oidc-demo-app/services/i18n.go

/*
 Copyright 2020, 2021 Jan Dittberner


 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 services

import (
	"context"
	"fmt"

	"github.com/nicksnyder/go-i18n/v2/i18n"
	"golang.org/x/text/language"

	"github.com/BurntSushi/toml"
	log "github.com/sirupsen/logrus"
)

func AddMessages(ctx context.Context) {
	messages := make(map[string]*i18n.Message)
	messages["IndexGreeting"] = &i18n.Message{
		ID:    "IndexGreeting",
		Other: "Hello {{ .User }}",
	}
	messages["IndexTitle"] = &i18n.Message{
		ID:    "IndexTitle",
		Other: "Welcome to the Demo application",
	}
	messages["LogoutLabel"] = &i18n.Message{
		ID:          "LogoutLabel",
		Description: "A label on a logout button or link",
		Other:       "Logout",
	}
	messages["IndexIntroductionText"] = &i18n.Message{
		ID:    "IndexIntroductionText",
		Other: "This is an authorization protected resource",
	}
	GetMessageCatalog(ctx).AddMessages(messages)
}

type contextKey int

const (
	ctxI18nBundle contextKey = iota
	ctxI18nCatalog
)

type MessageCatalog struct {
	messages map[string]*i18n.Message
	logger   *log.Logger
}

func (m *MessageCatalog) AddMessages(messages map[string]*i18n.Message) {
	for key, value := range messages {
		m.messages[key] = value
	}
}

func (m *MessageCatalog) LookupErrorMessage(tag string, field string, value interface{}, localizer *i18n.Localizer) string {
	var message *i18n.Message
	message, ok := m.messages[fmt.Sprintf("%s-%s", field, tag)]
	if !ok {
		m.logger.Infof("no specific error message %s-%s", field, tag)
		message, ok = m.messages[tag]
		if !ok {
			m.logger.Infof("no specific error message %s", tag)
			message, ok = m.messages["unknown"]
			if !ok {
				m.logger.Warnf("no default translation found")
				return tag
			}
		}
	}

	translation, err := localizer.Localize(&i18n.LocalizeConfig{
		DefaultMessage: message,
		TemplateData: map[string]interface{}{
			"Value": value,
		},
	})
	if err != nil {
		m.logger.Error(err)
		return tag
	}
	return translation
}

func (m *MessageCatalog) LookupMessage(id string, templateData map[string]interface{}, localizer *i18n.Localizer) string {
	if message, ok := m.messages[id]; ok {
		translation, err := localizer.Localize(&i18n.LocalizeConfig{
			DefaultMessage: message,
			TemplateData:   templateData,
		})
		if err != nil {
			switch err.(type) {
			case *i18n.MessageNotFoundErr:
				m.logger.Warnf("message %s not found: %v", id, err)
				if translation != "" {
					return translation
				}
				break
			default:
				m.logger.Error(err)
			}
			return id
		}
		return translation
	} else {
		m.logger.Warnf("no translation found for %s", id)
		return id
	}
}

func InitI18n(ctx context.Context, logger *log.Logger, languages []string) context.Context {
	bundle := i18n.NewBundle(language.English)
	bundle.RegisterUnmarshalFunc("toml", toml.Unmarshal)
	for _, lang := range languages {
		_, err := bundle.LoadMessageFile(fmt.Sprintf("active.%s.toml", lang))
		if err != nil {
			logger.Warnln("message bundle de.toml not found")
		}
	}
	catalog := initMessageCatalog(logger)
	ctx = context.WithValue(ctx, ctxI18nBundle, bundle)
	ctx = context.WithValue(ctx, ctxI18nCatalog, catalog)
	return ctx
}

func initMessageCatalog(logger *log.Logger) *MessageCatalog {
	messages := make(map[string]*i18n.Message)
	messages["ErrorTitle"] = &i18n.Message{
		ID:    "ErrorTitle",
		Other: "An error has occurred",
	}
	return &MessageCatalog{messages: messages, logger: logger}
}

func GetI18nBundle(ctx context.Context) *i18n.Bundle {
	return ctx.Value(ctxI18nBundle).(*i18n.Bundle)
}

func GetMessageCatalog(ctx context.Context) *MessageCatalog {
	return ctx.Value(ctxI18nCatalog).(*MessageCatalog)
}