Add calculation for cronStart and cronEnd times

pkg/fleetautoscalers/fleetautoscalers.go

@@ -418,9 +418,7 @@ func applyChainPolicy(c autoscalingv1.ChainPolicy, f *agonesv1.Fleet, gameServer
 
 // isScheduleActive checks if a chain entry's is active and returns a boolean, true if active, false otherwise
 func isScheduleActive(s *autoscalingv1.SchedulePolicy, currentTime time.Time) bool {
-	// When retrieving the next available cronTime it returns the next minute e.g. if you want a policy to run every minute (all the time)
-	// If the current time is 1:00, the next start time returned will be 1:01, thus we use a cronDelta of 90 seconds to
-	// adjust to the minute delta (since the next start time will always be ahead of the current time by 1 minute when the schedule is active).
+	// Used for checking ahead of the schedule for daylight savings purposes
 	cronDelta := (time.Minute * -1) + (time.Second * -30)
 
 	// If the current time is before the start time, the schedule is inactive so return false
@@ -443,23 +441,25 @@ func isScheduleActive(s *autoscalingv1.SchedulePolicy, currentTime time.Time) bo
 	location, _ := time.LoadLocation(s.ActivePeriod.Timezone)
 	startCron, _ := cron.ParseStandard(s.ActivePeriod.StartCron)
 	duration, _ := time.ParseDuration(s.ActivePeriod.Duration)
-	nextStartTime := startCron.Next(currentTime.In(location))
+
+	// Get the current time - duration
+	currentTimeMinusDuration := currentTime.Add(duration * -1)
+	// Take (current time - duration) to get the first available start time
+	cronStartTime := startCron.Next(currentTimeMinusDuration.In(location))
+	// Take the (cronStartTime + duration) to get the end time
+	cronEndTime := cronStartTime.Add(duration)
 
 	// If there's an err, then the duration field is empty, meaning duration is indefinite
 	if s.ActivePeriod.Duration == "" {
 		duration = 0 // Indefinite duration if not set
 	}
 
-	// If the current time is after the next start time, and the duration is indefinite or the current time is before the next start time + duration,
-	// then return true.
-	// e.g.
-	// startCron = * * * * *
-	// currentTime = 2024-08-01T14:30:00Z // 2:30 PM UTC on August 1, 2024
-	// nextStartTime = 2024-08-01T14:31:00Z // 2:31 PM UTC on August 1, 2024
-	// duration = 1 hour
-	// cronDelta = 1 Minute Delta 30 seconds
-	// This would return true since the currentTime > nextStartTime - cronDelta AND the currentTime < nextStartTime + duration.
-	if currentTime.After(nextStartTime.Add(cronDelta)) && (duration == 0 || currentTime.Before(nextStartTime.Add(duration))) {
+	// If the current time is after the cronStartTime - 90 seconds (for daylight saving purposes) AND the current time before the cronEndTime
+	// then return true
+	// Example: startCron = 0 14 * * * // 2:00 PM Everyday | duration = 1 hr | cronDelta = 90 seconds | currentTime = 2024-08-01T14:30:00Z | currentTimeMinusDuration = 2024-08-01T13:30:00Z 
+	// then cronStartTime = 2024-08-01T14:00:00Z and cronEndTime = 2024-08-01T15:00:00Z
+	// and since currentTime > cronStartTime + cronDelta AND currentTime < cronEndTime, we return true
+	if currentTime.After(cronStartTime.Add(cronDelta)) && currentTime.Before(cronEndTime) {
 		return true
 	}