Make the name of the function more agnostic.

android/app/build.gradle

@@ -6,7 +6,7 @@ plugins {
 }
 
 android {
-    namespace = "com.example.flutter_empty"
+    namespace = "com.hyperling.expense_tracker"
     compileSdk = flutter.compileSdkVersion
     ndkVersion = flutter.ndkVersion
 
@@ -21,7 +21,7 @@ android {
 
     defaultConfig {
         // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
-        applicationId = "com.example.flutter_empty"
+        applicationId = "com.hyperling.expense_tracker"
         // You can update the following values to match your application needs.
         // For more information, see: https://flutter.dev/to/review-gradle-config.
         minSdk = flutter.minSdkVersion

android/app/src/main/AndroidManifest.xml

@@ -1,6 +1,6 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
     <application
-        android:label="flutter_empty"
+        android:label="Recurring Expense Tracker"
         android:name="${applicationName}"
         android:icon="@mipmap/ic_launcher">
         <activity

lib/main.dart

@@ -7,26 +7,166 @@ void main() {
   runApp(const MainApp());
 }
 
-class MainApp extends StatefulWidget {
+// https://www.tutorialspoint.com/dart_programming/dart_programming_enumeration.htm
+enum Recurrence { daily, weekly, biweekly, montly, yearly }
+
+class Expense {
+  String name;
+  double cost;
+  Recurrence recurrence;
+  String description;
+
+  Expense(this.name, this.cost, this.recurrence, this.description);
+}
+
+class MainApp extends StatelessWidget {
   const MainApp({super.key});
 
   @override
-  State<MainApp> createState() => _MainAppState();
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: 'Recurring Expense Tracker',
+      theme: ThemeData(
+        useMaterial3: true,
+        colorScheme: ColorScheme.fromSeed(seedColor: Colors.green),
+      ),
+      home: HomePage(),
+    );
+  }
 }
 
-class _MainAppState extends State<MainApp> {
-  final nameFieldController = TextEditingController();
+class HomePage extends StatefulWidget {
+  const HomePage({
+    super.key,
+  });
 
   @override
-  void dispose() {
-    // Clean up the controller when the widget is disposed.
-    nameFieldController.dispose();
-    super.dispose();
+  State<HomePage> createState() => _HomePageState();
 }
 
+class _HomePageState extends State<HomePage> {
+  var pageSelected = 0;
+
   @override
   Widget build(BuildContext context) {
-    const inputWidth = 400.0;
+    Widget page;
+    Widget? dialog;
+    switch (pageSelected) {
+      case 0:
+        page = ExpensePage();
+        dialog = ExpenseInputForm();
+      case 1:
+        page = IncomePage();
+      case 2:
+        page = AssetPage();
+      case 3:
+        page = ProjectionPage();
+      case 4:
+        page = SettingsPage();
+      default:
+        throw UnimplementedError('No widget for page $pageSelected yet!');
+    }
+
+    Widget newValue() {
+      return AlertDialog(title: Text("Add New Value"), content: dialog);
+    }
+
+    Widget? floatingButton;
+    if (dialog != null) {
+      floatingButton = IconButton(
+        onPressed: newValue,
+        icon: Icon(Icons.add),
+        color: Theme.of(context).colorScheme.onSurface,
+      );
+    }
+
+    return LayoutBuilder(builder: (context, constraints) {
+      return Scaffold(
+        body: Row(
+          children: [
+            SafeArea(
+              child: NavigationRail(
+                extended: constraints.maxWidth >= 800,
+                destinations: [
+                  NavigationRailDestination(
+                    icon: Icon(Icons.payment),
+                    label: Text('Expenses'),
+                  ),
+                  NavigationRailDestination(
+                    icon: Icon(Icons.account_balance),
+                    label: Text('Income'),
+                  ),
+                  NavigationRailDestination(
+                    icon: Icon(Icons.attach_money),
+                    label: Text('Liquid Assets'),
+                  ),
+                  NavigationRailDestination(
+                    icon: Icon(Icons.bar_chart),
+                    label: Text('Projections'),
+                  ),
+                  NavigationRailDestination(
+                    icon: Icon(Icons.settings),
+                    label: Text('Settings'),
+                  ),
+                ],
+                selectedIndex: pageSelected,
+                onDestinationSelected: (value) {
+                  setState(() {
+                    pageSelected = value;
+                  });
+                },
+              ),
+            ),
+            Expanded(
+              child: Container(
+                color: Theme.of(context).colorScheme.primaryContainer,
+                child: page,
+              ),
+            ),
+          ],
+        ),
+        floatingActionButton: floatingButton,
+      );
+    });
+  }
+}
+
+class ExpensePage extends StatelessWidget {
+  const ExpensePage({
+    super.key,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return ListView(
+      children: [
+        ExpenseInputForm(),
+        ListTile(
+          title: Text("Fake Item 1"),
+          subtitle: Text("30.00 / month"),
+        ),
+        ListTile(
+          title: Text("Fake Item 2"),
+          subtitle: Text("180.00 / year"),
+        ),
+      ],
+    );
+  }
+}
+
+class ExpenseInputForm extends StatefulWidget {
+  const ExpenseInputForm({
+    super.key,
+  });
+
+  @override
+  State<ExpenseInputForm> createState() => _ExpenseInputFormState();
+}
+
+class _ExpenseInputFormState extends State<ExpenseInputForm> {
+  @override
+  Widget build(BuildContext context) {
+    const inputWidth = 300.0;
     const inputHeight = 50.0;
 
     const recurrenceValues = <DropdownMenuEntry>[
@@ -37,11 +177,9 @@ class _MainAppState extends State<MainApp> {
       DropdownMenuEntry(value: Recurrence.yearly, label: "Yearly"),
     ];
 
-    return const MaterialApp(
-      home: Scaffold(
-        body: Center(
+    return Center(
       child: Column(mainAxisSize: MainAxisSize.min, spacing: 10, children: [
-            Text('Input an expense below!'),
+        Text('New Expense'),
         SizedBox(
             width: inputWidth,
             height: inputHeight,
@@ -59,8 +197,8 @@ class _MainAppState extends State<MainApp> {
           height: inputHeight,
           child: TextField(
             keyboardType: TextInputType.numberWithOptions(decimal: true),
-                decoration: InputDecoration(
-                    labelText: "Cost", hintText: "Example: 10.00"),
+            decoration:
+                InputDecoration(labelText: "Cost", hintText: "Example: 10.00"),
           ),
         ),
         DropdownMenu(
@@ -76,25 +214,81 @@ class _MainAppState extends State<MainApp> {
               keyboardType: TextInputType.text,
               decoration: InputDecoration(
                   labelText: "Description",
-                      hintText:
-                          "Example: 1GB data with unlimited talk & text."
-                    ),
+                  hintText: "Example: 1GB data with unlimited talk & text."),
             )),
+        SizedBox(
+            width: inputWidth,
+            height: inputHeight,
+            child: Row(
+              mainAxisAlignment: MainAxisAlignment.spaceEvenly,
+              children: [
+                ElevatedButton.icon(
+                  onPressed: () {
+                    print("TODO: Clear fields!");
+                  },
+                  icon: Icon(Icons.cancel),
+                  label: Text('Cancel'),
+                ),
+                ElevatedButton.icon(
+                  onPressed: () {
+                    print("TODO: Save expense!");
+                  },
+                  icon: Icon(Icons.save),
+                  label: Text('Submit'),
+                ),
+              ],
+            ))
       ]),
-        ),
-      ),
     );
   }
 }
 
-// https://www.tutorialspoint.com/dart_programming/dart_programming_enumeration.htm
-enum Recurrence { daily, weekly, biweekly, montly, yearly }
+class IncomePage extends StatelessWidget {
+  const IncomePage({
+    super.key,
+  });
 
-class Expense {
-  String name;
-  double cost;
-  Recurrence recurrence;
-  String description;
-
-  Expense(this.name, this.cost, this.recurrence, this.description);
+  @override
+  Widget build(BuildContext context) {
+    return Center(
+        child: Column(
+      children: [
+        Text("TBD"),
+        Placeholder(),
+      ],
+    ));
+  }
+}
+
+class AssetPage extends StatelessWidget {
+  const AssetPage({
+    super.key,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return Placeholder();
+  }
+}
+
+class ProjectionPage extends StatelessWidget {
+  const ProjectionPage({
+    super.key,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return Placeholder();
+  }
+}
+
+class SettingsPage extends StatelessWidget {
+  const SettingsPage({
+    super.key,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return Placeholder();
+  }
 }

linux/CMakeLists.txt

@@ -4,10 +4,10 @@ project(runner LANGUAGES CXX)
 
 # The name of the executable created for the application. Change this to change
 # the on-disk name of your application.
-set(BINARY_NAME "flutter_empty")
+set(BINARY_NAME "expense_tracker")
 # The unique GTK application identifier for this application. See:
 # https://wiki.gnome.org/HowDoI/ChooseApplicationID
-set(APPLICATION_ID "com.example.flutter_empty")
+set(APPLICATION_ID "com.hyperling.expense_tracker")
 
 # Explicitly opt in to modern CMake behaviors to avoid warnings with recent
 # versions of CMake.

linux/runner/my_application.cc

@@ -40,11 +40,11 @@ static void my_application_activate(GApplication* application) {
   if (use_header_bar) {
     GtkHeaderBar* header_bar = GTK_HEADER_BAR(gtk_header_bar_new());
     gtk_widget_show(GTK_WIDGET(header_bar));
-    gtk_header_bar_set_title(header_bar, "flutter_empty");
+    gtk_header_bar_set_title(header_bar, "Recurring Expense Tracker");
     gtk_header_bar_set_show_close_button(header_bar, TRUE);
     gtk_window_set_titlebar(window, GTK_WIDGET(header_bar));
   } else {
-    gtk_window_set_title(window, "flutter_empty");
+    gtk_window_set_title(window, "Recurring Expense Tracker");
   }
 
   gtk_window_set_default_size(window, 1280, 720);

pubspec.yaml

@@ -1,5 +1,5 @@
-name: flutter_empty
-description: "A new Flutter project."
+name: flutter_expense_tracker
+description: Track recurring expenses against income and liquid assets.
 publish_to: 'none'
 version: 0.1.0
 

run_offline.sh

@@ -0,0 +1,3 @@
+#!/usr/bin/env bash
+
+flutter run --no-pub