Merge pull request #7428 from element-hq/feature/bma/timeoutInReadyToScanScreen

[LinkNewDevice] Ensure the notice screen is also protected by the timeout.

features/linknewdevice/impl/src/main/kotlin/io/element/android/features/linknewdevice/impl/LinkNewDesktopHandler.kt

@@ -39,6 +39,10 @@ class LinkNewDesktopHandler(
         LinkDesktopStep.Uninitialized
     )
 
+    /**
+     * A [StateFlow] that emits the current step of the link desktop process.
+     * It starts with [LinkDesktopStep.Uninitialized] and will emit other steps as they occur.
+     */
     val stepFlow: StateFlow<LinkDesktopStep>
         get() = linkDesktopStepFlow.asStateFlow()
 
@@ -53,15 +57,31 @@ class LinkNewDesktopHandler(
         timerJob = null
     }
 
-    fun createNewHandler() {
-        resetJobs()
-        handler = matrixClient.createLinkDesktopHandler().getOrNull()
+    /**
+     * Starts (or restarts) a timer that will emit an error in [stepFlow] after 2 minutes.
+     */
+    fun startTimer() {
+        timerJob?.cancel()
         timerJob = sessionScope.launch {
             delay(2.minutes)
             linkDesktopStepFlow.emit(LinkDesktopStep.Error(ErrorType.Expired("Scanning QrCode took too long.")))
         }
     }
 
+    /**
+     * Creates a new [LinkDesktopHandler] and cancels any existing job.
+     * This should be called when the user wants to retry scanning a QR code.
+     */
+    fun createNewHandler() {
+        currentJob?.cancel()
+        currentJob = null
+        handler = matrixClient.createLinkDesktopHandler().getOrNull()
+    }
+
+    /**
+     * Resets the state of the handler and cancels any existing job.
+     * This should be called when the user wants to start over.
+     */
     fun reset() {
         resetJobs()
         sessionScope.launch {
@@ -69,6 +89,12 @@ class LinkNewDesktopHandler(
         }
     }
 
+    /**
+     * Handles the scanned QR code data.
+     * This should be called when the user scans a QR code.
+     *
+     * @param data The scanned QR code data as a byte array.
+     */
     fun onScannedCode(data: ByteArray) {
         resetJobs()
         val currentHandler = handler

features/linknewdevice/impl/src/main/kotlin/io/element/android/features/linknewdevice/impl/LinkNewDeviceFlowNode.kt

@@ -263,6 +263,8 @@ class LinkNewDeviceFlowNode(
                                 }
                                 LinkDeviceType.Desktop -> {
                                     linkNewDesktopHandler.reset()
+                                    // Ensure unlock state does not last longer than the timeout for scanning the QR code, so start the timer after unlock
+                                    linkNewDesktopHandler.startTimer()
                                     backstack.push(NavTarget.DesktopNotice)
                                 }
                             }
@@ -278,10 +280,14 @@ class LinkNewDeviceFlowNode(
             NavTarget.DesktopNotice -> {
                 val callback = object : DesktopNoticeNode.Callback {
                     override fun navigateBack() {
+                        // Stop the timer when the user leaves the screen (user will have to authenticate again)
+                        linkNewDesktopHandler.reset()
                         backstack.pop()
                     }
 
                     override fun navigateToQrCodeScanner() {
+                        // Start again the timer when the user enters the next screen (they clicked on "Ready to scan")
+                        linkNewDesktopHandler.startTimer()
                         backstack.push(NavTarget.DesktopScanQrCode)
                     }
                 }
@@ -290,6 +296,8 @@ class LinkNewDeviceFlowNode(
             NavTarget.DesktopScanQrCode -> {
                 val callback = object : ScanQrCodeNode.Callback {
                     override fun cancel() {
+                        // start again the timer when the user goes back to the DesktopNoticeNode
+                        linkNewDesktopHandler.startTimer()
                         backstack.pop()
                     }
                 }

features/linknewdevice/impl/src/main/kotlin/io/element/android/features/linknewdevice/impl/LinkNewMobileHandler.kt

@@ -40,9 +40,19 @@ class LinkNewMobileHandler(
         LinkMobileStep.Uninitialized
     )
 
+    /**
+     * A [StateFlow] that emits the current step of the link mobile process.
+     * It starts with [LinkMobileStep.Uninitialized] and will emit other steps as they occur.
+     */
     val stepFlow: StateFlow<LinkMobileStep>
         get() = linkMobileStepFlow.asStateFlow()
 
+    /**
+     * Creates a new [LinkMobileHandler] and starts the linking process.
+     * If [forRotating] is true, it indicates that this is a rotation of the QR code.
+     *
+     * @param forRotating Whether this is a rotation of the QR code. Defaults to false.
+     */
     fun createAndStartNewHandler(forRotating: Boolean = false) {
         Timber.tag(loggerTag.value).d("createAndStartNewHandler()")
         currentJob?.cancel()
@@ -62,6 +72,10 @@ class LinkNewMobileHandler(
         }
     }
 
+    /**
+     * Resets the handler and cancels any ongoing job.
+     * This will also emit [LinkMobileStep.Uninitialized] to the [stepFlow].
+     */
     fun reset() {
         currentJob?.cancel()
         currentJob = null
@@ -70,10 +84,18 @@ class LinkNewMobileHandler(
         }
     }
 
+    /**
+     * Rotates the QR code by creating a new handler and starting the linking process.
+     * This is typically called when a timeout occurs for the current QR code.
+     */
     fun rotateQrCode() {
         createAndStartNewHandler(forRotating = true)
     }
 
+    /**
+     * Handles the case where there are too many QR code rotations.
+     * This will reset the handler and emit an error to the [stepFlow].
+     */
     fun onTooManyRotation() {
         reset()
         sessionScope.launch {