Bug 1861459 - Update AppState.mode based on selected tab changes

app/src/main/java/org/mozilla/fenix/bindings/BrowserStoreBinding.kt

@@ -0,0 +1,37 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.fenix.bindings
+
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.collectLatest
+import kotlinx.coroutines.flow.distinctUntilChangedBy
+import mozilla.components.browser.state.selector.selectedTab
+import mozilla.components.browser.state.state.BrowserState
+import mozilla.components.browser.state.store.BrowserStore
+import mozilla.components.lib.state.helpers.AbstractBinding
+import org.mozilla.fenix.components.AppStore
+import org.mozilla.fenix.components.appstate.AppAction
+
+/**
+ * Binding to update the [AppStore] based on changes to [BrowserState].
+ */
+class BrowserStoreBinding(
+    browserStore: BrowserStore,
+    private val appStore: AppStore,
+) : AbstractBinding<BrowserState>(browserStore) {
+    override suspend fun onState(flow: Flow<BrowserState>) {
+        // Update the AppStore with the latest selected tab
+        flow.distinctUntilChangedBy { it.selectedTabId }
+            .collectLatest { state ->
+                state.selectedTab?.let { tab ->
+                    // Ignore re-observations due to lifecycle events, or other pieces of state like
+                    // [mode] may get overwritten
+                    if (appStore.state.selectedTabId != tab.id) {
+                        appStore.dispatch(AppAction.SelectedTabChanged(tab))
+                    }
+                }
+            }
+    }
+}

app/src/main/java/org/mozilla/fenix/components/appstate/AppAction.kt

@@ -4,6 +4,7 @@
 
 package org.mozilla.fenix.components.appstate
 
+import mozilla.components.browser.state.state.TabSessionState
 import mozilla.components.feature.tab.collections.TabCollection
 import mozilla.components.feature.top.sites.TopSite
 import mozilla.components.lib.crash.Crash.NativeCodeCrash
@@ -128,6 +129,13 @@ sealed class AppAction : Action {
      */
     data class RemoveRecentSyncedTab(val syncedTab: RecentSyncedTab) : AppAction()
 
+    /**
+     * Action indicating that the selected tab has been changed.
+     *
+     * @property tab The tab that has been selected.
+     */
+    data class SelectedTabChanged(val tab: TabSessionState) : AppAction()
+
     /**
      * [Action]s related to interactions with the Messaging Framework.
      */

app/src/main/java/org/mozilla/fenix/components/appstate/AppState.kt

@@ -38,6 +38,7 @@ import org.mozilla.fenix.wallpapers.WallpaperState
  * @property expandedCollections A set containing the ids of the [TabCollection] that are expanded
  * in the [HomeFragment].
  * @property mode Whether the app is in private browsing mode.
+ * @property selectedTabId The currently selected tab ID. This should be bound to [BrowserStore].
  * @property topSites The list of [TopSite] in the [HomeFragment].
  * @property showCollectionPlaceholder If true, shows a placeholder when there are no collections.
  * @property recentTabs The list of recent [RecentTab] in the [HomeFragment].
@@ -64,6 +65,7 @@ data class AppState(
     val collections: List<TabCollection> = emptyList(),
     val expandedCollections: Set<Long> = emptySet(),
     val mode: BrowsingMode = BrowsingMode.Normal,
+    val selectedTabId: String? = null,
     val topSites: List<TopSite> = emptyList(),
     val showCollectionPlaceholder: Boolean = false,
     val recentTabs: List<RecentTab> = emptyList(),

app/src/main/java/org/mozilla/fenix/components/appstate/AppStoreReducer.kt

@@ -8,6 +8,7 @@ import androidx.annotation.VisibleForTesting
 import mozilla.components.service.pocket.PocketStory.PocketRecommendedStory
 import mozilla.components.service.pocket.PocketStory.PocketSponsoredStory
 import mozilla.components.service.pocket.ext.recordNewImpression
+import org.mozilla.fenix.browser.browsingmode.BrowsingMode
 import org.mozilla.fenix.components.AppStore
 import org.mozilla.fenix.components.appstate.shopping.ShoppingStateReducer
 import org.mozilla.fenix.ext.filterOutTab
@@ -100,6 +101,10 @@ internal object AppStoreReducer {
                 else -> state.recentSyncedTabState
             },
         )
+        is AppAction.SelectedTabChanged -> state.copy(
+            selectedTabId = action.tab.id,
+            mode = BrowsingMode.fromBoolean(action.tab.content.private),
+        )
         is AppAction.DisbandSearchGroupAction -> state.copy(
             recentHistory = state.recentHistory.filterNot {
                 it is RecentHistoryGroup && it.title.equals(action.searchTerm, true)

app/src/test/java/org/mozilla/fenix/bindings/BrowserStoreBindingTest.kt

@@ -0,0 +1,79 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.fenix.bindings
+
+import mozilla.components.browser.state.action.TabListAction
+import mozilla.components.browser.state.state.BrowserState
+import mozilla.components.browser.state.state.createTab
+import mozilla.components.browser.state.store.BrowserStore
+import mozilla.components.support.test.ext.joinBlocking
+import mozilla.components.support.test.rule.MainCoroutineRule
+import mozilla.components.support.test.rule.runTestOnMain
+import org.junit.Rule
+import org.junit.Test
+import org.mockito.Mockito.never
+import org.mockito.Mockito.spy
+import org.mockito.Mockito.verify
+import org.mozilla.fenix.components.AppStore
+import org.mozilla.fenix.components.appstate.AppAction
+import org.mozilla.fenix.components.appstate.AppState
+
+class BrowserStoreBindingTest {
+
+    @get:Rule
+    val coroutineRule = MainCoroutineRule()
+
+    lateinit var browserStore: BrowserStore
+    lateinit var appStore: AppStore
+
+    private val tabId1 = "1"
+    private val tabId2 = "2"
+    private val tab1 = createTab(url = tabId1, id = tabId1)
+    private val tab2 = createTab(url = tabId2, id = tabId2)
+
+    @Test
+    fun `WHEN selected tab changes THEN app action dispatched with update`() = runTestOnMain {
+        appStore = spy(AppStore())
+        browserStore = BrowserStore(
+            BrowserState(
+                tabs = listOf(tab1, tab2),
+                selectedTabId = tabId1,
+            ),
+        )
+
+        val binding = BrowserStoreBinding(browserStore, appStore)
+        binding.start()
+        browserStore.dispatch(TabListAction.SelectTabAction(tabId2)).joinBlocking()
+
+        // consume initial state
+        verify(appStore).dispatch(AppAction.SelectedTabChanged(tab1))
+        // verify response to Browser Store dispatch
+        verify(appStore).dispatch(AppAction.SelectedTabChanged(tab2))
+    }
+
+    @Test
+    fun `GIVEN selected tab id is set WHEN update is observed with same id THEN update is ignored`() {
+        appStore = spy(
+            AppStore(
+                AppState(
+                    selectedTabId = tabId2,
+                ),
+            ),
+        )
+        browserStore = BrowserStore(
+            BrowserState(
+                tabs = listOf(tab1, tab2),
+                selectedTabId = tabId2,
+            ),
+        )
+
+        val binding = BrowserStoreBinding(browserStore, appStore)
+        binding.start()
+        browserStore.dispatch(TabListAction.SelectTabAction(tabId2)).joinBlocking()
+
+        // the selected tab should only be dispatched on initialization
+        verify(appStore, never()).dispatch(AppAction.SelectedTabChanged(tab2))
+    }
+}

app/src/test/java/org/mozilla/fenix/components/appstate/AppStoreReducerTest.kt

@@ -5,10 +5,12 @@
 package org.mozilla.fenix.components.appstate
 
 import io.mockk.mockk
+import mozilla.components.browser.state.state.createTab
 import mozilla.components.lib.crash.Crash.NativeCodeCrash
 import org.junit.Assert.assertFalse
 import org.junit.Assert.assertTrue
 import org.junit.Test
+import org.mozilla.fenix.browser.browsingmode.BrowsingMode
 import org.mozilla.fenix.components.appstate.AppAction.AddNonFatalCrash
 import org.mozilla.fenix.components.appstate.AppAction.RemoveAllNonFatalCrashes
 import org.mozilla.fenix.components.appstate.AppAction.RemoveNonFatalCrash
@@ -69,4 +71,49 @@ class AppStoreReducerTest {
 
         assertTrue(updatedState.nonFatalCrashes.isEmpty())
     }
+
+    @Test
+    fun `GIVEN mode is private WHEN selected tab changes to normal mode THEN state is updated to normal mode`() {
+        val initialState = AppState(
+            selectedTabId = null,
+            mode = BrowsingMode.Private,
+        )
+
+        val updatedState = AppStoreReducer.reduce(
+            initialState,
+            AppAction.SelectedTabChanged(createTab("", private = false)),
+        )
+
+        assertFalse(updatedState.mode.isPrivate)
+    }
+
+    @Test
+    fun `GIVEN mode is normal WHEN selected tab changes to private mode THEN state is updated to private mode`() {
+        val initialState = AppState(
+            selectedTabId = null,
+            mode = BrowsingMode.Normal,
+        )
+
+        val updatedState = AppStoreReducer.reduce(
+            initialState,
+            AppAction.SelectedTabChanged(createTab("", private = true)),
+        )
+
+        assertTrue(updatedState.mode.isPrivate)
+    }
+
+    @Test
+    fun `WHEN selected tab changes to a tab in the same mode THEN mode is unchanged`() {
+        val initialState = AppState(
+            selectedTabId = null,
+            mode = BrowsingMode.Normal,
+        )
+
+        val updatedState = AppStoreReducer.reduce(
+            initialState,
+            AppAction.SelectedTabChanged(createTab("", private = false)),
+        )
+
+        assertFalse(updatedState.mode.isPrivate)
+    }
 }