cmd/gh-downloader: Use a regexp to do version parsing

cmd/gh-downloader/tag.go

@@ -1,50 +1,67 @@
 package main
 
 import (
-	"fmt"
+	"regexp"
+	"strconv"
 	"strings"
 )
 
+var versionRe = regexp.MustCompile(`((\w+)-)?v?(\d|x).(\d|x).(\d|x)(-(\w+))?`)
+
 type tag struct {
 	Project string
 	Major   int
 	Minor   int
 	Patch   int
+	Suffix  string
 }
 
 func newTag(name string) *tag {
-	var (
-		t tag
+	var ms = versionRe.FindStringSubmatch(name)
 
-		version = name
-	)
+	if len(ms) != 8 {
+		return nil
+	}
 
-	if splittedTagName := strings.Split(name, "-"); len(splittedTagName) > 1 {
-		t.Project = strings.Join(splittedTagName[:len(splittedTagName)-1], "-")
-		version = splittedTagName[len(splittedTagName)-1]
+	return &tag{
+		Project: ms[2],
+		Major:   parseVersionNumber(ms[3]),
+		Minor:   parseVersionNumber(ms[4]),
+		Patch:   parseVersionNumber(ms[5]),
+		Suffix:  ms[7],
 	}
+}
 
-	if n, err := fmt.Sscanf(
-		strings.TrimPrefix(version, "v"),
-		"%d.%d.%d",
-		&t.Major,
-		&t.Minor,
-		&t.Patch,
-	); n != 3 || err != nil {
-		return nil
+func parseVersionNumber(sv string) int {
+	if v, err := strconv.Atoi(sv); err == nil {
+		return v
 	}
 
-	return &t
+	return -1
 }
 
 func (t1 *tag) Less(t2 *tag) bool {
 	if t1.Project != t2.Project {
-		return false
+		return strings.Compare(t1.Project, t2.Project) < 0
+	}
+
+	if t1.Major != t2.Major {
+		return t1.Major < t2.Major
+	}
+
+	if t1.Minor != t2.Minor {
+		return t1.Minor < t2.Minor
+	}
+
+	if t1.Patch != t2.Patch {
+		return t1.Patch < t2.Patch
+	}
+
+	if t1.Suffix == "" || t2.Suffix == "" {
+		return t2.Suffix == ""
 	}
 
-	return t1.Major < t2.Major ||
-		(t1.Major == t2.Major && t1.Minor < t2.Minor) ||
-		(t1.Major == t2.Major && t1.Minor == t2.Minor && t1.Patch < t2.Patch)
+	return strings.Compare(t1.Suffix, t2.Suffix) < 0
 }
 
 func filterReleases(rs releases, scheme string) releases {
@@ -65,7 +82,8 @@ func filterReleases(rs releases, scheme string) releases {
 		if r.Project == schemeTag.Project &&
 			(schemeTag.Major == -1 || schemeTag.Major == r.Major) &&
 			(schemeTag.Minor == -1 || schemeTag.Minor == r.Minor) &&
-			(schemeTag.Patch == -1 || schemeTag.Patch == r.Patch) {
+			(schemeTag.Patch == -1 || schemeTag.Patch == r.Patch) &&
+			(schemeTag.Suffix == "*" || schemeTag.Suffix == r.Suffix) {
 			filteredReleases = append(filteredReleases, release)
 		}
 	}