//   Copyright 2012 Georg-August-Universität Göttingen, Germany
//
//   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 de.ugoe.cs.autoquest.usability.evaluation.result;

import java.io.IOException;
import java.io.InputStream;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBElement;
import javax.xml.bind.Unmarshaller;

import com.google.common.base.Optional;
import com.google.common.base.Predicate;
import com.google.common.collect.Iterables;

import de.ugoe.cs.autoquest.usability.DefectDescription;
import de.ugoe.cs.autoquest.usability.DefectDescriptions;
import de.ugoe.cs.autoquest.usability.evaluation.rule.set.UsabilityRule;

/**
 * <p>
 * TODO comment
 * </p>
 * 
 * @author Alexander Deicke
 */
public class UsabilityDefectXmlDescriptionResolver implements UsabilityDefectDescriptionResolver {

    private static final String DEFAULT_MESSAGES_FILE = "defectDescriptions_en.xml";

    private static final UsabilityDefectXmlDescriptionResolver instance =
        new UsabilityDefectXmlDescriptionResolver();

    private DefectDescriptions defectDescriptions;

    private UsabilityDefectXmlDescriptionResolver() {
        loadDescriptions();
    }

    @SuppressWarnings("unchecked")
    private void loadDescriptions() {
        InputStream inputStream = ClassLoader.getSystemResourceAsStream(DEFAULT_MESSAGES_FILE);
        try {
            String packageName = DefectDescriptions.class.getPackage().getName();
            JAXBContext jaxbContext = JAXBContext.newInstance(packageName);
            Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();

            defectDescriptions =
                ((JAXBElement<DefectDescriptions>) unmarshaller.unmarshal(inputStream)).getValue();
        }
        catch (Exception e) {
            throw new RuntimeException("error while initializing usability defect descriptions", e);
        }
        finally {
            if (inputStream != null) {
                try {
                    inputStream.close();
                }
                catch (IOException e) {
                    // ignore
                }
            }
        }
    }

    public static UsabilityDefectXmlDescriptionResolver instance() {
        return instance;
    }

    @Override
    public DefectDescription descriptionFor(final UsabilityRule usabilityRule) {
        Optional<DefectDescription> guidlineDescription =
            Iterables.tryFind(defectDescriptions.getDefectDescription(),
                              new Predicate<DefectDescription>() {

                                  public boolean apply(DefectDescription defectDescription) {
                                      return usabilityRule.ruleIdentifier()
                                          .equals(defectDescription.getDefectId());
                                  }

                              });
        if (!guidlineDescription.isPresent())
            throw new RuntimeException(
                                       "error while initializing usability defect descriptions. No " +
                                           "description text available for description " +
                                           usabilityRule.ruleIdentifier());
        return guidlineDescription.get();
    }

}