Closes #3027

app/src/main/java/fr/free/nrw/commons/category/CategoriesModel.java

@@ -48,8 +48,21 @@ public CategoriesModel(MediaWikiApi mwApi,
      */
     public Comparator<CategoryItem> sortBySimilarity(final String filter) {
         Comparator<String> stringSimilarityComparator = StringSortingUtils.sortBySimilarity(filter);
-        return (firstItem, secondItem) -> stringSimilarityComparator
-                .compare(firstItem.getName(), secondItem.getName());
+        return (firstItem, secondItem) -> {
+            //if the category is selected, it should get precedence
+            if (null != firstItem && firstItem.isSelected()) {
+                if (null != secondItem && secondItem.isSelected()) {
+                    return stringSimilarityComparator
+                            .compare(firstItem.getName(), secondItem.getName());
+                }
+                return -1;
+            }
+            if (null != secondItem && secondItem.isSelected()) {
+                return 1;
+            }
+            return stringSimilarityComparator
+                    .compare(firstItem.getName(), secondItem.getName());
+        };
     }
 
     /**
@@ -255,4 +268,38 @@ public void cleanUp() {
         this.categoriesCache.clear();
         this.selectedCategories.clear();
     }
+
+    /**
+     * Search for categories
+     */
+    public Observable<CategoryItem> searchCategories(String query, List<String> imageTitleList) {
+        if (TextUtils.isEmpty(query)) {
+            return gpsCategories()
+                    .concatWith(titleCategories(imageTitleList))
+                    .concatWith(recentCategories());
+        }
+
+        return mwApi
+                .searchCategories(query, SEARCH_CATS_LIMIT)
+                .map(s -> new CategoryItem(s, false));
+    }
+
+    /**
+     * Returns default categories
+     */
+    public Observable<CategoryItem> getDefaultCategories(List<String> titleList) {
+        Observable<CategoryItem> directCategories = directCategories();
+        if (hasDirectCategories()) {
+            Timber.d("Image has direct Categories");
+            return directCategories
+                    .concatWith(gpsCategories())
+                    .concatWith(titleCategories(titleList))
+                    .concatWith(recentCategories());
+        } else {
+            Timber.d("Image has no direct Categories");
+            return gpsCategories()
+                    .concatWith(titleCategories(titleList))
+                    .concatWith(recentCategories());
+        }
+    }
 }

app/src/main/java/fr/free/nrw/commons/repository/UploadRemoteDataSource.java

@@ -11,10 +11,8 @@
 import fr.free.nrw.commons.upload.UploadModel.UploadItem;
 import io.reactivex.Observable;
 import io.reactivex.Single;
-
 import java.util.Comparator;
 import java.util.List;
-
 import javax.inject.Inject;
 import javax.inject.Singleton;
 
@@ -167,7 +165,7 @@ public Observable<UploadItem> preProcessImage(UploadableFile uploadableFile, Pla
     }
 
     /**
-     * ask the UplaodModel for the image quality of the UploadItem
+     * ask the UploadModel for the image quality of the UploadItem
      *
      * @param uploadItem
      * @param shouldValidateTitle
@@ -176,4 +174,21 @@ public Observable<UploadItem> preProcessImage(UploadableFile uploadableFile, Pla
     public Single<Integer> getImageQuality(UploadItem uploadItem, boolean shouldValidateTitle) {
         return uploadModel.getImageQuality(uploadItem, shouldValidateTitle);
     }
+
+    /**
+     * Ask the CategoriesModel to search categories
+     * @param query
+     * @param imageTitleList
+     * @return
+     */
+    public Observable<CategoryItem> searchCategories(String query, List<String> imageTitleList) {
+        return categoriesModel.searchCategories(query, imageTitleList);
+    }
+
+    /**
+     * Ask the CategoriesModel for default categories
+     */
+    public Observable<CategoryItem> getDefaultCategories(List<String> imageTitleList) {
+        return categoriesModel.getDefaultCategories(imageTitleList);
+    }
 }

app/src/main/java/fr/free/nrw/commons/repository/UploadRepository.java

@@ -8,10 +8,8 @@
 import fr.free.nrw.commons.upload.UploadModel.UploadItem;
 import io.reactivex.Observable;
 import io.reactivex.Single;
-
 import java.util.Comparator;
 import java.util.List;
-
 import javax.inject.Inject;
 import javax.inject.Singleton;
 
@@ -262,4 +260,18 @@ public String getValue(String key, String value) {
     public void setSelectedLicense(String licenseName) {
         localDataSource.setSelectedLicense(licenseName);
     }
+
+    /**
+     * Ask the RemoteDataSource to search for categories
+     */
+    public Observable<CategoryItem> searchCategories(String query, List<String> imageTitleList) {
+        return remoteDataSource.searchCategories(query, imageTitleList);
+    }
+
+    /**
+     * Ask the RemoteDataSource to get default categories
+     */
+    public Observable<CategoryItem> getDefaultCategories(List<String> imageTitleList) {
+        return remoteDataSource.getDefaultCategories(imageTitleList);
+    }
 }

app/src/main/java/fr/free/nrw/commons/upload/categories/CategoriesPresenter.java

@@ -80,6 +80,9 @@ public void searchForCategories(String query) {
                 .observeOn(ioScheduler)
                 .concatWith(
                         repository.searchAll(query, imageTitleList)
+                                .mergeWith(repository.searchCategories(query, imageTitleList))
+                                .concatWith(TextUtils.isEmpty(query) ? repository
+                                        .getDefaultCategories(imageTitleList) : Observable.empty())
                 )
                 .filter(categoryItem -> !repository.containsYear(categoryItem.getName()))
                 .distinct();

app/src/main/java/fr/free/nrw/commons/upload/categories/UploadCategoriesFragment.java

@@ -89,7 +89,7 @@ private void init() {
     @Override
     public void onResume() {
         super.onResume();
-        if (presenter != null && isVisible && (categories == null || categories.isEmpty())) {
+        if (presenter != null && isVisible) {
             presenter.searchForCategories(null);
         }
     }
@@ -193,7 +193,7 @@ public void setUserVisibleHint(boolean isVisibleToUser) {
         super.setUserVisibleHint(isVisibleToUser);
         isVisible = isVisibleToUser;
 
-        if (presenter != null && isResumed() && (categories == null || categories.isEmpty())) {
+        if (presenter != null && isResumed()) {
             presenter.searchForCategories(null);
         }
     }

app/src/test/kotlin/fr/free/nrw/commons/upload/CategoriesPresenterTest.kt

@@ -57,7 +57,9 @@ class CategoriesPresenterTest {
     fun searchForCategoriesTest() {
         Mockito.`when`(repository?.sortBySimilarity(ArgumentMatchers.anyString())).thenReturn(Comparator<CategoryItem> { _, _ -> 1 })
         Mockito.`when`(repository?.selectedCategories).thenReturn(categoryItems)
-        Mockito.`when`(repository?.searchAll(ArgumentMatchers.anyString(), ArgumentMatchers.anyList())).thenReturn(Observable.empty())
+        Mockito.`when`(repository?.searchAll(ArgumentMatchers.anyString(), ArgumentMatchers.anyList())).thenReturn(testObservable)
+        Mockito.`when`(repository?.searchCategories(ArgumentMatchers.anyString(), ArgumentMatchers.anyList())).thenReturn(testObservable)
+        Mockito.`when`(repository?.getDefaultCategories(ArgumentMatchers.anyList())).thenReturn(testObservable)
         categoriesPresenter?.searchForCategories("test")
         verify(view)?.showProgress(true)
         verify(view)?.showError(null)