OCFileListFragment: make search async task static, fix loading animation usage

Signed-off-by: Álvaro Brey Vilas <alvaro.brey@nextcloud.com>

app/src/main/java/com/owncloud/android/ui/fragment/OCFileListFragment.java

@@ -77,7 +77,6 @@ import com.owncloud.android.ui.activity.FileActivity;
 import com.owncloud.android.ui.activity.FileDisplayActivity;
 import com.owncloud.android.ui.activity.FolderPickerActivity;
 import com.owncloud.android.ui.activity.OnEnforceableRefreshListener;
-import com.owncloud.android.ui.activity.ToolbarActivity;
 import com.owncloud.android.ui.activity.UploadFilesActivity;
 import com.owncloud.android.ui.adapter.OCFileListAdapter;
 import com.owncloud.android.ui.dialog.ChooseRichDocumentsTemplateDialogFragment;
@@ -114,6 +113,7 @@ import org.greenrobot.eventbus.Subscribe;
 import org.greenrobot.eventbus.ThreadMode;
 
 import java.io.File;
+import java.lang.ref.WeakReference;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
@@ -1510,6 +1510,87 @@ public class OCFileListFragment extends ExtendedListFragment implements
         handleSearchEvent(event);
     }
 
+    private static class SearchAsyncTask extends AsyncTask<Void, Void, Boolean> {
+
+        private final WeakReference<FileFragment.ContainerActivity> activityReference;
+        private final WeakReference<OCFileListFragment> fragmentReference;
+        private final RemoteOperation remoteOperation;
+        private final User currentUser;
+        private final SearchEvent event;
+
+        private SearchAsyncTask(final FileFragment.ContainerActivity containerActivity, final OCFileListFragment fragment, final RemoteOperation remoteOperation, final User currentUser, final SearchEvent event) {
+            this.activityReference = new WeakReference<>(containerActivity);
+            this.fragmentReference = new WeakReference<>(fragment);
+            this.remoteOperation = remoteOperation;
+            this.currentUser = currentUser;
+            this.event = event;
+        }
+
+        @Override
+        protected void onPreExecute() {
+            final OCFileListFragment fragment = fragmentReference.get();
+            if (fragment != null) {
+                new Handler(Looper.getMainLooper()).post(() -> {
+                    fragment.setLoading(true);
+                    fragment.setEmptyListLoadingMessage();
+                });
+            }
+        }
+
+        @Override
+        protected Boolean doInBackground(Void... voids) {
+            final OCFileListFragment fragment = fragmentReference.get();
+            if (fragment == null || isCancelled() || fragment.getContext() == null) {
+                return Boolean.FALSE;
+            }
+
+            fragment.setTitle();
+            RemoteOperationResult remoteOperationResult = remoteOperation.execute(
+                currentUser.toPlatformAccount(), fragment.getContext());
+
+            FileDataStorageManager storageManager = getFileDataStorageManager();
+
+            if (remoteOperationResult.isSuccess() && remoteOperationResult.getResultData() != null
+                && !isCancelled() && fragment.searchFragment) {
+                fragment.searchEvent = event;
+
+                if (remoteOperationResult.getResultData() == null || ((List) remoteOperationResult.getResultData()).isEmpty()) {
+                    fragment.setEmptyView(event);
+                } else {
+                    fragment.mAdapter.setData(((RemoteOperationResult<List>) remoteOperationResult).getResultData(),
+                                              fragment.currentSearchType,
+                                              storageManager,
+                                              fragment.mFile,
+                                              true);
+                }
+            }
+
+            return remoteOperationResult.isSuccess();
+        }
+
+        @Nullable
+        private FileDataStorageManager getFileDataStorageManager() {
+            FileDataStorageManager storageManager = null;
+            final FileFragment.ContainerActivity containerActivity = activityReference.get();
+            if (containerActivity != null && containerActivity.getStorageManager() != null) {
+                storageManager = containerActivity.getStorageManager();
+            }
+            return storageManager;
+        }
+
+        @Override
+        protected void onPostExecute(Boolean bool) {
+            final OCFileListFragment fragment = fragmentReference.get();
+            if (fragment != null) {
+                fragment.setLoading(false);
+                if (!isCancelled()) {
+                    fragment.mAdapter.notifyDataSetChanged();
+                }
+            }
+
+        }
+    }
+
     private void handleSearchEvent(SearchEvent event) {
         if (SearchRemoteOperation.SearchType.PHOTO_SEARCH == event.getSearchType()) {
             return;
@@ -1556,56 +1637,8 @@ public class OCFileListFragment extends ExtendedListFragment implements
             remoteOperation = new GetSharesRemoteOperation();
         }
 
-        remoteOperationAsyncTask = new AsyncTask<Void, Void, Boolean>() {
-            @Override
-            protected Boolean doInBackground(Void... voids) {
-                setTitle();
-                if (getContext() != null && !isCancelled()) {
-                    RemoteOperationResult remoteOperationResult = remoteOperation.execute(
-                        currentUser.toPlatformAccount(), getContext());
-
-                    FileDataStorageManager storageManager = null;
-                    if (mContainerActivity != null && mContainerActivity.getStorageManager() != null) {
-                        storageManager = mContainerActivity.getStorageManager();
-                    }
-
-                    if (remoteOperationResult.isSuccess() && remoteOperationResult.getResultData() != null
-                        && !isCancelled() && searchFragment) {
-                        searchEvent = event;
-
-                        if (remoteOperationResult.getResultData() == null || ((List) remoteOperationResult.getResultData()).isEmpty()) {
-                            setEmptyView(event);
-                        } else {
-                            mAdapter.setData(((RemoteOperationResult<List>) remoteOperationResult).getResultData(),
-                                             currentSearchType,
-                                             storageManager,
-                                             mFile,
-                                             true);
-                        }
-
-                        final ToolbarActivity fileDisplayActivity = (ToolbarActivity) getActivity();
-                        if (fileDisplayActivity != null) {
-                            fileDisplayActivity.runOnUiThread(() -> {
-                                if (fileDisplayActivity != null) {
-                                    setLoading(false);
-                                }
-                            });
-                        }
-                    }
-
-                    return remoteOperationResult.isSuccess();
-                } else {
-                    return Boolean.FALSE;
-                }
-            }
 
-            @Override
-            protected void onPostExecute(Boolean bool) {
-                if (!isCancelled()) {
-                    mAdapter.notifyDataSetChanged();
-                }
-            }
-        };
+        remoteOperationAsyncTask = new SearchAsyncTask(mContainerActivity, this, remoteOperation, currentUser, event);
 
         remoteOperationAsyncTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
     }