Merge #6769

6769: Closes #6538: Add navigation state to browser state r=pocmo a=csadilek

Need this for my reader mode refactor :). 
Co-authored-by: Christian Sadilek <christian.sadilek@gmail.com>

components/browser/session/src/main/java/mozilla/components/browser/session/Session.kt

@@ -18,6 +18,8 @@ import mozilla.components.browser.state.action.ContentAction.AddFindResultAction
 import mozilla.components.browser.state.action.ContentAction.ClearFindResultsAction
 import mozilla.components.browser.state.action.ContentAction.ConsumeHitResultAction
 import mozilla.components.browser.state.action.ContentAction.FullScreenChangedAction
+import mozilla.components.browser.state.action.ContentAction.UpdateBackNavigationStateAction
+import mozilla.components.browser.state.action.ContentAction.UpdateForwardNavigationStateAction
 import mozilla.components.browser.state.action.ContentAction.RemoveThumbnailAction
 import mozilla.components.browser.state.action.ContentAction.UpdateHitResultAction
 import mozilla.components.browser.state.action.ContentAction.UpdateLoadingStateAction
@@ -232,6 +234,7 @@ class Session(
      */
     var canGoBack: Boolean by Delegates.observable(false) { _, old, new ->
         notifyObservers(old, new) { onNavigationStateChanged(this@Session, new, canGoForward) }
+        store?.syncDispatch(UpdateBackNavigationStateAction(id, canGoBack))
     }
 
     /**
@@ -239,6 +242,7 @@ class Session(
      */
     var canGoForward: Boolean by Delegates.observable(false) { _, old, new ->
         notifyObservers(old, new) { onNavigationStateChanged(this@Session, canGoBack, new) }
+        store?.syncDispatch(UpdateForwardNavigationStateAction(id, canGoForward))
     }
 
     /**

components/browser/session/src/test/java/mozilla/components/browser/session/SessionTest.kt

@@ -932,4 +932,36 @@ class SessionTest {
         assertFalse(parentSession.hasParentSession)
         assertTrue(session.hasParentSession)
     }
+
+    @Test
+    fun `action is dispatched when back navigation state changes`() {
+        val store: BrowserStore = mock()
+        `when`(store.dispatch(any())).thenReturn(mock())
+
+        val session = Session("https://www.mozilla.org")
+        session.store = store
+        session.canGoBack = true
+        verify(store).dispatch(ContentAction.UpdateBackNavigationStateAction(session.id, true))
+
+        session.canGoBack = false
+        verify(store).dispatch(ContentAction.UpdateBackNavigationStateAction(session.id, false))
+
+        verifyNoMoreInteractions(store)
+    }
+
+    @Test
+    fun `action is dispatched when forward navigation state changes`() {
+        val store: BrowserStore = mock()
+        `when`(store.dispatch(any())).thenReturn(mock())
+
+        val session = Session("https://www.mozilla.org")
+        session.store = store
+        session.canGoForward = true
+        verify(store).dispatch(ContentAction.UpdateForwardNavigationStateAction(session.id, true))
+
+        session.canGoForward = false
+        verify(store).dispatch(ContentAction.UpdateForwardNavigationStateAction(session.id, false))
+
+        verifyNoMoreInteractions(store)
+    }
 }

components/browser/state/src/main/java/mozilla/components/browser/state/action/BrowserAction.kt

@@ -259,6 +259,16 @@ sealed class ContentAction : BrowserAction() {
      * @property layoutInDisplayCutoutMode value of defined in https://developer.android.com/reference/android/view/WindowManager.LayoutParams#layoutInDisplayCutoutMode
      */
     data class ViewportFitChangedAction(val sessionId: String, val layoutInDisplayCutoutMode: Int) : ContentAction()
+
+    /**
+     * Updates the [ContentState] of the given [sessionId] to indicate whether or not a back navigation is possible.
+     */
+    data class UpdateBackNavigationStateAction(val sessionId: String, val canGoBack: Boolean) : ContentAction()
+
+    /**
+     * Updates the [ContentState] of the given [sessionId] to indicate whether or not a forward navigation is possible.
+     */
+    data class UpdateForwardNavigationStateAction(val sessionId: String, val canGoForward: Boolean) : ContentAction()
 }
 
 /**

components/browser/state/src/main/java/mozilla/components/browser/state/reducer/ContentStateReducer.kt

@@ -105,6 +105,12 @@ internal object ContentStateReducer {
             is ContentAction.ViewportFitChangedAction -> updateContentState(state, action.sessionId) {
                 it.copy(layoutInDisplayCutoutMode = action.layoutInDisplayCutoutMode)
             }
+            is ContentAction.UpdateBackNavigationStateAction -> updateContentState(state, action.sessionId) {
+                it.copy(canGoBack = action.canGoBack)
+            }
+            is ContentAction.UpdateForwardNavigationStateAction -> updateContentState(state, action.sessionId) {
+                it.copy(canGoForward = action.canGoForward)
+            }
         }
     }
 }

components/browser/state/src/main/java/mozilla/components/browser/state/state/ContentState.kt

@@ -35,6 +35,8 @@ import mozilla.components.concept.engine.window.WindowRequest
  * @property searchRequest the last received [SearchRequest]
  * @property fullScreen true if the page is full screen, false if not.
  * @property layoutInDisplayCutoutMode the display layout cutout mode state.
+ * @property canGoBack whether or not there's an history item to navigate back to.
+ * @property canGoForward whether or not there's an history item to navigate forward to.
  */
 data class ContentState(
     val url: String,
@@ -53,5 +55,7 @@ data class ContentState(
     val windowRequest: WindowRequest? = null,
     val searchRequest: SearchRequest? = null,
     val fullScreen: Boolean = false,
-    val layoutInDisplayCutoutMode: Int = 0
+    val layoutInDisplayCutoutMode: Int = 0,
+    val canGoBack: Boolean = false,
+    val canGoForward: Boolean = false
 )

components/browser/state/src/test/java/mozilla/components/browser/state/action/ContentActionTest.kt

@@ -192,7 +192,7 @@ class ContentActionTest {
     }
 
     @Test
-    fun `UpdateSecurityInfo updates searchInfo`() {
+    fun `UpdateSecurityInfo updates securityInfo`() {
         val newSecurityInfo = SecurityInfoState(true, "mozilla.org", "The Mozilla Team")
 
         assertNotEquals(newSecurityInfo, tab.content.securityInfo)
@@ -527,4 +527,36 @@ class ContentActionTest {
 
         assertNull(tab.content.windowRequest)
     }
+
+    @Test
+    fun `UpdateBackNavigationStateAction updates canGoBack`() {
+        assertFalse(tab.content.canGoBack)
+        assertFalse(otherTab.content.canGoBack)
+
+        store.dispatch(ContentAction.UpdateBackNavigationStateAction(tab.id, true)).joinBlocking()
+
+        assertTrue(tab.content.canGoBack)
+        assertFalse(otherTab.content.canGoBack)
+
+        store.dispatch(ContentAction.UpdateBackNavigationStateAction(tab.id, false)).joinBlocking()
+
+        assertFalse(tab.content.canGoBack)
+        assertFalse(otherTab.content.canGoBack)
+    }
+
+    @Test
+    fun `UpdateForwardNavigationStateAction updates canGoForward`() {
+        assertFalse(tab.content.canGoForward)
+        assertFalse(otherTab.content.canGoForward)
+
+        store.dispatch(ContentAction.UpdateForwardNavigationStateAction(tab.id, true)).joinBlocking()
+
+        assertTrue(tab.content.canGoForward)
+        assertFalse(otherTab.content.canGoForward)
+
+        store.dispatch(ContentAction.UpdateForwardNavigationStateAction(tab.id, false)).joinBlocking()
+
+        assertFalse(tab.content.canGoForward)
+        assertFalse(otherTab.content.canGoForward)
+    }
 }
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