async triggers for either interval or next due, accept cron

server/ajax/ajax.go

@@ -87,37 +87,58 @@ func has(params url.Values, k string) bool {
 }
 
 func (a *Ajax) Async() {
+	var err error
+	nextDue := time.Now().Add(config.Loop)
 	c := time.NewTicker(config.Loop)
-	for range c.C {
+	for {
+		select {
+		case <-c.C:
+		case <-time.After(time.Until(nextDue)):
+		}
 		log.Println("loop tasks")
-		if err := a.loopTasks(); err != nil {
+		nextDue, err = a.loopTasks()
+		if err != nil {
 			log.Println("failed to loop tasks", err)
 		}
 	}
 }
 
-func (a *Ajax) loopTasks() error {
+func (a *Ajax) loopTasks() (time.Time, error) {
+	nextDue := time.Now().Add(time.Hour * 240)
 	lists, err := a.storageListLists()
 	if err != nil {
-		return err
+		return nextDue, err
 	}
 	for _, list := range lists {
 		tasks, err := a.storageListTasks(list.UUID, func(t *task.Task) bool {
 			return t.Complete
 		})
 		if err != nil {
-			return err
+			return nextDue, err
 		}
 		for _, task := range tasks {
-			if !task.Complete || task.Loop == 0 || time.Since(task.Completed) < task.Loop {
+			if !task.Complete {
+				continue
+			}
+			if task.Loop == 0 && task.Cron == "" {
+				continue
+			}
+			nextLoopTrigger := task.Completed.Add(task.Loop)
+			if task.Loop == 0 {
+				nextLoopTrigger = task.Cron.Next()
+			}
+			if time.Now().Before(nextLoopTrigger) {
+				if nextLoopTrigger.Before(nextDue) {
+					nextDue = nextLoopTrigger
+				}
 				continue
 			}
 			task.Complete = false
 			task.Completed = time.Time{}
 			if err := a.storageSetTask(list.UUID, task); err != nil {
-				return err
+				return nextDue, err
 			}
 		}
 	}
-	return nil
+	return nextDue, nil
 }

server/ajax/form/cron.go

@@ -0,0 +1,17 @@
+package form
+
+import (
+	"time"
+
+	"github.com/robfig/cron/v3"
+)
+
+type Cron string
+
+func (c Cron) Next() time.Time {
+	schedule, err := cron.ParseStandard(string(c))
+	if err != nil {
+		return time.Time{}
+	}
+	return schedule.Next(time.Now())
+}

server/ajax/task/task.go

@@ -24,6 +24,7 @@ type Task struct {
 	Note      []string
 	Due       time.Time
 	Loop      time.Duration
+	Cron      form.Cron
 
 	Index int
 }
@@ -45,6 +46,7 @@ func New(r *http.Request) (*Task, error) {
 		Edited:   time.Now(),
 		Due:      form.ToTime(form.Get(r, "duedate")),
 		Loop:     form.ToDuration(form.Get(r, "loop")),
+		Cron:     form.Cron(form.Get(r, "cron")),
 	}
 	task.SetNote(form.Get(r, "note"))
 	return task, task.validate()
@@ -75,7 +77,8 @@ func (t *Task) MarshalJSON() ([]byte, error) {
 	//    "dueStr":"",
 	//    "dueInt":33330000,
 	//    "dueTitle":"Due ",
-	//    "loop": "1m"}
+	//    "loop": "1m",
+	//    "cron": "* * * * *"}
 	// ]}
 	fullFormat := "02 Jan 2006 03:04 PM"
 	shortFormat := "02 Jan"
@@ -112,6 +115,7 @@ func (t *Task) MarshalJSON() ([]byte, error) {
 		"dueInt":                   t.Due.Unix(),
 		"dueTitle":                 "Due ",
 		"loop":                     t.Loop.String(),
+		"cron":                     t.Cron,
 	}
 	if t.Due.IsZero() {
 		for k := range m {