From 27a56e2974bb42a575b7607259a5ecace4feeb5a Mon Sep 17 00:00:00 2001
From: Jeff Boek <jeff@jeffboek.com>
Date: Thu, 31 Jan 2019 21:52:26 -0800
Subject: [PATCH] For #336 - allow the browser to intercept the back button

---
 app/src/main/java/org/mozilla/fenix/BackHandler.kt    | 11 +++++++++++
 app/src/main/java/org/mozilla/fenix/HomeActivity.kt   | 10 ++++++++++
 .../java/org/mozilla/fenix/browser/BrowserFragment.kt | 11 ++++++++++-
 app/src/main/res/navigation/nav_graph.xml             |  4 ++--
 4 files changed, 33 insertions(+), 3 deletions(-)
 create mode 100644 app/src/main/java/org/mozilla/fenix/BackHandler.kt

diff --git a/app/src/main/java/org/mozilla/fenix/BackHandler.kt b/app/src/main/java/org/mozilla/fenix/BackHandler.kt
new file mode 100644
index 000000000..2a8b4b3d6
--- /dev/null
+++ b/app/src/main/java/org/mozilla/fenix/BackHandler.kt
@@ -0,0 +1,11 @@
+package org.mozilla.fenix
+/* 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/. */
+
+/**
+ * Interface for fragments that want to handle 'back' button presses.
+ */
+interface BackHandler {
+    fun onBackPressed(): Boolean
+}
diff --git a/app/src/main/java/org/mozilla/fenix/HomeActivity.kt b/app/src/main/java/org/mozilla/fenix/HomeActivity.kt
index 96627667d..80f4741f1 100644
--- a/app/src/main/java/org/mozilla/fenix/HomeActivity.kt
+++ b/app/src/main/java/org/mozilla/fenix/HomeActivity.kt
@@ -31,4 +31,14 @@ class HomeActivity : AppCompatActivity() {
             ).asView()
             else -> super.onCreateView(parent, name, context, attrs)
         }
+
+    override fun onBackPressed() {
+        supportFragmentManager.primaryNavigationFragment?.childFragmentManager?.fragments?.forEach {
+            if (it is BackHandler && it.onBackPressed()) {
+                return
+            }
+        }
+
+        super.onBackPressed()
+    }
 }
diff --git a/app/src/main/java/org/mozilla/fenix/browser/BrowserFragment.kt b/app/src/main/java/org/mozilla/fenix/browser/BrowserFragment.kt
index 7f0dfdab5..ed6258afa 100644
--- a/app/src/main/java/org/mozilla/fenix/browser/BrowserFragment.kt
+++ b/app/src/main/java/org/mozilla/fenix/browser/BrowserFragment.kt
@@ -27,8 +27,9 @@ import org.mozilla.fenix.R
 import org.mozilla.fenix.components.toolbar.ToolbarIntegration
 import org.mozilla.fenix.ext.requireComponents
 import mozilla.components.feature.prompts.PromptFeature
+import org.mozilla.fenix.BackHandler
 
-class BrowserFragment : Fragment() {
+class BrowserFragment : Fragment(), BackHandler {
 
     private lateinit var contextMenuFeature: ContextMenuFeature
     private lateinit var downloadsFeature: DownloadsFeature
@@ -111,6 +112,14 @@ class BrowserFragment : Fragment() {
         }
     }
 
+    override fun onBackPressed(): Boolean {
+        if (sessionFeature.handleBackPressed()) return true
+
+        // We'll want to improve this when we add multitasking
+        requireComponents.core.sessionManager.remove()
+        return false
+    }
+
     override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<String>, grantResults: IntArray) {
         when (requestCode) {
             REQUEST_CODE_DOWNLOAD_PERMISSIONS -> downloadsFeature.onPermissionsResult(permissions, grantResults)
diff --git a/app/src/main/res/navigation/nav_graph.xml b/app/src/main/res/navigation/nav_graph.xml
index 6281ccb78..e1aba2210 100644
--- a/app/src/main/res/navigation/nav_graph.xml
+++ b/app/src/main/res/navigation/nav_graph.xml
@@ -38,8 +38,8 @@
         android:label="fragment_browser"
         tools:layout="@layout/fragment_browser">
         <action
-            android:id="@+id/action_browserFragment_to_homeFragment"
-            app:destination="@id/homeFragment" />
+                android:id="@+id/action_browserFragment_to_homeFragment"
+                app:destination="@id/homeFragment" app:popUpToInclusive="true" app:popUpTo="@+id/homeFragment"/>
         <action
             android:id="@+id/action_browserFragment_to_searchFragment"
             app:destination="@id/searchFragment" />