feat(#119): detect version and time for '--version' command from VSC (#124)

after 'go build'

Author: volodya-lombrozo

internal/util/version.go

@@ -1,36 +1,80 @@
 package util
 
 import (
+	"runtime/debug"
 	"strings"
 )
 
-const (
-	defaultVersion  = "dev"
-	defaultCommit   = "none"
-	defaultDatetime = "none"
-)
-
 var (
 	// Use the following command to change this value:
 	// go build -ldflags "-X github.com/cqfn/refrax/internal/util.version=<version>"
-	version string = defaultVersion
+	version string = ""
 
 	// Use the following command to change this value:
 	// go build -ldflags "-X github.com/cqfn/refrax/internal/util.commit=<commit-hash>"
-	commit string = defaultCommit
+	commit string = ""
 
 	// Use the following command to change this value:
 	// go build -ldflags "-X github.com/cqfn/refrax/internal/util.datetime=<date-time>"
-	datetime string = defaultDatetime
+	datetime string = ""
 )
 
 func Version() string {
-	parts := []string{version}
-	if commit != defaultCommit {
-		parts = append(parts, "commit", commit)
+	info := info()
+	parts := []string{ver(info)}
+	rev := revision(info)
+	if rev != "" {
+		parts = append(parts, "commit", rev)
 	}
-	if datetime != defaultDatetime {
-		parts = append(parts, "built at", datetime)
+	time := timestamp(info)
+	if time != "" {
+		parts = append(parts, "built at", time)
 	}
 	return strings.Join(parts, " ")
 }
+
+func ver(info map[string]string) string {
+	if version != "" {
+		return version
+	}
+	if iver, ok := info["version"]; ok {
+		return iver
+	}
+	return "dev"
+}
+
+func revision(info map[string]string) string {
+	if commit != "" {
+		return commit
+	}
+	if rev, ok := info["vcs.revision"]; ok {
+		return rev
+	}
+	return ""
+}
+
+func timestamp(info map[string]string) string {
+	if datetime != "" {
+		return datetime
+	}
+	if time, ok := info["vcs.time"]; ok {
+		return time
+	}
+	return ""
+}
+
+func info() map[string]string {
+	info, ok := debug.ReadBuildInfo()
+	if !ok {
+		panic("failed to read build info")
+	}
+	settings := make(map[string]string)
+	for _, s := range info.Settings {
+		settings[s.Key] = s.Value
+	}
+	vcsver := info.Main.Version
+	if vcsver != "" && vcsver != "(devel)" {
+		settings["version"] = vcsver
+	}
+	return settings
+}