Update search query results when messages disappear.

Previously, if a message disappeared while looking at it in the search
results, it'd still stick around. Now they'll disappear from the results
in real-time.

src/org/thoughtcrime/securesms/database/CursorList.java

@@ -1,6 +1,8 @@
 package org.thoughtcrime.securesms.database;
 
+import android.database.ContentObserver;
 import android.database.Cursor;
+import android.database.DataSetObserver;
 import android.database.MatrixCursor;
 import android.support.annotation.NonNull;
 
@@ -22,8 +24,6 @@ import java.util.ListIterator;
  */
 public class CursorList<T> implements List<T>, Closeable {
 
-  private static final Cursor EMPTY_CURSOR = new MatrixCursor(new String[] { "a" }, 0);
-
   private final Cursor          cursor;
   private final ModelBuilder<T> modelBuilder;
 
@@ -34,7 +34,11 @@ public class CursorList<T> implements List<T>, Closeable {
 
   public static <T> CursorList<T> emptyList() {
     //noinspection ConstantConditions,unchecked
-    return (CursorList<T>) new CursorList(EMPTY_CURSOR, null);
+    return (CursorList<T>) new CursorList(emptyCursor(), null);
+  }
+
+  private static Cursor emptyCursor() {
+    return new MatrixCursor(new String[] { "a" }, 0);
   }
 
   @Override
@@ -183,6 +187,14 @@ public class CursorList<T> implements List<T>, Closeable {
     }
   }
 
+  public void registerContentObserver(@NonNull ContentObserver observer) {
+    cursor.registerContentObserver(observer);
+  }
+
+  public void unregisterContentObserver(@NonNull ContentObserver observer) {
+    cursor.unregisterContentObserver(observer);
+  }
+
   public interface ModelBuilder<T> {
     T build(@NonNull Cursor cursor);
   }

src/org/thoughtcrime/securesms/database/SearchDatabase.java

@@ -83,7 +83,9 @@ public class SearchDatabase extends Database {
 
     String prefixQuery = query + '*';
 
-    return db.rawQuery(MESSAGES_QUERY, new String[] { prefixQuery, prefixQuery });
+    Cursor cursor = db.rawQuery(MESSAGES_QUERY, new String[] { prefixQuery, prefixQuery });
+    setNotifyConverationListListeners(cursor);
+    return cursor;
   }
 }
 

src/org/thoughtcrime/securesms/search/SearchViewModel.java

@@ -4,7 +4,10 @@ import android.arch.lifecycle.LiveData;
 import android.arch.lifecycle.MutableLiveData;
 import android.arch.lifecycle.ViewModel;
 import android.arch.lifecycle.ViewModelProvider;
+import android.database.ContentObserver;
+import android.os.Handler;
 import android.support.annotation.NonNull;
+import android.text.TextUtils;
 
 import org.thoughtcrime.securesms.search.model.SearchResult;
 import org.thoughtcrime.securesms.util.Debouncer;
@@ -19,16 +22,25 @@ import org.thoughtcrime.securesms.util.Debouncer;
  */
 class SearchViewModel extends ViewModel {
 
-  private final ClosingLiveData  searchResult;
+  private final ObservingLiveData searchResult;
   private final SearchRepository  searchRepository;
   private final Debouncer         debouncer;
 
   private String lastQuery;
 
   SearchViewModel(@NonNull SearchRepository searchRepository) {
-    this.searchResult     = new ClosingLiveData();
+    this.searchResult     = new ObservingLiveData();
     this.searchRepository = searchRepository;
     this.debouncer        = new Debouncer(500);
+
+    searchResult.registerContentObserver(new ContentObserver(new Handler()) {
+      @Override
+      public void onChange(boolean selfChange) {
+        if (!TextUtils.isEmpty(getLastQuery())) {
+          searchRepository.query(getLastQuery(), searchResult::postValue);
+        }
+      }
+    });
   }
 
   LiveData<SearchResult> getSearchResult() {
@@ -54,23 +66,36 @@ class SearchViewModel extends ViewModel {
   /**
    * Ensures that the previous {@link SearchResult} is always closed whenever we set a new one.
    */
-  private static class ClosingLiveData extends MutableLiveData<SearchResult> {
+  private static class ObservingLiveData extends MutableLiveData<SearchResult> {
+
+    private ContentObserver observer;
 
     @Override
     public void setValue(SearchResult value) {
       SearchResult previous = getValue();
+
       if (previous != null) {
+        previous.unregisterContentObserver(observer);
         previous.close();
       }
+
+      value.registerContentObserver(observer);
+
       super.setValue(value);
     }
 
-    public void close() {
+    void close() {
       SearchResult value = getValue();
+
       if (value != null) {
+        value.unregisterContentObserver(observer);
         value.close();
       }
     }
+
+    void registerContentObserver(@NonNull ContentObserver observer) {
+      this.observer = observer;
+    }
   }
 
   public static class Factory extends ViewModelProvider.NewInstanceFactory {

src/org/thoughtcrime/securesms/search/model/SearchResult.java

@@ -1,5 +1,7 @@
 package org.thoughtcrime.securesms.search.model;
 
+import android.database.ContentObserver;
+import android.database.DataSetObserver;
 import android.support.annotation.NonNull;
 
 import org.thoughtcrime.securesms.database.CursorList;
@@ -56,6 +58,18 @@ public class SearchResult {
     return size() == 0;
   }
 
+  public void registerContentObserver(@NonNull ContentObserver observer) {
+    contacts.registerContentObserver(observer);
+    conversations.registerContentObserver(observer);
+    messages.registerContentObserver(observer);
+  }
+
+  public void unregisterContentObserver(@NonNull ContentObserver observer) {
+    contacts.unregisterContentObserver(observer);
+    conversations.unregisterContentObserver(observer);
+    messages.unregisterContentObserver(observer);
+  }
+
   public void close() {
     contacts.close();
     conversations.close();