Fix SSE handling

backend/server.js

@@ -31,8 +31,6 @@ async function run() {
   await mongoClient.connect();
   const collection = mongoClient.db().collection(mongoCollection);
 
-  let eventArray = [];
-
   changeStream = collection.watch(pipeline, options);
   console.log("Started watching changes in database");
 
@@ -46,39 +44,32 @@ async function run() {
       secretKey: minioURI.password
     });
 
+    function wrapEvent(doc) {
+      if (doc.screenshot_count) {
+        doc.screenshots = [];
+        for (let i = 1; i <= doc.screenshot_count ; i++) {
+          minioClient.presignedUrl('GET', minioBucket, `${data.fullDocument.camera}/${data.fullDocument._id}/${i}.jpg`, 60 * 60, (err, presignedUrl) => {
+            if (err) { return console.log(err) };
+            doc.screenshots.push({ url: presignedUrl });
+          })
+        }
+      };
+      let blob = JSON.stringify(doc);
+      return `event: log-entry\ndata: ${blob}\n\n`
+    }
+
     // Notify SSE to React
     const header = { 'Content-Type': 'text/event-stream', 'Connection': 'keep-alive' };
     response.writeHead(200, "OK", header);
-    response.write('Connection established \n\n');
 
     const historyCursor = collection.find({}).sort({$natural : -1}).limit(historyNumber);
 
     historyCursor.forEach((document) => {
-      const stringFormat = JSON.stringify(document);
-      eventArray = [stringFormat, ...eventArray];
+      response.write(wrapEvent(document));
     })
-    response.write(`event: events \n`)
-    response.write(`data: [${[...eventArray]}]\n\n`)
 
     changeStream.on("change", data => {
-
-      let document = JSON.stringify(data.fullDocument);
-      eventArray = [document];
-
-      if (data.fullDocument.screenshot_count) {
-
-        for (let i = 1; i <= data.fullDocument.screenshot_count ; i++) {
-          minioClient.presignedUrl('GET', minioBucket, `${data.fullDocument.camera}/${data.fullDocument._id}/${i}.jpg`, 60 * 60, (err, presignedUrl) => {
-            if (err) { return console.log(err) };
-            const realURL = JSON.stringify({ picUrl: presignedUrl });
-            eventArray = [realURL, ...eventArray];
-          })
-        }
-
-      };
-
-      response.write(`data: [${[...eventArray]}]\n\n`);
-
+      response.write(wrapEvent(data.fullDocument));
     });
   });