attempt to add loco search indicator

lib/components/pages/loco_timeline.dart

@@ -0,0 +1,801 @@
+import 'dart:math' as math;
+
+import 'package:flutter/material.dart';
+import 'package:intl/intl.dart';
+import 'package:mileograph_flutter/objects/objects.dart';
+import 'package:mileograph_flutter/services/dataService.dart';
+import 'package:provider/provider.dart';
+
+class LocoTimelinePage extends StatefulWidget {
+  const LocoTimelinePage({
+    super.key,
+    required this.locoId,
+    required this.locoLabel,
+  });
+
+  final int locoId;
+  final String locoLabel;
+
+  @override
+  State<LocoTimelinePage> createState() => _LocoTimelinePageState();
+}
+
+class _LocoTimelinePageState extends State<LocoTimelinePage> {
+  @override
+  void initState() {
+    super.initState();
+    WidgetsBinding.instance.addPostFrameCallback((_) => _load());
+  }
+
+  Future<void> _load() {
+    return context.read<DataService>().fetchLocoTimeline(widget.locoId);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final data = context.watch<DataService>();
+    final timeline = data.timelineForLoco(widget.locoId);
+    final isLoading = data.isLocoTimelineLoading(widget.locoId);
+
+    return Scaffold(
+      appBar: AppBar(
+        leading: IconButton(
+          icon: const Icon(Icons.arrow_back),
+          onPressed: () => Navigator.of(context).maybePop(),
+        ),
+        title: Text('Timeline · ${widget.locoLabel}'),
+      ),
+      body: RefreshIndicator(
+        onRefresh: _load,
+        child: LayoutBuilder(
+          builder: (context, constraints) {
+            if (isLoading && timeline.isEmpty) {
+              return const Center(child: CircularProgressIndicator());
+            }
+            if (timeline.isEmpty) {
+              return Padding(
+                padding: const EdgeInsets.all(16.0),
+                child: Card(
+                  child: Padding(
+                    padding: const EdgeInsets.all(16.0),
+                    child: Column(
+                      crossAxisAlignment: CrossAxisAlignment.start,
+                      children: [
+                        Text(
+                          'No timeline data yet',
+                          style: Theme.of(context).textTheme.titleMedium?.copyWith(
+                                fontWeight: FontWeight.w700,
+                              ),
+                        ),
+                        const SizedBox(height: 8),
+                        const Text(
+                          'This locomotive does not have any attribute history to show right now.',
+                        ),
+                        const SizedBox(height: 12),
+                        OutlinedButton.icon(
+                          onPressed: _load,
+                          icon: const Icon(Icons.refresh),
+                          label: const Text('Try again'),
+                        ),
+                      ],
+                    ),
+                  ),
+                ),
+              );
+            }
+            return _TimelineGrid(
+              entries: timeline,
+              maxHeight: constraints.maxHeight,
+            );
+          },
+        ),
+      ),
+    );
+  }
+}
+
+class _TimelineGrid extends StatefulWidget {
+  const _TimelineGrid({
+    required this.entries,
+    required this.maxHeight,
+  });
+
+  final List<LocoAttrVersion> entries;
+  final double maxHeight;
+
+  @override
+  State<_TimelineGrid> createState() => _TimelineGridState();
+}
+
+class _TimelineGridState extends State<_TimelineGrid> {
+  final ScrollController _horizontalController = ScrollController();
+  final ScrollController _rightVerticalController = ScrollController();
+  final ScrollController _leftVerticalController = ScrollController();
+  bool _isSyncingScroll = false;
+  double _scrollOffset = 0;
+
+  @override
+  void initState() {
+    super.initState();
+    _rightVerticalController.addListener(_syncVerticalScroll);
+    _horizontalController.addListener(_onHorizontalScroll);
+  }
+
+  @override
+  void dispose() {
+    _rightVerticalController.removeListener(_syncVerticalScroll);
+    _horizontalController.removeListener(_onHorizontalScroll);
+    _horizontalController.dispose();
+    _rightVerticalController.dispose();
+    _leftVerticalController.dispose();
+    super.dispose();
+  }
+
+  void _syncVerticalScroll() {
+    if (_isSyncingScroll) return;
+    if (!_leftVerticalController.hasClients ||
+        !_rightVerticalController.hasClients) {
+      return;
+    }
+    _isSyncingScroll = true;
+    _leftVerticalController.jumpTo(
+      _rightVerticalController.offset.clamp(
+        0.0,
+        _leftVerticalController.position.maxScrollExtent,
+      ),
+    );
+    _isSyncingScroll = false;
+  }
+
+  void _onHorizontalScroll() {
+    if (!mounted) return;
+    setState(() {
+      _scrollOffset = _horizontalController.offset;
+    });
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final filteredEntries = widget.entries.where((e) {
+      final code = e.attrCode.toLowerCase();
+      return !{
+        'operational',
+        'gettable',
+        'build_prec',
+        'build_year',
+        'build_month',
+        'build_day',
+      }.contains(code);
+    }).toList();
+    final model = _TimelineModel.fromEntries(filteredEntries);
+    final axisSegments = model.axisSegments;
+    const labelWidth = 110.0;
+    const rowHeight = 52.0;
+    const double axisHeight = 48;
+    final rows = model.attrRows.entries.toList();
+    final totalRowsHeight = rows.length * rowHeight;
+    final axisWidth = math.max(model.axisTotalWidth, 120.0);
+    final paddingTop = MediaQuery.of(context).padding.top;
+    final double constraintHeight = widget.maxHeight.isFinite
+        ? widget.maxHeight
+        : MediaQuery.of(context).size.height;
+    final double availableHeight =
+        (constraintHeight - paddingTop - 24).clamp(axisHeight + 40, double.infinity);
+    final double viewHeight = availableHeight;
+
+    return Column(
+      crossAxisAlignment: CrossAxisAlignment.start,
+      mainAxisSize: MainAxisSize.min,
+      children: [
+        SizedBox(
+          height: viewHeight,
+          child: Row(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: [
+              SizedBox(
+                width: labelWidth,
+                child: Column(
+                  children: [
+                    SizedBox(
+                      height: axisHeight,
+                      child: Align(
+                        alignment: Alignment.centerLeft,
+                        child: Text(
+                          'Attribute',
+                          style: Theme.of(context).textTheme.labelLarge?.copyWith(
+                                fontWeight: FontWeight.w700,
+                              ),
+                        ),
+                      ),
+                    ),
+                    Expanded(
+                      child: Scrollbar(
+                        controller: _leftVerticalController,
+                        thumbVisibility: true,
+                        child: ListView.builder(
+                          controller: _leftVerticalController,
+                          physics: const NeverScrollableScrollPhysics(),
+                          itemExtent: rowHeight,
+                          itemCount: rows.length,
+                          itemBuilder: (_, index) {
+                            final label = _formatAttrLabel(rows[index].key);
+                            return Container(
+                              alignment: Alignment.centerLeft,
+                              padding: const EdgeInsets.symmetric(
+                                horizontal: 10,
+                              ),
+                              decoration: BoxDecoration(
+                                color: Theme.of(context)
+                                    .colorScheme
+                                    .surfaceContainerHighest,
+                                border: Border(
+                                  bottom: BorderSide(
+                                    color:
+                                        Theme.of(context).colorScheme.outlineVariant,
+                                  ),
+                                ),
+                              ),
+                              child: Text(
+                                label,
+                                style: Theme.of(context)
+                                    .textTheme
+                                    .labelLarge
+                                    ?.copyWith(fontWeight: FontWeight.w700),
+                              ),
+                            );
+                          },
+                        ),
+                      ),
+                    ),
+                  ],
+                ),
+              ),
+              const SizedBox(width: 8),
+              Expanded(
+                child: Scrollbar(
+                  controller: _horizontalController,
+                  thumbVisibility: true,
+                  child: SingleChildScrollView(
+                    controller: _horizontalController,
+                    scrollDirection: Axis.horizontal,
+                    child: SizedBox(
+                      width: axisWidth,
+                      child: Column(
+                        crossAxisAlignment: CrossAxisAlignment.start,
+                        children: [
+                          _AxisRow(
+                            segments: axisSegments,
+                            totalWidth: axisWidth,
+                            endLabel: model.endLabel,
+                          ),
+                          const SizedBox(height: 8),
+                          Expanded(
+                            child: ListView.builder(
+                              controller: _rightVerticalController,
+                              itemExtent: rowHeight,
+                              itemCount: rows.length,
+                              itemBuilder: (_, index) {
+                                final blocks = rows[index].value;
+                                return Padding(
+                                  padding:
+                                      const EdgeInsets.symmetric(vertical: 2.0),
+                                  child: _AttrRow(
+                                    rowHeight: rowHeight,
+                                    blocks: blocks,
+                                    model: model,
+                                    scrollOffset: _scrollOffset,
+                                    viewportWidth: axisWidth,
+                                  ),
+                                );
+                              },
+                            ),
+                          ),
+                        ],
+                      ),
+                    ),
+                  ),
+                ),
+              ),
+            ],
+          ),
+        ),
+      ],
+    );
+  }
+}
+
+class _AxisRow extends StatelessWidget {
+  const _AxisRow({
+    required this.segments,
+    required this.endLabel,
+    required this.totalWidth,
+  });
+
+  final List<_AxisSegment> segments;
+  final String endLabel;
+  final double totalWidth;
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    const double axisHeight = 48;
+    return SizedBox(
+      width: totalWidth,
+      height: axisHeight,
+      child: Stack(
+        children: [
+          for (int i = 0; i < segments.length; i++) ...[
+            Positioned(
+              left: segments[i].offset,
+              width: segments[i].width,
+              top: 0,
+              bottom: 0,
+              child: Align(
+                alignment: Alignment.centerLeft,
+                child: Text(
+                  segments[i].label,
+                  overflow: TextOverflow.ellipsis,
+                  maxLines: 1,
+                  style: theme.textTheme.labelSmall,
+                ),
+              ),
+            ),
+          ],
+          Positioned(
+            right: 0,
+            top: 0,
+            bottom: 0,
+            child: Align(
+              alignment: Alignment.centerRight,
+              child: Text(
+                endLabel,
+                overflow: TextOverflow.ellipsis,
+                maxLines: 1,
+                style: theme.textTheme.labelSmall,
+              ),
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+}
+
+class _AttrRow extends StatelessWidget {
+  const _AttrRow({
+    required this.rowHeight,
+    required this.blocks,
+    required this.model,
+    required this.scrollOffset,
+    required this.viewportWidth,
+  });
+
+  final double rowHeight;
+  final List<_ValueBlock> blocks;
+  final _TimelineModel model;
+  final double scrollOffset;
+  final double viewportWidth;
+
+  @override
+  Widget build(BuildContext context) {
+    final width = math.max(model.axisTotalWidth, 120.0);
+    final activeBlock = _activeBlock(blocks, scrollOffset);
+    final double stickyWidth = activeBlock == null
+        ? 0
+        : (activeBlock.right - scrollOffset).clamp(20.0, viewportWidth);
+
+    return SizedBox(
+      width: width,
+      height: rowHeight,
+      child: Stack(
+        clipBehavior: Clip.hardEdge,
+        children: [
+          for (final block in blocks)
+            Positioned(
+              left: block.left,
+              width: block.width,
+              top: 0,
+              bottom: 0,
+              child: _ValueBlockView(block: block),
+            ),
+          if (activeBlock != null)
+            Positioned(
+              left: scrollOffset,
+              width: stickyWidth,
+              top: 0,
+              bottom: 0,
+              child: IgnorePointer(
+                child: ClipRect(
+                  child: _ValueBlockView(
+                    block: activeBlock.copyWith(
+                      left: scrollOffset,
+                      width: stickyWidth,
+                    ),
+                    clipLeftEdge: scrollOffset > activeBlock.left + 0.1,
+                  ),
+                ),
+              ),
+            ),
+        ],
+      ),
+    );
+  }
+
+  _ValueBlock? _activeBlock(List<_ValueBlock> blocks, double offset) {
+    for (final block in blocks) {
+      if (offset >= block.left && offset < block.right) return block;
+    }
+    return null;
+  }
+}
+
+class _ValueBlockView extends StatelessWidget {
+  const _ValueBlockView({
+    required this.block,
+    this.clipLeftEdge = false,
+  });
+
+  final _ValueBlock block;
+  final bool clipLeftEdge;
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final color = block.cell.color.withOpacity(0.9);
+    final textColor = ThemeData.estimateBrightnessForColor(color) ==
+            Brightness.dark
+        ? Colors.white
+        : Colors.black87;
+
+    final radius = BorderRadius.only(
+      topLeft: Radius.circular(clipLeftEdge ? 0 : 12),
+      bottomLeft: Radius.circular(clipLeftEdge ? 0 : 12),
+      topRight: const Radius.circular(12),
+      bottomRight: const Radius.circular(12),
+    );
+
+    return ClipRRect(
+      borderRadius: radius,
+      child: Container(
+        padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 8),
+        decoration: BoxDecoration(
+          color: block.cell.value.isEmpty
+              ? theme.colorScheme.surfaceContainerHighest
+              : color,
+          borderRadius: BorderRadius.zero,
+          border: Border.all(color: theme.colorScheme.outlineVariant),
+        ),
+        child: block.cell.value.isEmpty
+            ? const SizedBox.shrink()
+            : FittedBox(
+                alignment: Alignment.topLeft,
+                fit: BoxFit.scaleDown,
+                child: ConstrainedBox(
+                  constraints: const BoxConstraints(minWidth: 1, minHeight: 1),
+                  child: Column(
+                    crossAxisAlignment: CrossAxisAlignment.start,
+                    mainAxisAlignment: MainAxisAlignment.center,
+                    children: [
+                      Text(
+                        block.cell.value,
+                        maxLines: 1,
+                        overflow: TextOverflow.ellipsis,
+                        style: theme.textTheme.bodyMedium?.copyWith(
+                              fontWeight: FontWeight.w700,
+                              color: textColor,
+                            ) ??
+                            TextStyle(
+                              fontWeight: FontWeight.w700,
+                              color: textColor,
+                            ),
+                      ),
+                      const SizedBox(height: 4),
+                      Text(
+                        block.cell.rangeLabel,
+                        maxLines: 1,
+                        overflow: TextOverflow.ellipsis,
+                        style: theme.textTheme.labelSmall?.copyWith(
+                              color: textColor.withOpacity(0.9),
+                            ) ??
+                            TextStyle(color: textColor.withOpacity(0.9)),
+                      ),
+                    ],
+                  ),
+                ),
+              ),
+      ),
+    );
+  }
+}
+final DateFormat _dateFormat = DateFormat('yyyy-MM-dd');
+
+String? _formatDate(DateTime? date) {
+  if (date == null) return null;
+  return _dateFormat.format(date);
+}
+
+String _formatAttrLabel(String code) {
+  if (code.isEmpty) return 'Attribute';
+  final parts = code.split('_').where((p) => p.isNotEmpty).toList();
+  if (parts.isEmpty) return code;
+  return parts
+      .map((part) => part.length == 1
+          ? part.toUpperCase()
+          : part[0].toUpperCase() + part.substring(1))
+      .join(' ');
+}
+
+DateTime? _parseDateString(String? value) {
+  if (value == null || value.isEmpty) return null;
+  return DateTime.tryParse(value);
+}
+
+DateTime? _effectiveStart(LocoAttrVersion entry) {
+  return entry.validFrom ??
+      _parseDateString(entry.maskedValidFrom) ??
+      entry.txnFrom;
+}
+
+DateTime _safeEnd(DateTime start, DateTime? end) {
+  if (end == null || !end.isAfter(start)) {
+    return start.add(const Duration(days: 1));
+  }
+  return end;
+}
+
+class _TimelineModel {
+  final List<_AxisSegment> axisSegments;
+  final Map<String, List<_ValueBlock>> attrRows;
+  final String endLabel;
+  final List<DateTime> boundaries;
+  final double axisTotalWidth;
+
+  _TimelineModel({
+    required this.axisSegments,
+    required this.attrRows,
+    required this.endLabel,
+    required this.boundaries,
+    required this.axisTotalWidth,
+  });
+
+  factory _TimelineModel.fromEntries(List<LocoAttrVersion> entries) {
+    final grouped = <String, List<LocoAttrVersion>>{};
+    for (final entry in entries) {
+      grouped.putIfAbsent(entry.attrCode, () => []).add(entry);
+    }
+    final now = DateTime.now();
+    DateTime? minStart;
+    DateTime? maxEnd;
+    final attrSegments = <String, List<_ValueSegment>>{};
+
+    grouped.forEach((attr, items) {
+      items.sort(
+        (a, b) => (_effectiveStart(a) ?? now)
+            .compareTo(_effectiveStart(b) ?? now),
+      );
+      final segments = <_ValueSegment>[];
+      for (int i = 0; i < items.length; i++) {
+        final entry = items[i];
+        final start = _effectiveStart(entry) ?? now;
+        final nextStart = i < items.length - 1
+            ? _effectiveStart(items[i + 1])
+            : null;
+        final rawEnd = entry.validTo ?? nextStart ?? now;
+        final end = _safeEnd(start, rawEnd);
+        if (segments.isNotEmpty && segments.last.value == entry.valueLabel) {
+          final last = segments.removeLast();
+          segments.add(
+            last.copyWith(
+              end: end.isAfter(last.end) ? end : last.end,
+            ),
+          );
+        } else {
+          segments.add(
+            _ValueSegment(
+              start: start,
+              end: end,
+              value: entry.valueLabel,
+              entry: entry,
+            ),
+          );
+        }
+        minStart = minStart == null || start.isBefore(minStart!)
+            ? start
+            : minStart;
+        maxEnd = maxEnd == null || end.isAfter(maxEnd!) ? end : maxEnd;
+      }
+      attrSegments[attr] = segments;
+    });
+
+    minStart ??= now.subtract(const Duration(days: 1));
+    final effectiveMaxEnd = maxEnd ?? now;
+
+    final boundaryDates = <DateTime>{};
+    for (final segments in attrSegments.values) {
+      for (final seg in segments) {
+        boundaryDates.add(seg.start);
+        boundaryDates.add(seg.end);
+      }
+    }
+    boundaryDates.add(effectiveMaxEnd);
+    var boundaries = boundaryDates.toList()..sort();
+    if (boundaries.length < 2) {
+      boundaries = [minStart!, effectiveMaxEnd];
+    }
+
+    final axisSegments = <_AxisSegment>[];
+    const double yearWidth = 240.0;
+    for (int i = 0; i < boundaries.length - 1; i++) {
+      final start = boundaries[i];
+      final end = boundaries[i + 1];
+      final width = yearWidth;
+      final double offset = axisSegments.isEmpty
+          ? 0.0
+          : axisSegments.last.offset + axisSegments.last.width;
+      axisSegments.add(
+        _AxisSegment(
+          start: start,
+          end: end,
+          width: width,
+          offset: offset,
+          label: _formatDate(start) ?? '',
+        ),
+      );
+    }
+    final axisTotalWidth =
+        axisSegments.fold<double>(0, (sum, seg) => sum + seg.width);
+
+    final attrRows = <String, List<_ValueBlock>>{};
+    for (final entry in attrSegments.entries) {
+      final blocks = <_ValueBlock>[];
+      for (final seg in entry.value) {
+        final left = _positionForDate(seg.start, boundaries, axisSegments);
+        final right = _positionForDate(seg.end, boundaries, axisSegments);
+        final span = right - left;
+        final width = span < 2.0 ? 2.0 : span;
+        blocks.add(
+          _ValueBlock(
+            left: left,
+            width: width,
+            cell: _RowCell.fromSegment(seg),
+          ),
+        );
+      }
+      attrRows[entry.key] = blocks;
+    }
+
+    final endLabel = _formatDate(effectiveMaxEnd) ?? 'Now';
+    return _TimelineModel(
+      axisSegments: axisSegments,
+      attrRows: attrRows,
+      endLabel: endLabel,
+      boundaries: boundaries,
+      axisTotalWidth: axisTotalWidth,
+    );
+  }
+
+  static double _positionForDate(
+    DateTime date,
+    List<DateTime> boundaries,
+    List<_AxisSegment> segments,
+  ) {
+    for (int i = 0; i < boundaries.length - 1; i++) {
+      final start = boundaries[i];
+      final end = boundaries[i + 1];
+      if (!date.isAfter(end)) {
+        final seg = segments[i];
+        final span = end.difference(start).inMilliseconds;
+        final elapsed = date.difference(start).inMilliseconds.clamp(0, span);
+        if (span <= 0) return seg.offset;
+        final fraction = elapsed / span;
+        return seg.offset + (seg.width * fraction);
+      }
+    }
+    return segments.isNotEmpty
+        ? segments.last.offset + segments.last.width
+        : 0.0;
+  }
+}
+
+class _AxisSegment {
+  final DateTime start;
+  final DateTime end;
+  final double width;
+  final double offset;
+  final String label;
+
+  _AxisSegment({
+    required this.start,
+    required this.end,
+    required this.width,
+    required this.offset,
+    required this.label,
+  });
+}
+
+class _ValueSegment {
+  final DateTime start;
+  final DateTime end;
+  final String value;
+  final LocoAttrVersion? entry;
+
+  _ValueSegment({
+    required this.start,
+    required this.end,
+    required this.value,
+    this.entry,
+  });
+
+  bool overlaps(DateTime s, DateTime e) {
+    return start.isBefore(e) && end.isAfter(s);
+  }
+
+  _ValueSegment copyWith({DateTime? start, DateTime? end, String? value}) {
+    return _ValueSegment(
+      start: start ?? this.start,
+      end: end ?? this.end,
+      value: value ?? this.value,
+      entry: entry,
+    );
+  }
+}
+
+class _RowCell {
+  final String value;
+  final String rangeLabel;
+  final Color color;
+
+  const _RowCell({
+    required this.value,
+    required this.rangeLabel,
+    required this.color,
+  });
+
+  factory _RowCell.fromSegment(_ValueSegment seg) {
+    if (seg.value.isEmpty) {
+      return const _RowCell(
+        value: '',
+        rangeLabel: '',
+        color: Colors.transparent,
+      );
+    }
+    final displayStart = _formatDate(seg.start) ?? '';
+    return _RowCell(
+      value: seg.value,
+      rangeLabel: displayStart,
+      color: _colorForValue(seg.value),
+    );
+  }
+}
+
+class _ValueBlock {
+  final double left;
+  final double width;
+  final _RowCell cell;
+
+  const _ValueBlock({
+    required this.left,
+    required this.width,
+    required this.cell,
+  });
+
+  double get right => left + width;
+
+  _ValueBlock copyWith({
+    double? left,
+    double? width,
+    _RowCell? cell,
+  }) {
+    return _ValueBlock(
+      left: left ?? this.left,
+      width: width ?? this.width,
+      cell: cell ?? this.cell,
+    );
+  }
+}
+
+Color _colorForValue(String value) {
+  final hue = (value.hashCode % 360).toDouble();
+  final hsl = HSLColor.fromAHSL(1, hue, 0.55, 0.55);
+  return hsl.toColor();
+}

lib/components/pages/traction.dart

@@ -423,57 +423,68 @@ class _TractionPageState extends State<TractionPage> {
             ),
           ),
           const SizedBox(height: 12),
-          if (data.isTractionLoading && traction.isEmpty)
+          Stack(
-            const Center(
+            children: [
-              child: Padding(
+              if (data.isTractionLoading && traction.isEmpty)
-                padding: EdgeInsets.symmetric(vertical: 24.0),
+                const Padding(
-                child: CircularProgressIndicator(),
+                  padding: EdgeInsets.symmetric(vertical: 32.0),
-              ),
+                  child: Center(child: CircularProgressIndicator()),
-            )
+                )
-          else if (traction.isEmpty)
+              else if (traction.isEmpty)
-            Card(
+                Card(
-              child: Padding(
+                  child: Padding(
-                padding: const EdgeInsets.all(16.0),
+                    padding: const EdgeInsets.all(16.0),
-                child: Column(
+                    child: Column(
-                  crossAxisAlignment: CrossAxisAlignment.start,
+                      crossAxisAlignment: CrossAxisAlignment.start,
-                  children: [
+                      children: [
-                    Text(
+                        Text(
-                      'No traction found',
+                          'No traction found',
-                      style: Theme.of(context).textTheme.titleMedium?.copyWith(
+                          style: Theme.of(context).textTheme.titleMedium?.copyWith(
-                        fontWeight: FontWeight.w700,
+                            fontWeight: FontWeight.w700,
-                      ),
+                          ),
-                    ),
+                        ),
-                    const SizedBox(height: 8),
+                        const SizedBox(height: 8),
-                    const Text('Try relaxing the filters or sync again.'),
+                        const Text('Try relaxing the filters or sync again.'),
-                  ],
+                      ],
-                ),
-              ),
-            )
-          else
-            Column(
-              children: [
-                ...traction.map((loco) => _buildTractionCard(context, loco)),
-                if (data.tractionHasMore || data.isTractionLoading)
-                  Padding(
-                    padding: const EdgeInsets.only(top: 8.0),
-                    child: OutlinedButton.icon(
-                      onPressed: data.isTractionLoading
-                          ? null
-                          : () => _refreshTraction(append: true),
-                      icon: data.isTractionLoading
-                          ? const SizedBox(
-                              height: 14,
-                              width: 14,
-                              child: CircularProgressIndicator(strokeWidth: 2),
-                            )
-                          : const Icon(Icons.expand_more),
-                      label: Text(
-                        data.isTractionLoading ? 'Loading...' : 'Load more',
-                      ),
                     ),
                   ),
-              ],
+                )
-            ),
+              else
+                Column(
+                  children: [
+                    ...traction.map((loco) => _buildTractionCard(context, loco)),
+                    if (data.tractionHasMore || data.isTractionLoading)
+                      Padding(
+                        padding: const EdgeInsets.only(top: 8.0),
+                        child: OutlinedButton.icon(
+                          onPressed: data.isTractionLoading
+                              ? null
+                              : () => _refreshTraction(append: true),
+                          icon: data.isTractionLoading
+                              ? const SizedBox(
+                                  height: 14,
+                                  width: 14,
+                                  child: CircularProgressIndicator(strokeWidth: 2),
+                                )
+                              : const Icon(Icons.expand_more),
+                          label: Text(
+                            data.isTractionLoading ? 'Loading...' : 'Load more',
+                          ),
+                        ),
+                      ),
+                  ],
+                ),
+              if (data.isTractionLoading)
+                Positioned.fill(
+                  child: IgnorePointer(
+                    child: Container(
+                      color: Theme.of(context).colorScheme.surface.withOpacity(0.6),
+                      child: const Center(child: CircularProgressIndicator()),
+                    ),
+                  ),
+                ),
+            ],
+          ),
         ],
       ),
     );
@@ -574,6 +585,12 @@ class _TractionPageState extends State<TractionPage> {
                   icon: const Icon(Icons.info_outline),
                   label: const Text('Details'),
                 ),
+                const SizedBox(width: 8),
+                TextButton.icon(
+                  onPressed: () => _openTimeline(loco),
+                  icon: const Icon(Icons.timeline),
+                  label: const Text('Timeline'),
+                ),
                 const Spacer(),
                 if (widget.selectionMode)
                   TextButton.icon(
@@ -692,6 +709,14 @@ class _TractionPageState extends State<TractionPage> {
     return (background, foreground);
   }
 
+  void _openTimeline(LocoSummary loco) {
+    final label = '${loco.locoClass} ${loco.number}'.trim();
+    context.push(
+      '/traction/${loco.id}/timeline',
+      extra: {'label': label},
+    );
+  }
+
   Future<void> _showLocoInfo(LocoSummary loco) async {
     await showModalBottomSheet(
       context: context,

lib/main.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:dynamic_color/dynamic_color.dart';
 import 'package:mileograph_flutter/components/pages/calculator.dart';
+import 'package:mileograph_flutter/components/pages/loco_timeline.dart';
 import 'package:mileograph_flutter/components/pages/new_entry.dart';
 import 'package:mileograph_flutter/components/pages/new_traction.dart';
 import 'package:mileograph_flutter/components/pages/traction.dart';
@@ -95,6 +96,27 @@ class MyApp extends StatelessWidget {
             ),
             GoRoute(path: '/legs', builder: (_, __) => LegsPage()),
             GoRoute(path: '/traction', builder: (_, __) => TractionPage()),
+            GoRoute(
+              path: '/traction/:id/timeline',
+              builder: (_, state) {
+                final idParam = state.pathParameters['id'];
+                final locoId = int.tryParse(idParam ?? '') ?? 0;
+                final extra = state.extra;
+                String label = state.uri.queryParameters['label'] ?? '';
+                if (extra is Map && extra['label'] is String) {
+                  label = extra['label'] as String;
+                } else if (extra is String && extra.isNotEmpty) {
+                  label = extra;
+                }
+                if (label.trim().isEmpty) {
+                  label = 'Loco $locoId';
+                }
+                return LocoTimelinePage(
+                  locoId: locoId,
+                  locoLabel: label,
+                );
+              },
+            ),
             GoRoute(
               path: '/traction/new',
               builder: (_, __) => const NewTractionPage(),

lib/objects/objects.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'package:intl/intl.dart';
 
 class DestinationObject {
   const DestinationObject(
@@ -190,6 +191,143 @@ class LocoSummary extends Loco {
   );
 }
 
+class LocoAttrVersion {
+  final String attrCode;
+  final int? versionId;
+  final int locoId;
+  final int? attrTypeId;
+  final String? valueStr;
+  final int? valueInt;
+  final DateTime? valueDate;
+  final bool? valueBool;
+  final String? valueEnum;
+  final DateTime? validFrom;
+  final DateTime? validTo;
+  final DateTime? txnFrom;
+  final DateTime? txnTo;
+  final String? suggestedBy;
+  final String? approvedBy;
+  final DateTime? approvedAt;
+  final int? sourceEventId;
+  final String? precisionLevel;
+  final String? maskedValidFrom;
+  final dynamic valueNorm;
+
+  const LocoAttrVersion({
+    required this.attrCode,
+    required this.locoId,
+    this.versionId,
+    this.attrTypeId,
+    this.valueStr,
+    this.valueInt,
+    this.valueDate,
+    this.valueBool,
+    this.valueEnum,
+    this.validFrom,
+    this.validTo,
+    this.txnFrom,
+    this.txnTo,
+    this.suggestedBy,
+    this.approvedBy,
+    this.approvedAt,
+    this.sourceEventId,
+    this.precisionLevel,
+    this.maskedValidFrom,
+    this.valueNorm,
+  });
+
+  factory LocoAttrVersion.fromJson(Map<String, dynamic> json) {
+    return LocoAttrVersion(
+      attrCode: json['attr_code']?.toString() ?? '',
+      locoId: (json['loco_id'] as num?)?.toInt() ?? 0,
+      versionId: (json['loco_attr_v_id'] as num?)?.toInt(),
+      attrTypeId: (json['attr_type_id'] as num?)?.toInt(),
+      valueStr: json['value_str']?.toString(),
+      valueInt: (json['value_int'] as num?)?.toInt(),
+      valueDate: _parseDate(json['value_date']),
+      valueBool: _parseBool(json['value_bool']),
+      valueEnum: json['value_enum']?.toString(),
+      validFrom: _parseDate(json['valid_from']),
+      validTo: _parseDate(json['valid_to']),
+      txnFrom: _parseDate(json['txn_from']),
+      txnTo: _parseDate(json['txn_to']),
+      suggestedBy: json['suggested_by']?.toString(),
+      approvedBy: json['approved_by']?.toString(),
+      approvedAt: _parseDate(json['approved_at']),
+      sourceEventId: (json['source_event_id'] as num?)?.toInt(),
+      precisionLevel: json['precision_level']?.toString(),
+      maskedValidFrom: json['masked_valid_from']?.toString(),
+      valueNorm: json['value_norm'],
+    );
+  }
+
+  static DateTime? _parseDate(dynamic value) {
+    if (value == null) return null;
+    if (value is DateTime) return value;
+    return DateTime.tryParse(value.toString());
+  }
+
+  static bool? _parseBool(dynamic value) {
+    if (value == null) return null;
+    if (value is bool) return value;
+    if (value is num) return value != 0;
+    final str = value.toString().toLowerCase();
+    if (['true', '1', 'yes'].contains(str)) return true;
+    if (['false', '0', 'no'].contains(str)) return false;
+    return null;
+  }
+
+  static List<LocoAttrVersion> fromGroupedJson(dynamic json) {
+    final List<LocoAttrVersion> items = [];
+    if (json is Map) {
+      json.forEach((key, value) {
+        if (value is List) {
+          for (final entry in value) {
+            if (entry is Map<String, dynamic>) {
+              final merged = Map<String, dynamic>.from(entry);
+              merged.putIfAbsent('attr_code', () => key);
+              items.add(LocoAttrVersion.fromJson(merged));
+            }
+          }
+        }
+      });
+    }
+    items.sort(
+      (a, b) {
+        final aDate = a.validFrom ?? a.txnFrom ?? DateTime.fromMillisecondsSinceEpoch(0);
+        final bDate = b.validFrom ?? b.txnFrom ?? DateTime.fromMillisecondsSinceEpoch(0);
+        final dateCompare = aDate.compareTo(bDate);
+        if (dateCompare != 0) return dateCompare;
+        return a.attrCode.compareTo(b.attrCode);
+      },
+    );
+    return items;
+  }
+
+  String get valueLabel {
+    if (valueStr != null && valueStr!.isNotEmpty) return valueStr!;
+    if (valueEnum != null && valueEnum!.isNotEmpty) return valueEnum!;
+    if (valueInt != null) return valueInt!.toString();
+    if (valueBool != null) return valueBool! ? 'Yes' : 'No';
+    if (valueDate != null) return DateFormat('yyyy-MM-dd').format(valueDate!);
+    if (valueNorm != null && valueNorm.toString().isNotEmpty) {
+      return valueNorm.toString();
+    }
+    return '—';
+  }
+
+  String get validityRange {
+    final start = maskedValidFrom ?? _formatDate(validFrom) ?? 'Unknown';
+    final end = _formatDate(validTo, fallback: 'Present') ?? 'Present';
+    return '$start → $end';
+  }
+
+  String? _formatDate(DateTime? value, {String? fallback}) {
+    if (value == null) return fallback;
+    return DateFormat('yyyy-MM-dd').format(value);
+  }
+}
+
 class LeaderboardEntry {
   final String userId, username, userFullName;
   final double mileage;

lib/services/dataService.dart

@@ -49,6 +49,12 @@ class DataService extends ChangeNotifier {
   bool get isTractionLoading => _isTractionLoading;
   bool _tractionHasMore = false;
   bool get tractionHasMore => _tractionHasMore;
+  final Map<int, List<LocoAttrVersion>> _locoTimelines = {};
+  final Map<int, bool> _isLocoTimelineLoading = {};
+  List<LocoAttrVersion> timelineForLoco(int locoId) =>
+      _locoTimelines[locoId] ?? [];
+  bool isLocoTimelineLoading(int locoId) =>
+      _isLocoTimelineLoading[locoId] ?? false;
 
   // Trips
   List<TripSummary> _trips = [];
@@ -235,6 +241,24 @@ class DataService extends ChangeNotifier {
     }
   }
 
+  Future<List<LocoAttrVersion>> fetchLocoTimeline(int locoId) async {
+    _isLocoTimelineLoading[locoId] = true;
+    _notifyAsync();
+    try {
+      final json = await api.get('/loco/get-timeline/$locoId');
+      final timeline = LocoAttrVersion.fromGroupedJson(json);
+      _locoTimelines[locoId] = timeline;
+      return timeline;
+    } catch (e) {
+      debugPrint('Failed to fetch loco timeline for $locoId: $e');
+      _locoTimelines[locoId] = [];
+      return [];
+    } finally {
+      _isLocoTimelineLoading[locoId] = false;
+      _notifyAsync();
+    }
+  }
+
   Future<dynamic> createLoco(Map<String, dynamic> payload) async {
     try {
       final response = await api.put('/loco/new', payload);
@@ -424,6 +448,8 @@ class DataService extends ChangeNotifier {
     _trips = [];
     _tripDetails = [];
     _eventFields = [];
+    _locoTimelines.clear();
+    _isLocoTimelineLoading.clear();
     _notifyAsync();
   }
 

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: 0.1.5+1
+version: 0.1.6+1
 
 environment:
   sdk: ^3.8.1