feat: add endpoint to get all available time zones

go.mod

@@ -57,6 +57,7 @@ require (
 	github.com/spf13/viper v1.10.1
 	github.com/stretchr/testify v1.7.0
 	github.com/swaggo/swag v1.7.8
+	github.com/tkuchiki/go-timezone v0.2.2 // indirect
 	github.com/ulule/limiter/v3 v3.9.0
 	github.com/yuin/goldmark v1.4.4
 	golang.org/x/crypto v0.0.0-20220112180741-5e0467b6c7ce

go.sum

@@ -741,6 +741,8 @@ github.com/swaggo/swag v1.7.8 h1:w249t0l/kc/DKMGlS0fppNJQxKyJ8heNaUWB6nsH3zc=
 github.com/swaggo/swag v1.7.8/go.mod h1:gZ+TJ2w/Ve1RwQsA2IRoSOTidHz6DX+PIG8GWvbnoLU=
 github.com/syndtr/goleveldb v1.0.0 h1:fBdIW9lB4Iz0n9khmH8w27SJ3QEJ7+IgjPEwGSZiFdE=
 github.com/syndtr/goleveldb v1.0.0/go.mod h1:ZVVdQEZoIme9iO1Ch2Jdy24qqXrMMOU6lpPAyBWyWuQ=
+github.com/tkuchiki/go-timezone v0.2.2 h1:MdHR65KwgVTwWFQrota4SKzc4L5EfuH5SdZZGtk/P2Q=
+github.com/tkuchiki/go-timezone v0.2.2/go.mod h1:oFweWxYl35C/s7HMVZXiA19Jr9Y0qJHMaG/J2TES4LY=
 github.com/tv42/httpunix v0.0.0-20150427012821-b75d8614f926/go.mod h1:9ESjWnEqriFuLhtthL60Sar/7RFoluCcXsuvEwTV5KM=
 github.com/ugorji/go v1.1.4/go.mod h1:uQMGLiO92mf5W77hV/PUCpI3pbzQx3CRekS0kk+RGrc=
 github.com/ugorji/go v1.1.7/go.mod h1:kZn38zHttfInRq0xu/PH0az30d+z6vm202qpg1oXVMw=

pkg/routes/api/v1/user_settings.go

@@ -17,6 +17,7 @@
 package v1
 
 import (
+	"github.com/tkuchiki/go-timezone"
 	"net/http"
 
 	"code.vikunja.io/api/pkg/db"
@@ -197,3 +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/routes.go

@@ -321,6 +321,7 @@ func registerAPIRoutes(a *echo.Group) {
 	u.POST("/settings/general", apiv1.UpdateGeneralUserSettings)
 	u.POST("/export/request", apiv1.RequestUserDataExport)
 	u.POST("/export/download", apiv1.DownloadUserDataExport)
+	u.GET("/timezones", apiv1.GetAvailableTimezones)
 
 	if config.ServiceEnableTotp.GetBool() {
 		u.GET("/settings/totp", apiv1.UserTOTP)