from UM.i18n import i18nCatalog
from UM.Logger import Logger

from cura.OAuth2.Models import AuthenticationResponse, UserProfile, OAuth2Settings
catalog = i18nCatalog("cura")
TOKEN_TIMESTAMP_FORMAT = "%Y-%m-%d %H:%M:%S"

##  Class containing several helpers to deal with the authorization flow.
class AuthorizationHelpers:
    def __init__(self, settings: "OAuth2Settings") -> None:
        self._settings = settings
        self._token_url = "{}/token".format(self._settings.OAUTH_SERVER_URL)

    @property
    ##  The OAuth2 settings object.
    def settings(self) -> "OAuth2Settings":
        return self._settings

    ##  Request the access token from the authorization server.
    #   \param authorization_code: The authorization code from the 1st step.
    #   \param verification_code: The verification code needed for the PKCE
    #   extension.
    #   \return An AuthenticationResponse object.
    def getAccessTokenUsingAuthorizationCode(self, authorization_code: str, verification_code: str) -> "AuthenticationResponse":
        data = {
            "client_id": self._settings.CLIENT_ID if self._settings.CLIENT_ID is not None else "",
            "redirect_uri": self._settings.CALLBACK_URL if self._settings.CALLBACK_URL is not None else "",
            "grant_type": "authorization_code",
            "code": authorization_code,
            "code_verifier": verification_code,
            "scope": self._settings.CLIENT_SCOPES if self._settings.CLIENT_SCOPES is not None else "",
            }
        try:
            return self.parseTokenResponse(requests.post(self._token_url, data = data))  # type: ignore
        except requests.exceptions.ConnectionError:
            return AuthenticationResponse(success=False, err_message="Unable to connect to remote server")

    ##  Request the access token from the authorization server using a refresh token.
    #   \param refresh_token:
    #   \return An AuthenticationResponse object.
    def getAccessTokenUsingRefreshToken(self, refresh_token: str) -> "AuthenticationResponse":
        Logger.log("d", "Refreshing the access token.")
        data = {
            "client_id": self._settings.CLIENT_ID if self._settings.CLIENT_ID is not None else "",
            "redirect_uri": self._settings.CALLBACK_URL if self._settings.CALLBACK_URL is not None else "",
            "grant_type": "refresh_token",
            "refresh_token": refresh_token,
            "scope": self._settings.CLIENT_SCOPES if self._settings.CLIENT_SCOPES is not None else "",
        }
        try:
            return self.parseTokenResponse(requests.post(self._token_url, data = data))  # type: ignore
        except requests.exceptions.ConnectionError:
            return AuthenticationResponse(success=False, err_message="Unable to connect to remote server")

    @staticmethod
    ##  Parse the token response from the authorization server into an AuthenticationResponse object.
    #   \param token_response: The JSON string data response from the authorization server.
    #   \return An AuthenticationResponse object.
    def parseTokenResponse(token_response: requests.models.Response) -> "AuthenticationResponse":
        token_data = None

        try:
            token_data = json.loads(token_response.text)
        except ValueError:
            Logger.log("w", "Could not parse token response data: %s", token_response.text)

        if not token_data:
            return AuthenticationResponse(success = False, err_message = catalog.i18nc("@message", "Could not read response."))

        if token_response.status_code not in (200, 201):
            return AuthenticationResponse(success = False, err_message = token_data["error_description"])

        return AuthenticationResponse(success=True,
                                      token_type=token_data["token_type"],
                                      access_token=token_data["access_token"],
                                      refresh_token=token_data["refresh_token"],
                                      expires_in=token_data["expires_in"],
                                      scope=token_data["scope"],
                                      received_at=datetime.now().strftime(TOKEN_TIMESTAMP_FORMAT))

    ##  Calls the authentication API endpoint to get the token data.
    #   \param access_token: The encoded JWT token.
    #   \return Dict containing some profile data.
    def parseJWT(self, access_token: str) -> Optional["UserProfile"]:
        try:
            token_request = requests.get("{}/check-token".format(self._settings.OAUTH_SERVER_URL), headers = {
                "Authorization": "Bearer {}".format(access_token)
            })
        except requests.exceptions.ConnectionError:
            # Connection was suddenly dropped. Nothing we can do about that.
            Logger.logException("w", "Something failed while attempting to parse the JWT token")
            return None
        if token_request.status_code not in (200, 201):
            Logger.log("w", "Could not retrieve token data from auth server: %s", token_request.text)
            return None
        user_data = token_request.json().get("data")
        if not user_data or not isinstance(user_data, dict):
            Logger.log("w", "Could not parse user data from token: %s", user_data)
            return None
        return UserProfile(
            user_id = user_data["user_id"],
            username = user_data["username"],
            profile_image_url = user_data.get("profile_image_url", "")
        )

    @staticmethod
    ##  Generate a verification code of arbitrary length.
    #   \param code_length: How long should the code be? This should never be lower than 16, but it's probably better to
    #   leave it at 32
    def generateVerificationCode(code_length: int = 32) -> str:
        return "".join(random.choice("0123456789ABCDEF") for i in range(code_length))

    @staticmethod
    ##  Generates a base64 encoded sha512 encrypted version of a given string.
    #   \param verification_code:
    #   \return The encrypted code in base64 format.
    def generateVerificationCodeChallenge(verification_code: str) -> str:
        encoded = sha512(verification_code.encode()).digest()
        return b64encode(encoded, altchars = b"_-").decode()