refactor and move stuff

lib/tools/external_stream_state.dart

@@ -0,0 +1,27 @@
+import 'dart:async';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+// Caches a state value which can be changed from anywhere
+// Creates a provider interface that notices when the value changes
+class ExternalStreamState<T> {
+  T currentState;
+  StreamController<T> streamController;
+  ExternalStreamState(T initialState)
+      : currentState = initialState,
+        streamController = StreamController<T>.broadcast();
+  void add(T newState) {
+    currentState = newState;
+    streamController.add(newState);
+  }
+
+  AutoDisposeStreamProvider<T> provider() {
+    return AutoDisposeStreamProvider<T>((ref) async* {
+      if (await streamController.stream.isEmpty) {
+        yield currentState;
+      }
+      await for (final value in streamController.stream) {
+        yield value;
+      }
+    });
+  }
+}