Added code to debounce filtering on the client-side so we don't send a

bunch of extra requests to the backend when searching.

src/musikdroid/app/src/main/java/io/casey/musikcube/remote/AlbumBrowseActivity.java

@@ -61,7 +61,7 @@ public class AlbumBrowseActivity extends WebSocketActivityBase implements Filter
     private TransportFragment transport;
     private String categoryName;
     private long categoryId;
-    private String filter = "";
+    private String lastFilter = "";
 
     @Override
     protected void onCreate(@Nullable Bundle savedInstanceState) {
@@ -97,8 +97,8 @@ public class AlbumBrowseActivity extends WebSocketActivityBase implements Filter
 
     @Override
     public void setFilter(String filter) {
-        this.filter = filter;
+        this.lastFilter = filter;
-        requery();
+        filterDebouncer.call(filter);
     }
 
     @Override
@@ -122,17 +122,28 @@ public class AlbumBrowseActivity extends WebSocketActivityBase implements Filter
                 .request(Messages.Request.QueryAlbums)
                 .addOption(Messages.Key.CATEGORY, categoryName)
                 .addOption(Messages.Key.CATEGORY_ID, categoryId)
-                .addOption(Key.FILTER, filter)
+                .addOption(Key.FILTER, lastFilter)
                 .build();
 
         wss.send(message, socketClient, (SocketMessage response) ->
             adapter.setModel(response.getJsonArrayOption(Messages.Key.DATA)));
     }
 
+
+    private final Debouncer<String> filterDebouncer = new Debouncer<String>(350) {
+        @Override
+        protected void onDebounced(String context) {
+            if (!isPaused()) {
+                requery();
+            }
+        }
+    };
+
     private WebSocketService.Client socketClient = new WebSocketService.Client() {
         @Override
         public void onStateChanged(WebSocketService.State newState, WebSocketService.State oldState) {
             if (newState == WebSocketService.State.Connected) {
+                filterDebouncer.call();
                 requery();
             }
         }

src/musikdroid/app/src/main/java/io/casey/musikcube/remote/CategoryBrowseActivity.java

@@ -56,7 +56,7 @@ public class CategoryBrowseActivity extends WebSocketActivityBase implements Fil
 
     private String category;
     private Adapter adapter;
-    private String filter;
+    private String lastFilter;
     private TransportFragment transport;
     private int deepLinkType;
 
@@ -102,8 +102,8 @@ public class CategoryBrowseActivity extends WebSocketActivityBase implements Fil
 
     @Override
     public void setFilter(String filter) {
-        this.filter = filter;
+        this.lastFilter = filter;
-        requery();
+        this.filterDebouncer.call();
     }
 
     @Override
@@ -115,7 +115,7 @@ public class CategoryBrowseActivity extends WebSocketActivityBase implements Fil
         final SocketMessage request = SocketMessage.Builder
             .request(Messages.Request.QueryCategory)
             .addOption(Messages.Key.CATEGORY, category)
-            .addOption(Messages.Key.FILTER, filter)
+            .addOption(Messages.Key.FILTER, lastFilter)
             .build();
 
         getWebSocketService().send(request, this.socketClient, (SocketMessage response) -> {
@@ -126,10 +126,20 @@ public class CategoryBrowseActivity extends WebSocketActivityBase implements Fil
         });
     }
 
+    private final Debouncer<String> filterDebouncer = new Debouncer<String>(350) {
+        @Override
+        protected void onDebounced(String caller) {
+            if (!isPaused()) {
+                requery();
+            }
+        }
+    };
+
     private WebSocketService.Client socketClient = new WebSocketService.Client() {
         @Override
         public void onStateChanged(WebSocketService.State newState, WebSocketService.State oldState) {
             if (newState == WebSocketService.State.Connected) {
+                filterDebouncer.cancel();
                 requery();
             }
         }

src/musikdroid/app/src/main/java/io/casey/musikcube/remote/Debouncer.java

@@ -0,0 +1,35 @@
+package io.casey.musikcube.remote;
+
+import android.os.Handler;
+import android.os.Looper;
+
+public abstract class Debouncer<T> {
+    private Handler handler = new Handler(Looper.getMainLooper());
+    private T t = null;
+    private long delay;
+
+    public Debouncer(long delay) {
+        this.delay = delay;
+    }
+
+    public void call() {
+        handler.removeCallbacks(deferred);
+        handler.postDelayed(deferred, delay);
+    }
+
+    public void call(T t) {
+        this.t = t;
+        handler.removeCallbacks(deferred);
+        handler.postDelayed(deferred, delay);
+    }
+
+    public void cancel() {
+        handler.removeCallbacks(deferred);
+    }
+
+    protected abstract void onDebounced(T caller);
+
+    private Runnable deferred = () -> {
+        onDebounced(t);
+    };
+}

src/musikdroid/app/src/main/java/io/casey/musikcube/remote/MainActivity.java

@@ -373,6 +373,13 @@ public class MainActivity extends WebSocketActivityBase {
         }
     }
 
+    private void clearUi() {
+        model.reset();
+        albumArtModel = new AlbumArtModel();
+        updateAlbumArt();
+        rebindUi();
+    }
+
     private void setMetadataDisplayMode(DisplayMode mode) {
         if (metadataAnim1 != null) {
             metadataAnim1.cancel();
@@ -547,14 +554,12 @@ public class MainActivity extends WebSocketActivityBase {
             if (newState == WebSocketService.State.Connected) {
                 wss.send(SocketMessage.Builder.request(
                     Messages.Request.GetPlaybackOverview.toString()).build());
+
+                rebindUi();
             }
             else if (newState == WebSocketService.State.Disconnected) {
-                model.reset();
+                clearUi();
-                albumArtModel = new AlbumArtModel();
-                updateAlbumArt();
             }
-
-            rebindUi();
         }
 
         @Override

src/musikdroid/app/src/main/java/io/casey/musikcube/remote/TrackListActivity.java

@@ -49,7 +49,7 @@ public class TrackListActivity extends WebSocketActivityBase implements Filterab
     private TransportFragment transport;
     private String categoryType;
     private long categoryId;
-    private String filter = "";
+    private String lastFilter = "";
 
     @Override
     protected void onCreate(@Nullable Bundle savedInstanceState) {
@@ -107,14 +107,15 @@ public class TrackListActivity extends WebSocketActivityBase implements Filterab
 
     @Override
     public void setFilter(String filter) {
-        this.filter = filter;
+        this.lastFilter = filter;
-        tracks.requery();
+        this.filterDebouncer.call();
     }
 
     private WebSocketService.Client socketServiceClient = new WebSocketService.Client() {
         @Override
         public void onStateChanged(WebSocketService.State newState, WebSocketService.State oldState) {
             if (newState == WebSocketService.State.Connected) {
+                filterDebouncer.cancel();
                 tracks.requery();
             }
         }
@@ -128,6 +129,15 @@ public class TrackListActivity extends WebSocketActivityBase implements Filterab
         }
     };
 
+    private final Debouncer<String> filterDebouncer = new Debouncer<String>(350) {
+        @Override
+        protected void onDebounced(String caller) {
+            if (!isPaused()) {
+                tracks.requery();
+            }
+        }
+    };
+
     private View.OnClickListener onItemClickListener = (View view) -> {
         int index = (Integer) view.getTag();
         SocketMessage request;
@@ -138,14 +148,14 @@ public class TrackListActivity extends WebSocketActivityBase implements Filterab
                 .addOption(Messages.Key.CATEGORY, categoryType)
                 .addOption(Messages.Key.ID, categoryId)
                 .addOption(Messages.Key.INDEX, index)
-                .addOption(Messages.Key.FILTER, filter)
+                .addOption(Messages.Key.FILTER, lastFilter)
                 .build();
         }
         else {
             request = SocketMessage.Builder
                 .request(Messages.Request.PlayAllTracks)
                 .addOption(Messages.Key.INDEX, index)
-                .addOption(Messages.Key.FILTER, filter)
+                .addOption(Messages.Key.FILTER, lastFilter)
                 .build();
         }
 
@@ -232,7 +242,7 @@ public class TrackListActivity extends WebSocketActivityBase implements Filterab
                         .addOption(Messages.Key.CATEGORY, categoryType)
                         .addOption(Messages.Key.ID, categoryId)
                         .addOption(Messages.Key.COUNT_ONLY, true)
-                        .addOption(Messages.Key.FILTER, filter)
+                        .addOption(Messages.Key.FILTER, lastFilter)
                         .build();
                 }
 
@@ -244,7 +254,7 @@ public class TrackListActivity extends WebSocketActivityBase implements Filterab
                         .addOption(Messages.Key.ID, categoryId)
                         .addOption(Messages.Key.OFFSET, offset)
                         .addOption(Messages.Key.LIMIT, limit)
-                        .addOption(Messages.Key.FILTER, filter)
+                        .addOption(Messages.Key.FILTER, lastFilter)
                         .build();
                 }
             };
@@ -256,7 +266,7 @@ public class TrackListActivity extends WebSocketActivityBase implements Filterab
                 public SocketMessage getRequeryMessage() {
                     return SocketMessage.Builder
                         .request(Messages.Request.QueryTracks)
-                        .addOption(Messages.Key.FILTER, filter)
+                        .addOption(Messages.Key.FILTER, lastFilter)
                         .addOption(Messages.Key.COUNT_ONLY, true)
                         .build();
                 }
@@ -267,7 +277,7 @@ public class TrackListActivity extends WebSocketActivityBase implements Filterab
                         .request(Messages.Request.QueryTracks)
                         .addOption(Messages.Key.OFFSET, offset)
                         .addOption(Messages.Key.LIMIT, limit)
-                        .addOption(Messages.Key.FILTER, filter)
+                        .addOption(Messages.Key.FILTER, lastFilter)
                         .build();
                 }
             };

src/musikdroid/app/src/main/java/io/casey/musikcube/remote/WebSocketActivityBase.java

@@ -7,6 +7,7 @@ import android.view.KeyEvent;
 
 public abstract class WebSocketActivityBase extends AppCompatActivity {
     private WebSocketService wss;
+    private boolean paused = true;
 
     @Override
     protected void onCreate(@Nullable Bundle savedInstanceState) {
@@ -18,12 +19,14 @@ public abstract class WebSocketActivityBase extends AppCompatActivity {
     protected void onPause() {
         super.onPause();
         this.wss.removeClient(getWebSocketServiceClient());
+        this.paused = true;
     }
 
     @Override
     protected void onResume() {
         super.onResume();
         this.wss.addClient(getWebSocketServiceClient());
+        this.paused = false;
     }
 
     @Override
@@ -49,6 +52,10 @@ public abstract class WebSocketActivityBase extends AppCompatActivity {
         return super.onKeyDown(keyCode, event);
     }
 
+    protected final boolean isPaused() {
+        return this.paused;
+    }
+
     protected final WebSocketService getWebSocketService() {
         return this.wss;
     }