mivExchangeCalendar.js: getItemsFromMemoryCache: fix looking for item…

…s in cache

The code before were using simple day index to go through start and end of the
range. Furthermore, it didn't managed that range were given in local timezone
and memory cache is in UTC.

This fix use Lightning tools to go through range and it converts local timezone
to UTC, so the cache is correctly read.

Fixes #67

interfaces/exchangeCalendar/mivExchangeCalendar.js

@@ -2842,30 +2842,31 @@ calExchangeCalendar.prototype = {
 
 		// This is by using the this.itemCacheByStartDate and this.itemCacheByEndDate index.
 		if (wantEvents) {
-
-			var startYear = aRangeStart.year;
-			var startYearday = aRangeStart.yearday;
-
-			var endYear = aRangeEnd.year;
-			var endYearday = aRangeEnd.yearday;
-			var doStop = false;
-			var ids = {};
-			while (!doStop) {
-				if ((startYear == endYear) && (startYearday == endYearday)) {
-					doStop = true;
-				}
-
-				if ((this.itemCacheByStartDate) && (this.itemCacheByStartDate[startYear]) && (this.itemCacheByStartDate[startYear][startYearday])) {
-					for (var itemid in this.itemCacheByStartDate[startYear][startYearday]) {
+			let ids = {};
+
+			let dayOffset = cal.createDuration();
+			dayOffset.days = 1;
+
+			let dayPos = cal.createDateTime();
+			dayPos = aRangeStart.clone();
+
+			// Convert date from local timezone to UTC
+			// Given range is in local timezone and cache save in UTC
+			dayPos.isDate = false;
+			dayPos = dayPos.getInTimezone(cal.UTC());
+			dayPos.isDate = true;
+
+			// Go through all days bewteen the range start day and the range end day
+			while (dayPos.compare(aRangeEnd) < 0 ) {
+				if (this.itemCacheByStartDate
+					&& this.itemCacheByStartDate[dayPos.year]
+					&& this.itemCacheByStartDate[dayPos.year][dayPos.yearday]) {
+					for (let itemid in this.itemCacheByStartDate[dayPos.year][dayPos.yearday]) {
 						ids[itemid] = true;
 					}
 				}
 
-				startYearday++;
-				if (startYearday > 366) {
-					startYear++;
-					startYearday = 1;
-				}
+				dayPos.addDuration(dayOffset);
 			}
 
 			// For all found ids, if item cache has it, push it to events answer