add stats page

lib/components/pages/stats.dart

@@ -0,0 +1,216 @@
+import 'package:flutter/material.dart';
+import 'package:intl/intl.dart';
+import 'package:mileograph_flutter/objects/objects.dart';
+import 'package:mileograph_flutter/services/data_service.dart';
+import 'package:provider/provider.dart';
+
+class StatsPage extends StatefulWidget {
+  const StatsPage({super.key});
+
+  @override
+  State<StatsPage> createState() => _StatsPageState();
+}
+
+class _StatsPageState extends State<StatsPage> {
+  final NumberFormat _mileageFormat = NumberFormat('#,##0.##');
+  final NumberFormat _countFormat = NumberFormat.decimalPattern();
+
+  @override
+  void initState() {
+    super.initState();
+    WidgetsBinding.instance.addPostFrameCallback((_) {
+      _loadStats();
+    });
+  }
+
+  Future<void> _loadStats({bool force = false}) {
+    return context.read<DataService>().fetchAboutStats(force: force);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final data = context.watch<DataService>();
+    return Scaffold(
+      appBar: AppBar(title: const Text('Stats')),
+      body: RefreshIndicator(
+        onRefresh: () => _loadStats(force: true),
+        child: _buildContent(data),
+      ),
+    );
+  }
+
+  Widget _buildContent(DataService data) {
+    final stats = data.aboutStats;
+    final loading = data.isAboutStatsLoading;
+
+    if (loading && stats == null) {
+      return ListView(
+        physics: const AlwaysScrollableScrollPhysics(),
+        children: const [
+          SizedBox(height: 140),
+          Center(child: CircularProgressIndicator()),
+          SizedBox(height: 140),
+        ],
+      );
+    }
+
+    if (stats == null || stats.sortedYears.isEmpty) {
+      return ListView(
+        physics: const AlwaysScrollableScrollPhysics(),
+        padding: const EdgeInsets.all(24),
+        children: [
+          const SizedBox(height: 40),
+          const Center(child: Text('No stats available yet.')),
+          const SizedBox(height: 12),
+          Center(
+            child: OutlinedButton(
+              onPressed: () => _loadStats(force: true),
+              child: const Text('Retry'),
+            ),
+          ),
+        ],
+      );
+    }
+
+    final years = stats.sortedYears;
+    return ListView.builder(
+      padding: const EdgeInsets.all(16),
+      itemCount: years.length,
+      itemBuilder: (context, index) {
+        return Padding(
+          padding: EdgeInsets.only(bottom: index == years.length - 1 ? 0 : 12),
+          child: _buildYearCard(context, years[index]),
+        );
+      },
+    );
+  }
+
+  Widget _buildYearCard(BuildContext context, StatsYear year) {
+    final theme = Theme.of(context);
+    return Card(
+      child: Padding(
+        padding: const EdgeInsets.all(12),
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            Row(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              children: [
+                Text(
+                  year.year.toString(),
+                  style: theme.textTheme.titleLarge,
+                ),
+                const Spacer(),
+                Wrap(
+                  spacing: 8,
+                  runSpacing: 8,
+                  alignment: WrapAlignment.end,
+                  children: [
+                    _buildInfoChip(
+                      context,
+                      label: 'Mileage',
+                      value: '${_mileageFormat.format(year.mileage)} mi',
+                    ),
+                    _buildInfoChip(
+                      context,
+                      label: 'Winners',
+                      value: _countFormat.format(year.winnerCount),
+                    ),
+                  ],
+                ),
+              ],
+            ),
+            const SizedBox(height: 8),
+            _buildSection<StatsClassMileage>(
+              context,
+              title: 'Top classes',
+              items: year.topClasses,
+              emptyLabel: 'No class data',
+              itemBuilder: (item, index) => ListTile(
+                dense: true,
+                contentPadding: const EdgeInsets.symmetric(horizontal: 8),
+                title: Text(item.locoClass),
+                trailing: Text('${_mileageFormat.format(item.mileage)} mi'),
+              ),
+            ),
+            _buildSection<StatsNetworkMileage>(
+              context,
+              title: 'Top networks',
+              items: year.topNetworks,
+              emptyLabel: 'No network data',
+              itemBuilder: (item, index) => ListTile(
+                dense: true,
+                contentPadding: const EdgeInsets.symmetric(horizontal: 8),
+                title: Text(item.network),
+                trailing: Text('${_mileageFormat.format(item.mileage)} mi'),
+              ),
+            ),
+            _buildSection<StatsStationVisits>(
+              context,
+              title: 'Top stations',
+              items: year.topStations,
+              emptyLabel: 'No station data',
+              itemBuilder: (item, index) => ListTile(
+                dense: true,
+                contentPadding: const EdgeInsets.symmetric(horizontal: 8),
+                title: Text(item.station),
+                trailing: Text(
+                  '${_countFormat.format(item.visits)} visit${item.visits == 1 ? '' : 's'}',
+                ),
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+
+  Widget _buildInfoChip(BuildContext context,
+      {required String label, required String value}) {
+    final theme = Theme.of(context);
+    return Chip(
+      padding: const EdgeInsets.symmetric(horizontal: 8),
+      label: Text(
+        '$label: $value',
+        style: theme.textTheme.labelLarge,
+      ),
+    );
+  }
+
+  Widget _buildSection<T>(
+    BuildContext context, {
+    required String title,
+    required List<T> items,
+    required Widget Function(T item, int index) itemBuilder,
+    String emptyLabel = 'No data',
+  }) {
+    final theme = Theme.of(context);
+    return Padding(
+      padding: const EdgeInsets.only(top: 4),
+      child: ExpansionTile(
+        tilePadding: const EdgeInsets.symmetric(horizontal: 8),
+        childrenPadding:
+            const EdgeInsets.only(left: 8, right: 8, bottom: 8),
+        title: Text(
+          title,
+          style: theme.textTheme.titleMedium,
+        ),
+        children: items.isEmpty
+            ? [
+                Padding(
+                  padding: const EdgeInsets.symmetric(vertical: 8),
+                  child: Text(
+                    emptyLabel,
+                    style: theme.textTheme.bodySmall,
+                  ),
+                ),
+              ]
+            : items
+                .asMap()
+                .entries
+                .map((entry) => itemBuilder(entry.value, entry.key))
+                .toList(),
+      ),
+    );
+  }
+}