feat: retrieve version from runtime/debug.Main.Version or latest git tag

- set version from runtime/debug.Main.Version
- use latest git tag as fallback
- allow GoTomatoVersion to be overwritten via ldflags

internal/metadata/version.go

@@ -1,7 +1,37 @@
 package metadata
 
-import "strings"
+import (
+	"os/exec"
+	"runtime/debug"
+	"strings"
+)
 
-// This will be overwritten by goreleaser on build
-var GoTomatoVersion = "devel"                                // The GoTomato version
-var ProtocolVersion = strings.Split(GoTomatoVersion, ".")[0] // The protocol version
+var (
+	GoTomatoVersion = "" // The GoTomato version
+	ProtocolVersion = "" // The protocol version
+)
+
+func stripVersionPrefix(version string) string {
+	return strings.TrimLeft(version, "v")
+}
+
+func getLatestTag() string {
+	bytes, _ := exec.Command("git", "describe", "--tags").Output()
+	output := strings.TrimSpace(string(bytes))
+	return stripVersionPrefix(output)
+}
+
+// set GoTomatoVersion from runtime/debug.Main.Version
+// use latest git tag as fallback
+// can be overwritten via ldflags (e,g. by goreleaser)
+func init() {
+	if GoTomatoVersion == "" {
+		info, _ := debug.ReadBuildInfo()
+		if info.Main.Version != "(devel)" {
+			GoTomatoVersion = stripVersionPrefix(info.Main.Version)
+		} else {
+			GoTomatoVersion = getLatestTag()
+		}
+	}
+	ProtocolVersion = strings.Split(GoTomatoVersion, ".")[0]
+}