add active flow page

lib/pages/flow.dart

@@ -36,6 +36,31 @@ class _FlowsPageState extends State<FlowsPage> {
     );
   }
 
+  Widget listFlowInfoByActive(
+      BuildContext context, Map<String, API.FlowInfo> infos) {
+    return FutureBuilder(future: () async {
+      var included = [];
+
+      for (var key in infos.keys) {
+        var active = await API.API().getActiveFlowsOf(key);
+        if (active.isNotEmpty) {
+          included.add(infos[key]);
+        }
+      }
+
+      return included;
+    }(), builder: (context, snapshot) {
+      if (!snapshot.hasData) {
+        return const CircularProgressIndicator();
+      }
+
+      var included = snapshot.data!;
+
+      return ListView(
+          children: included.map((x) => flowTile(context, x)).toList());
+    });
+  }
+
   Widget listAllFlowInfos(
       BuildContext context, Map<String, API.FlowInfo> infos) {
     return ListView(
@@ -101,8 +126,6 @@ class _FlowsPageState extends State<FlowsPage> {
 
   @override
   Widget build(BuildContext context) {
-    // todo : list currently active
-
     if (flowInfos == null) {
       return const CircularProgressIndicator();
     }
@@ -111,7 +134,12 @@ class _FlowsPageState extends State<FlowsPage> {
         appBar: AppBar(
             title: const Text("Flows"),
             bottom: TabBar(
-              tabs: const [Text("All"), Text("Produces"), Text("Depends")],
+              tabs: const [
+                Text("All"),
+                Text("Produces"),
+                Text("Depends"),
+                Text("Active")
+              ],
               onTap: (value) {
                 setState(() {
                   tabSelection = value;
@@ -122,6 +150,7 @@ class _FlowsPageState extends State<FlowsPage> {
           0 => listAllFlowInfos(context, flowInfos!),
           1 => listFlowInfoByProduced(context, flowInfos!),
           2 => listFlowInfoByDependant(context, flowInfos!),
+          3 => listFlowInfoByActive(context, flowInfos!),
           _ => const Text("..."),
         });
   }