Improve language handling in URLs

The current "rendering language" is needed outside of Site. This commit moves the Language type to the helpers package, and then used to get correct correct language configuration in the markdownify template func.
This commit also adds two new template funcs: relLangURL and absLangURL.

See #2309

hugolib/multilingual.go

@@ -1,3 +1,16 @@
+// Copyright 2016-present The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 package hugolib
 
 import (
@@ -10,58 +23,21 @@ import (
 	"fmt"
 
 	"github.com/spf13/cast"
-	"github.com/spf13/viper"
+	"github.com/spf13/hugo/helpers"
 )
 
-type Language struct {
-	Lang       string
-	Title      string
-	Weight     int
-	params     map[string]interface{}
-	paramsInit sync.Once
-}
-
-func NewLanguage(lang string) *Language {
-	return &Language{Lang: lang, params: make(map[string]interface{})}
-}
-
-func newDefaultLanguage() *Language {
-	defaultLang := viper.GetString("DefaultContentLanguage")
-
-	if defaultLang == "" {
-		defaultLang = "en"
-	}
-
-	return NewLanguage(defaultLang)
-}
-
-type Languages []*Language
-
-func NewLanguages(l ...*Language) Languages {
-	languages := make(Languages, len(l))
-	for i := 0; i < len(l); i++ {
-		languages[i] = l[i]
-	}
-	sort.Sort(languages)
-	return languages
-}
-
-func (l Languages) Len() int           { return len(l) }
-func (l Languages) Less(i, j int) bool { return l[i].Weight < l[j].Weight }
-func (l Languages) Swap(i, j int)      { l[i], l[j] = l[j], l[i] }
-
 type Multilingual struct {
-	Languages Languages
+	Languages helpers.Languages
 
-	DefaultLang *Language
+	DefaultLang *helpers.Language
 
-	langMap     map[string]*Language
+	langMap     map[string]*helpers.Language
 	langMapInit sync.Once
 }
 
-func (ml *Multilingual) Language(lang string) *Language {
+func (ml *Multilingual) Language(lang string) *helpers.Language {
 	ml.langMapInit.Do(func() {
-		ml.langMap = make(map[string]*Language)
+		ml.langMap = make(map[string]*helpers.Language)
 		for _, l := range ml.Languages {
 			ml.langMap[l.Lang] = l
 		}
@@ -70,7 +46,7 @@ func (ml *Multilingual) Language(lang string) *Language {
 }
 
 func newMultiLingualFromSites(sites ...*Site) (*Multilingual, error) {
-	languages := make(Languages, len(sites))
+	languages := make(helpers.Languages, len(sites))
 
 	for i, s := range sites {
 		if s.Language == nil {
@@ -79,61 +55,22 @@ func newMultiLingualFromSites(sites ...*Site) (*Multilingual, error) {
 		languages[i] = s.Language
 	}
 
-	return &Multilingual{Languages: languages, DefaultLang: newDefaultLanguage()}, nil
+	return &Multilingual{Languages: languages, DefaultLang: helpers.NewDefaultLanguage()}, nil
 
 }
 
 func newMultiLingualDefaultLanguage() *Multilingual {
-	return newMultiLingualForLanguage(newDefaultLanguage())
+	return newMultiLingualForLanguage(helpers.NewDefaultLanguage())
 }
 
-func newMultiLingualForLanguage(language *Language) *Multilingual {
-	languages := Languages{language}
+func newMultiLingualForLanguage(language *helpers.Language) *Multilingual {
+	languages := helpers.Languages{language}
 	return &Multilingual{Languages: languages, DefaultLang: language}
 }
 func (ml *Multilingual) enabled() bool {
 	return len(ml.Languages) > 1
 }
 
-func (l *Language) Params() map[string]interface{} {
-	l.paramsInit.Do(func() {
-		// Merge with global config.
-		// TODO(bep) consider making this part of a constructor func.
-
-		globalParams := viper.GetStringMap("Params")
-		for k, v := range globalParams {
-			if _, ok := l.params[k]; !ok {
-				l.params[k] = v
-			}
-		}
-	})
-	return l.params
-}
-
-func (l *Language) SetParam(k string, v interface{}) {
-	l.params[k] = v
-}
-
-func (l *Language) GetString(key string) string { return cast.ToString(l.Get(key)) }
-func (ml *Language) GetStringMap(key string) map[string]interface{} {
-	return cast.ToStringMap(ml.Get(key))
-}
-
-func (l *Language) GetStringMapString(key string) map[string]string {
-	return cast.ToStringMapString(l.Get(key))
-}
-
-func (l *Language) Get(key string) interface{} {
-	if l == nil {
-		panic("language not set")
-	}
-	key = strings.ToLower(key)
-	if v, ok := l.params[key]; ok {
-		return v
-	}
-	return viper.Get(key)
-}
-
 func (s *Site) multilingualEnabled() bool {
 	return s.Multilingual != nil && s.Multilingual.enabled()
 }
@@ -143,12 +80,12 @@ func (s *Site) currentLanguageString() string {
 	return s.currentLanguage().Lang
 }
 
-func (s *Site) currentLanguage() *Language {
+func (s *Site) currentLanguage() *helpers.Language {
 	return s.Language
 }
 
-func toSortedLanguages(l map[string]interface{}) (Languages, error) {
-	langs := make(Languages, len(l))
+func toSortedLanguages(l map[string]interface{}) (helpers.Languages, error) {
+	langs := make(helpers.Languages, len(l))
 	i := 0
 
 	for lang, langConf := range l {
@@ -158,7 +95,7 @@ func toSortedLanguages(l map[string]interface{}) (Languages, error) {
 			return nil, fmt.Errorf("Language config is not a map: %v", langsMap)
 		}
 
-		language := NewLanguage(lang)
+		language := helpers.NewLanguage(lang)
 
 		for k, v := range langsMap {
 			loki := strings.ToLower(k)