feat: Implement the tracker

frontend/src/pages/review.tsx

@@ -34,6 +34,8 @@ import {
     REVIEW_HELP_MOD
 } from "../config";
 
+import { BACKEND_URL } from "../config";
+
 import { Queue } from "../utils/queue";
 
 interface IProps {
@@ -103,6 +105,18 @@ const ReviewPageWithRouter = withRouter(
                 [ReviewType.QUEUE]: () => vocabByQueueW(),
             }[reviewType];
 
+            // Track the start of a session
+            fetch(`${BACKEND_URL}/api/tracker`, {
+                headers: new Headers({
+                    "Content-Type": "application/json",
+                }),
+                method: "POST",
+                body: JSON.stringify({
+                    session: window.sessionStorage.getItem("tracker_session"),
+                    event: "START_LEARNING",
+                }),
+            });
+
             getVocab().then((res: IVocab[]) => {
                 // Check if we received any vocabulary
                 if (res.length === 0) {
@@ -145,6 +159,18 @@ const ReviewPageWithRouter = withRouter(
         cancelReview = () => {
             this.closeDialog();
 
+            // Track the cancellation of a learning session
+            fetch(`${BACKEND_URL}/api/tracker`, {
+                headers: new Headers({
+                    "Content-Type": "application/json",
+                }),
+                method: "POST",
+                body: JSON.stringify({
+                    session: window.sessionStorage.getItem("tracker_session"),
+                    event: "CANCEL_LEARNING",
+                }),
+            });
+
             // Show the drawer button again
             this.props.drawerButtonState(true);