feat(nordvpn): filter with SERVER_CATEGORIES (#1806)

- update NordVPN servers data built-in

internal/provider/utils/filtering.go

@@ -61,6 +61,10 @@ func filterServer(server models.Server,
 		return true
 	}
 
+	if filterAnyByPossibilities(server.Categories, selection.Categories) {
+		return true
+	}
+
 	if filterByPossibilities(server.Region, selection.Regions) {
 		return true
 	}
@@ -101,3 +105,17 @@ func filterByPossibilities[T string | uint16](value T, possibilities []T) (filte
 	}
 	return true
 }
+
+func filterAnyByPossibilities(values, possibilities []string) (filtered bool) {
+	if len(possibilities) == 0 {
+		return false
+	}
+
+	for _, value := range values {
+		if !filterByPossibilities(value, possibilities) {
+			return false // found a valid value
+		}
+	}
+
+	return true
+}

internal/provider/utils/filtering_test.go

@@ -179,6 +179,19 @@ func Test_FilterServers(t *testing.T) {
 				{City: "b", VPN: vpn.OpenVPN, UDP: true},
 			},
 		},
+		"filter by category": {
+			selection: settings.ServerSelection{
+				Categories: []string{"legacy_p2p"},
+			}.WithDefaults(providers.Nordvpn),
+			servers: []models.Server{
+				{Categories: []string{"legacy_p2p"}, VPN: vpn.OpenVPN, UDP: true},
+				{Categories: []string{"legacy_standard"}, VPN: vpn.OpenVPN, UDP: true},
+				{VPN: vpn.OpenVPN, UDP: true},
+			},
+			filtered: []models.Server{
+				{Categories: []string{"legacy_p2p"}, VPN: vpn.OpenVPN, UDP: true},
+			},
+		},
 		"filter by ISP": {
 			selection: settings.ServerSelection{
 				ISPs: []string{"b"},