Initial commit

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

lib/services/time_service.dart

@@ -0,0 +1,103 @@
+import 'package:flutter_timezone/flutter_timezone.dart';
+import 'package:timezone/data/latest.dart' as tzdata;
+import 'package:timezone/timezone.dart' as tz;
+
+class TimeService {
+  static const String estLocationName = 'America/New_York';
+
+  static bool _initialized = false;
+
+  static Future<void> initialize() async {
+    if (_initialized) {
+      return;
+    }
+
+    tzdata.initializeTimeZones();
+    final localName = await FlutterTimezone.getLocalTimezone();
+    tz.setLocalLocation(tz.getLocation(localName));
+    _initialized = true;
+  }
+
+  static tz.Location get est => tz.getLocation(estLocationName);
+
+  static tz.TZDateTime estNow() => tz.TZDateTime.now(est);
+
+  static DateTime localNow() => tz.TZDateTime.now(tz.local);
+
+  static tz.TZDateTime estDeadlinePassedAt(int year, int month) {
+    return tz.TZDateTime(est, year, month, 2, 0, 0);
+  }
+
+  static tz.TZDateTime estFirstReminderAt(int year, int month) {
+    return tz.TZDateTime(est, year, month, 2, 0, 5);
+  }
+
+  static bool isOnTimeByDeadline(DateTime paidAtUtc, int year, int month) {
+    final estPaidAt = tz.TZDateTime.from(paidAtUtc, est);
+    final cutoff = tz.TZDateTime(est, year, month, 1, 23, 59, 59, 999);
+    return !estPaidAt.isAfter(cutoff);
+  }
+
+  static DateTime applyQuietHours({
+    required DateTime localTime,
+    required int quietHourStart,
+    required int fallbackHour,
+  }) {
+    if (localTime.hour >= quietHourStart) {
+      return DateTime(
+        localTime.year,
+        localTime.month,
+        localTime.day + 1,
+        fallbackHour,
+      );
+    }
+
+    return localTime;
+  }
+
+  static DateTime nextEligibleLocal({
+    required DateTime candidate,
+    required int quietHourStart,
+    required int fallbackHour,
+  }) {
+    final now = localNow();
+    var result = candidate;
+
+    if (result.isBefore(now)) {
+      result = now.add(const Duration(minutes: 1));
+    }
+
+    if (result.hour >= quietHourStart) {
+      result = DateTime(
+        result.year,
+        result.month,
+        result.day + 1,
+        fallbackHour,
+      );
+    }
+
+    return result;
+  }
+
+  static bool monthAtOrAfter({
+    required int year,
+    required int month,
+    required int pivotYear,
+    required int pivotMonth,
+  }) {
+    return year > pivotYear || (year == pivotYear && month >= pivotMonth);
+  }
+
+  static bool monthBefore({
+    required int year,
+    required int month,
+    required int otherYear,
+    required int otherMonth,
+  }) {
+    return year < otherYear || (year == otherYear && month < otherMonth);
+  }
+
+  static String monthKey(int year, int month) {
+    return '$year-${month.toString().padLeft(2, '0')}';
+  }
+}