feat: add time zone setting for reminders (#1092)

Instead of naeveily checking for all reminders due in the next minute, we now check all reminders in all time zones in the next minutes. This essentially means checking for reminders due in the next 14 or past 12 hours. We then check for each user who would receive a reminder from that result if it is actually due in their time zone.

This should prevent issues where users would get the reminder in the time zone of their server, not in their own.

Co-authored-by: kolaente <k@knt.li>
Reviewed-on: https://kolaente.dev/vikunja/api/pulls/1092
Co-authored-by: konrad <k@knt.li>
Co-committed-by: konrad <k@knt.li>

pkg/routes/api/v1/user_settings.go

@@ -19,12 +19,13 @@ package v1
 import (
 	"net/http"
 
-	"code.vikunja.io/api/pkg/db"
+	"github.com/labstack/echo/v4"
+	"github.com/tkuchiki/go-timezone"
 
+	"code.vikunja.io/api/pkg/db"
 	"code.vikunja.io/api/pkg/models"
 	user2 "code.vikunja.io/api/pkg/user"
 	"code.vikunja.io/web/handler"
-	"github.com/labstack/echo/v4"
 )
 
 // UserAvatarProvider holds the user avatar provider type
@@ -52,6 +53,8 @@ type UserSettings struct {
 	WeekStart int `json:"week_start"`
 	// The user's language
 	Language string `json:"language"`
+	// The user's time zone. Used to send task reminders in the time zone of the user.
+	Timezone string `json:"timezone"`
 }
 
 // GetUserAvatarProvider returns the currently set user avatar
@@ -180,6 +183,7 @@ func UpdateGeneralUserSettings(c echo.Context) error {
 	user.DefaultListID = us.DefaultListID
 	user.WeekStart = us.WeekStart
 	user.Language = us.Language
+	user.Timezone = us.Timezone
 
 	_, err = user2.UpdateUser(s, user)
 	if err != nil {
@@ -194,3 +198,31 @@ func UpdateGeneralUserSettings(c echo.Context) error {
 
 	return c.JSON(http.StatusOK, &models.Message{Message: "The settings were updated successfully."})
 }
+
+// GetAvailableTimezones
+// @Summary Get all available time zones on this vikunja instance
+// @Description Because available time zones depend on the system Vikunja is running on, this endpoint returns a list of all valid time zones this particular Vikunja instance can handle. The list of time zones is not sorted, you should sort it on the client.
+// @tags user
+// @Accept json
+// @Produce json
+// @Security JWTKeyAuth
+// @Success 200 {array} string "All available time zones."
+// @Failure 500 {object} models.Message "Internal server error."
+// @Router /user/timezones [get]
+func GetAvailableTimezones(c echo.Context) error {
+
+	allTimezones := timezone.New().Timezones()
+	timezoneMap := make(map[string]bool) // to filter all duplicates
+	for _, s := range allTimezones {
+		for _, t := range s {
+			timezoneMap[t] = true
+		}
+	}
+
+	ts := []string{}
+	for s := range timezoneMap {
+		ts = append(ts, s)
+	}
+
+	return c.JSON(http.StatusOK, ts)
+}

pkg/routes/api/v1/user_show.go

@@ -74,6 +74,7 @@ func UserShow(c echo.Context) error {
 			DefaultListID:                u.DefaultListID,
 			WeekStart:                    u.WeekStart,
 			Language:                     u.Language,
+			Timezone:                     u.Timezone,
 		},
 		DeletionScheduledAt: u.DeletionScheduledAt,
 		IsLocalUser:         u.Issuer == user.IssuerLocal,