Automate the Hugo release process

This commit adds a work flow aroung GoReleaser to get the Hugo release process automated and more uniform:

* It can be run fully automated or in two steps to allow for manual edits of the relase notes.
* It supports both patch and full releases.
* It fetches author, issue, repo info. etc. for the release notes from GitHub.
* The file names produced are mainly the same as before, but we no use tar.gz as archive for all Unix versions.
* There isn't a fully automated CI setup in place yet, but the release tag is marked in the commit message with "[ci deploy]"

Fixes #3358

3 files changed, 45 insertions, 32 deletions

diff --git a/helpers/general.go b/helpers/general.go
index ac2af4936..ea3620119 100644
--- a/helpers/general.go
+++ b/helpers/general.go
@@ -286,7 +286,7 @@ func InitLoggers() {
 // plenty of time to fix their templates.
 func Deprecated(object, item, alternative string, err bool) {
 	if err {
-		DistinctErrorLog.Printf("%s's %s is deprecated and will be removed in Hugo %s. %s.", object, item, NextHugoReleaseVersion(), alternative)
+		DistinctErrorLog.Printf("%s's %s is deprecated and will be removed in Hugo %s. %s.", object, item, CurrentHugoVersion.Next().ReleaseVersion(), alternative)
 
 	} else {
 		// Make sure the users see this while avoiding build breakage. This will not lead to an os.Exit(-1)
diff --git a/helpers/hugo.go b/helpers/hugo.go
index 2fda7cdc4..05e47306c 100644
--- a/helpers/hugo.go
+++ b/helpers/hugo.go
@@ -20,35 +20,51 @@ import (
 	"github.com/spf13/cast"
 )
 
-// HugoVersionNumber represents the current build version.
-// This should be the only one
-const (
+// HugoVersion represents the Hugo build version.
+type HugoVersion struct {
 	// Major and minor version.
-	HugoVersionNumber = 0.21
+	Number float32
 
 	// Increment this for bug releases
-	HugoPatchVersion = 0
-)
+	PatchLevel int
+
+	// HugoVersionSuffix is the suffix used in the Hugo version string.
+	// It will be blank for release versions.
+	Suffix string
+}
+
+func (v HugoVersion) String() string {
+	return hugoVersion(v.Number, v.PatchLevel, v.Suffix)
+}
+
+// ReleaseVersion represents the release version.
+func (v HugoVersion) ReleaseVersion() HugoVersion {
+	v.Suffix = ""
+	return v
+}
 
-// HugoVersionSuffix is the suffix used in the Hugo version string.
-// It will be blank for release versions.
-const HugoVersionSuffix = "-DEV" // use this when not doing a release
-//const HugoVersionSuffix = "" // use this line when doing a release
+// Next returns the next Hugo release version.
+func (v HugoVersion) Next() HugoVersion {
+	return HugoVersion{Number: v.Number + 0.01}
+}
 
-// HugoVersion returns the current Hugo version. It will include
-// a suffix, typically '-DEV', if it's development version.
-func HugoVersion() string {
-	return hugoVersion(HugoVersionNumber, HugoPatchVersion, HugoVersionSuffix)
+// Pre returns the previous Hugo release version.
+func (v HugoVersion) Prev() HugoVersion {
+	return HugoVersion{Number: v.Number - 0.01}
 }
 
-// HugoReleaseVersion is same as HugoVersion, but no suffix.
-func HugoReleaseVersion() string {
-	return hugoVersionNoSuffix(HugoVersionNumber, HugoPatchVersion)
+// NextPatchLevel returns the next patch/bugfix Hugo version.
+// This will be a patch increment on the previous Hugo version.
+func (v HugoVersion) NextPatchLevel(level int) HugoVersion {
+	return HugoVersion{Number: v.Number - 0.01, PatchLevel: level}
 }
 
-// NextHugoReleaseVersion returns the next Hugo release version.
-func NextHugoReleaseVersion() string {
-	return hugoVersionNoSuffix(HugoVersionNumber+0.01, 0)
+// CurrentHugoVersion represents the current build version.
+// This should be the only one.
+var CurrentHugoVersion = HugoVersion{
+	Number:     0.21,
+	PatchLevel: 0,
+	Suffix:     "-DEV",
 }
 
 func hugoVersion(version float32, patchVersion int, suffix string) string {
@@ -58,19 +74,12 @@ func hugoVersion(version float32, patchVersion int, suffix string) string {
 	return fmt.Sprintf("%.2f%s", version, suffix)
 }
 
-func hugoVersionNoSuffix(version float32, patchVersion int) string {
-	if patchVersion > 0 {
-		return fmt.Sprintf("%.2f.%d", version, patchVersion)
-	}
-	return fmt.Sprintf("%.2f", version)
-}
-
 // CompareVersion compares the given version string or number against the
 // running Hugo version.
 // It returns -1 if the given version is less than, 0 if equal and 1 if greater than
 // the running version.
 func CompareVersion(version interface{}) int {
-	return compareVersions(HugoVersionNumber, HugoPatchVersion, version)
+	return compareVersions(CurrentHugoVersion.Number, CurrentHugoVersion.PatchLevel, version)
 }
 
 func compareVersions(inVersion float32, inPatchVersion int, in interface{}) int {
diff --git a/helpers/hugo_test.go b/helpers/hugo_test.go
index b71517f71..c96a1351b 100644
--- a/helpers/hugo_test.go
+++ b/helpers/hugo_test.go
@@ -22,10 +22,14 @@ import (
 
 func TestHugoVersion(t *testing.T) {
 	assert.Equal(t, "0.15-DEV", hugoVersion(0.15, 0, "-DEV"))
-	assert.Equal(t, "0.17", hugoVersionNoSuffix(0.16+0.01, 0))
-	assert.Equal(t, "0.20", hugoVersionNoSuffix(0.20, 0))
 	assert.Equal(t, "0.15.2-DEV", hugoVersion(0.15, 2, "-DEV"))
-	assert.Equal(t, "0.17.3", hugoVersionNoSuffix(0.16+0.01, 3))
+
+	v := HugoVersion{Number: 0.21, PatchLevel: 0, Suffix: "-DEV"}
+
+	require.Equal(t, v.ReleaseVersion().String(), "0.21")
+	require.Equal(t, "0.21-DEV", v.String())
+	require.Equal(t, "0.22", v.Next().String())
+	require.Equal(t, "0.20.3", v.NextPatchLevel(3).String())
 }
 
 func TestCompareVersions(t *testing.T) {