fix #128

lib/foundation/appdata.dart

@@ -150,6 +150,7 @@ class _Settings with ChangeNotifier {
     'enableCustomImageProcessing': false,
     'customImageProcessing': _defaultCustomImageProcessing,
     'sni': true,
+    'autoAddLanguageFilter': 'none', // none, chinese, english, japanese
   };
 
   operator [](String key) {

lib/pages/search_page.dart

@@ -139,7 +139,9 @@ class _SearchPageState extends State<SearchPage> {
   @override
   void initState() {
     var defaultSearchTarget = appdata.settings['defaultSearchTarget'];
-    if (defaultSearchTarget != null &&
+    if (defaultSearchTarget == "_aggregated_") {
+      aggregatedSearch = true;
+    } else if (defaultSearchTarget != null &&
         ComicSource.find(defaultSearchTarget) != null) {
       searchTarget = defaultSearchTarget;
     } else {

lib/pages/search_result_page.dart

@@ -45,8 +45,9 @@ class _SearchResultPageState extends State<SearchResultPage> {
       if (suggestionsController.entry != null) {
         suggestionsController.remove();
       }
+      text = checkAutoLanguage(text);
       setState(() {
-        this.text = text;
+        this.text = text!;
       });
       appdata.addSearchHistory(text);
       controller.currentText = text;
@@ -92,13 +93,33 @@ class _SearchResultPageState extends State<SearchResultPage> {
     super.dispose();
   }
 
+  String checkAutoLanguage(String text) {
+    var setting = appdata.settings["autoAddLanguageFilter"] ?? 'none';
+    if (setting == 'none') {
+      return text;
+    }
+    var searchSource = sourceKey;
+    // TODO: Move it to a better place
+    const enabledSources = [
+      'nhentai',
+      'ehentai',
+    ];
+    if (!enabledSources.contains(searchSource)) {
+      return text;
+    }
+    if (!text.contains('language:')) {
+      return '$text language:$setting';
+    }
+    return text;
+  }
+
   @override
   void initState() {
+    sourceKey = widget.sourceKey;
     controller = SearchBarController(
-      currentText: widget.text,
+      currentText: checkAutoLanguage(widget.text),
       onSearch: search,
     );
-    sourceKey = widget.sourceKey;
     options = widget.options ?? const [];
     validateOptions();
     text = widget.text;
@@ -162,6 +183,12 @@ class _SearchResultPageState extends State<SearchResultPage> {
       child: IconButton(
         icon: const Icon(Icons.tune),
         onPressed: () async {
+          if (suggestionOverlay != null) {
+            suggestionsController.remove();
+          }
+
+          var previousOptions = options;
+          var previousSourceKey = sourceKey;
           await showDialog(
             context: context,
             useRootNavigator: true,
@@ -169,7 +196,11 @@ class _SearchResultPageState extends State<SearchResultPage> {
               return _SearchSettingsDialog(state: this);
             },
           );
-          setState(() {});
+          if (previousOptions != options || previousSourceKey != sourceKey) {
+            text = checkAutoLanguage(controller.text);
+            controller.currentText = text;
+            setState(() {});
+          }
         },
       ),
     );

lib/pages/settings/explore_settings.dart

@@ -88,6 +88,30 @@ class _ExploreSettingsState extends State<ExploreSettings> {
           title: "Keyword blocking".tl,
           builder: () => const _ManageBlockingWordView(),
         ).toSliver(),
+        SelectSetting(
+          title: "Default Search Target".tl,
+          settingKey: "defaultSearchTarget",
+          optionTranslation: {
+            '_aggregated_': "Aggregated".tl,
+            ...((){
+              var map = <String, String>{};
+              for (var c in ComicSource.all()) {
+                map[c.key] = c.name;
+              }
+              return map;
+            }()),
+          },
+        ).toSliver(),
+        SelectSetting(
+          title: "Auto Language Filters".tl,
+          settingKey: "autoAddLanguageFilter",
+          optionTranslation: {
+            'none': "None".tl,
+            'chinese': "Chinese",
+            'english': "English",
+            'japanese': "Japanese",
+          },
+        ).toSliver(),
       ],
     );
   }
@@ -150,7 +174,7 @@ class _ManageBlockingWordViewState extends State<_ManageBlockingWordView> {
                 errorText: error,
               ),
               onChanged: (s) {
-                if(error != null){
+                if (error != null) {
                   setState(() {
                     error = null;
                   });
@@ -160,7 +184,8 @@ class _ManageBlockingWordViewState extends State<_ManageBlockingWordView> {
             actions: [
               Button.filled(
                 onPressed: () {
-                  if(appdata.settings["blockedWords"].contains(controller.text)){
+                  if (appdata.settings["blockedWords"]
+                      .contains(controller.text)) {
                     setState(() {
                       error = "Keyword already exists".tl;
                     });