2 files changed, 32 insertions, 1 deletions

diff --git a/src/app.js b/src/app.js
index 9b47728..a374995 100644
--- a/src/app.js
+++ b/src/app.js
@@ -1,9 +1,10 @@
 const bodyParser = require('body-parser');
 const express = require('express');
-const { isSubscribed, getSubscriptions, getSubscriptionFromNumber, subscribe } = require('./db');
+const { isSubscribed, getSubscriptions, getSubscriptionFromNumber, subscribe, load: loadData } = require('./db');
 const { sendTextMessage } = require('./sendTextMessage');
 const { MessagingResponse } = require('twilio').twiml;
 
+loadData();
 const app = express();
 
 app.use(bodyParser.urlencoded({ extended: false }));
diff --git a/src/db.js b/src/db.js
index ba37a30..c277f7c 100644
--- a/src/db.js
+++ b/src/db.js
@@ -1,6 +1,8 @@
 // Ideally, we should write to a file and read it at app start in case of crashes.
 // An actual SQL database would probably be overkill.
 
+const { readFileSync, writeFile } = require("fs");
+
 /** @type Array<{ name: string, number: string }> */
 const subscriptions = [];
 
@@ -11,6 +13,7 @@ const subscriptions = [];
 function subscribe(number, name) {
   const subscription = { name, number };
   subscriptions.push(subscription);
+  void save();
   return subscription;
 }
 
@@ -37,9 +40,36 @@ function getSubscriptionFromNumber(number) {
   return subscriptions.find(sub => sub.number === number);
 }
 
+async function save() {
+  try {
+    await writeFile('../data.json', JSON.stringify({ subscriptions }));
+  } catch (err) {
+    if (typeof err === 'string') {
+      console.error(`Error writing data: ${err}`);
+    } else {
+      console.error(`Error writing data: ${JSON.stringify(err)}`);
+    }
+  }
+}
+
+function load() {
+  try {
+    const data = JSON.parse(readFileSync('../data.json'));
+    while (subscriptions.pop()) {}
+    subscriptions.push(...data['subscriptions']);
+  } catch (err){
+    if (typeof err === 'string') {
+      console.error(`Error reading data: ${err}`);
+    } else {
+      console.error(`Error reading data: ${JSON.stringify(err)}`);
+    }
+  }
+}
+
 module.exports = {
   subscribe,
   isSubscribed,
   getSubscriptions,
   getSubscriptionFromNumber,
+  load,
 };
\ No newline at end of file