FIX #56 implement "load more"

app/src/main/java/chat/rocket/android/api/MethodCallHelper.java

@@ -238,7 +238,7 @@ public class MethodCallHelper {
   /**
    * Load messages for room.
    */
-  public Task<Void> loadHistory(final String roomId, final long timestamp,
+  public Task<JSONArray> loadHistory(final String roomId, final long timestamp,
       final int count, final long lastSeen) {
     return call("loadHistory", TIMEOUT_MS, () -> new JSONArray()
         .put(roomId)
@@ -261,7 +261,7 @@ public class MethodCallHelper {
               realm.createOrUpdateAllFromJson(Message.class, messages);
             }
             return null;
-          });
+          }).onSuccessTask(_task -> Task.forResult(messages));
         });
   }
 

app/src/main/java/chat/rocket/android/fragment/chatroom/RoomFragment.java

@@ -5,6 +5,7 @@ import android.support.annotation.Nullable;
 import android.support.v7.widget.LinearLayoutManager;
 import android.support.v7.widget.RecyclerView;
 import chat.rocket.android.R;
+import chat.rocket.android.helper.LoadMoreScrollListener;
 import chat.rocket.android.helper.LogcatIfError;
 import chat.rocket.android.layouthelper.chatroom.MessageListAdapter;
 import chat.rocket.android.model.ServerConfig;
@@ -15,10 +16,10 @@ import chat.rocket.android.model.internal.LoadMessageProcedure;
 import chat.rocket.android.realm_helper.RealmHelper;
 import chat.rocket.android.realm_helper.RealmObjectObserver;
 import chat.rocket.android.realm_helper.RealmStore;
-import io.realm.Realm;
-import io.realm.RealmResults;
+import chat.rocket.android.service.RocketChatService;
 import io.realm.Sort;
 import org.json.JSONObject;
+import timber.log.Timber;
 
 /**
  * Chat room screen.
@@ -29,6 +30,8 @@ public class RoomFragment extends AbstractChatRoomFragment {
   private String roomId;
   private RealmObjectObserver<RoomSubscription> roomObserver;
   private String hostname;
+  private LoadMoreScrollListener scrollListener;
+  private RealmObjectObserver<LoadMessageProcedure> procedureObserver;
 
   /**
    * create fragment with roomId.
@@ -61,7 +64,13 @@ public class RoomFragment extends AbstractChatRoomFragment {
         .createObjectObserver(realm -> realm.where(RoomSubscription.class).equalTo("rid", roomId))
         .setOnUpdateListener(this::onRenderRoom);
 
-    initialRequest();
+    procedureObserver = realmHelper
+        .createObjectObserver(realm ->
+            realm.where(LoadMessageProcedure.class).equalTo("roomId", roomId))
+        .setOnUpdateListener(this::onUpdateLoadMessageProcedure);
+    if (savedInstanceState == null) {
+      initialRequest();
+    }
   }
 
   @Override protected int getLayout() {
@@ -77,36 +86,84 @@ public class RoomFragment extends AbstractChatRoomFragment {
         context -> new MessageListAdapter(context, hostname)
     ));
 
-    RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getContext(),
+    LinearLayoutManager layoutManager = new LinearLayoutManager(getContext(),
         LinearLayoutManager.VERTICAL, true);
     listView.setLayoutManager(layoutManager);
+
+    scrollListener = new LoadMoreScrollListener(layoutManager, 40) {
+      @Override public void requestMoreItem() {
+        loadMoreRequest();
+      }
+    };
+    listView.addOnScrollListener(scrollListener);
   }
 
   private void onRenderRoom(RoomSubscription roomSubscription) {
     activityToolbar.setTitle(roomSubscription.getName());
   }
 
+  private void onUpdateLoadMessageProcedure(LoadMessageProcedure procedure) {
+    if (procedure == null) {
+      return;
+    }
+    RecyclerView listView = (RecyclerView) rootView.findViewById(R.id.recyclerview);
+    if (listView != null && listView.getAdapter() instanceof MessageListAdapter) {
+      MessageListAdapter adapter = (MessageListAdapter) listView.getAdapter();
+      final int syncstate = procedure.getSyncstate();
+      final boolean hasNext = procedure.isHasNext();
+      Timber.d("hasNext: %s syncstate: %d", hasNext, syncstate);
+      if (syncstate == SyncState.SYNCED || syncstate == SyncState.FAILED) {
+        scrollListener.setLoadingDone();
+        adapter.updateFooter(hasNext, true);
+      } else {
+        adapter.updateFooter(hasNext, false);
+      }
+    }
+  }
+
   private void initialRequest() {
     realmHelper.executeTransaction(realm -> {
       realm.createOrUpdateObjectFromJson(LoadMessageProcedure.class, new JSONObject()
           .put("roomId", roomId)
           .put("syncstate", SyncState.NOT_SYNCED)
-          .put("count", 50)
+          .put("count", 100)
           .put("reset", true));
       return null;
+    }).onSuccessTask(task -> {
+      RocketChatService.keepalive(getContext());
+      return task;
     }).continueWith(new LogcatIfError());
   }
 
-  private RealmResults<Message> queryItems(Realm realm) {
-    return realm.where(Message.class).equalTo("rid", roomId).findAllSorted("ts");
+  private void loadMoreRequest() {
+    realmHelper.executeTransaction(realm -> {
+      LoadMessageProcedure procedure = realm.where(LoadMessageProcedure.class)
+          .equalTo("roomId", roomId)
+          .beginGroup()
+          .equalTo("syncstate", SyncState.SYNCED)
+          .or()
+          .equalTo("syncstate", SyncState.FAILED)
+          .endGroup()
+          .equalTo("hasNext", true)
+          .findFirst();
+      if (procedure != null) {
+        procedure.setSyncstate(SyncState.NOT_SYNCED);
+      }
+      return null;
+    }).onSuccessTask(task -> {
+      RocketChatService.keepalive(getContext());
+      return task;
+    }).continueWith(new LogcatIfError());
   }
 
   @Override public void onResume() {
     super.onResume();
     roomObserver.sub();
+    procedureObserver.sub();
   }
 
   @Override public void onPause() {
+    procedureObserver.unsub();
     roomObserver.unsub();
     super.onPause();
   }

app/src/main/java/chat/rocket/android/helper/LoadMoreScrollListener.java

+package chat.rocket.android.helper;
+
+import android.support.v7.widget.LinearLayoutManager;
+import android.support.v7.widget.RecyclerView;
+
+public abstract class LoadMoreScrollListener extends RecyclerView.OnScrollListener {
+
+  private final LinearLayoutManager layoutManager;
+  private final int loadThreshold;
+  private boolean isLoading;
+
+  public LoadMoreScrollListener(LinearLayoutManager layoutManager, int loadThreshold) {
+    this.layoutManager = layoutManager;
+    this.loadThreshold = loadThreshold;
+    setLoadingDone();
+  }
+
+  @Override public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
+    super.onScrolled(recyclerView, dx, dy);
+
+    final int visibleItemCount = recyclerView.getChildCount();
+    final int totalItemCount = layoutManager.getItemCount();
+    final int firstVisibleItem = layoutManager.findFirstVisibleItemPosition();
+
+    if (!isLoading
+        && firstVisibleItem + visibleItemCount >= totalItemCount - loadThreshold
+        && visibleItemCount < totalItemCount
+        && dy < 0) {
+      isLoading = true;
+      requestMoreItem();
+    }
+  }
+
+  public void setLoadingDone() {
+    isLoading = false;
+  }
+
+  public abstract void requestMoreItem();
+}
\ No newline at end of file

app/src/main/java/chat/rocket/android/layouthelper/ExtRealmModelListAdapter.java

+package chat.rocket.android.layouthelper;
+
+import android.content.Context;
+import android.support.annotation.LayoutRes;
+import chat.rocket.android.realm_helper.RealmModelListAdapter;
+import chat.rocket.android.realm_helper.RealmModelViewHolder;
+import io.realm.RealmObject;
+
+/**
+ * RealmModelListAdapter with header and footer.
+ */
+public abstract class ExtRealmModelListAdapter<T extends RealmObject, VM,
+    VH extends RealmModelViewHolder<VM>> extends RealmModelListAdapter<T, VM, VH> {
+  protected static final int VIEW_TYPE_HEADER = -1;
+  protected static final int VIEW_TYPE_FOOTER = -2;
+
+  protected ExtRealmModelListAdapter(Context context) {
+    super(context);
+  }
+
+  @Override public int getItemCount() {
+    return super.getItemCount() + 2;
+  }
+
+  protected void notifyHeaderChanged() {
+    notifyItemChanged(0);
+  }
+
+  protected void notifyFooterChanged() {
+    notifyItemChanged(super.getItemCount() + 1);
+  }
+
+  protected void notifyRealmModelItemChanged(int position) {
+    notifyItemChanged(position + 1);
+  }
+
+  @Override public int getItemViewType(int position) {
+    if (position == 0) {
+      return VIEW_TYPE_HEADER;
+    }
+    if (position == super.getItemCount() + 1) {
+      return VIEW_TYPE_FOOTER;
+    }
+
+    // rely on getRealmModelViewType(VM model).
+    return super.getItemViewType(position - 1);
+  }
+
+  protected abstract @LayoutRes int getHeaderLayout();
+
+  protected abstract @LayoutRes int getFooterLayout();
+
+  protected abstract @LayoutRes int getRealmModelLayout(int viewType);
+
+  @Override protected final int getLayout(int viewType) {
+    if (viewType == VIEW_TYPE_HEADER) {
+      return getHeaderLayout();
+    }
+    if (viewType == VIEW_TYPE_FOOTER) {
+      return getFooterLayout();
+    }
+
+    return getRealmModelLayout(viewType);
+  }
+
+  @Override public final void onBindViewHolder(VH holder, int position) {
+    if (position == 0 || position == super.getItemCount() + 1) {
+      return;
+    }
+
+    // rely on VH.bind().
+    super.onBindViewHolder(holder, position - 1);
+  }
+}

app/src/main/java/chat/rocket/android/layouthelper/chatroom/MessageListAdapter.java

@@ -3,8 +3,8 @@ package chat.rocket.android.layouthelper.chatroom;
 import android.content.Context;
 import android.view.View;
 import chat.rocket.android.R;
+import chat.rocket.android.layouthelper.ExtRealmModelListAdapter;
 import chat.rocket.android.model.ddp.Message;
-import chat.rocket.android.realm_helper.RealmModelListAdapter;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
@@ -13,20 +13,42 @@ import java.util.List;
  * target list adapter for chat room.
  */
 public class MessageListAdapter
-    extends RealmModelListAdapter<Message, PairedMessage, MessageViewHolder> {
-
+    extends ExtRealmModelListAdapter<Message, PairedMessage, MessageViewHolder> {
   private final String hostname;
+  private boolean hasNext;
+  private boolean isLoaded;
 
   public MessageListAdapter(Context context, String hostname) {
     super(context);
     this.hostname = hostname;
   }
 
+  /**
+   * update Footer state considering hasNext and isLoaded.
+   */
+  public void updateFooter(boolean hasNext, boolean isLoaded) {
+    this.hasNext = hasNext;
+    this.isLoaded = isLoaded;
+    notifyFooterChanged();
+  }
+
+  @Override protected int getHeaderLayout() {
+    return R.layout.list_item_message_header;
+  }
+
+  @Override protected int getFooterLayout() {
+    if (!hasNext || isLoaded) {
+      return R.layout.list_item_message_start_of_conversation;
+    } else {
+      return R.layout.list_item_message_loading;
+    }
+  }
+
   @Override protected int getRealmModelViewType(PairedMessage model) {
     return 0;
   }
 
-  @Override protected int getLayout(int viewType) {
+  @Override protected int getRealmModelLayout(int viewType) {
     return R.layout.list_item_message;
   }
 

app/src/main/java/chat/rocket/android/service/observer/LoadMessageProcedureObserver.java

@@ -57,14 +57,16 @@ public class LoadMessageProcedureObserver extends AbstractModelObserver<LoadMess
                   realm.where(Message.class)
                       .equalTo("rid", roomId)
                       .equalTo("syncstate", SyncState.SYNCED)
-                      .findAllSorted("ts", Sort.ASCENDING).last(null));
+                      .findAllSorted("ts", Sort.ASCENDING).first(null));
               long lastTs = lastMessage != null ? lastMessage.getTs() : 0;
+              int messageCount = _task.getResult().length();
               return realmHelper.executeTransaction(realm ->
                   realm.createOrUpdateObjectFromJson(LoadMessageProcedure.class, new JSONObject()
                       .put("roomId", roomId)
                       .put("syncstate", SyncState.SYNCED)
                       .put("timestamp", lastTs)
-                      .put("hasNext", lastTs > 0)));
+                      .put("reset", false)
+                      .put("hasNext", messageCount == count)));
             })
     ).continueWithTask(task -> {
       if (task.isFaulted()) {

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

@@ -10,7 +10,7 @@
       />
 
   <android.support.design.widget.FloatingActionButton
-      android:id="@+id/btn_compose"
+      android:id="@+id/fab_compose"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:layout_gravity="end|bottom"

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

+<?xml version="1.0" encoding="utf-8"?>
+<Space
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/space"
+    android:layout_width="match_parent"
+    android:layout_height="88dp"
+    />
\ No newline at end of file

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

+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:orientation="vertical"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:theme="@style/AppTheme"
+    >
+
+  <chat.rocket.android.widget.WaitingView
+      android:layout_width="wrap_content"
+      android:layout_height="wrap_content"
+      android:layout_gravity="center"
+      android:layout_margin="@dimen/margin_8"
+      />
+
+</FrameLayout>
\ No newline at end of file

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

+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:orientation="vertical"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:theme="@style/AppTheme"
+    >
+
+  <TextView
+      android:layout_width="wrap_content"
+      android:layout_height="wrap_content"
+      android:layout_margin="@dimen/margin_16"
+      android:text="@string/start_of_conversation"
+      android:textAppearance="@style/TextAppearance.AppCompat.Body1"
+      android:layout_gravity="center"
+      />
+
+</FrameLayout>
\ No newline at end of file

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

@@ -7,4 +7,6 @@
   <string name="user_status_busy">Busy</string>
   <string name="user_status_invisible">Invisible</string>
   <string name="fragment_sidebar_main_logout_title">Logout</string>
+
+  <string name="start_of_conversation">Start of conversation</string>
 </resources>

realm-helpers/src/main/java/chat/rocket/android/realm_helper/RealmModelListAdapter.java

@@ -16,7 +16,7 @@ public abstract class RealmModelListAdapter<T extends RealmObject, VM,
     RealmModelListAdapter<T, VM, VH> getNewInstance(Context context);
   }
 
-  private final LayoutInflater inflater;
+  protected final LayoutInflater inflater;
   private RealmListObserver<T> realmListObserver;
   private List<VM> adapterData;
 
@@ -54,11 +54,11 @@ public abstract class RealmModelListAdapter<T extends RealmObject, VM,
   protected abstract List<VM> mapResultsToViewModel(List<T> results);
 
 
-  @Override public final int getItemViewType(int position) {
+  @Override public int getItemViewType(int position) {
     return getRealmModelViewType(getItem(position));
   }
 
-  @Override public VH onCreateViewHolder(ViewGroup parent, int viewType) {
+  @Override public final VH onCreateViewHolder(ViewGroup parent, int viewType) {
     View itemView = inflater.inflate(getLayout(viewType), parent, false);
     return onCreateRealmModelViewHolder(viewType, itemView);
   }