Fix same page restore visits when returning to a web screen from a native screen

core/src/main/assets/js/turbo.js

@@ -57,6 +57,22 @@
       }
     }
 
+    restoreCurrentVisit() {
+      // A synthetic "restore" visit to the currently rendered location can occur when
+      // visiting a web -> native -> back to web screen. In this situation, the connect()
+      // callback (from Stimulus) in bridge component controllers will not be called,
+      // since they are already connected. We need to notify the web bridge library
+      // that the webview has been reattached to manually trigger connect() and notify
+      // the native app so the native bridge component view state can be restored.
+      document.dispatchEvent(new Event("native:restore"))
+    }
+
+    cacheSnapshot() {
+      if (window.Turbo) {
+        Turbo.session.view.cacheSnapshot()
+      }
+    }
+
     // Current visit
 
     issueRequestForVisitWithIdentifier(identifier) {

core/src/main/kotlin/dev/hotwire/core/turbo/session/Session.kt

@@ -181,9 +181,27 @@ class Session(
         visitRendered(visit.identifier)
         visitCompleted(visit.identifier, restorationIdentifier)
 
+        webView.restoreCurrentVisit()
+
         return true
     }
 
+    /**
+     * Cache a snapshot of the current visit.
+     */
+    fun cacheSnapshot() {
+        if (!isReady) return
+
+        currentVisit?.let {
+            logEvent("cacheSnapshot",
+                "location" to it.location,
+                "visitIdentifier" to it.identifier
+            )
+
+            webView.cacheSnapshot()
+        }
+    }
+
     fun removeCallback(callback: SessionCallback) {
         currentVisit?.let { visit ->
             if (visit.callback == callback) {

core/src/main/kotlin/dev/hotwire/core/turbo/webview/HotwireWebView.kt

@@ -72,6 +72,14 @@ open class HotwireWebView @JvmOverloads constructor(
         runJavascript("turboNative.visitRenderedForColdBoot('$coldBootVisitIdentifier')")
     }
 
+    internal fun cacheSnapshot() {
+        runJavascript("turboNative.cacheSnapshot()")
+    }
+
+    internal fun restoreCurrentVisit() {
+        runJavascript("turboNative.restoreCurrentVisit()")
+    }
+
     internal fun installBridge(onBridgeInstalled: () -> Unit) {
         val script = "window.turboNative == null"
         val bridge = context.contentFromAsset("js/turbo.js")

core/src/test/kotlin/dev/hotwire/core/turbo/session/SessionTest.kt

@@ -276,6 +276,7 @@ class SessionTest : BaseRepositoryTest() {
 
         assertThat(session.restoreCurrentVisit(callback)).isTrue()
         verify(callback, times(2)).visitCompleted(false)
+        verify(webView, times(1)).restoreCurrentVisit()
     }
 
     @Test

navigation-fragments/src/main/java/dev/hotwire/navigation/fragments/HotwireWebBottomSheetFragment.kt

@@ -55,6 +55,7 @@ open class HotwireWebBottomSheetFragment : HotwireBottomSheetFragment(), Hotwire
 
     override fun onDestroyView() {
         super.onDestroyView()
+        webDelegate.onDestroyView()
         viewLifecycleOwner.lifecycle.removeObserver(bridgeDelegate)
     }
 

navigation-fragments/src/main/java/dev/hotwire/navigation/fragments/HotwireWebFragment.kt

@@ -55,6 +55,7 @@ open class HotwireWebFragment : HotwireFragment(), HotwireWebFragmentCallback {
 
     override fun onDestroyView() {
         super.onDestroyView()
+        webDelegate.onDestroyView()
         viewLifecycleOwner.lifecycle.removeObserver(bridgeDelegate)
     }
 

navigation-fragments/src/main/java/dev/hotwire/navigation/fragments/HotwireWebFragmentDelegate.kt

@@ -131,6 +131,19 @@ internal class HotwireWebFragmentDelegate(
         }
     }
 
+    /**
+     * Should be called by the implementing Fragment during
+     * [androidx.fragment.app.Fragment.onDestroyView].
+     */
+    fun onDestroyView() {
+        // Manually cache a snapshot of the WebView when navigating from a
+        // web screen to a native screen. This allows a "restore" visit when
+        // revisiting this location again.
+        if (navigator.session.currentVisit?.location != navigator.location) {
+            navigator.session.cacheSnapshot()
+        }
+    }
+
     /**
      * Should be called by the implementing Fragment during [HotwireDestination.refresh].
      */