fix:#3 fetch room occupancy once

frontend/src/api/fetchRoomOccupancy.ts

@@ -16,11 +16,67 @@
 
 import { BSON } from "bson";
 import { RoomOccupancyList } from "@/model/roomOccupancyList.ts";
+import { Duration, NormalizedInterval, add, addDays, addMinutes, addMonths, clamp, differenceInMinutes, eachDayOfInterval, endOfDay, interval, isAfter, isBefore, isEqual, max, min, startOfDay, subDays } from "date-fns";
+import { formatYearMonthDay } from "@/helpers/dates";
+
+const END_OF_SUMMER_SEMESTER = "0930";
+const END_OF_WINTER_SEMESTER = "0331";
+
+/** 
+ * check if date is in winter semester before summer semester
+ * @param date - The date to check
+ * @returns boolean - true if date is in winter semester
+ */
+export function isBeforeSummer(date: Date): boolean {
+  const formattedDate = formatYearMonthDay(date).slice(4);
+  return formattedDate <= END_OF_WINTER_SEMESTER;
+}
+
+/** 
+ * check if date is in winter semester after summer semester
+ * @param date - The date to check
+ * @returns boolean - true if date is in winter semester
+ */
+export function isAfterSummer(date: Date): boolean {
+  const formattedDate = formatYearMonthDay(date).slice(4);
+  return formattedDate > END_OF_SUMMER_SEMESTER;
+}
+
+/**
+ * Gets the start date of the current semester
+ * @param date - The date to check
+ * @returns Date - The start date of the current semester
+ */
+export function getSemesterStart(date: Date): Date {
+  if (isBeforeSummer(date)) {
+    return new Date(date.getFullYear()-1, 9, 1);
+  } else if (isAfterSummer(date)) {
+    return new Date(date.getFullYear(), 9, 1);
+  } else {
+    return new Date(date.getFullYear(), 3, 1);
+  }
+}
+
+/**
+ *  Fetches the room occupancy for a given date range.
+ * @param from_date the start date of the date range
+ * @param to_date  the end date of the date range
+ * @returns RoomOccupancyList - the room occupancy list
+ */
 
 export async function fetchRoomOccupancy(
-  from_date: string,
-  to_date: string,
+  from_date?: string,
+  to_date?: string
 ): Promise<RoomOccupancyList> {
+  if (from_date == undefined) {
+    let new_from_date = getSemesterStart(new Date());
+    from_date = new_from_date.toISOString();
+  }
+  if (to_date == undefined) {
+    let new_to_date = getSemesterStart(addMonths(new Date(), 6));
+    to_date = new_to_date.toISOString();
+  }
+
   var roomOccupancyList: RoomOccupancyList = new RoomOccupancyList(
     new Date(), 0, 0, []
   );

frontend/src/components/RoomOccupation.vue

@@ -86,7 +86,7 @@ const { data: occupations } = useQuery({
       showFree: event.free,
     })),
   enabled: () => selectedRoom.value !== "" && currentDateFrom.value !== "",
-  staleTime: 5000000, // 500 seconds
+  staleTime: 5000000, // 5000 seconds
 });
 
 watch(occupations, () => fullCalendar.value?.getApi().refetchEvents());

frontend/src/components/RoomOccupationOffline.vue

@@ -87,16 +87,16 @@ function transformData(data: RoomOccupancyList) {
     return events;
 }
 
-const { data: occupations } = useQuery({
-  queryKey: ["roomOccupation", selectedRoom, currentDateFrom, currentDateTo],
+const { data: occupancy } = useQuery({
+  queryKey: ["roomOccupancy"],//, selectedRoom, currentDateFrom, currentDateTo],
   queryFn: () =>
-    fetchRoomOccupancy(
-      new Date(currentDateFrom.value).toISOString(),
-      new Date(currentDateTo.value).toISOString()
-    ),
-  select: (data) => transformData(data),
-  enabled: () => selectedRoom.value !== "" && currentDateFrom.value !== "",
-  staleTime: 5000000, // 500 seconds
+    fetchRoomOccupancy(),
+  staleTime: 12 * 3600000, // 12 hours
+});
+
+const occupations = computed(() => {
+  if (!occupancy.value) return;
+  return transformData(occupancy.value);
 });
 
 watch(occupations, () => fullCalendar.value?.getApi().refetchEvents());

frontend/src/model/roomOccupancyList.ts

@@ -70,15 +70,16 @@ export class RoomOccupancyList {
   public decodeOccupancy(room : string, from : Date, to : Date) : AnonymizedOccupancy[] {
     const roomOccupancy = this.rooms.find((r) => r.name === room);
 
-    if (roomOccupancy === undefined) {
+    // Get start and end of decoded time range (within encoded list and requested range)
+    let decodeInterval = interval(clamp(from, this.getOccupancyInterval()), clamp(to, this.getOccupancyInterval()));
+    
+    // if the room is not in the list or the time range is empty, return stub events
+    if (roomOccupancy === undefined || isEqual(decodeInterval.start, decodeInterval.end)) {
       return RoomOccupancyList.generateStubEvents(room, from, to);
     }
 
     const occupancyList = [];
 
-    // Get start and end of decoded time range (within encoded list and requested range)
-    let decodeInterval = interval(clamp(from, this.getOccupancyInterval()), clamp(to, this.getOccupancyInterval()));
-
     let {decodeSliceStart, decodeSlice} = this.sliceOccupancy(
       decodeInterval,
       roomOccupancy.occupancy.buffer