SimpleFin (#296)

* Initial support for SimpleFin.

* Added release notes and lint cleanup.

* Changed some notes for better context.

* Fixed logic.

* Changes per requests on PR.

* More cleanup of null checks.

Author: zachwhelchel

src/app-simplefin/app-simplefin.js

@@ -0,0 +1,227 @@
+import express from 'express';
+import { inspect } from 'util';
+import https from 'https';
+import { SecretName, secretsService } from '../services/secrets-service.js';
+
+const app = express();
+export { app as handlers };
+app.use(express.json());
+
+app.post('/status', async (req, res) => {
+  let configured = false;
+
+  let token = secretsService.get(SecretName.simplefin_token);
+  if (token != null && token !== 'Forbidden') {
+    configured = true;
+  }
+
+  res.send({
+    status: 'ok',
+    data: {
+      configured: configured,
+    },
+  });
+});
+
+app.post('/accounts', async (req, res) => {
+  let accessKey = secretsService.get(SecretName.simplefin_accessKey);
+
+  if (accessKey == null || accessKey === 'Forbidden') {
+    let token = secretsService.get(SecretName.simplefin_token);
+    if (token == null || token === 'Forbidden') {
+      return;
+    } else {
+      accessKey = await getAccessKey(token);
+      secretsService.set(SecretName.simplefin_accessKey, accessKey);
+    }
+  }
+
+  const now = new Date();
+  let startDate = new Date(now.getFullYear(), now.getMonth(), 1);
+  let endDate = new Date(now.getFullYear(), now.getMonth() + 1, 1);
+
+  let accounts = await getAccounts(accessKey, startDate, endDate);
+
+  res.send({
+    status: 'ok',
+    data: {
+      accounts: accounts.accounts,
+    },
+  });
+});
+
+app.post('/transactions', async (req, res) => {
+  const { accountId, startDate } = req.body;
+
+  let accessKey = secretsService.get(SecretName.simplefin_accessKey);
+
+  if (accessKey == null || accessKey === 'Forbidden') {
+    return;
+  }
+
+  try {
+    let results = await getTransactions(accessKey, new Date(startDate));
+
+    let account = results.accounts.find((a) => a.id === accountId);
+
+    let response = {};
+
+    let balance = parseInt(account.balance.replace('.', ''));
+    let date = new Date(account['balance-date'] * 1000)
+      .toISOString()
+      .split('T')[0];
+
+    response.balances = [
+      {
+        balanceAmount: { amount: account.balance, currency: account.currency },
+        balanceType: 'expected',
+        referenceDate: date,
+      },
+      {
+        balanceAmount: { amount: account.balance, currency: account.currency },
+        balanceType: 'interimAvailable',
+        referenceDate: date,
+      },
+    ];
+    //response.iban = don't have compared to GoCardless
+    //response.institutionId = don't have compared to GoCardless
+    response.startingBalance = balance; // could be named differently in this use case.
+
+    let allTransactions = [];
+
+    for (let trans of account.transactions) {
+      let newTrans = {};
+
+      //newTrans.bankTransactionCode = don't have compared to GoCardless
+      newTrans.booked = true;
+      newTrans.bookingDate = new Date(trans.posted * 1000)
+        .toISOString()
+        .split('T')[0];
+      newTrans.date = new Date(trans.posted * 1000).toISOString().split('T')[0];
+      newTrans.debtorName = trans.payee;
+      //newTrans.debtorAccount = don't have compared to GoCardless
+      newTrans.remittanceInformationUnstructured = trans.description;
+      newTrans.transactionAmount = { amount: trans.amount, currency: 'USD' };
+      newTrans.transactionId = trans.id;
+      newTrans.valueDate = new Date(trans.posted * 1000)
+        .toISOString()
+        .split('T')[0];
+
+      allTransactions.push(newTrans);
+    }
+
+    response.transactions = {
+      all: allTransactions,
+      booked: allTransactions,
+      pending: [],
+    };
+
+    res.send({
+      status: 'ok',
+      data: response,
+    });
+  } catch (error) {
+    const sendErrorResponse = (data) =>
+      res.send({ status: 'ok', data: { ...data, details: error.details } });
+    console.log(
+      'Something went wrong',
+      inspect(error, { depth: null }),
+      sendErrorResponse,
+    );
+  }
+});
+
+function parseAccessKey(accessKey) {
+  let scheme = null;
+  let rest = null;
+  let auth = null;
+  let username = null;
+  let password = null;
+  let baseUrl = null;
+  [scheme, rest] = accessKey.split('//');
+  [auth, rest] = rest.split('@');
+  [username, password] = auth.split(':');
+  baseUrl = `${scheme}//${rest}`;
+  return {
+    baseUrl: baseUrl,
+    username: username,
+    password: password,
+  };
+}
+
+async function getAccessKey(base64Token) {
+  const token = Buffer.from(base64Token, 'base64').toString();
+  const options = {
+    method: 'POST',
+    port: 443,
+    headers: { 'Content-Length': 0 },
+  };
+  return new Promise((resolve, reject) => {
+    const req = https.request(new URL(token), options, (res) => {
+      res.on('data', (d) => {
+        resolve(d.toString());
+      });
+    });
+    req.on('error', (e) => {
+      reject(e);
+    });
+    req.end();
+  });
+}
+
+async function getTransactions(accessKey, startDate, endDate) {
+  const now = new Date();
+  startDate = startDate || new Date(now.getFullYear(), now.getMonth(), 1);
+  endDate = endDate || new Date(now.getFullYear(), now.getMonth() + 1, 1);
+  console.log(
+    `${startDate.toISOString().split('T')[0]} - ${
+      endDate.toISOString().split('T')[0]
+    }`,
+  );
+  return await getAccounts(accessKey, startDate, endDate);
+}
+
+function normalizeDate(date) {
+  return (date.valueOf() - date.getTimezoneOffset() * 60 * 1000) / 1000;
+}
+
+async function getAccounts(accessKey, startDate, endDate) {
+  const sfin = parseAccessKey(accessKey);
+  const options = {
+    headers: {
+      Authorization: `Basic ${Buffer.from(
+        `${sfin.username}:${sfin.password}`,
+      ).toString('base64')}`,
+    },
+  };
+  const params = [];
+  let queryString = '';
+  if (startDate) {
+    params.push(`start-date=${normalizeDate(startDate)}`);
+  }
+  if (endDate) {
+    params.push(`end-date=${normalizeDate(endDate)}`);
+  }
+  if (params.length > 0) {
+    queryString += '?' + params.join('&');
+  }
+  return new Promise((resolve, reject) => {
+    const req = https.request(
+      new URL(`${sfin.baseUrl}/accounts${queryString}`),
+      options,
+      (res) => {
+        let data = '';
+        res.on('data', (d) => {
+          data += d;
+        });
+        res.on('end', () => {
+          resolve(JSON.parse(data));
+        });
+      },
+    );
+    req.on('error', (e) => {
+      reject(e);
+    });
+    req.end();
+  });
+}

src/app.js

@@ -9,6 +9,7 @@ import rateLimit from 'express-rate-limit';
 import * as accountApp from './app-account.js';
 import * as syncApp from './app-sync.js';
 import * as goCardlessApp from './app-gocardless/app-gocardless.js';
+import * as simpleFinApp from './app-simplefin/app-simplefin.js';
 import * as secretApp from './app-secrets.js';
 
 const app = express();
@@ -44,6 +45,7 @@ app.use(
 app.use('/sync', syncApp.handlers);
 app.use('/account', accountApp.handlers);
 app.use('/gocardless', goCardlessApp.handlers);
+app.use('/simplefin', simpleFinApp.handlers);
 app.use('/secret', secretApp.handlers);
 
 app.get('/mode', (req, res) => {

src/services/secrets-service.js

@@ -9,6 +9,8 @@ import getAccountDb from '../account-db.js';
 export const SecretName = {
   gocardless_secretId: 'gocardless_secretId',
   gocardless_secretKey: 'gocardless_secretKey',
+  simplefin_token: 'simplefin_token',
+  simplefin_accessKey: 'simplefin_accessKey',
 };
 
 class SecretsDb {

upcoming-release-notes/296.md

@@ -0,0 +1,6 @@
+---
+category: Enhancements
+authors: [zachwhelchel,duplaja,lancepick,latetedemelon]
+---
+
+Add option to link an account to SimpleFIN for syncing transactions.