Restore narrow and scroll after theme switch.

Fix:#406

app/src/main/java/com/zulip/android/ZulipApp.java

@@ -27,6 +27,7 @@
 import com.j256.ormlite.misc.TransactionManager;
 import com.zulip.android.activities.ZulipActivity;
 import com.zulip.android.database.DatabaseHelper;
+import com.zulip.android.filters.NarrowFilter;
 import com.zulip.android.models.Emoji;
 import com.zulip.android.models.Message;
 import com.zulip.android.models.MessageType;
@@ -133,6 +134,19 @@ public void setZulipActivity(ZulipActivity zulipActivity) {
         this.zulipActivity = zulipActivity;
     }
 
+    //store narrowFilter before switching theme
+    private NarrowFilter narrowFilter = null;
+
+    //set it after restore
+    //for narrowed view
+    private int tempNarrowedViewPointer = -1;
+    //for home view
+    private int tempHomeViewPointer = -1;
+
+    //useful when switch takes place from narrowed view
+    //on switch theme activity is recreated
+    private boolean isThemeSwitchedFromHome = true;
+
     @Override
     public void onCreate() {
         super.onCreate();
@@ -602,4 +616,36 @@ public void setMessageContentEditParams(int seconds, boolean param) {
             }
         }
     }
+
+    public NarrowFilter getNarrowFilter() {
+        return narrowFilter;
+    }
+
+    public void setNarrowFilter(NarrowFilter narrowFilter) {
+        this.narrowFilter = narrowFilter;
+    }
+
+    public void setTempNarrowedViewPointer(int mID) {
+        this.tempNarrowedViewPointer = mID;
+    }
+
+    public int getTempNarrowedViewPointer() {
+        return tempNarrowedViewPointer;
+    }
+
+    public int getTempHomeViewPointer() {
+        return tempHomeViewPointer;
+    }
+
+    public void setTempHomeViewPointer(int tempHomeViewPointer) {
+        this.tempHomeViewPointer = tempHomeViewPointer;
+    }
+
+    public boolean isThemeSwitchedFromHome() {
+        return isThemeSwitchedFromHome;
+    }
+
+    public void setThemeSwitchedFromHome(boolean themeSwitchedFromHome) {
+        isThemeSwitchedFromHome = themeSwitchedFromHome;
+    }
 }

app/src/main/java/com/zulip/android/activities/MessageListFragment.java

@@ -422,7 +422,7 @@ public void onTaskFailure(String result) {
                 100, filter);
     }
 
-    private void selectPointer() {
+    public void selectPointer() {
         if (filter != null) {
             Where<Message, Object> filteredWhere;
             try {
@@ -440,16 +440,38 @@ private void selectPointer() {
 
                 // use anchor message id if message was narrowed
                 if (anchorId != -1) {
-                    selectMessage(getMessageById(anchorId));
+                    if (app.getTempNarrowedViewPointer() != -1 && app.getTempNarrowedViewPointer() < anchorId) {
+                        //user have scrolled above before switching theme
+                        scrollWithZeroOffset(getMessageById(app.getTempNarrowedViewPointer()));
+                        app.setTempNarrowedViewPointer(-1);
+                    } else {
+                        selectMessage(getMessageById(anchorId));
+                    }
                 } else {
-                    recyclerView.scrollToPosition(adapter.getItemIndex(closestMessage));
+                    if (app.getTempNarrowedViewPointer() != -1 && adapter.getItemIndex(getMessageById(app.getTempNarrowedViewPointer())) < adapter.getItemIndex(closestMessage)) {
+                        //user have scrolled above before switching theme
+                        scrollWithZeroOffset(getMessageById(app.getTempNarrowedViewPointer()));
+                        app.setTempNarrowedViewPointer(-1);
+                    }else {
+                        recyclerView.scrollToPosition(adapter.getItemIndex(closestMessage));
+                    }
                 }
             } catch (SQLException e) {
                 throw new RuntimeException(e);
             }
         } else {
             int anc = app.getPointer();
-            selectMessage(getMessageById(anc));
+            int tempPointer = app.getTempHomeViewPointer();
+            if (tempPointer != -1 && tempPointer < anc) {
+                //user have scrolled above before switching theme
+                scrollWithZeroOffset(getMessageById(tempPointer));
+                //will be useful when user switch theme from narrowed view and back trace to home
+                if (app.isThemeSwitchedFromHome()) {
+                    app.setTempHomeViewPointer(-1);
+                }
+            } else {
+                selectMessage(getMessageById(anc));
+            }
         }
     }
 
@@ -849,6 +871,16 @@ private void selectMessage(final Message message) {
         recyclerView.scrollToPosition(adapter.getItemIndex(message));
     }
 
+    /**
+     * scroll such that message comes to top of the view
+     *
+     * @param message that should come to top
+     * @see {@link <a href="http://stackoverflow.com/questions/26875061/scroll-recyclerview-to-show-selected-item-on-top"/>}
+     */
+    private void scrollWithZeroOffset(Message message) {
+        linearLayoutManager.scrollToPositionWithOffset(adapter.getItemIndex(message), 0);
+    }
+
     private Message getMessageById(int id) {
         return this.messageIndex.get(id);
     }
@@ -889,4 +921,26 @@ public interface Listener {
         void setLayoutBehaviour(LinearLayoutManager linearLayoutManager, RecyclerMessageAdapter adapter);
 
     }
+
+    /**
+     * get messageId of FirstCompletelyVisibleItem
+     * loop until we get message
+     * skip message header
+     *
+     * @return messagedId of message which is at top
+     */
+    public int getTopMessageId() {
+        int position = linearLayoutManager.findFirstCompletelyVisibleItemPosition();
+        //if there aren't any visible items position = -1
+        if (position >= 0) {
+            for (int i = position; i < adapter.getItemCount(); i++) {
+                Object topObject = adapter.getItem(i);
+                if (topObject instanceof Message) {
+                    return ((Message) topObject).getID();
+                }
+            }
+        }
+        return -1;
+
+    }
 }

app/src/main/java/com/zulip/android/activities/ZulipActivity.java

@@ -642,10 +642,14 @@ public void onBackStackChanged() {
                 if (menu == null)
                     return;
                 if (narrowedList == null) {
+                    //will be useful when user switch theme from narrowed view and back trace to home
+                    app.setThemeSwitchedFromHome(true);
                     calendar = Calendar.getInstance();
                     menu.getItem(2).getSubMenu().getItem(0).setTitle(R.string.menu_today);
                     switchToStream();
                     checkForChatBoxFocusRequest();
+                    //on narrowed view is restored after switching and coming back to homeView set pointer accordingly
+                    homeList.selectPointer();
                 } else if (narrowedList.filter instanceof NarrowFilterByDate) {
                     menu.getItem(2).getSubMenu().getItem(0).setTitle(R.string.menu_one_day_before);
                 }
@@ -933,6 +937,17 @@ protected void onNewIntent(Intent intent) {
         }
     }
 
+    @Override
+    public void onAttachedToWindow() {
+        super.onAttachedToWindow();
+        //check if it was narrowed before switching theme
+        if (app.getNarrowFilter() != null) {
+            //restore narrow
+            doNarrow(app.getNarrowFilter());
+            app.setNarrowFilter(null);
+        }
+    }
+
     @Override
     protected void onActivityResult(int requestCode, int resultCode, Intent data) {
         if (requestCode == REQUEST_TAKE_PHOTO && resultCode == RESULT_OK) {
@@ -2061,7 +2076,12 @@ private void pushListFragment(MessageListFragment list, String back) {
         transaction.replace(R.id.list_fragment_container, list);
         if (back != null) {
             transaction.addToBackStack(back);
-            clearSearch();
+            //searchView is in menu
+            //menu is inflated in onCreateOptionsMenu
+            //onCreateOptionsMenu is called somewhere in between onCreate is executing
+            if (searchView != null) {
+                clearSearch();
+            }
         }
         transaction.commit();
         getSupportFragmentManager().executePendingTransactions();
@@ -2355,6 +2375,16 @@ public void onClick(
                 }
                 break;
             case R.id.daynight:
+                //for narrowed view
+                if (narrowedList != null) {
+                    app.setNarrowFilter(narrowedList.filter);
+                    app.setTempNarrowedViewPointer(narrowedList.getTopMessageId());
+                    app.setThemeSwitchedFromHome(false);
+                }
+                //for home view
+                if (app.getTempHomeViewPointer() == -1 || app.isThemeSwitchedFromHome()) {
+                    app.setTempHomeViewPointer(homeList.getTopMessageId());
+                }
                 switch (AppCompatDelegate.getDefaultNightMode()) {
                     case -1:
                     case AppCompatDelegate.MODE_NIGHT_NO: