Implement husband-wife connection dialogue and theme support for learn articles

lib/services/cycle_service.dart

@@ -175,6 +175,66 @@ class CycleService {
     );
   }
 
+  /// Calculates the cycle phase for a specific date (past or future)
+  static CyclePhase? getPhaseForDate(DateTime date, UserProfile? user) {
+    if (user == null || user.lastPeriodStartDate == null) return null;
+
+    final lastPeriodStart = user.lastPeriodStartDate!;
+    
+    // Normalize dates
+    final checkDate = DateTime(date.year, date.month, date.day);
+    final startCycle = DateTime(lastPeriodStart.year, lastPeriodStart.month, lastPeriodStart.day);
+
+    final daysDifference = checkDate.difference(startCycle).inDays;
+    
+    // If date is before the last known period, we can't reliably predict using this simple logic
+    // (though in reality we could project backwards, but let's stick to forward/current)
+    if (daysDifference < 0) return null;
+
+    final cycleLength = user.averageCycleLength;
+    final dayOfCycle = (daysDifference % cycleLength) + 1;
+
+    if (dayOfCycle <= user.averagePeriodLength) return CyclePhase.menstrual;
+    if (dayOfCycle <= 13) return CyclePhase.follicular;
+    if (dayOfCycle <= 16) return CyclePhase.ovulation;
+    return CyclePhase.luteal;
+  }
+
+  /// Predicts period days for the next [months] months
+  static List<DateTime> predictNextPeriodDays(UserProfile? user, {int months = 12}) {
+    if (user == null || user.lastPeriodStartDate == null) return [];
+
+    final predictedDays = <DateTime>[];
+    final lastPeriodStart = user.lastPeriodStartDate!;
+    final cycleLength = user.averageCycleLength;
+    final periodLength = user.averagePeriodLength;
+
+    // Start predicting from the NEXT cycle if the current one is finished, 
+    // or just project out from the last start date.
+    // We want to list all future period days.
+    
+    DateTime currentCycleStart = lastPeriodStart;
+    
+    // Project forward for roughly 'months' months
+    // A safe upper bound for loop is months * 30 days
+    final limitDate = DateTime.now().add(Duration(days: months * 30));
+
+    while (currentCycleStart.isBefore(limitDate)) {
+      // Add period days for this cycle
+      for (int i = 0; i < periodLength; i++) {
+        final periodDay = currentCycleStart.add(Duration(days: i));
+        if (periodDay.isAfter(DateTime.now())) {
+          predictedDays.add(periodDay);
+        }
+      }
+      
+      // Move to next cycle
+      currentCycleStart = currentCycleStart.add(Duration(days: cycleLength));
+    }
+    
+    return predictedDays;
+  }
+
   /// Format cycle day for display
   static String getDayOfCycleDisplay(int day) => 'Day $day';
 

lib/services/ics_service.dart

@@ -1,24 +1,14 @@
 import 'dart:io';
 import 'package:intl/intl.dart';
 import 'package:path_provider/path_provider.dart';
-import 'package:share_plus/share_plus.dart'; // Ensure share_plus is in dependencies or use printing/share mechanism
-import '../models/cycle_entry.dart';
-
-// Since we might not have share_plus in the pubspec explicitly seen earlier (user plan said adding dependencies),
-// keeping it safe. The pubspec had 'pdf', 'printing', 'path_provider', 'universal_html'.
-// 'share_plus' was not explicitly in the list I viewed in Step 258, but 'printing' can share PDF.
-// For ICS, we need a way to share the file. 'printing' relies on pdf.
-// Wait, Step 258 pubspec content lines 9-48...
-// I don't see `share_plus`.
-// I'll check `pubspec.yaml` again to be absolutely sure or add it via `flutter pub add`.
-// Actually, `printing` has a share method but it's specific to PDF bytes usually? No, `Printing.sharePdf`.
-// I should use `share_plus` if I want to share a text/ics file. 
-// Or I can just write to file and open it with `open_filex`.
-
 import 'package:open_filex/open_filex.dart';
+import '../models/cycle_entry.dart';
+import '../models/user_profile.dart';
+import 'cycle_service.dart';
+import 'package:uuid/uuid.dart';
 
 class IcsService {
-  static Future<void> generateCycleCalendar(List<CycleEntry> entries) async {
+  static Future<void> generateCycleCalendar(List<CycleEntry> entries, {UserProfile? user, bool includePredictions = true}) async {
     final buffer = StringBuffer();
     buffer.writeln('BEGIN:VCALENDAR');
     buffer.writeln('VERSION:2.0');
@@ -27,6 +17,7 @@ class IcsService {
     // Sort entries
     entries.sort((a, b) => a.date.compareTo(b.date));
 
+    // 1. Logged Entries
     for (var entry in entries) {
       if (entry.isPeriodDay) {
         final dateStr = DateFormat('yyyyMMdd').format(entry.date);
@@ -41,6 +32,26 @@ class IcsService {
       }
     }
 
+    // 2. Predicted Entries
+    if (includePredictions && user != null) {
+      final predictedDays = CycleService.predictNextPeriodDays(user);
+      
+      for (var date in predictedDays) {
+        final dateStr = DateFormat('yyyyMMdd').format(date);
+        final uuid = const Uuid().v4();
+        
+        buffer.writeln('BEGIN:VEVENT');
+        buffer.writeln('UID:$uuid');
+        buffer.writeln('DTSTAMP:${DateFormat('yyyyMMddTHHmmss').format(DateTime.now())}Z');
+        buffer.writeln('DTSTART;VALUE=DATE:$dateStr'); 
+        buffer.writeln('DTEND;VALUE=DATE:${DateFormat('yyyyMMdd').format(date.add(const Duration(days: 1)))}');
+        buffer.writeln('SUMMARY:Predicted Period');
+        buffer.writeln('DESCRIPTION:Predicted period day based on cycle history.');
+        buffer.writeln('STATUS:TENTATIVE'); // Mark as tentative
+        buffer.writeln('END:VEVENT');
+      }
+    }
+
     buffer.writeln('END:VCALENDAR');
 
     // Save to file