add redate functionality to set the earliest date of entries

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;
+}

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: 0.8.2+19
+version: 0.8.3+20
 
 environment:
   sdk: ^3.8.1