[MM-8497] Ability to set Do Not Disturb for a specified period of time (#17680)

* Revert "Revert "[MM-8497] Ability to set Do Not Disturb for a specified period of time (#16067)" (#17657)"

This reverts commit ff383990f8.

* add debug log for recurring function

* add feature flag for dnd timed status

* refactoring changes

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

model/scheduled_task.go

@@ -11,42 +11,65 @@ import (
 type TaskFunc func()
 
 type ScheduledTask struct {
-	Name      string        `json:"name"`
-	Interval  time.Duration `json:"interval"`
-	Recurring bool          `json:"recurring"`
-	function  func()
-	cancel    chan struct{}
-	cancelled chan struct{}
+	Name                 string        `json:"name"`
+	Interval             time.Duration `json:"interval"`
+	Recurring            bool          `json:"recurring"`
+	function             func()
+	cancel               chan struct{}
+	cancelled            chan struct{}
+	fromNextIntervalTime bool
 }
 
 func CreateTask(name string, function TaskFunc, timeToExecution time.Duration) *ScheduledTask {
-	return createTask(name, function, timeToExecution, false)
+	return createTask(name, function, timeToExecution, false, false)
 }
 
 func CreateRecurringTask(name string, function TaskFunc, interval time.Duration) *ScheduledTask {
-	return createTask(name, function, interval, true)
+	return createTask(name, function, interval, true, false)
 }
 
-func createTask(name string, function TaskFunc, interval time.Duration, recurring bool) *ScheduledTask {
+func CreateRecurringTaskFromNextIntervalTime(name string, function TaskFunc, interval time.Duration) *ScheduledTask {
+	return createTask(name, function, interval, true, true)
+}
+
+func createTask(name string, function TaskFunc, interval time.Duration, recurring bool, fromNextIntervalTime bool) *ScheduledTask {
 	task := &ScheduledTask{
-		Name:      name,
-		Interval:  interval,
-		Recurring: recurring,
-		function:  function,
-		cancel:    make(chan struct{}),
-		cancelled: make(chan struct{}),
+		Name:                 name,
+		Interval:             interval,
+		Recurring:            recurring,
+		function:             function,
+		cancel:               make(chan struct{}),
+		cancelled:            make(chan struct{}),
+		fromNextIntervalTime: fromNextIntervalTime,
 	}
 
 	go func() {
 		defer close(task.cancelled)
 
-		ticker := time.NewTicker(interval)
+		var firstTick <-chan time.Time
+		var ticker *time.Ticker
+
+		if task.fromNextIntervalTime {
+			currTime := time.Now()
+			first := currTime.Truncate(interval)
+			if first.Before(currTime) {
+				first = first.Add(interval)
+			}
+			firstTick = time.After(time.Until(first))
+			ticker = &time.Ticker{C: nil}
+		} else {
+			firstTick = nil
+			ticker = time.NewTicker(interval)
+		}
 		defer func() {
 			ticker.Stop()
 		}()
 
 		for {
 			select {
+			case <-firstTick:
+				ticker = time.NewTicker(interval)
+				function()
 			case <-ticker.C:
 				function()
 			case <-task.cancel: