Show empty state feedback for latest + categories

The text is more comprehensive on the main screen than on categories,
because this is the view that all users will see when they first open
F-Droid.

Fixes #879.

app/src/main/java/org/fdroid/fdroid/views/main/CategoriesViewBinder.java

@@ -12,6 +12,7 @@ import android.support.v7.widget.LinearLayoutManager;
 import android.support.v7.widget.RecyclerView;
 import android.view.View;
 import android.widget.FrameLayout;
+import android.widget.TextView;
 
 import org.fdroid.fdroid.R;
 import org.fdroid.fdroid.data.CategoryProvider;
@@ -30,6 +31,8 @@ class CategoriesViewBinder implements LoaderManager.LoaderCallbacks<Cursor> {
 
     private final CategoryAdapter categoryAdapter;
     private final AppCompatActivity activity;
+    private final TextView emptyState;
+    private final RecyclerView categoriesList;
 
     CategoriesViewBinder(final AppCompatActivity activity, FrameLayout parent) {
         this.activity = activity;
@@ -38,7 +41,9 @@ class CategoriesViewBinder implements LoaderManager.LoaderCallbacks<Cursor> {
 
         categoryAdapter = new CategoryAdapter(activity, activity.getSupportLoaderManager());
 
-        RecyclerView categoriesList = (RecyclerView) categoriesView.findViewById(R.id.category_list);
+        emptyState = (TextView) categoriesView.findViewById(R.id.empty_state);
+
+        categoriesList = (RecyclerView) categoriesView.findViewById(R.id.category_list);
         categoriesList.setHasFixedSize(true);
         categoriesList.setLayoutManager(new LinearLayoutManager(activity));
         categoriesList.setAdapter(categoryAdapter);
@@ -77,6 +82,14 @@ class CategoriesViewBinder implements LoaderManager.LoaderCallbacks<Cursor> {
         }
 
         categoryAdapter.setCategoriesCursor(cursor);
+
+        if (categoryAdapter.getItemCount() == 0) {
+            emptyState.setVisibility(View.VISIBLE);
+            categoriesList.setVisibility(View.GONE);
+        } else {
+            emptyState.setVisibility(View.GONE);
+            categoriesList.setVisibility(View.VISIBLE);
+        }
     }
 
     @Override

app/src/main/java/org/fdroid/fdroid/views/main/WhatsNewViewBinder.java

@@ -13,14 +13,20 @@ import android.support.v7.widget.GridLayoutManager;
 import android.support.v7.widget.RecyclerView;
 import android.view.View;
 import android.widget.FrameLayout;
+import android.widget.TextView;
 
 import org.fdroid.fdroid.R;
 import org.fdroid.fdroid.UpdateService;
 import org.fdroid.fdroid.data.AppProvider;
+import org.fdroid.fdroid.data.RepoProvider;
 import org.fdroid.fdroid.data.Schema;
 import org.fdroid.fdroid.views.apps.AppListActivity;
 import org.fdroid.fdroid.views.whatsnew.WhatsNewAdapter;
 
+import java.util.Calendar;
+import java.util.Date;
+import java.util.concurrent.TimeUnit;
+
 /**
  * Loads a list of newly added or recently updated apps and displays them to the user.
  */
@@ -30,6 +36,8 @@ class WhatsNewViewBinder implements LoaderManager.LoaderCallbacks<Cursor> {
 
     private final WhatsNewAdapter whatsNewAdapter;
     private final AppCompatActivity activity;
+    private final TextView emptyState;
+    private final RecyclerView appList;
 
     WhatsNewViewBinder(final AppCompatActivity activity, FrameLayout parent) {
         this.activity = activity;
@@ -41,7 +49,9 @@ class WhatsNewViewBinder implements LoaderManager.LoaderCallbacks<Cursor> {
         GridLayoutManager layoutManager = new GridLayoutManager(activity, 2);
         layoutManager.setSpanSizeLookup(new WhatsNewAdapter.SpanSizeLookup());
 
-        RecyclerView appList = (RecyclerView) whatsNewView.findViewById(R.id.app_list);
+        emptyState = (TextView) whatsNewView.findViewById(R.id.empty_state);
+
+        appList = (RecyclerView) whatsNewView.findViewById(R.id.app_list);
         appList.setHasFixedSize(true);
         appList.setLayoutManager(layoutManager);
         appList.setAdapter(whatsNewAdapter);
@@ -89,6 +99,37 @@ class WhatsNewViewBinder implements LoaderManager.LoaderCallbacks<Cursor> {
         }
 
         whatsNewAdapter.setAppsCursor(cursor);
+
+        if (whatsNewAdapter.getItemCount() == 0) {
+            emptyState.setVisibility(View.VISIBLE);
+            appList.setVisibility(View.GONE);
+            explainEmptyStateToUser();
+        } else {
+            emptyState.setVisibility(View.GONE);
+            appList.setVisibility(View.VISIBLE);
+        }
+    }
+
+    private void explainEmptyStateToUser() {
+        StringBuilder emptyStateText = new StringBuilder();
+        emptyStateText.append(activity.getString(R.string.latest__empty_state__no_recent_apps));
+        emptyStateText.append("\n\n");
+
+        int repoCount = RepoProvider.Helper.countEnabledRepos(activity);
+        if (repoCount == 0) {
+            emptyStateText.append(activity.getString(R.string.latest__empty_state__no_enabled_repos));
+        } else {
+            Date lastUpdate = RepoProvider.Helper.lastUpdate(activity);
+            if (lastUpdate == null) {
+                emptyStateText.append(activity.getString(R.string.latest__empty_state__never_updated));
+            } else {
+                long msDiff = Calendar.getInstance().getTimeInMillis() - lastUpdate.getTime();
+                int daysDiff = (int) TimeUnit.MILLISECONDS.toDays(msDiff);
+                emptyStateText.append(activity.getResources().getQuantityString(R.plurals.details_last_update_days, daysDiff, daysDiff));
+            }
+        }
+
+        emptyState.setText(emptyStateText.toString());
     }
 
     @Override

app/src/main/res/layout/main_tab_categories.xml

@@ -16,6 +16,18 @@
         app:layout_constraintEnd_toEndOf="parent"
         tools:layout_editor_absoluteX="8dp" />
 
+    <TextView
+        android:id="@+id/empty_state"
+        android:layout_width="0dp"
+        android:layout_height="0dp"
+        style="@style/AppListEmptyText"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        android:visibility="gone"
+        android:text="@string/categories__empty_state__no_categories" />
+
     <android.support.v7.widget.RecyclerView
         android:id="@+id/category_list"
         android:layout_width="0dp"

app/src/main/res/layout/main_tab_whats_new.xml

@@ -21,6 +21,14 @@
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content" />
 
+            <TextView
+                android:id="@+id/empty_state"
+                android:layout_width="match_parent"
+                android:layout_height="match_parent"
+                style="@style/AppListEmptyText"
+                android:visibility="gone"
+                tools:text="@string/latest__empty_state__no_recent_apps"/>
+
             <android.support.v7.widget.RecyclerView
                 android:id="@+id/app_list"
                 android:layout_width="match_parent"

app/src/main/res/values/strings.xml

@@ -159,6 +159,12 @@
     <string name="main_menu__categories">Categories</string>
     <string name="main_menu__swap_nearby">Nearby</string>
 
+    <string name="latest__empty_state__no_recent_apps">No recent apps found</string>
+    <string name="latest__empty_state__never_updated">Once your list of apps has been updated, the latest apps should show here</string>
+    <string name="latest__empty_state__no_enabled_repos">Once you enable a repository and let it update, the latest apps should show here</string>
+
+    <string name="categories__empty_state__no_categories">No categories to display</string>
+
     <string name="preference_category__my_apps">My Apps</string>
     <string name="preference_manage_installed_apps">Manage Installed Apps</string>
 

app/src/main/res/values/styles.xml

@@ -93,6 +93,13 @@
     </style>
     <style name="BodyText" parent="BodyTextBase" />
 
+    <style name="AppListEmptyText">
+        <item name="android:id">@android:id/empty</item>
+        <item name="android:gravity">center</item>
+        <item name="android:padding">20dp</item>
+        <item name="android:textSize">20sp</item>
+    </style>
+
     <style name="SwapTheme.Wizard" parent="Theme.AppCompat.Light.NoActionBar">
         <item name="colorButtonNormal">@color/swap_bright_blue</item>
         <item name="actionButtonStyle">@style/SwapTheme.Wizard.ActionButton</item>