rework debounce hook to be more friendly

lib/hooks/debounce.dart

@@ -6,18 +6,16 @@ import 'package:flutter_hooks/flutter_hooks.dart';
 import 'ref.dart';
 
 class Debounce {
-  final bool pending;
   final bool loading;
-  final void Function() start;
-  final void Function() cancel;
-  final void Function() reset;
+  final void Function() bounce;
+
+  call() {
+    bounce();
+  }
 
   const Debounce({
-    @required this.pending,
     @required this.loading,
-    @required this.start,
-    @required this.cancel,
-    @required this.reset,
+    @required this.bounce,
   });
 }
 
@@ -25,33 +23,28 @@ class Debounce {
 /// and loading is triggered after [delayDuration].
 /// Everything can be reset with [.cancel()]
 Debounce useDebounce(
-  Function(Function cancel) onDebounce, [
+  Future<Null> Function() onDebounce, [
   Duration delayDuration = const Duration(milliseconds: 500),
 ]) {
   final loading = useState(false);
-  final pending = useState(false);
   final timerHandle = useRef<Timer>(null);
 
   cancel() {
     timerHandle.current?.cancel();
-    pending.value = false;
     loading.value = false;
   }
 
   start() {
-    timerHandle.current = Timer(delayDuration, () {
+    timerHandle.current = Timer(delayDuration, () async {
       loading.value = true;
-      onDebounce(cancel);
+      await onDebounce();
+      cancel();
     });
-    pending.value = true;
   }
 
   return Debounce(
       loading: loading.value,
-      pending: pending.value,
-      start: start,
-      cancel: cancel,
-      reset: () {
+      bounce: () {
         cancel();
         start();
       });

lib/pages/add_instance.dart

@@ -15,39 +15,27 @@ class AddInstancePage extends HookWidget {
     final instanceController = useTextEditingController();
     useValueListenable(instanceController);
     final accountsStore = useAccountsStore();
-    final delayedLoading = useDelayedLoading(Duration(milliseconds: 1000));
+    final delayedLoading = useDelayedLoading(Duration(milliseconds: 500));
 
     final isSite = useState<bool>(null);
-    final input = useState('');
     final loading = useState(false);
     final icon = useState<String>(null);
-    final debounce = useDebounce((cancel) async {
-      if (instanceController.text.isNotEmpty) {
-        try {
-          icon.value =
-              (await LemmyApi(instanceController.text).v1.getSite()).site.icon;
-          isSite.value = true;
-        } catch (e) {
-          isSite.value = false;
-        }
-        cancel();
+    final debounce = useDebounce(() async {
+      if (instanceController.text.isEmpty) {
+        isSite.value = null;
+        return;
+      }
+
+      try {
+        icon.value =
+            (await LemmyApi(instanceController.text).v1.getSite()).site.icon;
+        isSite.value = true;
+      } catch (e) {
+        isSite.value = false;
       }
     });
 
-    onType() {
-      if (input.value != instanceController.text) {
-        isSite.value = null;
-        input.value = instanceController.text;
-        if (instanceController.text.isEmpty) {
-          debounce.reset();
-          debounce.cancel();
-        } else {
-          debounce.reset();
-        }
-      }
-    }
-
-    instanceController.addListener(onType);
+    instanceController.addListener(debounce);
 
     handleOnAdd() async {
       delayedLoading.start();