pluto/handler/sinks/truelayer.py

# Twisted/Klein imports
from twisted.internet.task import LoopingCall

# Other library imports
import requests
from simplejson.errors import JSONDecodeError
from time import time
from json import dumps, loads
import urllib

# Project imports
from settings import settings
import util


class TrueLayer(util.Base):
    """
    Class to manage calls to Open Banking APIs through TrueLayer.
    """

    def __init__(self):
        super().__init__()
        self.tokens = {}

        # account we are authenticating - where to store the refresh keys
        self.current_authcode_account = None
        self.lc = LoopingCall(self.get_new_tokens_all)
        self.lc.start(int(settings.TrueLayer.RefreshSec))

    def add_refresh_token(self, refresh_token):
        """
        Add an API key to the configuration.
        Data type: {"monzo":   refresh_token,
                    "revolut": refresh_token}
        """
        account = self.current_authcode_account
        if not account:
            return False
        existing_entry = loads(settings.TrueLayer.RefreshKeys)
        existing_entry[account] = refresh_token
        settings.TrueLayer.RefreshKeys = dumps(existing_entry)
        settings.write()

    def get_refresh_tokens(self):
        existing_entry = loads(settings.TrueLayer.RefreshKeys)
        return existing_entry

    def get_key(self, account):
        if account in self.tokens:
            return self.tokens[account]
        else:
            return False

    def create_auth_url(self, account):
        query = urllib.parse.urlencode(
            {
                "response_type": "code",
                "response_mode": "form_post",
                "client_id": settings.TrueLayer.ID,
                "scope": "info accounts balance transactions offline_access",
                "nonce": int(time()),
                "redirect_uri": settings.TrueLayer.CallbackURL,
                "enable_mock": "true",
            }
        )
        auth_uri = f"{settings.TrueLayer.AuthBase}/?{query}&redirect_uri={settings.TrueLayer.CallbackURL}"
        self.current_authcode_account = account
        return auth_uri

    def handle_authcode_received(self, authcode):
        data = {
            "client_id": settings.TrueLayer.ID,
            "client_secret": settings.TrueLayer.Key,
            "code": authcode,
            "grant_type": "authorization_code",
            "redirect_uri": settings.TrueLayer.CallbackURL,
        }
        r = requests.post(f"{settings.TrueLayer.AuthBase}/connect/token", data=data)
        try:
            parsed = r.json()
        except JSONDecodeError:
            return False
        if "error" in parsed:
            self.log.error("Error requesting refresh token: {parsed['error']}")
            return False

        # Extract the access tokens
        refresh_token = parsed["refresh_token"]
        access_token = parsed["access_token"]

        # Add the refresh token
        self.add_refresh_token(refresh_token)

        # Add the access
        if self.current_authcode_account:
            self.tokens[self.current_authcode_account] = access_token
        else:
            self.log.error(f"Received an authcode we didn't ask for")
            return
        self.log.info(f"Retrieved access/refresh tokens for {self.current_authcode_account}")

    def get_new_tokens_all(self):
        refresh_list = loads(settings.TrueLayer.RefreshKeys)
        for account in refresh_list:
            self.get_new_token(account)

    def get_new_token(self, account):
        """
        Exchange our refresh token for an access token.
        :param account: account to refresh the token for
        :type account:
        """
        refresh_tokens = self.get_refresh_tokens()
        if account not in refresh_tokens:
            return

        headers = {"Content-Type": "application/x-www-form-urlencoded"}
        data = {
            "grant_type": "refresh_token",
            "refresh_token": refresh_tokens[account],
            "client_id": settings.TrueLayer.ID,
            "client_secret": settings.TrueLayer.Key,
        }
        r = requests.post(f"{settings.TrueLayer.AuthBase}/connect/token", data=data, headers=headers)
        try:
            parsed = r.json()
        except JSONDecodeError:
            return False
        if r.status_code == 200:
            if "access_token" in parsed.keys():
                self.tokens[account] = parsed["access_token"]
                self.log.info(f"Refreshed access token for {account}")
                return True
            else:
                self.log.error(f"Token refresh didn't contain access token: {parsed}", parsed=parsed)
                return False
        else:
            self.log.error(f"Cannot refresh token: {parsed}", parsed=parsed)
            return False

    def get_accounts(self, account):
        """
        Get a list of accounts.
        """
        token = self.get_key(account)
        headers = {"Authorization": f"Bearer {token}"}
        path = f"{settings.TrueLayer.DataBase}/accounts"
        r = requests.get(path, headers=headers)
        try:
            parsed = r.json()
        except JSONDecodeError:
            self.log.error("Error parsing accounts response: {content}", content=r.content)
            return False

        return parsed

    def get_transactions(self, account, account_id):
        """
        Get a list of transactions from an account.
        :param account_id: account to fetch transactions for
        :return: list of transactions
        :rtype: dict
        """
        token = self.get_key(account)
        headers = {"Authorization": f"Bearer {token}"}
        path = f"{settings.TrueLayer.DataBase}/accounts/{account_id}/transactions"
        r = requests.get(path, headers=headers)
        try:
            parsed = r.json()
        except JSONDecodeError:
            self.log.error("Error parsing transactions response: {content}", content=r.content)
            return False

        return parsed["results"]