first commit

lib/screens/settings_screen.dart

@@ -0,0 +1,105 @@
+import 'package:file_picker/file_picker.dart';
+import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+
+import '../services/app_state.dart';
+
+class SettingsScreen extends StatefulWidget {
+  const SettingsScreen({super.key});
+
+  @override
+  State<SettingsScreen> createState() => _SettingsScreenState();
+}
+
+class _SettingsScreenState extends State<SettingsScreen> {
+  bool _changing = false;
+  String? _error;
+
+  Future<void> _chooseFolder() async {
+    setState(() => _error = null);
+
+    final selectedPath = await FilePicker.platform.getDirectoryPath(
+      dialogTitle: 'Choose a folder for receipts and data',
+    );
+    if (selectedPath == null || !mounted) return;
+
+    setState(() => _changing = true);
+    try {
+      await context.read<AppState>().changeSaveDirectory(selectedPath);
+    } catch (e) {
+      setState(() => _error = 'Could not switch to that folder: $e');
+    } finally {
+      if (mounted) setState(() => _changing = false);
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final appState = context.watch<AppState>();
+    final saveDir = appState.storage.saveDirectory.path;
+
+    return Scaffold(
+      appBar: AppBar(title: const Text('Settings')),
+      body: ListView(
+        padding: const EdgeInsets.all(16),
+        children: [
+          Card(
+            child: Padding(
+              padding: const EdgeInsets.all(16),
+              child: Column(
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: [
+                  Text('Save Location', style: Theme.of(context).textTheme.titleMedium),
+                  const SizedBox(height: 8),
+                  Text(
+                    'Receipt photos and the data file are stored here:',
+                    style: Theme.of(context).textTheme.bodyMedium,
+                  ),
+                  const SizedBox(height: 4),
+                  SelectableText(
+                    saveDir,
+                    style: Theme.of(context).textTheme.bodySmall?.copyWith(
+                          fontFamily: 'monospace',
+                        ),
+                  ),
+                  const SizedBox(height: 16),
+                  if (_error != null) ...[
+                    Text(_error!, style: TextStyle(color: Theme.of(context).colorScheme.error)),
+                    const SizedBox(height: 8),
+                  ],
+                  FilledButton.icon(
+                    onPressed: _changing ? null : _chooseFolder,
+                    icon: _changing
+                        ? const SizedBox(
+                            height: 16,
+                            width: 16,
+                            child: CircularProgressIndicator(strokeWidth: 2),
+                          )
+                        : const Icon(Icons.folder_open),
+                    label: const Text('Choose Folder'),
+                  ),
+                ],
+              ),
+            ),
+          ),
+          const SizedBox(height: 16),
+          Card(
+            child: Padding(
+              padding: const EdgeInsets.all(16),
+              child: Column(
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: [
+                  Text('Summary', style: Theme.of(context).textTheme.titleMedium),
+                  const SizedBox(height: 8),
+                  Text('${appState.vehicles.length} vehicle(s)'),
+                  Text('${appState.fuelEntries.length} fuel entries'),
+                  Text('${appState.totalGallonsAllVehicles.toStringAsFixed(3)} total gallons logged'),
+                ],
+              ),
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+}