/*
    * Licensed to The Apereo Foundation under one or more contributor license
    * agreements. See the NOTICE file distributed with this work for additional
    * information regarding copyright ownership.
    *
    *
    * The Apereo Foundation licenses this file to you under the Educational
    * Community 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://opensource.org/licenses/ecl2.txt
   *
   * 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.opencastproject.mediapackage;
  
  import static org.apache.commons.io.IOUtils.toInputStream;
  
  import org.opencastproject.util.XmlSafeParser;
  import org.opencastproject.util.data.Function;
  
  import org.xml.sax.SAXException;
  
  import java.io.IOException;
  import java.io.StringWriter;
  import java.util.Collection;
  import java.util.Iterator;
  import java.util.LinkedList;
  import java.util.List;
  
  import javax.xml.bind.JAXBException;
  import javax.xml.bind.Marshaller;
  import javax.xml.bind.Unmarshaller;
  
  /**
   * Convenience implementation that supports serializing and deserializing media package elements.
   */
  public final class MediaPackageElementParser {
  
    /**
     * Private constructor to prohibit instances of this static utility class.
     */
    private MediaPackageElementParser() {
      // Nothing to do
    }
  
    /**
     * Serializes the media package element to a string.
     *
     * @param element
     *         the element
     * @return the serialized media package element
     * @throws MediaPackageException
     *         if serialization failed
     */
    public static String getAsXml(MediaPackageElement element) throws MediaPackageException {
      if (element == null)
        throw new IllegalArgumentException("Mediapackage element must not be null");
      StringWriter writer = new StringWriter();
      Marshaller m = null;
      try {
        m = MediaPackageImpl.context.createMarshaller();
        m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, false);
        m.marshal(element, writer);
        return writer.toString();
      } catch (JAXBException e) {
        throw new MediaPackageException(e.getLinkedException() != null ? e.getLinkedException() : e);
      }
    }
  
    /** {@link #getAsXml(MediaPackageElement)} as function. */
    public static <A extends MediaPackageElement> Function<A, String> getAsXml() {
      return new Function.X<A, String>() {
        @Override protected String xapply(MediaPackageElement elem) throws Exception {
          return getAsXml(elem);
        }
      };
    }
  
    /**
     * Parses the serialized media package element and returns its object representation.
     *
     * @param xml
     *         the serialized element
     * @return the media package element instance
     * @throws MediaPackageException
     *         if de-serializing the element fails
     */
    public static MediaPackageElement getFromXml(String xml) throws MediaPackageException {
      Unmarshaller m = null;
      try {
        m = MediaPackageImpl.context.createUnmarshaller();
       return (MediaPackageElement) m.unmarshal(XmlSafeParser.parse(toInputStream(xml)));
     } catch (JAXBException e) {
       throw new MediaPackageException(e.getLinkedException() != null ? e.getLinkedException() : e);
     } catch (IOException | SAXException e) {
       throw new MediaPackageException(e);
     }
   }
 
   /**
    * Serializes media package element list to a string.
    *
    * @param elements
    *         element list to be serialized
    * @return serialized media package element list
    * @throws MediaPackageException
    *         if serialization fails
    */
   public static String getArrayAsXml(Collection<? extends MediaPackageElement> elements) throws MediaPackageException {
     // TODO write real serialization function
     if (elements == null || elements.isEmpty()) return "";
     try {
       StringBuilder builder = new StringBuilder();
       Iterator<? extends MediaPackageElement> it = elements.iterator();
       builder.append(getAsXml(it.next()));
       while (it.hasNext()) {
         builder.append("###");
         builder.append(getAsXml(it.next()));
       }
       return builder.toString();
     } catch (Exception e) {
       if (e instanceof MediaPackageException) {
         throw (MediaPackageException) e;
       } else {
         throw new MediaPackageException(e);
       }
     }
   }
 
   /**
    * Parses the serialized media package element list.
    *
    * @param xml
    *         String to be parsed
    * @return parsed media package element list
    * @throws MediaPackageException
    *         if de-serialization fails
    */
   public static List<? extends MediaPackageElement> getArrayFromXml(String xml) throws MediaPackageException {
     // TODO write real deserialization function
     try {
       List<MediaPackageElement> elements = new LinkedList<MediaPackageElement>();
       String[] xmlArray = xml.split("###");
       for (String xmlElement : xmlArray) {
         if ("".equals(xmlElement.trim())) continue;
         elements.add(getFromXml(xmlElement.trim()));
       }
       return elements;
     } catch (Exception e) {
       if (e instanceof MediaPackageException) {
         throw (MediaPackageException) e;
       } else {
         throw new MediaPackageException(e);
       }
     }
   }
 
   /**
    * Same as getArrayFromXml(), but throwing a RuntimeException instead of a checked exception. Useful in streams.
    *
    * @param xml
    *         String to be parsed
    * @return parsed media package element list
    *
    * @throws MediaPackageRuntimeException
    *         if de-serialization fails
    */
   public static List<? extends MediaPackageElement> getArrayFromXmlUnchecked(String xml) {
     try {
       return getArrayFromXml(xml);
     } catch (MediaPackageException e) {
       throw new MediaPackageRuntimeException(e);
     }
   }
 
 }