/*
    * 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.elementbuilder;
  
  import org.opencastproject.mediapackage.Attachment;
  import org.opencastproject.mediapackage.MediaPackageElement;
  import org.opencastproject.mediapackage.MediaPackageElementFlavor;
  import org.opencastproject.mediapackage.MediaPackageReferenceImpl;
  import org.opencastproject.mediapackage.MediaPackageSerializer;
  import org.opencastproject.mediapackage.UnsupportedElementException;
  import org.opencastproject.mediapackage.attachment.AttachmentImpl;
  import org.opencastproject.util.Checksum;
  import org.opencastproject.util.MimeType;
  import org.opencastproject.util.MimeTypes;
  
  import org.apache.commons.lang3.StringUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.w3c.dom.Node;
  import org.w3c.dom.NodeList;
  
  import java.net.URI;
  import java.net.URISyntaxException;
  import java.security.NoSuchAlgorithmException;
  
  import javax.xml.xpath.XPathConstants;
  import javax.xml.xpath.XPathExpressionException;
  
  /**
   * This implementation of the {@link MediaPackageElementBuilderPlugin} recognizes attachments and provides utility
   * methods for creating media package element representations for them.
   */
  public abstract class AbstractAttachmentBuilderPlugin extends AbstractElementBuilderPlugin {
  
    /** the logging facility provided by log4j */
    private static final Logger logger = LoggerFactory.getLogger(AbstractAttachmentBuilderPlugin.class);
  
    /** The flavor to look for */
    protected MediaPackageElementFlavor flavor = null;
  
    /**
     * Creates a new attachment plugin builder that will accept attachments with any flavor.
     */
    public AbstractAttachmentBuilderPlugin() {
      this(null);
    }
  
    /**
     * Creates a new attachment plugin builder that will accept attachments with the given flavor.
     *
     * @param flavor
     *          the attachment flavor
     */
    public AbstractAttachmentBuilderPlugin(MediaPackageElementFlavor flavor) {
      this.flavor = flavor;
    }
  
    /**
     * @see org.opencastproject.mediapackage.elementbuilder.MediaPackageElementBuilderPlugin#accept(URI,
     *      org.opencastproject.mediapackage.MediaPackageElement.Type ,
     *      org.opencastproject.mediapackage.MediaPackageElementFlavor)
     */
    @Override
    public boolean accept(URI uri, MediaPackageElement.Type type, MediaPackageElementFlavor flavor) {
      return accept(type, flavor);
    }
  
    /**
     * This implementation of <code>accept</code> tests for the element type (attachment).
     *
     * @see org.opencastproject.mediapackage.elementbuilder.MediaPackageElementBuilderPlugin#accept(org.opencastproject.mediapackage.MediaPackageElement.Type
     *      , org.opencastproject.mediapackage.MediaPackageElementFlavor)
     */
    @Override
    public boolean accept(MediaPackageElement.Type type, MediaPackageElementFlavor flavor) {
      if (this.flavor != null && !this.flavor.equals(flavor))
        return false;
      return type == null || MediaPackageElement.Type.Attachment.toString().equalsIgnoreCase(type.toString());
    }
 
   /**
    * This implementation of <code>accept</code> tests for the correct node type (attachment).
    *
    * @see org.opencastproject.mediapackage.elementbuilder.MediaPackageElementBuilderPlugin#accept(org.w3c.dom.Node)
    */
   @Override
   public boolean accept(Node elementNode) {
     try {
       // Test for attachment
       String nodeName = elementNode.getNodeName();
       if (nodeName.contains(":")) {
         nodeName = nodeName.substring(nodeName.indexOf(":") + 1);
       }
       if (!MediaPackageElement.Type.Attachment.toString().equalsIgnoreCase(nodeName))
         return false;
       // Check flavor
       if (this.flavor != null) {
         String nodeFlavor = (String) xpath.evaluate("@type", elementNode, XPathConstants.STRING);
         if (!flavor.eq(nodeFlavor))
           return false;
       }
       // Check mime type
       if (mimeTypes != null && mimeTypes.size() > 0) {
         String nodeMimeType = (String) xpath.evaluate("mimetype", elementNode, XPathConstants.STRING);
         MimeType mimeType = MimeTypes.parseMimeType(nodeMimeType);
         if (!mimeTypes.contains(mimeType))
           return false;
       }
 
       return true;
     } catch (XPathExpressionException e) {
       logger.warn("Error while reading attachment flavor from manifest: " + e.getMessage());
       return false;
     }
   }
 
   /**
    * @see org.opencastproject.mediapackage.MediaPackageElementBuilder#newElement(org.opencastproject.mediapackage.MediaPackageElement.Type
    *      , org.opencastproject.mediapackage.MediaPackageElementFlavor)
    */
   @Override
   public MediaPackageElement newElement(MediaPackageElement.Type type, MediaPackageElementFlavor flavor) {
     Attachment attachment = new AttachmentImpl();
     attachment.setFlavor(flavor);
     return attachment;
   }
 
   /**
    * @see org.opencastproject.mediapackage.elementbuilder.MediaPackageElementBuilderPlugin#elementFromManifest(org.w3c.dom.Node,
    *      org.opencastproject.mediapackage.MediaPackageSerializer)
    */
   @Override
   public MediaPackageElement elementFromManifest(Node elementNode, MediaPackageSerializer serializer)
           throws UnsupportedElementException {
 
     String id = null;
     String attachmentFlavor = null;
     String reference = null;
     URI uri = null;
     long size = -1;
     Checksum checksum = null;
     MimeType mimeType = null;
 
     try {
       // id
       id = (String) xpath.evaluate("@id", elementNode, XPathConstants.STRING);
 
       // flavor
       attachmentFlavor = (String) xpath.evaluate("@type", elementNode, XPathConstants.STRING);
 
       // reference
       reference = (String) xpath.evaluate("@ref", elementNode, XPathConstants.STRING);
 
       // url
       uri = serializer.decodeURI(new URI(xpath.evaluate("url/text()", elementNode).trim()));
 
       // size
       String attachmentSize = xpath.evaluate("size/text()", elementNode).trim();
       if (!"".equals(attachmentSize))
         size = Long.parseLong(attachmentSize);
 
       // checksum
       String checksumValue = (String) xpath.evaluate("checksum/text()", elementNode, XPathConstants.STRING);
       String checksumType = (String) xpath.evaluate("checksum/@type", elementNode, XPathConstants.STRING);
       if (StringUtils.isNotEmpty(checksumValue) && checksumType != null)
         checksum = Checksum.create(checksumType.trim(), checksumValue.trim());
 
       // mimetype
       String mimeTypeValue = (String) xpath.evaluate("mimetype/text()", elementNode, XPathConstants.STRING);
       if (StringUtils.isNotEmpty(mimeTypeValue))
         mimeType = MimeTypes.parseMimeType(mimeTypeValue);
 
       // create the attachment
       AttachmentImpl attachment = (AttachmentImpl) AttachmentImpl.fromURI(uri);
 
       if (StringUtils.isNotEmpty(id))
         attachment.setIdentifier(id);
 
       // Add url
       attachment.setURI(uri);
 
       // Add reference
       if (StringUtils.isNotEmpty(reference))
         attachment.referTo(MediaPackageReferenceImpl.fromString(reference));
 
       // Add type/flavor information
       if (StringUtils.isNotEmpty(attachmentFlavor)) {
         try {
           MediaPackageElementFlavor flavor = MediaPackageElementFlavor.parseFlavor(attachmentFlavor);
           attachment.setFlavor(flavor);
         } catch (IllegalArgumentException e) {
           logger.warn("Unable to read attachment flavor: " + e.getMessage());
         }
       }
 
       // Set the size
       if (size > 0)
         attachment.setSize(size);
 
       // Set checksum
       if (checksum != null)
         attachment.setChecksum(checksum);
 
       // Set mimetype
       if (mimeType != null)
         attachment.setMimeType(mimeType);
 
       // Set the description
       String description = xpath.evaluate("description/text()", elementNode);
       if (StringUtils.isNotEmpty(description))
         attachment.setElementDescription(description.trim());
 
       // Set tags
       NodeList tagNodes = (NodeList) xpath.evaluate("tags/tag", elementNode, XPathConstants.NODESET);
       for (int i = 0; i < tagNodes.getLength(); i++) {
         attachment.addTag(tagNodes.item(i).getTextContent());
       }
 
       return specializeAttachment(attachment);
     } catch (XPathExpressionException e) {
       throw new UnsupportedElementException("Error while reading attachment from manifest: " + e.getMessage());
     } catch (NoSuchAlgorithmException e) {
       throw new UnsupportedElementException("Unsupported digest algorithm: " + e.getMessage());
     } catch (URISyntaxException e) {
       throw new UnsupportedElementException("Error while reading attachment file " + uri + ": " + e.getMessage());
     }
   }
 
   /**
    * Utility method that returns an attachment object from the given url.
    *
    * @param uri
    *          the element location
    * @return an attachment object
    * @throws UnsupportedElementException
    *           if the attachment cannto be read
    */
   @Override
   public MediaPackageElement elementFromURI(URI uri) throws UnsupportedElementException {
     logger.trace("Creating attachment from " + uri);
     return specializeAttachment(AttachmentImpl.fromURI(uri));
   }
 
   /**
    * @see org.opencastproject.mediapackage.MediaPackageElementBuilder#elementFromURI(URI,
    *      org.opencastproject.mediapackage.MediaPackageElement.Type ,
    *      org.opencastproject.mediapackage.MediaPackageElementFlavor)
    */
   public MediaPackageElement elementFromURI(URI uri, MediaPackageElement.Type type, MediaPackageElementFlavor flavor)
           throws UnsupportedElementException {
     return elementFromURI(uri);
   }
 
   /**
    * Overwrite this method in order to return a specialization of the attachment. This implementation just returns the
    * attachment that is was given.
    *
    * @param attachment
    *          the general attachment representation
    * @return a specialized attachment
    * @throws UnsupportedElementException
    *           if the attachment fails to be specialized
    */
   protected Attachment specializeAttachment(Attachment attachment) throws UnsupportedElementException {
     return attachment;
   }
 
   /**
    * @see java.lang.Object#toString()
    */
   @Override
   public String toString() {
     return "Attachment Builder Plugin";
   }
 
 }