pluto/handler/sinks/nordigen.py

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

# Other library imports
import requests
from simplejson.errors import JSONDecodeError
from json import dumps, loads
from lib.serde.nordigen import TXRoot, AccessToken, Institutions, Agreement, Requisitions, AccountDetails, AccountBalancesRoot
from serde import ValidationError

# Project imports
from settings import settings
import util


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

    def __init__(self, sinks):
        super().__init__()
        self.sinks = sinks
        self.token = None
        self.banks = {}
        self.authed = False

        # Get the banks from the config and cache them
        self.get_mapped_accounts()

        self.lc = LoopingCall(self.get_access_token)
        self.lc.start(int(settings.Nordigen.TokenRefreshSec))

    def __authed__(self):
        """
        Called when we have received the access token.
        """
        self.log.info("Connection authenticated.")
        account_infos = self.get_all_account_info()

        # Filter for added accounts since we only do that for TrueLayer
        account_infos = {
            bank: accounts for bank, accounts in account_infos.items() for account in accounts if account["account_id"] in self.banks
        }

        self.sinks.got_account_info("nordigen", account_infos)

        self.lc_tx = LoopingCall(self.transaction_loop)
        self.lc_tx.start(int(settings.Nordigen.RefreshSec))

    def transaction_loop(self):
        for account_id in self.banks:
            transactions = self.get_transactions(account_id)
            self.sinks.got_transactions("nordigen", account_id, transactions)

    def get_access_token(self):
        """
        Get an access token.
        :return: True or False
        :rtype: bool
        """
        headers = {"accept": "application/json", "Content-Type": "application/json"}
        data = {
            "secret_id": settings.Nordigen.ID,
            "secret_key": settings.Nordigen.Key,
        }
        path = f"{settings.Nordigen.Base}/token/new/"
        r = requests.post(path, headers=headers, data=dumps(data))
        try:
            obj = AccessToken.from_json(r.content)
        except ValidationError as err:
            self.log.error(f"Validation error: {err}")
            return
        parsed = obj.to_dict()
        self.token = parsed["access"]
        self.log.info("Refreshed access token")
        if not self.authed:
            self.__authed__()
            self.authed = True

    def get_institutions(self, country, filter_name=None):
        """
        Get a list of supported institutions.
        :param country: country to query
        :param filter_name: return only results with this in the name
        :return: list of institutions
        :rtype: list
        """
        if not len(country) == 2:
            return False
        headers = {"accept": "application/json", "Authorization": f"Bearer {self.token}"}
        path = f"{settings.Nordigen.Base}/institutions/?country={country}"
        r = requests.get(path, headers=headers)
        try:
            parsed_pre = r.json()
        except JSONDecodeError:
            self.log.error(f"Error parsing institutions response: {r.content}")
            return False
        parsed = {"institutions": parsed_pre}
        try:
            obj = Institutions.from_dict(parsed)
        except ValidationError as err:
            self.log.error(f"Validation error: {err}")
            return
        parsed = obj.to_dict()["institutions"]
        new_list = []
        if filter_name:
            for i in parsed:
                if filter_name in i["name"]:
                    new_list.append(i)
            return new_list
        return parsed

    def build_link(self, institution_id):
        """Create a link to access an institution.
        :param institution_id: ID of the institution
        """
        headers = {"accept": "application/json", "Authorization": f"Bearer {self.token}"}
        path = f"{settings.Nordigen.Base}/requisitions/"
        data = {"institution_id": institution_id, "redirect": settings.Nordigen.CallbackURL}
        r = requests.post(path, headers=headers, data=data)
        try:
            obj = Agreement.from_json(r.content)
        except ValidationError as err:
            self.log.error(f"Validation error: {err}")
            return
        parsed = obj.to_dict()
        if "link" in parsed:
            return parsed["link"]
        return False

    def create_auth_url(self, country, bank_name):
        """Helper to look up a bank and create a link.
        :param country: country
        :param bank_name: bank name string to search"""
        institutions = self.get_institutions(country, filter_name=bank_name)
        # We were not precise enough to have one result
        if not len(institutions) == 1:
            return False
        institution = institutions[0]
        link = self.build_link(institution["id"])
        if not link:
            return False
        return link

    def get_requisitions(self):
        """
        Get a list of active accounts.
        """
        headers = {"accept": "application/json", "Authorization": f"Bearer {self.token}"}
        path = f"{settings.Nordigen.Base}/requisitions"
        r = requests.get(path, headers=headers)
        try:
            obj = Requisitions.from_json(r.content)
        except ValidationError as err:
            self.log.error(f"Validation error: {err}")
            return
        parsed = obj.to_dict()
        if "results" in parsed:
            return parsed["results"]
        else:
            self.log.error(f"Results not in requisitions response: {parsed}")

        return False

    def get_accounts(self, requisition):
        """
        Get a list of accounts for a requisition.
        :param requisition: requisition ID"""
        headers = {"accept": "application/json", "Authorization": f"Bearer {self.token}"}
        path = f"{settings.Nordigen.Base}/requisitions/{requisition}/"
        r = requests.get(path, headers=headers)
        try:
            obj = Agreement.from_json(r.content)
        except ValidationError as err:
            self.log.error(f"Validation error: {err}")
            return
        parsed = obj.to_dict()
        if "accounts" in parsed:
            return parsed["accounts"]
        return False

    def get_account(self, account_id):
        """
        Get details of an account.
        :param requisition: requisition ID"""
        headers = {"accept": "application/json", "Authorization": f"Bearer {self.token}"}
        path = f"{settings.Nordigen.Base}/accounts/{account_id}/details/"
        r = requests.get(path, headers=headers)
        try:
            obj = AccountDetails.from_json(r.content)
        except ValidationError as err:
            self.log.error(f"Validation error: {err}")
            return
        parsed = obj.to_dict()["account"]
        if "bban" in parsed and parsed["currency"] == "GBP":
            sort_code = parsed["bban"][0:6]
            account_number = parsed["bban"][6:]
            del parsed["bban"]
            del parsed["iban"]
            sort_code = "-".join(list(map("".join, zip(*[iter(sort_code)] * 2))))
            parsed["sort_code"] = sort_code
            parsed["number"] = account_number
        # Let's add the account ID so we can reference it later
        parsed["account_id"] = account_id
        return parsed

    def get_mapped_accounts(self):
        existing_entry = loads(settings.Nordigen.Maps)
        self.banks = existing_entry

    def map_account(self, account_id):
        """
        Map an account_id at a bank to an account_name.
        This enables the account for fetching.
        Data type: {"monzo":   [account, ids, here],
                    "revolut": [account, ids, here]}
        """
        account_data = self.get_account(account_id)
        currency = account_data["currency"]

        existing_entry = loads(settings.Nordigen.Maps)
        if account_id in existing_entry:
            return
        else:
            existing_entry.append(account_id)

        settings.Nordigen.Maps = dumps(existing_entry)
        self.banks = existing_entry
        settings.write()

        return currency

    def get_all_account_info(self):
        to_return = {}
        requisitions = self.get_requisitions()
        if not requisitions:
            self.log.error("Could not get requisitions.")
            return {}
        for req in requisitions:
            if not req["accounts"]:
                continue
            accounts = self.get_accounts(req["id"])
            for account_id in accounts:
                account_info = self.get_account(account_id)
                if not account_info:
                    continue
                if req["institution_id"] in to_return:
                    to_return[req["institution_id"]].append(account_info)
                else:
                    to_return[req["institution_id"]] = [account_info]
        return to_return

    def normalise_transactions(self, transactions):
        for transaction in transactions:
            # Rename ID
            transaction["transaction_id"] = transaction["transactionId"]
            del transaction["transactionId"]

            # Rename timestamp
            transaction["timestamp"] = transaction["bookingDate"]
            del transaction["bookingDate"]

            transaction["amount"] = float(transaction["transactionAmount"]["amount"])
            transaction["currency"] = transaction["transactionAmount"]["currency"]
            del transaction["transactionAmount"]

            transaction["reference"] = transaction["remittanceInformationUnstructured"]
            del transaction["remittanceInformationUnstructured"]

    def get_transactions(self, account_id):
        """
        Get all transactions for an account.
        :param account_id: account to fetch transactions for
        :return: list of transactions
        :rtype: dict
        """
        headers = {"accept": "application/json", "Authorization": f"Bearer {self.token}"}
        path = f"{settings.Nordigen.Base}/accounts/{account_id}/transactions/"
        r = requests.get(path, headers=headers)
        try:
            obj = TXRoot.from_json(r.content)
        except ValidationError as err:
            self.log.error(f"Validation error: {err}")
            return
        parsed = obj.to_dict()["transactions"]["booked"]
        self.normalise_transactions(parsed)
        return parsed

    def get_balance(self, account_id):
        """
        Get the balance and currency of an account.
        :param account_id: the account ID
        :return: tuple of (currency, amount)
        :rtype: tuple
        """
        headers = {"accept": "application/json", "Authorization": f"Bearer {self.token}"}
        path = f"{settings.Nordigen.Base}/accounts/{account_id}/balances/"
        r = requests.get(path, headers=headers)
        try:
            obj = AccountBalancesRoot.from_json(r.content)
        except ValidationError as err:
            self.log.error(f"Validation error: {err}")
            return
        parsed = obj.to_dict()["balances"]
        total = 0
        currency = None
        for entry in parsed:
            if currency:
                if not currency == entry["balanceAmount"]["currency"]:
                    self.log.error("Different currencies in balance query.")
                    return
            total += float(entry["balanceAmount"]["amount"])
            currency = entry["balanceAmount"]["currency"]
        return (currency, total)

    def get_total_map(self):
        """
        Return a dictionary keyed by currencies with the amounts as values.
        :return: dict keyed by currency, values are amounts
        :rtype: dict
        """
        totals = {}
        for account_id in self.banks:
            currency, amount = self.get_balance(account_id)
            if not amount:
                continue
            if currency in totals:
                totals[currency] += amount
            else:
                totals[currency] = amount
        return totals