Add updates module and fix issues

updates/filename.go

@@ -0,0 +1,41 @@
+package updates
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+)
+
+var versionRegex = regexp.MustCompile("_v[0-9]+-[0-9]+-[0-9]+b?")
+
+func getIdentifierAndVersion(versionedPath string) (identifier, version string, ok bool) {
+	// extract version
+	rawVersion := versionRegex.FindString(versionedPath)
+	if rawVersion == "" {
+		return "", "", false
+	}
+
+	// replace - with . and trim _
+	version = strings.Replace(strings.TrimLeft(rawVersion, "_v"), "-", ".", -1)
+
+	// put together without version
+	i := strings.Index(versionedPath, rawVersion)
+	if i < 0 {
+		// extracted version not in string (impossible)
+		return "", "", false
+	}
+	return versionedPath[:i] + versionedPath[i+len(rawVersion):], version, true
+}
+
+func getVersionedPath(identifier, version string) (versionedPath string) {
+	// split in half
+	splittedFilePath := strings.SplitN(identifier, ".", 2)
+	// replace . with -
+	transformedVersion := strings.Replace(version, ".", "-", -1)
+
+	// put together
+	if len(splittedFilePath) == 1 {
+		return fmt.Sprintf("%s_v%s", splittedFilePath[0], transformedVersion)
+	}
+	return fmt.Sprintf("%s_v%s.%s", splittedFilePath[0], transformedVersion, splittedFilePath[1])
+}