IPVanish support (#475)

- Fix #410 and #416

internal/updater/providers/ipvanish/filename.go

@@ -0,0 +1,39 @@
+package ipvanish
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/qdm12/gluetun/internal/constants"
+)
+
+var errCountryCodeUnknown = errors.New("country code is unknown")
+
+func parseFilename(fileName, hostname string) (
+	country, city string, err error) {
+	const prefix = "ipvanish-"
+	s := strings.TrimPrefix(fileName, prefix)
+
+	const ext = ".ovpn"
+	host := strings.Split(hostname, ".")[0]
+	suffix := "-" + host + ext
+	s = strings.TrimSuffix(s, suffix)
+
+	parts := strings.Split(s, "-")
+
+	countryCodes := constants.CountryCodes()
+	countryCode := strings.ToLower(parts[0])
+	country, ok := countryCodes[countryCode]
+	if !ok {
+		return "", "", fmt.Errorf("%w: %s", errCountryCodeUnknown, countryCode)
+	}
+	country = strings.Title(country)
+
+	if len(parts) > 1 {
+		city = strings.Join(parts[1:], " ")
+		city = strings.Title(city)
+	}
+
+	return country, city, nil
+}