State Transitions and Reverse

lib/definitions.dart

@@ -1,5 +1,6 @@
-abstract class IState {
+class StateTransition {
     Branch branch;
+    bool reverse = false;
 }
 
 typedef void StateSet();

lib/graph/renderGraph.dart

@@ -3,22 +3,22 @@ import '../node/login.dart';
 import 'package:flutter/material.dart';
 
 abstract class Transition {
-  Widget create(Animation<double> animation, Widget from, Widget to);
+  Widget create(Animation<double> animation, Widget from, Widget to, bool reverse);
 }
 
 class PageSlideTransition implements Transition {
-  Widget create(Animation<double> animation, Widget from, Widget to) {
+  Widget create(Animation<double> animation, Widget from, Widget to, bool reverse) {
     return Stack(textDirection: TextDirection.ltr, children: <Widget>[
       SlideTransition(
         position: Tween<Offset>(
           begin: Offset.zero,
-          end: const Offset(-1.0, 0.0),
+          end: Offset(reverse ? 1.0 : -1.0, 0.0),
         ).animate(animation),
         child: from,
       ),
       SlideTransition(
         position: Tween<Offset>(
-          begin: const Offset(1.0, 0.0),
+          begin: Offset(reverse ? -1.0 : 1.0, 0.0),
           end: Offset.zero,
         ).animate(animation),
         child: to,
@@ -36,7 +36,7 @@ class RenderGraph {
     _state = state;
   }
 
-  static Widget build(IState state) {
+  static Widget build(StateTransition state) {
     var buildState = _build(state);
 
     if (_current == null) {
@@ -48,19 +48,22 @@ class RenderGraph {
             vsync: _state, duration: const Duration(milliseconds: 1000));
 
         var transition = (buildState.transition as PageSlideTransition)
-            .create(_animationController, _current, buildState.widget);
+            .create(_animationController, _current, buildState.widget, state.reverse);
 
         _current = buildState.widget;
 
         _animationController.forward();
+
+        state.reverse = false;
+
         return transition;
       } else {
         return buildState.widget;
       }
     }
   }
 
-  static WidgetState _build(IState state) {
+  static WidgetState _build(StateTransition state) {
     // Compiled state management
     if (state.branch == Branch.login)
       return WidgetState(LoginNode.render(state),
@@ -81,4 +84,4 @@ class WidgetState {
 
   final Widget widget;
   final Transition transition;
-}
+}

lib/graph/stateGraph.dart

@@ -4,29 +4,30 @@ import '../repository/api.dart';
 class StateGraph {
   static StateSet _triggerBuild;
 
-  static List<IState> _state = new List<IState>();
+  static List<StateTransition> _state = new List<StateTransition>();
   static initialize(StateSet setState) {
     _triggerBuild = setState;
   }
 
-  static setInitialState(IState state) {
+  static setInitialState(StateTransition state) {
     _state.add(state);
   }
 
   static reverse() {
     _state.removeAt(_state.length - 1);
+    _state[_state.length - 1].reverse = true;
     _triggerBuild();
   }
 
-  static apply(IState state) {
+  static apply(StateTransition state) {
     _state.add(state);
     _triggerBuild();
   }
 
   // Get token from state graph
   static ApiState apiState() => ApiState(send, "token");
 
-  static IState current() {
+  static StateTransition current() {
     return _state[_state.length - 1];
   }
 }

lib/node/login.dart

@@ -3,23 +3,23 @@ import 'package:flutter/material.dart';
 import '../graph/stateGraph.dart';
 import '../repository/account.dart';
 
-class DefaultLoginState implements IState {
+class DefaultLoginState extends StateTransition {
   Branch branch = Branch.login;
 }
 
 class LoginErrorState extends DefaultLoginState {
   String loginErrorMessage = "There was an error";
 }
 
-typedef IState LoginFunction(
+typedef StateTransition LoginFunction(
     LoginRequest loginRequest, String username, String password);
 
 class LoginNode {
-  static Widget render(IState state) {
+  static Widget render(StateTransition state) {
     return _render(state);
   }
 
-  static Widget _render(IState state) {
+  static Widget _render(StateTransition state) {
     if (state is LoginErrorState)
       return Container(
           padding: EdgeInsets.fromLTRB(0.0, 20.0, 0.0, 0.0),
@@ -56,7 +56,7 @@ class LoginNode {
           ])));
   }
 
-  static IState login(
+  static StateTransition login(
       LoginRequest loginRequest, String username, String password) {
     final result = loginRequest(username, password);