From dfb98a06d9fc6802f2dffaaef44a2f1bfa749994 Mon Sep 17 00:00:00 2001
From: Maksim Sadym <sadym@chromium.org>
Date: Thu, 2 May 2024 11:29:11 +0200
Subject: [PATCH] chore: user prompt before the mapper tab closed

---
 src/bidiServer/MapperCdpConnection.ts | 7 +++++++
 src/bidiTab/bidiTab.ts                | 5 +++++
 src/bidiTab/mapperTabPage.ts          | 4 ++++
 3 files changed, 16 insertions(+)

diff --git a/src/bidiServer/MapperCdpConnection.ts b/src/bidiServer/MapperCdpConnection.ts
index 49c15d15b0..b25146fecb 100644
--- a/src/bidiServer/MapperCdpConnection.ts
+++ b/src/bidiServer/MapperCdpConnection.ts
@@ -160,6 +160,13 @@ export class MapperServerCdpConnection {
 
     const mapperCdpClient = cdpConnection.getCdpClient(mapperSessionId);
 
+    // Click on the body to interact with the page in order to "beforeunload" being
+    // triggered when the tab is closed.
+    await mapperCdpClient.sendCommand('Runtime.evaluate', {
+      expression: 'document.body.click()',
+      userGesture: true,
+    });
+
     const bidiSession = new SimpleTransport(
       async (message) => await this.#sendMessage(mapperCdpClient, message)
     );
diff --git a/src/bidiTab/bidiTab.ts b/src/bidiTab/bidiTab.ts
index c3fa89786d..bea60d4e7e 100644
--- a/src/bidiTab/bidiTab.ts
+++ b/src/bidiTab/bidiTab.ts
@@ -48,6 +48,11 @@ declare global {
 
     // Set from the server side if verbose logging is required.
     sendDebugMessage?: ((message: string) => void) | null;
+
+    // Required to prevent the user from closing the tab.
+    onbeforeunload:
+      | ((this: WindowEventHandlers, ev: BeforeUnloadEvent) => any)
+      | null;
   }
 }
 
diff --git a/src/bidiTab/mapperTabPage.ts b/src/bidiTab/mapperTabPage.ts
index ac292d25d5..7c1eda83d8 100644
--- a/src/bidiTab/mapperTabPage.ts
+++ b/src/bidiTab/mapperTabPage.ts
@@ -26,6 +26,10 @@ export function generatePage() {
     return;
   }
   globalThis.document.documentElement.innerHTML = mapperPageSource;
+
+  // Show a confirmation dialog when the user tries to leave the Mapper tab.
+  globalThis.window.onbeforeunload = () =>
+    'Closing or reloading this tab will stop the BiDi process. Are you sure you want to leave?';
 }
 
 function stringify(message: unknown) {