Make API and RSS refresh notifications change-only

src/web/lib/data-source-refresh.js

@@ -69,6 +69,43 @@ async function notifyAffectedScreens(connection, common, notifyPlayerScreens, sl
   await notifyPlayerScreens(slugs, 'refresh');
 }
 
+function normalizeSnapshotValue(value) {
+  return String(value || '').trim();
+}
+
+async function hasRssFeedChanged(connection, rssFeedId, items) {
+  const [rows] = await connection.query(
+    `SELECT item_json
+     FROM i_rss_feed_items
+     WHERE rss_feed_id = ?
+     ORDER BY position ASC, id ASC`,
+    [rssFeedId]
+  );
+
+  const currentSnapshots = (rows || []).map(function (row) {
+    return normalizeSnapshotValue(row && row.item_json);
+  });
+  const nextSnapshots = (Array.isArray(items) ? items : []).map(function (item) {
+    return normalizeSnapshotValue(JSON.stringify(item || {}));
+  });
+
+  if (currentSnapshots.length !== nextSnapshots.length) {
+    return true;
+  }
+
+  for (let index = 0; index < currentSnapshots.length; index += 1) {
+    if (currentSnapshots[index] !== nextSnapshots[index]) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+function hasApiSourceChanged(apiSource, responseDetails) {
+  return normalizeSnapshotValue(apiSource && apiSource.last_response_json) !== normalizeSnapshotValue(responseDetails && responseDetails.responseJson);
+}
+
 async function refreshApiSource(pool, common, apiSourceOrId, actorId, notifyPlayerScreens) {
   const connection = await pool.getConnection();
   try {
@@ -97,7 +134,7 @@ async function refreshApiSource(pool, common, apiSourceOrId, actorId, notifyPlay
     );
     await connection.commit();
 
-    if (!pullError) {
+    if (!pullError && hasApiSourceChanged(apiSource, responseDetails)) {
       try {
         await notifyAffectedScreens(connection, common, notifyPlayerScreens, 'source_id', apiSource.id);
       } catch (notifyError) {
@@ -129,12 +166,13 @@ async function refreshRssFeed(pool, common, rssFeedId, feedUrl, itemLimit, actor
     }
 
     await connection.beginTransaction();
+    const rssFeedChanged = await hasRssFeedChanged(connection, rssFeedId, updatedItems);
     if (typeof common.replaceRssFeedItems === 'function') {
       await common.replaceRssFeedItems(connection, rssFeedId, updatedItems);
     }
     await connection.commit();
 
-    if (!pullError) {
+    if (!pullError && rssFeedChanged) {
       try {
         await notifyAffectedScreens(connection, common, notifyPlayerScreens, 'feed_id', rssFeedId);
       } catch (notifyError) {