Add absURL template func

Fixes #1106

helpers/url.go

@@ -138,13 +138,22 @@ func MakePermalink(host, plink string) *url.URL {
 	base.Path = path.Join(base.Path, p.Path)
 
 	// path.Join will strip off the last /, so put it back if it was there.
-	if strings.HasSuffix(p.Path, "/") && !strings.HasSuffix(base.Path, "/") {
+	hadTrailingSlash := (plink == "" && strings.HasSuffix(host, "/")) || strings.HasSuffix(p.Path, "/")
+	if hadTrailingSlash && !strings.HasSuffix(base.Path, "/") {
 		base.Path = base.Path + "/"
 	}
 
 	return base
 }
 
+// AbsURL creates a absolute URL from the relative path given and the BaseURL set in config.
+func AbsURL(path string) string {
+	if strings.HasPrefix(path, "http") || strings.HasPrefix(path, "//") {
+		return path
+	}
+	return MakePermalink(string(viper.GetString("BaseURL")), path).String()
+}
+
 // AddContextRoot adds the context root to an URL if it's not already set.
 // For relative URL entries on sites with a base url with a context root set (i.e. http://example.com/mysite),
 // relative URLs must not include the context root if canonifyURLs is enabled. But if it's disabled, it must be set.

helpers/url_test.go

@@ -1,6 +1,7 @@
 package helpers
 
 import (
+	"github.com/spf13/viper"
 	"github.com/stretchr/testify/assert"
 	"strings"
 	"testing"
@@ -26,6 +27,28 @@ func TestURLize(t *testing.T) {
 	}
 }
 
+func TestAbsURL(t *testing.T) {
+	tests := []struct {
+		input    string
+		baseURL  string
+		expected string
+	}{
+		{"/test/foo", "http://base/", "http://base/test/foo"},
+		{"", "http://base/ace/", "http://base/ace/"},
+		{"/test/2/foo/", "http://base", "http://base/test/2/foo/"},
+		{"http://abs", "http://base/", "http://abs"},
+		{"//schemaless", "http://base/", "//schemaless"},
+	}
+
+	for _, test := range tests {
+		viper.Set("BaseURL", test.baseURL)
+		output := AbsURL(test.input)
+		if output != test.expected {
+			t.Errorf("Expected %#v, got %#v\n", test.expected, output)
+		}
+	}
+}
+
 func TestSanitizeURL(t *testing.T) {
 	tests := []struct {
 		input    string

tpl/template_funcs.go

@@ -1196,6 +1196,7 @@ func init() {
 		"safeHTML":    SafeHTML,
 		"safeCSS":     SafeCSS,
 		"safeURL":     SafeURL,
+		"absURL":      func(a string) template.HTML { return template.HTML(helpers.AbsURL(a)) },
 		"markdownify": Markdownify,
 		"first":       First,
 		"where":       Where,