TranslationServiceImpl.java

/*******************************************************************************
 * Copyright 2013 Thomas Letsch (contact@thomas-letsch.de)
 *
 * 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 org.vaadin.addons.javaee.i18n;

import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.Collection;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import javax.enterprise.inject.Instance;
import javax.inject.Inject;
import javax.inject.Singleton;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Singleton
public class TranslationServiceImpl implements TranslationService {

    private static final long serialVersionUID = 1L;

    private static Logger log = LoggerFactory.getLogger(TranslationServiceImpl.class);

    @Inject
    private Instance<TranslationSPI> providers;

    @Inject
    private SelectedLocale selectedLocale;

    public TranslationServiceImpl() {
        log.debug("Cosntructor called");
    }

    @Override
    public Map<String, String> get(String prefix, Collection<String> values) {
        Map<String, String> map = new LinkedHashMap<>(values.size());
        for (String value : values) {
            map.put(value, getText(prefix + "." + value));
        }
        return map;
    }

    @Override
    public String getText(String key, Object... params) {
        if (key == null) {
            throw new IllegalArgumentException("key may not be null!");
        }
        List<String> variations = getPossibleKeyVariations(key);
        for (String variation : variations) {
            String translation = searchInAllProviders(variation);
            if (isTranslated(variation, translation)) {
                translation = MessageFormat.format(translation, params);
                return translation;
            }
        }
        return key;
    }

    boolean isTranslated(String key, String translation) {
        return !key.equals(translation);
    }

    private String searchInAllProviders(String key) {
        for (TranslationSPI spi : providers) {
            String translation = spi.get(key, selectedLocale.getLocale());
            if (isTranslated(key, translation)) {
                return translation;
            }
        }
        return key;
    }

    List<String> getPossibleKeyVariations(String key) {
        if (key == null) {
            throw new IllegalArgumentException("key may not be null!");
        }
        List<String> result = new ArrayList<String>();
        result.add(key);
        int pos = key.indexOf(".");
        while (pos > 0) {
            key = key.substring(pos + 1);
            result.add(key);
            pos = key.indexOf(".");
        }
        return result;
    }

}