add redate functionality to set the earliest date of entries

lib/components/pages/legs.dart

@@ -14,6 +14,10 @@ class LegsPage extends StatefulWidget {
 }
 
 class _LegsPageState extends State<LegsPage> {
+  static const int _pageSize = 100;
+  static const double _loadMoreTriggerExtent = 400;
+  static double _persistedScrollOffset = 0;
+
   int _sortDirection = 0;
   DateTime? _startDate;
   DateTime? _endDate;
@@ -23,6 +27,18 @@ class _LegsPageState extends State<LegsPage> {
   bool _loadingNetworks = false;
   List<String> _availableNetworks = [];
   List<String> _selectedNetworks = [];
+  String? _lastQuerySignature;
+  late final ScrollController _scrollController;
+  bool _showBackToTop = false;
+  bool _isAutoLoadingMore = false;
+
+  @override
+  void initState() {
+    super.initState();
+    _scrollController = ScrollController(
+      initialScrollOffset: _persistedScrollOffset,
+    )..addListener(_onScroll);
+  }
 
   @override
   void didChangeDependencies() {
@@ -34,6 +50,49 @@ class _LegsPageState extends State<LegsPage> {
     }
   }
 
+  @override
+  void dispose() {
+    _persistedScrollOffset =
+        _scrollController.hasClients ? _scrollController.offset : 0;
+    _scrollController.removeListener(_onScroll);
+    _scrollController.dispose();
+    super.dispose();
+  }
+
+  void _onScroll() {
+    if (!_scrollController.hasClients) return;
+    _persistedScrollOffset = _scrollController.offset;
+    final shouldShow = _scrollController.offset > 500;
+    if (shouldShow != _showBackToTop) {
+      setState(() => _showBackToTop = shouldShow);
+    }
+    _maybeAutoLoadMore();
+  }
+
+  Future<void> _maybeAutoLoadMore() async {
+    if (!mounted || !_scrollController.hasClients || _isAutoLoadingMore) return;
+    final position = _scrollController.position;
+    if (position.extentAfter > _loadMoreTriggerExtent) return;
+    final data = context.read<DataService>();
+    if (data.isLegsLoading || !data.legsHasMore) return;
+
+    _isAutoLoadingMore = true;
+    try {
+      await _loadMore();
+    } finally {
+      _isAutoLoadingMore = false;
+    }
+  }
+
+  Future<void> _scrollToTop() async {
+    if (!_scrollController.hasClients) return;
+    await _scrollController.animateTo(
+      0,
+      duration: const Duration(milliseconds: 250),
+      curve: Curves.easeOutCubic,
+    );
+  }
+
   Future<void> _loadNetworks() async {
     setState(() => _loadingNetworks = true);
     final data = context.read<DataService>();
@@ -47,7 +106,16 @@ class _LegsPageState extends State<LegsPage> {
 
   Future<void> _refreshLegs() async {
     final data = context.read<DataService>();
+    final signature = _legsQuerySignature();
+    final queryChanged =
+        _lastQuerySignature != null && signature != _lastQuerySignature;
+    _lastQuerySignature = signature;
+
+    final currentCount = data.legs.length;
+    final shouldPreserveLoadedCount = !queryChanged && currentCount > _pageSize;
+    final limit = shouldPreserveLoadedCount ? currentCount : _pageSize;
     await data.fetchLegs(
+      limit: limit,
       sortDirection: _sortDirection,
       dateRangeStart: _formatDate(_startDate),
       dateRangeEnd: _formatDate(_endDate),
@@ -58,17 +126,30 @@ class _LegsPageState extends State<LegsPage> {
 
   Future<void> _loadMore() async {
     final data = context.read<DataService>();
+    final offset = data.legs.length;
     await data.fetchLegs(
       sortDirection: _sortDirection,
       dateRangeStart: _formatDate(_startDate),
       dateRangeEnd: _formatDate(_endDate),
-      offset: data.legs.length,
+      offset: offset,
+      limit: _pageSize,
       append: true,
       unallocatedOnly: _unallocatedOnly,
       networkFilter: _selectedNetworks,
     );
   }
 
+  String _legsQuerySignature() {
+    final networks = [..._selectedNetworks]..sort();
+    return [
+      'sort=$_sortDirection',
+      'start=${_formatDate(_startDate) ?? ''}',
+      'end=${_formatDate(_endDate) ?? ''}',
+      'unallocated=$_unallocatedOnly',
+      'networks=${networks.join(',')}',
+    ].join(';');
+  }
+
   double _pageMileage(List legs) {
     return legs.fold<double>(
       0,
@@ -120,12 +201,15 @@ class _LegsPageState extends State<LegsPage> {
     final legs = data.legs;
     final pageMileage = _pageMileage(legs);
 
-    return RefreshIndicator(
-      onRefresh: _refreshLegs,
-      child: ListView(
-        padding: const EdgeInsets.all(16),
-        physics: const AlwaysScrollableScrollPhysics(),
-        children: [
+    return Stack(
+      children: [
+        RefreshIndicator(
+          onRefresh: _refreshLegs,
+          child: ListView(
+            controller: _scrollController,
+            padding: const EdgeInsets.all(16),
+            physics: const AlwaysScrollableScrollPhysics(),
+            children: [
           Row(
             mainAxisAlignment: MainAxisAlignment.spaceBetween,
             children: [
@@ -298,28 +382,62 @@ class _LegsPageState extends State<LegsPage> {
               children: [
                 ..._buildLegsWithDividers(context, legs, distanceUnits),
                 const SizedBox(height: 8),
-                if (data.legsHasMore || data.isLegsLoading)
-                  Align(
+                if (data.isLegsLoading)
+                  const Align(
                     alignment: Alignment.center,
-                    child: OutlinedButton.icon(
-                      onPressed:
-                          data.isLegsLoading ? null : () => _loadMore(),
-                      icon: data.isLegsLoading
-                          ? const SizedBox(
-                              height: 14,
-                              width: 14,
-                              child: CircularProgressIndicator(strokeWidth: 2),
-                            )
-                          : const Icon(Icons.expand_more),
-                      label: Text(
-                        data.isLegsLoading ? 'Loading...' : 'Load more',
+                    child: Padding(
+                      padding: EdgeInsets.symmetric(vertical: 12),
+                      child: SizedBox(
+                        height: 18,
+                        width: 18,
+                        child: CircularProgressIndicator(strokeWidth: 2),
                       ),
                     ),
                   ),
+                if (data.legsHasMore && !data.isLegsLoading)
+                  Padding(
+                    padding: const EdgeInsets.symmetric(vertical: 12),
+                    child: Row(
+                      mainAxisAlignment: MainAxisAlignment.center,
+                      children: [
+                        const SizedBox(
+                          height: 18,
+                          width: 18,
+                          child: CircularProgressIndicator(strokeWidth: 2),
+                        ),
+                        const SizedBox(width: 10),
+                        Text(
+                          'Loading',
+                          style: Theme.of(context).textTheme.bodySmall,
+                        ),
+                      ],
+                    ),
+                  ),
               ],
             ),
-        ],
-      ),
+            ],
+          ),
+        ),
+        Positioned(
+          right: 16,
+          bottom: 16,
+          child: AnimatedSlide(
+            offset: _showBackToTop ? Offset.zero : const Offset(0, 1.2),
+            duration: const Duration(milliseconds: 180),
+            curve: Curves.easeOut,
+            child: AnimatedOpacity(
+              opacity: _showBackToTop ? 1 : 0,
+              duration: const Duration(milliseconds: 180),
+              child: FloatingActionButton.small(
+                heroTag: 'legsBackToTop',
+                tooltip: 'Back to top',
+                onPressed: _scrollToTop,
+                child: const Icon(Icons.arrow_upward),
+              ),
+            ),
+          ),
+        ),
+      ],
     );
   }
 

lib/components/pages/loco_timeline.dart

@@ -13,6 +13,8 @@ import 'package:shared_preferences/shared_preferences.dart';
 part 'loco_timeline/timeline_grid.dart';
 part 'loco_timeline/event_editor.dart';
 
+enum _TimelineMenuAction { redate }
+
 class LocoTimelinePage extends StatefulWidget {
   const LocoTimelinePage({
     super.key,
@@ -537,6 +539,239 @@ class _LocoTimelinePageState extends State<LocoTimelinePage> {
     return _draftEvents.every(_draftIsValid);
   }
 
+  Future<void> _handleTimelineMenuAction(
+    _TimelineMenuAction action,
+    List<LocoAttrVersion> timeline,
+  ) async {
+    switch (action) {
+      case _TimelineMenuAction.redate:
+        await _startMassRedate(timeline);
+        break;
+    }
+  }
+
+  Future<void> _startMassRedate(List<LocoAttrVersion> timeline) async {
+    final messenger = ScaffoldMessenger.of(context);
+    final eventDate = await _showRedateDateDialog();
+    if (!mounted || eventDate == null) return;
+
+    final earliestByAttr = _earliestEntriesByAttr(timeline);
+    if (earliestByAttr.isEmpty) {
+      messenger.showSnackBar(
+        const SnackBar(content: Text('No timeline values available to redate.')),
+      );
+      return;
+    }
+
+    final result = await _showMassRedateProgressDialog(
+      eventDate: eventDate,
+      entries: earliestByAttr,
+    );
+    if (!mounted || result == null) return;
+
+    await _load();
+    if (!mounted) return;
+    final successCount = result.total - result.failures;
+    final message = result.failures == 0
+        ? 'Redated $successCount attributes.'
+        : 'Redated $successCount of ${result.total} attributes (${result.failures} failed).';
+    messenger.showSnackBar(SnackBar(content: Text(message)));
+  }
+
+  List<LocoAttrVersion> _earliestEntriesByAttr(List<LocoAttrVersion> timeline) {
+    final byAttr = <String, LocoAttrVersion>{};
+    for (final entry in timeline) {
+      if (entry.isPending) continue;
+      final key = entry.attrCode.trim().toLowerCase();
+      if (key.isEmpty) continue;
+      final current = byAttr[key];
+      if (current == null || LocoAttrVersion.compareByStart(entry, current) < 0) {
+        byAttr[key] = entry;
+      }
+    }
+    final entries = byAttr.values.toList()
+      ..sort((a, b) => a.attrCode.compareTo(b.attrCode));
+    return entries;
+  }
+
+  Future<String?> _showRedateDateDialog() async {
+    final controller = TextEditingController(
+      text: DateFormat('yyyy-MM-dd').format(DateTime.now()),
+    );
+    String? validationError;
+    final result = await showDialog<String>(
+      context: context,
+      builder: (dialogContext) {
+        return StatefulBuilder(
+          builder: (dialogContext, setDialogState) {
+            Future<void> pickDate() async {
+              final initial = DateTime.tryParse(controller.text.trim()) ??
+                  DateTime.now();
+              final picked = await showDatePicker(
+                context: dialogContext,
+                initialDate: initial,
+                firstDate: DateTime(1800),
+                lastDate: DateTime(2500),
+              );
+              if (picked == null) return;
+              final nextValue = DateFormat('yyyy-MM-dd').format(picked);
+              setDialogState(() {
+                controller.text = nextValue;
+                validationError = null;
+              });
+            }
+
+            return AlertDialog(
+              title: const Text('Redate timeline attributes'),
+              content: Column(
+                mainAxisSize: MainAxisSize.min,
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: [
+                  const Text(
+                    'Enter the target date. The earliest value of each attribute will be submitted at this date.',
+                  ),
+                  const SizedBox(height: 12),
+                  TextField(
+                    controller: controller,
+                    decoration: InputDecoration(
+                      labelText: 'Date',
+                      hintText: 'YYYY-MM-DD',
+                      errorText: validationError,
+                      suffixIcon: IconButton(
+                        tooltip: 'Pick date',
+                        icon: const Icon(Icons.calendar_month),
+                        onPressed: pickDate,
+                      ),
+                    ),
+                    onSubmitted: (_) {
+                      final value = controller.text.trim();
+                      if (!_isValidDateString(value)) {
+                        setDialogState(() {
+                          validationError = 'Use format YYYY-MM-DD.';
+                        });
+                        return;
+                      }
+                      Navigator.of(dialogContext).pop(value);
+                    },
+                  ),
+                ],
+              ),
+              actions: [
+                TextButton(
+                  onPressed: () => Navigator.of(dialogContext).pop(),
+                  child: const Text('Cancel'),
+                ),
+                FilledButton(
+                  onPressed: () {
+                    final value = controller.text.trim();
+                    if (!_isValidDateString(value)) {
+                      setDialogState(() {
+                        validationError = 'Use format YYYY-MM-DD.';
+                      });
+                      return;
+                    }
+                    Navigator.of(dialogContext).pop(value);
+                  },
+                  child: const Text('Run'),
+                ),
+              ],
+            );
+          },
+        );
+      },
+    );
+    controller.dispose();
+    return result;
+  }
+
+  Future<_MassRedateResult?> _showMassRedateProgressDialog({
+    required String eventDate,
+    required List<LocoAttrVersion> entries,
+  }) async {
+    final data = context.read<DataService>();
+    var started = false;
+    var completed = 0;
+    var failures = 0;
+    var currentAttrLabel = '';
+
+    return showDialog<_MassRedateResult>(
+      context: context,
+      barrierDismissible: false,
+      builder: (dialogContext) {
+        return StatefulBuilder(
+          builder: (dialogContext, setDialogState) {
+            Future<void> run() async {
+              for (final entry in entries) {
+                if (!mounted) return;
+                setDialogState(() {
+                  currentAttrLabel = _formatAttrLabel(entry.attrCode);
+                });
+
+                final value = _valueForEntry(entry);
+                final isBlank = value is String && value.trim().isEmpty;
+                if (value == null || isBlank) {
+                  failures += 1;
+                  setDialogState(() {
+                    completed += 1;
+                  });
+                  continue;
+                }
+
+                try {
+                  await data.createLocoEvent(
+                    locoId: widget.locoId,
+                    eventDate: eventDate,
+                    values: {entry.attrCode: value},
+                    details: '',
+                  );
+                } catch (_) {
+                  failures += 1;
+                }
+                if (!mounted || !dialogContext.mounted) return;
+                setDialogState(() {
+                  completed += 1;
+                });
+              }
+
+              if (!mounted || !dialogContext.mounted) return;
+              Navigator.of(dialogContext).pop(
+                _MassRedateResult(total: entries.length, failures: failures),
+              );
+            }
+
+            if (!started) {
+              started = true;
+              WidgetsBinding.instance.addPostFrameCallback((_) {
+                run();
+              });
+            }
+
+            final total = entries.length;
+            final progress = total == 0 ? 0.0 : completed / total;
+            return AlertDialog(
+              title: const Text('Redating attributes'),
+              content: Column(
+                mainAxisSize: MainAxisSize.min,
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: [
+                  LinearProgressIndicator(value: progress),
+                  const SizedBox(height: 12),
+                  Text('$completed / $total complete'),
+                  const SizedBox(height: 8),
+                  Text(
+                    currentAttrLabel.isEmpty
+                        ? 'Preparing requests...'
+                        : 'Current: $currentAttrLabel',
+                  ),
+                ],
+              ),
+            );
+          },
+        );
+      },
+    );
+  }
+
   @override
   Widget build(BuildContext context) {
     final data = context.watch<DataService>();
@@ -554,6 +789,20 @@ class _LocoTimelinePageState extends State<LocoTimelinePage> {
           onPressed: () => Navigator.of(context).maybePop(),
         ),
         title: Text('Timeline · ${widget.locoLabel}'),
+        actions: [
+          PopupMenuButton<_TimelineMenuAction>(
+            tooltip: 'Timeline actions',
+            icon: const Icon(Icons.more_vert),
+            onSelected: (action) =>
+                _handleTimelineMenuAction(action, visibleTimeline),
+            itemBuilder: (context) => const [
+              PopupMenuItem<_TimelineMenuAction>(
+                value: _TimelineMenuAction.redate,
+                child: Text('Redate'),
+              ),
+            ],
+          ),
+        ],
       ),
       body: RefreshIndicator(
         onRefresh: _load,
@@ -684,3 +933,13 @@ class _LocoTimelinePageState extends State<LocoTimelinePage> {
     );
   }
 }
+
+class _MassRedateResult {
+  const _MassRedateResult({
+    required this.total,
+    required this.failures,
+  });
+
+  final int total;
+  final int failures;
+}

lib/services/data_service/data_service_core.dart

@@ -18,6 +18,26 @@ class _LegFetchOptions {
     this.unallocatedOnly = false,
     this.networkFilter = const [],
   });
+
+  _LegFetchOptions copyWith({
+    int? limit,
+    String? sortBy,
+    int? sortDirection,
+    String? dateRangeStart,
+    String? dateRangeEnd,
+    bool? unallocatedOnly,
+    List<String>? networkFilter,
+  }) {
+    return _LegFetchOptions(
+      limit: limit ?? this.limit,
+      sortBy: sortBy ?? this.sortBy,
+      sortDirection: sortDirection ?? this.sortDirection,
+      dateRangeStart: dateRangeStart ?? this.dateRangeStart,
+      dateRangeEnd: dateRangeEnd ?? this.dateRangeEnd,
+      unallocatedOnly: unallocatedOnly ?? this.unallocatedOnly,
+      networkFilter: networkFilter ?? this.networkFilter,
+    );
+  }
 }
 
 class DataService extends ChangeNotifier {
@@ -397,11 +417,11 @@ class DataService extends ChangeNotifier {
     List<String> networkFilter = const [],
   }) async {
     _isLegsLoading = true;
+    final normalizedNetworks = networkFilter
+        .map((network) => network.trim())
+        .where((network) => network.isNotEmpty)
+        .toList();
     if (!append) {
-      final normalizedNetworks = networkFilter
-          .map((network) => network.trim())
-          .where((network) => network.isNotEmpty)
-          .toList();
       _lastLegsFetch = _LegFetchOptions(
         limit: limit,
         sortBy: sortBy,
@@ -437,6 +457,17 @@ class DataService extends ChangeNotifier {
       if (json is List) {
         final newLegs = json.map((e) => Leg.fromJson(e)).toList();
         _legs = append ? [..._legs, ...newLegs] : newLegs;
+        if (append) {
+          _lastLegsFetch = _lastLegsFetch.copyWith(
+            limit: _legs.length,
+            sortBy: sortBy,
+            sortDirection: sortDirection,
+            dateRangeStart: dateRangeStart,
+            dateRangeEnd: dateRangeEnd,
+            unallocatedOnly: unallocatedOnly,
+            networkFilter: normalizedNetworks,
+          );
+        }
         // Keep "load more" available as long as the server returns items; hide only on empty.
         _legsHasMore = newLegs.isNotEmpty;
       } else {

lib/services/data_service/data_service_traction.dart

@@ -32,7 +32,7 @@ extension DataServiceTraction on DataService {
         payload['class'] = locoClass;
       }
       if (locoNumber != null && locoNumber.isNotEmpty) {
-        payload['number'] = locoNumber;
+        payload['number'] = _withLikeWildcards(locoNumber);
       }
       if (filters != null) {
         filters.forEach((key, value) {
@@ -67,6 +67,14 @@ extension DataServiceTraction on DataService {
 
   }
 
+  String _withLikeWildcards(String rawValue) {
+    final value = rawValue.trim();
+    if (value.isEmpty) return value;
+    final hasLeadingWildcard = value.startsWith('%');
+    final hasTrailingWildcard = value.endsWith('%');
+    return '${hasLeadingWildcard ? '' : '%'}$value${hasTrailingWildcard ? '' : '%'}';
+  }
+
   Future<List<LocoAttrVersion>> fetchLocoTimeline(
     int locoId, {
     bool includeAllPending = false,

pubspec.yaml

@@ -16,7 +16,7 @@ publish_to: "none" # Remove this line if you wish to publish to pub.dev
 # https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
 # In Windows, build-name is used as the major, minor, and patch parts
 # of the product and file versions while build-number is used as the build suffix.
-version: 0.8.1+18
+version: 0.8.3+20
 
 environment:
   sdk: ^3.8.1