1 files changed, 115 insertions, 0 deletions
diff --git a/src/data/updates.js b/src/data/updates.js
new file mode 100644
index 0000000..a57bc62
--- /dev/null
+++ b/src/data/updates.js
@@ -0,0 +1,115 @@
+const url = require('url');
+const https = require('https');
+const moment = require('moment');
+const knex = require('../knex');
+const config = require('../config');
+
+const UPDATE_CHECK_FREQUENCY = 12; // In hours
+let updateCheckPromise = null;
+
+async function initUpdatesTable() {
+  const row = await knex('updates').first();
+  if (! row) {
+    await knex('updates').insert({
+      available_version: null,
+      last_checked: null,
+    });
+  }
+}
+
+/**
+ * Update current and available versions in the database.
+ * Only works when `repository` in package.json is set to a GitHub repository
+ * @returns {Promise<void>}
+ */
+async function refreshVersions() {
+  await initUpdatesTable();
+  const { last_checked } = await knex('updates').first();
+
+  // Only refresh available version if it's been more than UPDATE_CHECK_FREQUENCY since our last check
+  if (last_checked != null && last_checked > moment.utc().subtract(UPDATE_CHECK_FREQUENCY, 'hours').format('YYYY-MM-DD HH:mm:ss')) return;
+
+  const packageJson = require('../../package.json');
+  const repositoryUrl = packageJson.repository && packageJson.repository.url;
+  if (! repositoryUrl) return;
+
+  const parsedUrl = url.parse(repositoryUrl);
+  if (parsedUrl.hostname !== 'github.com') return;
+
+  const [, owner, repo] = parsedUrl.pathname.split('/');
+  if (! owner || ! repo) return;
+
+  https.get(
+    {
+      hostname: 'api.github.com',
+      path: `/repos/${owner}/${repo}/tags`,
+      headers: {
+        'User-Agent': `Modmail Bot (https://github.com/${owner}/${repo}) (${packageJson.version})`
+      }
+    },
+    async res => {
+      if (res.statusCode !== 200) {
+        await knex('updates').update({
+          last_checked: moment.utc().format('YYYY-MM-DD HH:mm:ss')
+        });
+        console.warn(`[WARN] Got status code ${res.statusCode} when checking for available updates`);
+        return;
+      }
+
+      let data = '';
+      res.on('data', chunk => data += chunk);
+      res.on('end', async () => {
+        const parsed = JSON.parse(data);
+        if (! Array.isArray(parsed) || parsed.length === 0) return;
+
+        const latestVersion = parsed[0].name;
+        await knex('updates').update({
+          available_version: latestVersion,
+          last_checked: moment.utc().format('YYYY-MM-DD HH:mm:ss')
+        });
+      });
+    }
+  );
+}
+
+/**
+ * @param {String} a Version string, e.g. "2.20.0"
+ * @param {String} b Version string, e.g. "2.20.0"
+ * @returns {Number} 1 if version a is larger than b, -1 is version a is smaller than b, 0 if they are equal
+ */
+function compareVersions(a, b) {
+  const aParts = a.split('.');
+  const bParts = b.split('.');
+  for (let i = 0; i < Math.max(aParts.length, bParts.length); i++) {
+    let aPart = parseInt((aParts[i] || '0').match(/\d+/)[0] || '0', 10);
+    let bPart = parseInt((bParts[i] || '0').match(/\d+/)[0] || '0', 10);
+    if (aPart > bPart) return 1;
+    if (aPart < bPart) return -1;
+  }
+  return 0;
+}
+
+async function getAvailableUpdate() {
+  await initUpdatesTable();
+
+  const packageJson = require('../../package.json');
+  const currentVersion = packageJson.version;
+  const { available_version: availableVersion } = await knex('updates').first();
+  if (availableVersion == null) return null;
+  if (currentVersion == null) return availableVersion;
+
+  const versionDiff = compareVersions(currentVersion, availableVersion);
+  if (versionDiff === -1) return availableVersion;
+
+  return null;
+}
+
+async function refreshVersionsLoop() {
+  await refreshVersions();
+  setTimeout(refreshVersionsLoop, UPDATE_CHECK_FREQUENCY * 60 * 60 * 1000);
+}
+
+module.exports = {
+  getAvailableUpdate,
+  startVersionRefreshLoop: refreshVersionsLoop
+};