Fix for Mobile Google Calendar Odd/Even Week Imports

website/src/utils/ical.test.ts

@@ -174,7 +174,7 @@ describe(calculateNumericWeek, () => {
         new Date('2016-10-31T14:00+0800'), // 12
       ]),
     );
-  });
+  }); 
 
   test('generates exclusions for holidays', () => {
     // 2016 holidays
@@ -258,8 +258,9 @@ test('iCalEventForLesson generates correct output', () => {
     description: 'Personal Development & Career Management\nSectional Teaching Group A1',
     location: 'BIZ1-0303',
     repeating: {
+      interval: 1,
       freq: 'WEEKLY',
-      count: 14,
+      count: 6,
       byDay: ['Mo'],
       exclude: expect.arrayContaining([]), // Tested in previous tests
     },
@@ -291,6 +292,7 @@ test('work for half hour lesson offsets', () => {
     description: 'Personal Development & Career Management\nSectional Teaching Group A1',
     location: 'BIZ1-0303',
     repeating: {
+      interval: 1,
       freq: 'WEEKLY',
       count: 14,
       byDay: ['Mo'],

website/src/utils/ical.ts

@@ -81,6 +81,21 @@ function calculateStartEnd(date: Date, startTime: StartTime, endTime: EndTime) {
   return { start, end };
 }
 
+function calculateLargestInterval(weeks: NumericWeeks) {
+  let largestInterval = 1;
+  for (let i = 0; i < weeks.length - 1; i++) {
+    const diff = weeks[i + 1] - weeks[i];
+    if (diff > largestInterval) {
+      largestInterval = diff;
+    }
+  }
+  return largestInterval;
+}
+
+function isSplitOverRecess(weeks: NumericWeeks) {
+  return weeks.some((week) => week <= 6) && weeks.some((week) => week > 6);
+}
+
 export function calculateNumericWeek(
   lesson: RawLesson,
   _semester: Semester,
@@ -91,12 +106,21 @@ export function calculateNumericWeek(
   const { start, end } = calculateStartEnd(lessonDay, lesson.startTime, lesson.endTime);
   const excludedWeeks = _.difference([RECESS_WEEK, ...ALL_WEEKS], weeks);
 
+  // Sets interval to 2 for odd and even weeks. Fix for mobile GCal imports.
+  const isAlternate =
+    weeks.every((week) => ODD_WEEKS.includes(week)) ||
+    weeks.every((week) => EVEN_WEEKS.includes(week));
+  const interval = isAlternate ? 2 : 1;
+  const largestInterval = calculateLargestInterval(weeks);
+  const adjCount = ((largestInterval === interval) && !isSplitOverRecess(weeks)) ? weeks.length : NUM_WEEKS_IN_A_SEM;
+
   return {
     start,
     end,
     repeating: {
+      interval,
       freq: 'WEEKLY',
-      count: NUM_WEEKS_IN_A_SEM,
+      count: adjCount,
       byDay: [lesson.day.slice(0, 2)],
       exclude: [
         ...excludedWeeks.map((week) => datesForAcademicWeeks(start, week)),
@@ -187,7 +211,15 @@ export default function iCalForTimetable(
 
     _.each(lessonConfig, (lessons) => {
       lessons.forEach((lesson) => {
-        events.push(iCalEventForLesson(lesson, moduleData[moduleCode], semester, firstDayOfSchool));
+        // If the lesson is split across recess week, we need to create two separate events for mobile GCal imports as it does not support exclusion rules.
+        if (isSplitOverRecess(lesson.weeks) && lesson.weeks.length <= NUM_WEEKS_IN_A_SEM/2) {
+          const lessonsFirstHalf = lesson.weeks.slice(0, 6);
+          const lessonsSecondHalf = lesson.weeks.slice(6);
+          events.push(iCalEventForLesson(lessonsFirstHalf, moduleData[moduleCode], semester, firstDayOfSchool));
+          events.push(iCalEventForLesson(lessonsSecondHalf, moduleData[moduleCode], semester, firstDayOfSchool));          
+        } else {
+          events.push(iCalEventForLesson(lesson, moduleData[moduleCode], semester, firstDayOfSchool));
+        }
       });
     });