Harden app for 24-7 offline-first operation

lib/data/services/sync_service.dart

@@ -77,16 +77,75 @@ class ScheduleCacheStatus {
 class SyncService {
   SyncService._();
   static final SyncService instance = SyncService._();
+  static const Duration _autoRefreshCooldown = Duration(hours: 12);
+
+  static Set<String> rollingWindowMonths(DateTime referenceDate) {
+    final currentMonth = DateTime(referenceDate.year, referenceDate.month, 1);
+    final nextMonth = DateTime(referenceDate.year, referenceDate.month + 1, 1);
+    return {
+      DateFormat('yyyy-MM').format(currentMonth),
+      DateFormat('yyyy-MM').format(nextMonth),
+    };
+  }
+
+  static List<String> staleScheduleKeys(
+    Iterable<String> keys,
+    DateTime referenceDate,
+  ) {
+    final allowedMonths = rollingWindowMonths(referenceDate);
+    final staleKeys = <String>[];
+
+    for (final key in keys) {
+      final parsed = DateTime.tryParse(key);
+      if (parsed == null) {
+        staleKeys.add(key);
+        continue;
+      }
+
+      final monthKey = DateFormat('yyyy-MM').format(parsed);
+      if (!allowedMonths.contains(monthKey)) {
+        staleKeys.add(key);
+      }
+    }
+
+    return staleKeys;
+  }
+
+  Future<void> _pruneScheduleCache(
+    Box<DailyPrayerSchedule> scheduleBox,
+    DateTime referenceDate,
+  ) async {
+    final staleKeys = staleScheduleKeys(
+      scheduleBox.keys.cast<String>(),
+      referenceDate,
+    );
+    if (staleKeys.isNotEmpty) {
+      await scheduleBox.deleteAll(staleKeys);
+      await scheduleBox.compact();
+    }
+  }
+
+  bool _shouldAttemptAutoRefresh({
+    required ScheduleCacheStatus status,
+    required bool hasTodayData,
+  }) {
+    return !hasTodayData || !status.hasData || status.needsRefreshSoon;
+  }
+
+  DateTime? _parseAttemptTimestamp(String? value) {
+    if (value == null || value.isEmpty) return null;
+    return DateTime.tryParse(value);
+  }
 
   /// Sync current month + next month prayer data for the configured city.
   /// Returns true on success.
-  Future<bool> syncMonthlyData() async {
+  Future<bool> syncMonthlyData({DateTime? referenceDate}) async {
     final settingsBox = Hive.box<AppSettings>(HiveBoxes.settings);
     final settings = settingsBox.get('default');
     if (settings == null) return false;
 
     final cityId = settings.cityIdApi;
-    final now = DateTime.now();
+    final now = referenceDate ?? DateTime.now();
     final currentMonth = DateFormat('yyyy-MM').format(now);
 
     // Also fetch next month for continuity
@@ -97,10 +156,13 @@ class SyncService {
     final scheduleBox = Hive.box<DailyPrayerSchedule>(HiveBoxes.prayerSchedule);
 
     var success = false;
+    var hasCurrentMonth = false;
+    var hasNextMonth = false;
 
     // Fetch current month
     final currentData = await api.getMonthlySchedule(cityId, currentMonth);
     if (currentData.isNotEmpty) {
+      hasCurrentMonth = true;
       for (final entry in currentData.entries) {
         final jadwal = entry.value;
         scheduleBox.put(
@@ -124,6 +186,7 @@ class SyncService {
     // Fetch next month
     final nextData = await api.getMonthlySchedule(cityId, nextMonth);
     if (nextData.isNotEmpty) {
+      hasNextMonth = true;
       for (final entry in nextData.entries) {
         final jadwal = entry.value;
         scheduleBox.put(
@@ -144,6 +207,9 @@ class SyncService {
     }
 
     if (success) {
+      if (hasCurrentMonth && hasNextMonth) {
+        await _pruneScheduleCache(scheduleBox, now);
+      }
       settings.lastSyncDate = DateFormat('yyyy-MM-dd HH:mm').format(now);
       await settings.save();
     }
@@ -151,6 +217,38 @@ class SyncService {
     return success;
   }
 
+  Future<AutoRefreshResult> autoRefreshIfNeeded({
+    DateTime? referenceDate,
+  }) async {
+    final settingsBox = Hive.box<AppSettings>(HiveBoxes.settings);
+    final settings = settingsBox.get('default');
+    if (settings == null) {
+      return const AutoRefreshResult.skipped('settings-missing');
+    }
+
+    final now = referenceDate ?? DateTime.now();
+    final status = getCacheStatus(now);
+    final hasTodayData = getTodaySchedule(now) != null;
+
+    if (!_shouldAttemptAutoRefresh(status: status, hasTodayData: hasTodayData)) {
+      return const AutoRefreshResult.skipped('cache-fresh');
+    }
+
+    final lastAttempt = _parseAttemptTimestamp(settings.lastAutoSyncAttemptDate);
+    if (lastAttempt != null &&
+        now.difference(lastAttempt) < _autoRefreshCooldown) {
+      return const AutoRefreshResult.skipped('cooldown');
+    }
+
+    settings.lastAutoSyncAttemptDate = now.toIso8601String();
+    await settings.save();
+
+    final synced = await syncMonthlyData(referenceDate: now);
+    return synced
+        ? const AutoRefreshResult.synced()
+        : const AutoRefreshResult.failed('sync-failed');
+  }
+
   /// Get today's prayer schedule from local Hive cache.
   DailyPrayerSchedule? getTodaySchedule([DateTime? targetDate]) {
     final scheduleBox =
@@ -169,3 +267,24 @@ class SyncService {
     );
   }
 }
+
+class AutoRefreshResult {
+  final bool attempted;
+  final bool synced;
+  final String reason;
+
+  const AutoRefreshResult._({
+    required this.attempted,
+    required this.synced,
+    required this.reason,
+  });
+
+  const AutoRefreshResult.skipped(String reason)
+      : this._(attempted: false, synced: false, reason: reason);
+
+  const AutoRefreshResult.synced()
+      : this._(attempted: true, synced: true, reason: 'synced');
+
+  const AutoRefreshResult.failed(String reason)
+      : this._(attempted: true, synced: false, reason: reason);
+}