chore(validation): move functions from constants

- Move validation functions from `internal/constants` to `internal/configuration/settings/validation`
- Concatenate all OpenVPN constants in `internal/constants/openvpn.go`

internal/configuration/settings/serverselection.go

@@ -6,6 +6,7 @@ import (
 	"strings"
 
 	"github.com/qdm12/gluetun/internal/configuration/settings/helpers"
+	"github.com/qdm12/gluetun/internal/configuration/settings/validation"
 	"github.com/qdm12/gluetun/internal/constants"
 	"github.com/qdm12/gluetun/internal/models"
 	"github.com/qdm12/gotree"
@@ -71,84 +72,84 @@ func (ss *ServerSelection) validate(vpnServiceProvider string,
 	case constants.Custom:
 	case constants.Cyberghost:
 		servers := allServers.GetCyberghost()
-		countryChoices = constants.CyberghostCountryChoices(servers)
-		hostnameChoices = constants.CyberghostHostnameChoices(servers)
+		countryChoices = validation.CyberghostCountryChoices(servers)
+		hostnameChoices = validation.CyberghostHostnameChoices(servers)
 	case constants.Expressvpn:
 		servers := allServers.GetExpressvpn()
-		countryChoices = constants.ExpressvpnCountriesChoices(servers)
-		cityChoices = constants.ExpressvpnCityChoices(servers)
-		hostnameChoices = constants.ExpressvpnHostnameChoices(servers)
+		countryChoices = validation.ExpressvpnCountriesChoices(servers)
+		cityChoices = validation.ExpressvpnCityChoices(servers)
+		hostnameChoices = validation.ExpressvpnHostnameChoices(servers)
 	case constants.Fastestvpn:
 		servers := allServers.GetFastestvpn()
-		countryChoices = constants.FastestvpnCountriesChoices(servers)
-		hostnameChoices = constants.FastestvpnHostnameChoices(servers)
+		countryChoices = validation.FastestvpnCountriesChoices(servers)
+		hostnameChoices = validation.FastestvpnHostnameChoices(servers)
 	case constants.HideMyAss:
 		servers := allServers.GetHideMyAss()
-		countryChoices = constants.HideMyAssCountryChoices(servers)
-		regionChoices = constants.HideMyAssRegionChoices(servers)
-		cityChoices = constants.HideMyAssCityChoices(servers)
-		hostnameChoices = constants.HideMyAssHostnameChoices(servers)
+		countryChoices = validation.HideMyAssCountryChoices(servers)
+		regionChoices = validation.HideMyAssRegionChoices(servers)
+		cityChoices = validation.HideMyAssCityChoices(servers)
+		hostnameChoices = validation.HideMyAssHostnameChoices(servers)
 	case constants.Ipvanish:
 		servers := allServers.GetIpvanish()
-		countryChoices = constants.IpvanishCountryChoices(servers)
-		cityChoices = constants.IpvanishCityChoices(servers)
-		hostnameChoices = constants.IpvanishHostnameChoices(servers)
+		countryChoices = validation.IpvanishCountryChoices(servers)
+		cityChoices = validation.IpvanishCityChoices(servers)
+		hostnameChoices = validation.IpvanishHostnameChoices(servers)
 	case constants.Ivpn:
 		servers := allServers.GetIvpn()
-		countryChoices = constants.IvpnCountryChoices(servers)
-		cityChoices = constants.IvpnCityChoices(servers)
-		ispChoices = constants.IvpnISPChoices(servers)
-		hostnameChoices = constants.IvpnHostnameChoices(servers)
+		countryChoices = validation.IvpnCountryChoices(servers)
+		cityChoices = validation.IvpnCityChoices(servers)
+		ispChoices = validation.IvpnISPChoices(servers)
+		hostnameChoices = validation.IvpnHostnameChoices(servers)
 	case constants.Mullvad:
 		servers := allServers.GetMullvad()
-		countryChoices = constants.MullvadCountryChoices(servers)
-		cityChoices = constants.MullvadCityChoices(servers)
-		ispChoices = constants.MullvadISPChoices(servers)
-		hostnameChoices = constants.MullvadHostnameChoices(servers)
+		countryChoices = validation.MullvadCountryChoices(servers)
+		cityChoices = validation.MullvadCityChoices(servers)
+		ispChoices = validation.MullvadISPChoices(servers)
+		hostnameChoices = validation.MullvadHostnameChoices(servers)
 	case constants.Nordvpn:
 		servers := allServers.GetNordvpn()
-		regionChoices = constants.NordvpnRegionChoices(servers)
-		hostnameChoices = constants.NordvpnHostnameChoices(servers)
+		regionChoices = validation.NordvpnRegionChoices(servers)
+		hostnameChoices = validation.NordvpnHostnameChoices(servers)
 	case constants.Perfectprivacy:
 		servers := allServers.GetPerfectprivacy()
-		cityChoices = constants.PerfectprivacyCityChoices(servers)
+		cityChoices = validation.PerfectprivacyCityChoices(servers)
 	case constants.Privado:
 		servers := allServers.GetPrivado()
-		countryChoices = constants.PrivadoCountryChoices(servers)
-		regionChoices = constants.PrivadoRegionChoices(servers)
-		cityChoices = constants.PrivadoCityChoices(servers)
-		hostnameChoices = constants.PrivadoHostnameChoices(servers)
+		countryChoices = validation.PrivadoCountryChoices(servers)
+		regionChoices = validation.PrivadoRegionChoices(servers)
+		cityChoices = validation.PrivadoCityChoices(servers)
+		hostnameChoices = validation.PrivadoHostnameChoices(servers)
 	case constants.PrivateInternetAccess:
 		servers := allServers.GetPia()
-		regionChoices = constants.PIAGeoChoices(servers)
-		hostnameChoices = constants.PIAHostnameChoices(servers)
-		nameChoices = constants.PIANameChoices(servers)
+		regionChoices = validation.PIAGeoChoices(servers)
+		hostnameChoices = validation.PIAHostnameChoices(servers)
+		nameChoices = validation.PIANameChoices(servers)
 	case constants.Privatevpn:
 		servers := allServers.GetPrivatevpn()
-		countryChoices = constants.PrivatevpnCountryChoices(servers)
-		cityChoices = constants.PrivatevpnCityChoices(servers)
-		hostnameChoices = constants.PrivatevpnHostnameChoices(servers)
+		countryChoices = validation.PrivatevpnCountryChoices(servers)
+		cityChoices = validation.PrivatevpnCityChoices(servers)
+		hostnameChoices = validation.PrivatevpnHostnameChoices(servers)
 	case constants.Protonvpn:
 		servers := allServers.GetProtonvpn()
-		countryChoices = constants.ProtonvpnCountryChoices(servers)
-		regionChoices = constants.ProtonvpnRegionChoices(servers)
-		cityChoices = constants.ProtonvpnCityChoices(servers)
-		nameChoices = constants.ProtonvpnNameChoices(servers)
-		hostnameChoices = constants.ProtonvpnHostnameChoices(servers)
+		countryChoices = validation.ProtonvpnCountryChoices(servers)
+		regionChoices = validation.ProtonvpnRegionChoices(servers)
+		cityChoices = validation.ProtonvpnCityChoices(servers)
+		nameChoices = validation.ProtonvpnNameChoices(servers)
+		hostnameChoices = validation.ProtonvpnHostnameChoices(servers)
 	case constants.Purevpn:
 		servers := allServers.GetPurevpn()
-		countryChoices = constants.PurevpnCountryChoices(servers)
-		regionChoices = constants.PurevpnRegionChoices(servers)
-		cityChoices = constants.PurevpnCityChoices(servers)
-		hostnameChoices = constants.PurevpnHostnameChoices(servers)
+		countryChoices = validation.PurevpnCountryChoices(servers)
+		regionChoices = validation.PurevpnRegionChoices(servers)
+		cityChoices = validation.PurevpnCityChoices(servers)
+		hostnameChoices = validation.PurevpnHostnameChoices(servers)
 	case constants.Surfshark:
 		servers := allServers.GetSurfshark()
-		countryChoices = constants.SurfsharkCountryChoices(servers)
-		cityChoices = constants.SurfsharkCityChoices(servers)
-		hostnameChoices = constants.SurfsharkHostnameChoices(servers)
-		regionChoices = constants.SurfsharkRegionChoices(servers)
+		countryChoices = validation.SurfsharkCountryChoices(servers)
+		cityChoices = validation.SurfsharkCityChoices(servers)
+		hostnameChoices = validation.SurfsharkHostnameChoices(servers)
+		regionChoices = validation.SurfsharkRegionChoices(servers)
 		// TODO v4 remove
-		regionChoices = append(regionChoices, constants.SurfsharkRetroLocChoices(servers)...)
+		regionChoices = append(regionChoices, validation.SurfsharkRetroLocChoices()...)
 		if err := helpers.AreAllOneOf(ss.Regions, regionChoices); err != nil {
 			return fmt.Errorf("%w: %s", ErrRegionNotValid, err)
 		}
@@ -157,26 +158,26 @@ func (ss *ServerSelection) validate(vpnServiceProvider string,
 		*ss = surfsharkRetroRegion(*ss)
 	case constants.Torguard:
 		servers := allServers.GetTorguard()
-		countryChoices = constants.TorguardCountryChoices(servers)
-		cityChoices = constants.TorguardCityChoices(servers)
-		hostnameChoices = constants.TorguardHostnameChoices(servers)
+		countryChoices = validation.TorguardCountryChoices(servers)
+		cityChoices = validation.TorguardCityChoices(servers)
+		hostnameChoices = validation.TorguardHostnameChoices(servers)
 	case constants.VPNUnlimited:
 		servers := allServers.GetVPNUnlimited()
-		countryChoices = constants.VPNUnlimitedCountryChoices(servers)
-		cityChoices = constants.VPNUnlimitedCityChoices(servers)
-		hostnameChoices = constants.VPNUnlimitedHostnameChoices(servers)
+		countryChoices = validation.VPNUnlimitedCountryChoices(servers)
+		cityChoices = validation.VPNUnlimitedCityChoices(servers)
+		hostnameChoices = validation.VPNUnlimitedHostnameChoices(servers)
 	case constants.Vyprvpn:
 		servers := allServers.GetVyprvpn()
-		regionChoices = constants.VyprvpnRegionChoices(servers)
+		regionChoices = validation.VyprvpnRegionChoices(servers)
 	case constants.Wevpn:
 		servers := allServers.GetWevpn()
-		cityChoices = constants.WevpnCityChoices(servers)
-		hostnameChoices = constants.WevpnHostnameChoices(servers)
+		cityChoices = validation.WevpnCityChoices(servers)
+		hostnameChoices = validation.WevpnHostnameChoices(servers)
 	case constants.Windscribe:
 		servers := allServers.GetWindscribe()
-		regionChoices = constants.WindscribeRegionChoices(servers)
-		cityChoices = constants.WindscribeCityChoices(servers)
-		hostnameChoices = constants.WindscribeHostnameChoices(servers)
+		regionChoices = validation.WindscribeRegionChoices(servers)
+		cityChoices = validation.WindscribeCityChoices(servers)
+		hostnameChoices = validation.WindscribeHostnameChoices(servers)
 	default:
 		return fmt.Errorf("%w: %s", ErrVPNProviderNameNotValid, vpnServiceProvider)
 	}

internal/configuration/settings/validation/cyberghost.go

@@ -0,0 +1,21 @@
+package validation
+
+import (
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func CyberghostCountryChoices(servers []models.CyberghostServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Country
+	}
+	return makeUnique(choices)
+}
+
+func CyberghostHostnameChoices(servers []models.CyberghostServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Hostname
+	}
+	return makeUnique(choices)
+}

internal/configuration/settings/validation/expressvpn.go

@@ -0,0 +1,29 @@
+package validation
+
+import (
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func ExpressvpnCountriesChoices(servers []models.ExpressvpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Country
+	}
+	return makeUnique(choices)
+}
+
+func ExpressvpnCityChoices(servers []models.ExpressvpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].City
+	}
+	return makeUnique(choices)
+}
+
+func ExpressvpnHostnameChoices(servers []models.ExpressvpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Hostname
+	}
+	return makeUnique(choices)
+}

internal/configuration/settings/validation/fastestvpn.go

@@ -0,0 +1,21 @@
+package validation
+
+import (
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func FastestvpnCountriesChoices(servers []models.FastestvpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Country
+	}
+	return makeUnique(choices)
+}
+
+func FastestvpnHostnameChoices(servers []models.FastestvpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Hostname
+	}
+	return makeUnique(choices)
+}

internal/configuration/settings/validation/helpers.go

@@ -0,0 +1,23 @@
+package validation
+
+import "sort"
+
+func makeUnique(choices []string) (uniqueChoices []string) {
+	seen := make(map[string]struct{}, len(choices))
+	uniqueChoices = make([]string, 0, len(uniqueChoices))
+
+	for _, choice := range choices {
+		if _, ok := seen[choice]; ok {
+			continue
+		}
+		seen[choice] = struct{}{}
+
+		uniqueChoices = append(uniqueChoices, choice)
+	}
+
+	sort.Slice(uniqueChoices, func(i, j int) bool {
+		return uniqueChoices[i] < uniqueChoices[j]
+	})
+
+	return uniqueChoices
+}

internal/configuration/settings/validation/hidemyass.go

@@ -0,0 +1,37 @@
+package validation
+
+import (
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func HideMyAssCountryChoices(servers []models.HideMyAssServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Country
+	}
+	return makeUnique(choices)
+}
+
+func HideMyAssRegionChoices(servers []models.HideMyAssServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Region
+	}
+	return makeUnique(choices)
+}
+
+func HideMyAssCityChoices(servers []models.HideMyAssServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].City
+	}
+	return makeUnique(choices)
+}
+
+func HideMyAssHostnameChoices(servers []models.HideMyAssServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Hostname
+	}
+	return makeUnique(choices)
+}

internal/configuration/settings/validation/ipvanish.go

@@ -0,0 +1,29 @@
+package validation
+
+import (
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func IpvanishCountryChoices(servers []models.IpvanishServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Country
+	}
+	return makeUnique(choices)
+}
+
+func IpvanishCityChoices(servers []models.IpvanishServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].City
+	}
+	return makeUnique(choices)
+}
+
+func IpvanishHostnameChoices(servers []models.IpvanishServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Hostname
+	}
+	return makeUnique(choices)
+}

internal/configuration/settings/validation/ivpn.go

@@ -0,0 +1,37 @@
+package validation
+
+import (
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func IvpnCountryChoices(servers []models.IvpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Country
+	}
+	return makeUnique(choices)
+}
+
+func IvpnCityChoices(servers []models.IvpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].City
+	}
+	return makeUnique(choices)
+}
+
+func IvpnISPChoices(servers []models.IvpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].ISP
+	}
+	return makeUnique(choices)
+}
+
+func IvpnHostnameChoices(servers []models.IvpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Hostname
+	}
+	return makeUnique(choices)
+}

internal/configuration/settings/validation/mullvad.go

@@ -0,0 +1,37 @@
+package validation
+
+import (
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func MullvadCountryChoices(servers []models.MullvadServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Country
+	}
+	return makeUnique(choices)
+}
+
+func MullvadCityChoices(servers []models.MullvadServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].City
+	}
+	return makeUnique(choices)
+}
+
+func MullvadHostnameChoices(servers []models.MullvadServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Hostname
+	}
+	return makeUnique(choices)
+}
+
+func MullvadISPChoices(servers []models.MullvadServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].ISP
+	}
+	return makeUnique(choices)
+}

internal/configuration/settings/validation/nordvpn.go

@@ -0,0 +1,21 @@
+package validation
+
+import (
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func NordvpnRegionChoices(servers []models.NordvpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Region
+	}
+	return makeUnique(choices)
+}
+
+func NordvpnHostnameChoices(servers []models.NordvpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Hostname
+	}
+	return makeUnique(choices)
+}

internal/configuration/settings/validation/perfectprivacy.go

@@ -0,0 +1,13 @@
+package validation
+
+import (
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func PerfectprivacyCityChoices(servers []models.PerfectprivacyServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].City
+	}
+	return makeUnique(choices)
+}

internal/configuration/settings/validation/pia.go

@@ -0,0 +1,29 @@
+package validation
+
+import (
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func PIAGeoChoices(servers []models.PIAServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Region
+	}
+	return makeUnique(choices)
+}
+
+func PIAHostnameChoices(servers []models.PIAServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Hostname
+	}
+	return makeUnique(choices)
+}
+
+func PIANameChoices(servers []models.PIAServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].ServerName
+	}
+	return makeUnique(choices)
+}

internal/configuration/settings/validation/privado.go

@@ -0,0 +1,35 @@
+package validation
+
+import "github.com/qdm12/gluetun/internal/models"
+
+func PrivadoCountryChoices(servers []models.PrivadoServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Country
+	}
+	return makeUnique(choices)
+}
+
+func PrivadoRegionChoices(servers []models.PrivadoServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Region
+	}
+	return makeUnique(choices)
+}
+
+func PrivadoCityChoices(servers []models.PrivadoServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].City
+	}
+	return makeUnique(choices)
+}
+
+func PrivadoHostnameChoices(servers []models.PrivadoServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Hostname
+	}
+	return makeUnique(choices)
+}

internal/configuration/settings/validation/privatevpn.go

@@ -0,0 +1,27 @@
+package validation
+
+import "github.com/qdm12/gluetun/internal/models"
+
+func PrivatevpnCountryChoices(servers []models.PrivatevpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Country
+	}
+	return makeUnique(choices)
+}
+
+func PrivatevpnCityChoices(servers []models.PrivatevpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].City
+	}
+	return makeUnique(choices)
+}
+
+func PrivatevpnHostnameChoices(servers []models.PrivatevpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Hostname
+	}
+	return makeUnique(choices)
+}

internal/configuration/settings/validation/protonvpn.go

@@ -0,0 +1,43 @@
+package validation
+
+import "github.com/qdm12/gluetun/internal/models"
+
+func ProtonvpnCountryChoices(servers []models.ProtonvpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Country
+	}
+	return makeUnique(choices)
+}
+
+func ProtonvpnRegionChoices(servers []models.ProtonvpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Region
+	}
+	return makeUnique(choices)
+}
+
+func ProtonvpnCityChoices(servers []models.ProtonvpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].City
+	}
+	return makeUnique(choices)
+}
+
+func ProtonvpnNameChoices(servers []models.ProtonvpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Name
+	}
+	return makeUnique(choices)
+}
+
+func ProtonvpnHostnameChoices(servers []models.ProtonvpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Hostname
+	}
+	return makeUnique(choices)
+}

internal/configuration/settings/validation/purevpn.go

@@ -0,0 +1,35 @@
+package validation
+
+import "github.com/qdm12/gluetun/internal/models"
+
+func PurevpnRegionChoices(servers []models.PurevpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Region
+	}
+	return makeUnique(choices)
+}
+
+func PurevpnCountryChoices(servers []models.PurevpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Country
+	}
+	return makeUnique(choices)
+}
+
+func PurevpnCityChoices(servers []models.PurevpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].City
+	}
+	return makeUnique(choices)
+}
+
+func PurevpnHostnameChoices(servers []models.PurevpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Hostname
+	}
+	return makeUnique(choices)
+}

internal/configuration/settings/validation/surfshark.go

@@ -0,0 +1,60 @@
+package validation
+
+import (
+	"sort"
+
+	"github.com/qdm12/gluetun/internal/constants"
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func SurfsharkRegionChoices(servers []models.SurfsharkServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Region
+	}
+	return makeUnique(choices)
+}
+
+func SurfsharkCountryChoices(servers []models.SurfsharkServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Country
+	}
+	return makeUnique(choices)
+}
+
+func SurfsharkCityChoices(servers []models.SurfsharkServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].City
+	}
+	return makeUnique(choices)
+}
+
+func SurfsharkHostnameChoices(servers []models.SurfsharkServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Hostname
+	}
+	return makeUnique(choices)
+}
+
+// TODO remove in v4.
+func SurfsharkRetroLocChoices() (choices []string) {
+	locationData := constants.SurfsharkLocationData()
+	choices = make([]string, 0, len(locationData))
+	seen := make(map[string]struct{}, len(locationData))
+	for _, data := range locationData {
+		if _, ok := seen[data.RetroLoc]; ok {
+			continue
+		}
+		seen[data.RetroLoc] = struct{}{}
+		choices = append(choices, data.RetroLoc)
+	}
+
+	sort.Slice(choices, func(i, j int) bool {
+		return choices[i] < choices[j]
+	})
+
+	return choices
+}

internal/configuration/settings/validation/torguard.go

@@ -0,0 +1,29 @@
+package validation
+
+import (
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func TorguardCountryChoices(servers []models.TorguardServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Country
+	}
+	return makeUnique(choices)
+}
+
+func TorguardCityChoices(servers []models.TorguardServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].City
+	}
+	return makeUnique(choices)
+}
+
+func TorguardHostnameChoices(servers []models.TorguardServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Hostname
+	}
+	return makeUnique(choices)
+}

internal/configuration/settings/validation/vpnunlimited.go

@@ -0,0 +1,29 @@
+package validation
+
+import (
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func VPNUnlimitedCountryChoices(servers []models.VPNUnlimitedServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Country
+	}
+	return makeUnique(choices)
+}
+
+func VPNUnlimitedCityChoices(servers []models.VPNUnlimitedServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].City
+	}
+	return makeUnique(choices)
+}
+
+func VPNUnlimitedHostnameChoices(servers []models.VPNUnlimitedServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Hostname
+	}
+	return makeUnique(choices)
+}

internal/configuration/settings/validation/vyprvpn.go

@@ -0,0 +1,13 @@
+package validation
+
+import (
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func VyprvpnRegionChoices(servers []models.VyprvpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Region
+	}
+	return makeUnique(choices)
+}

internal/configuration/settings/validation/wevpn.go

@@ -0,0 +1,19 @@
+package validation
+
+import "github.com/qdm12/gluetun/internal/models"
+
+func WevpnCityChoices(servers []models.WevpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].City
+	}
+	return makeUnique(choices)
+}
+
+func WevpnHostnameChoices(servers []models.WevpnServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Hostname
+	}
+	return makeUnique(choices)
+}

internal/configuration/settings/validation/windscribe.go

@@ -0,0 +1,27 @@
+package validation
+
+import "github.com/qdm12/gluetun/internal/models"
+
+func WindscribeRegionChoices(servers []models.WindscribeServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Region
+	}
+	return makeUnique(choices)
+}
+
+func WindscribeCityChoices(servers []models.WindscribeServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].City
+	}
+	return makeUnique(choices)
+}
+
+func WindscribeHostnameChoices(servers []models.WindscribeServer) (choices []string) {
+	choices = make([]string, len(servers))
+	for i := range servers {
+		choices[i] = servers[i].Hostname
+	}
+	return makeUnique(choices)
+}