feat(caldav): add support for repeating tasks

Resolves https://github.com/go-vikunja/api/issues/57#issuecomment-1364373103

pkg/caldav/caldav.go

@@ -57,10 +57,12 @@ type Todo struct {
 	RelatedToUID string
 	Color        string
 
-	Start    time.Time
-	End      time.Time
-	DueDate  time.Time
-	Duration time.Duration
+	Start       time.Time
+	End         time.Time
+	DueDate     time.Time
+	Duration    time.Duration
+	RepeatAfter int64
+	RepeatMode  string
 
 	Created time.Time
 	Updated time.Time // last-mod
@@ -225,6 +227,16 @@ CREATED:` + makeCalDavTimeFromTimeStamp(t.Created)
 PRIORITY:` + strconv.Itoa(mapPriorityToCaldav(t.Priority))
 		}
 
+		if t.RepeatAfter > 0 || t.RepeatMode == "MONTHLY" {
+			if t.RepeatMode == "MONTHLY" {
+				caldavtodos += `
+RRULE:FREQ=MONTHLY;BYMONTHDAY=` + t.DueDate.Format("02") // Day of the month
+			} else {
+				caldavtodos += `
+RRULE:FREQ=SECONDLY;INTERVAL=` + strconv.FormatInt(t.RepeatAfter, 10)
+			}
+		}
+
 		caldavtodos += `
 LAST-MODIFIED:` + makeCalDavTimeFromTimeStamp(t.Updated)
 

pkg/caldav/caldav_test.go

@@ -408,6 +408,77 @@ DESCRIPTION:Lorem Ipsum
 PRIORITY:9
 LAST-MODIFIED:00010101T000000Z
 END:VTODO
+END:VCALENDAR`,
+		},
+		{
+			name: "with repeating monthly",
+			args: args{
+				config: &Config{
+					Name:   "test",
+					ProdID: "RandomProdID which is not random",
+				},
+				todos: []*Todo{
+					{
+						Summary:     "Todo #1",
+						Description: "Lorem Ipsum",
+						UID:         "randommduid",
+						Timestamp:   time.Unix(1543626724, 0).In(config.GetTimeZone()),
+						RepeatMode:  "MONTHLY",
+						DueDate:     time.Unix(1543626724, 0).In(config.GetTimeZone()),
+					},
+				},
+			},
+			wantCaldavtasks: `BEGIN:VCALENDAR
+VERSION:2.0
+METHOD:PUBLISH
+X-PUBLISHED-TTL:PT4H
+X-WR-CALNAME:test
+PRODID:-//RandomProdID which is not random//EN
+BEGIN:VTODO
+UID:randommduid
+DTSTAMP:20181201T011204Z
+SUMMARY:Todo #1
+DESCRIPTION:Lorem Ipsum
+DUE:20181201T011204Z
+RRULE:FREQ=MONTHLY;BYMONTHDAY=01
+LAST-MODIFIED:00010101T000000Z
+END:VTODO
+END:VCALENDAR`,
+		},
+		{
+			name: "with repeat mode default",
+			args: args{
+				config: &Config{
+					Name:   "test",
+					ProdID: "RandomProdID which is not random",
+				},
+				todos: []*Todo{
+					{
+						Summary:     "Todo #1",
+						Description: "Lorem Ipsum",
+						UID:         "randommduid",
+						Timestamp:   time.Unix(1543626724, 0).In(config.GetTimeZone()),
+						RepeatMode:  "DEFAULT",
+						DueDate:     time.Unix(1543626724, 0).In(config.GetTimeZone()),
+						RepeatAfter: 435,
+					},
+				},
+			},
+			wantCaldavtasks: `BEGIN:VCALENDAR
+VERSION:2.0
+METHOD:PUBLISH
+X-PUBLISHED-TTL:PT4H
+X-WR-CALNAME:test
+PRODID:-//RandomProdID which is not random//EN
+BEGIN:VTODO
+UID:randommduid
+DTSTAMP:20181201T011204Z
+SUMMARY:Todo #1
+DESCRIPTION:Lorem Ipsum
+DUE:20181201T011204Z
+RRULE:FREQ=SECONDLY;INTERVAL=435
+LAST-MODIFIED:00010101T000000Z
+END:VTODO
 END:VCALENDAR`,
 		},
 	}

pkg/caldav/parsing.go

@@ -35,6 +35,11 @@ func GetCaldavTodosForTasks(list *models.ListWithTasksAndBuckets, listTasks []*m
 
 		duration := t.EndDate.Sub(t.StartDate)
 
+		repeatMode := "DEFAULT"
+		if t.RepeatMode == models.TaskRepeatModeMonth {
+			repeatMode = "MONTHLY"
+		}
+
 		caldavtodos = append(caldavtodos, &Todo{
 			Timestamp:   t.Updated,
 			UID:         t.UID,
@@ -42,13 +47,15 @@ func GetCaldavTodosForTasks(list *models.ListWithTasksAndBuckets, listTasks []*m
 			Description: t.Description,
 			Completed:   t.DoneAt,
 			// Organizer:     &t.CreatedBy, // Disabled until we figure out how this works
-			Priority: t.Priority,
-			Start:    t.StartDate,
-			End:      t.EndDate,
-			Created:  t.Created,
-			Updated:  t.Updated,
-			DueDate:  t.DueDate,
-			Duration: duration,
+			Priority:    t.Priority,
+			Start:       t.StartDate,
+			End:         t.EndDate,
+			Created:     t.Created,
+			Updated:     t.Updated,
+			DueDate:     t.DueDate,
+			Duration:    duration,
+			RepeatAfter: t.RepeatAfter,
+			RepeatMode:  repeatMode,
 		})
 	}
 

pkg/models/tasks.go

@@ -1369,7 +1369,7 @@ func setTaskDatesFromCurrentDateRepeat(oldTask, newTask *Task) {
 
 // This helper function updates the reminders, doneAt, start and end dates of the *old* task
 // and saves the new values in the newTask object.
-// We make a few assumtions here:
+// We make a few assumptions here:
 //  1. Everything in oldTask is the truth - we figure out if we update anything at all if oldTask.RepeatAfter has a value > 0
 //  2. Because of 1., this functions should not be used to update values other than Done in the same go
 func updateDone(oldTask *Task, newTask *Task) {