transform: Explicitly bind LiveReload to server port

If hugo server is run on port 80 or 443, LiveReload does not
correctly bind to the same port, instead using port 35729.
This commit adds functionality to inform LiveReload of the
correct port to bind to.

See https://github.com/livereload/livereload-js/issues/16

Partially contributed by Jeff Minard (@chuyskywalker).

Fixes #2205

transform/livereloadinject.go

@@ -16,18 +16,21 @@ package transform
 import (
 	"bytes"
 	"fmt"
+
+	"github.com/spf13/viper"
 )
 
 func LiveReloadInject(ct contentTransformer) {
 	endBodyTag := "</body>"
 	match := []byte(endBodyTag)
-	replaceTemplate := `<script data-no-instant>document.write('<script src="/livereload.js?mindelay=10"></' + 'script>')</script>%s`
+	port := viper.Get("port")
-	replace := []byte(fmt.Sprintf(replaceTemplate, endBodyTag))
+	replaceTemplate := `<script data-no-instant>document.write('<script src="/livereload.js?port=%d&mindelay=10"></' + 'script>')</script>%s`
+	replace := []byte(fmt.Sprintf(replaceTemplate, port, endBodyTag))
 
 	newcontent := bytes.Replace(ct.Content(), match, replace, 1)
 	if len(newcontent) == len(ct.Content()) {
 		endBodyTag = "</BODY>"
-		replace := []byte(fmt.Sprintf(replaceTemplate, endBodyTag))
+		replace := []byte(fmt.Sprintf(replaceTemplate, port, endBodyTag))
 		match := []byte(endBodyTag)
 		newcontent = bytes.Replace(ct.Content(), match, replace, 1)
 	}

transform/livereloadinject_test.go

@@ -18,6 +18,8 @@ import (
 	"fmt"
 	"strings"
 	"testing"
+
+	"github.com/spf13/viper"
 )
 
 func TestLiveReloadInject(t *testing.T) {
@@ -26,13 +28,14 @@ func TestLiveReloadInject(t *testing.T) {
 }
 
 func doTestLiveReloadInject(t *testing.T, bodyEndTag string) {
+	viper.Set("port", 1313)
 	out := new(bytes.Buffer)
 	in := strings.NewReader(bodyEndTag)
 
 	tr := NewChain(LiveReloadInject)
 	tr.Apply(out, in, []byte("path"))
 
-	expected := fmt.Sprintf(`<script data-no-instant>document.write('<script src="/livereload.js?mindelay=10"></' + 'script>')</script>%s`, bodyEndTag)
+	expected := fmt.Sprintf(`<script data-no-instant>document.write('<script src="/livereload.js?port=1313&mindelay=10"></' + 'script>')</script>%s`, bodyEndTag)
 	if string(out.Bytes()) != expected {
 		t.Errorf("Expected %s got %s", expected, string(out.Bytes()))
 	}