feat: assume an initial version of 0.0.0 if no initial version is found (#43)

* feat: initial version for #29

* Couple more fixes

* refactor: fixing merge conflict

Author: drewstinnett

internal/git/git.go

@@ -55,7 +55,11 @@ func DescribeTag(tagMode string, pattern string) (string, error) {
 }
 
 func Changelog(tag string) (string, error) {
-	return gitLog(fmt.Sprintf("tags/%s..HEAD", tag))
+	if tag == "" {
+		return gitLog("HEAD")
+	} else {
+		return gitLog(fmt.Sprintf("tags/%s..HEAD", tag))
+	}
 }
 
 func run(args ...string) (string, error) {

main.go

@@ -41,8 +41,8 @@ func main() {
 	tag, err := git.DescribeTag(*tagMode, *pattern)
 	app.FatalIfError(err, "failed to get current tag for repo")
 
-	current, err := semver.NewVersion(strings.TrimPrefix(tag, *prefix))
-	app.FatalIfError(err, "version %s is not semantic", tag)
+	current, err := getCurrentVersion(tag)
+	app.FatalIfError(err, "could not get current version from tag: '%s'", tag)
 
 	if !*metadata {
 		current = unsetMetadata(current)
@@ -75,6 +75,18 @@ func main() {
 	fmt.Println(getVersion(tag, *prefix, result.String(), *suffix, *stripPrefix))
 }
 
+func getCurrentVersion(tag string) (*semver.Version, error) {
+	var current *semver.Version
+	var err error
+	if tag == "" {
+		current, err = semver.NewVersion(strings.TrimPrefix("0.0.0", *prefix))
+	} else {
+		current, err = semver.NewVersion(strings.TrimPrefix(tag, *prefix))
+	}
+	return current, err
+
+}
+
 func getVersion(tag, prefix, result, suffix string, stripPrefix bool) string {
 	if stripPrefix {
 		prefix = ""