coverting captcha webview to a viewstub in order to catch errors when the system webview is missing or has been disabled

vector/src/main/java/im/vector/app/features/onboarding/ftueauth/FtueAuthCaptchaFragment.kt

@@ -16,15 +16,22 @@
 
 package im.vector.app.features.onboarding.ftueauth
 
+import android.os.Bundle
 import android.os.Parcelable
 import android.view.LayoutInflater
+import android.view.View
 import android.view.ViewGroup
+import android.view.ViewStub
 import com.airbnb.mvrx.args
+import com.google.android.material.dialog.MaterialAlertDialogBuilder
+import im.vector.app.R
 import im.vector.app.databinding.FragmentFtueLoginCaptchaBinding
+import im.vector.app.databinding.ViewStubWebviewBinding
 import im.vector.app.features.onboarding.OnboardingAction
 import im.vector.app.features.onboarding.OnboardingViewState
 import im.vector.app.features.onboarding.RegisterAction
 import kotlinx.parcelize.Parcelize
+import org.matrix.android.sdk.api.extensions.orFalse
 import javax.inject.Inject
 
 @Parcelize
@@ -40,10 +47,32 @@ class FtueAuthCaptchaFragment @Inject constructor(
 ) : AbstractFtueAuthFragment<FragmentFtueLoginCaptchaBinding>() {
 
     private val params: FtueAuthCaptchaFragmentArgument by args()
+    private var webViewBinding: ViewStubWebviewBinding? = null
     private var isWebViewLoaded = false
 
     override fun getBinding(inflater: LayoutInflater, container: ViewGroup?): FragmentFtueLoginCaptchaBinding {
-        return FragmentFtueLoginCaptchaBinding.inflate(inflater, container, false)
+        return FragmentFtueLoginCaptchaBinding.inflate(inflater, container, false).also {
+            it.loginCaptchaWebViewStub.setOnInflateListener { _, inflated ->
+                webViewBinding = ViewStubWebviewBinding.bind(inflated)
+            }
+        }
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+        inflateWebViewOrShowError()
+    }
+
+    private fun inflateWebViewOrShowError() {
+        views.loginCaptchaWebViewStub.inflateWebView(onError = {
+            MaterialAlertDialogBuilder(requireActivity())
+                    .setTitle(R.string.dialog_title_error)
+                    .setMessage(it.localizedMessage)
+                    .setPositiveButton(R.string.ok) { _, _ ->
+                        requireActivity().recreate()
+                    }
+                    .show()
+        })
     }
 
     override fun resetViewModel() {
@@ -51,11 +80,38 @@ class FtueAuthCaptchaFragment @Inject constructor(
     }
 
     override fun updateWithState(state: OnboardingViewState) {
-        if (!isWebViewLoaded) {
-            captchaWebview.setupWebView(this, views.loginCaptchaWevView, views.loginCaptchaProgress, params.siteKey, state) {
+        if (!isWebViewLoaded && webViewBinding != null) {
+            captchaWebview.setupWebView(this, webViewBinding!!.root, views.loginCaptchaProgress, params.siteKey, state) {
                 viewModel.handle(OnboardingAction.PostRegisterAction(RegisterAction.CaptchaDone(it)))
             }
             isWebViewLoaded = true
         }
     }
 }
+
+private fun ViewStub.inflateWebView(onError: (Throwable) -> Unit) {
+    try {
+        inflate()
+    } catch (e: Exception) {
+        val isMissingWebView = e.crawlCausesFor { it.message?.contains("MissingWebViewPackageException").orFalse() }
+        if (isMissingWebView) {
+            onError(MissingWebViewException(e))
+        } else {
+            onError(e)
+        }
+    }
+}
+
+private fun Throwable?.crawlCausesFor(predicate: (Throwable) -> Boolean): Boolean {
+    return when {
+        this == null -> false
+        else -> {
+            when (predicate(this)) {
+                true -> true
+                else -> this.cause.crawlCausesFor(predicate)
+            }
+        }
+    }
+}
+
+private class MissingWebViewException(cause: Throwable) : IllegalStateException("Failed to load WebView provider: No WebView installed", cause)

vector/src/main/res/layout/fragment_ftue_login_captcha.xml

@@ -64,15 +64,27 @@
         android:id="@+id/titleContentSpacing"
         android:layout_width="match_parent"
         android:layout_height="0dp"
-        app:layout_constraintBottom_toTopOf="@id/loginCaptchaWevView"
+        app:layout_constraintBottom_toTopOf="@id/loginWebViewBarrier"
         app:layout_constraintHeight_percent="0.03"
         app:layout_constraintTop_toBottomOf="@id/captchaHeaderTitle" />
 
-    <WebView
-        android:id="@+id/loginCaptchaWevView"
+    <androidx.constraintlayout.widget.Barrier
+        android:id="@+id/loginWebViewBarrier"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        app:constraint_referenced_ids="loginCaptchaWebViewStub,loginCaptchaWebView"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintEnd_toEndOf="@id/captchaGutterEnd"
+        app:layout_constraintStart_toStartOf="@id/captchaGutterStart"
+        app:layout_constraintTop_toBottomOf="@id/titleContentSpacing"/>
+
+    <ViewStub
+        android:id="@+id/loginCaptchaWebViewStub"
         android:layout_width="0dp"
         android:layout_height="0dp"
         android:contentDescription="@string/login_a11y_captcha_container"
+        android:layout="@layout/view_stub_webview"
+        android:inflatedId="@+id/loginCaptchaWebView"
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintEnd_toEndOf="@id/captchaGutterEnd"
         app:layout_constraintStart_toStartOf="@id/captchaGutterStart"

vector/src/main/res/layout/view_stub_webview.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<WebView xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent" />