/*
    * 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.metadata.mpeg7;
  
  import org.opencastproject.util.XmlSafeParser;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.xml.sax.Attributes;
  import org.xml.sax.SAXException;
  import org.xml.sax.SAXParseException;
  import org.xml.sax.helpers.DefaultHandler;
  
  import java.awt.Rectangle;
  import java.io.IOException;
  import java.io.InputStream;
  import java.net.URI;
  import java.text.DecimalFormat;
  import java.text.DecimalFormatSymbols;
  import java.text.ParseException;
  import java.util.Locale;
  
  import javax.xml.parsers.ParserConfigurationException;
  import javax.xml.parsers.SAXParser;
  import javax.xml.parsers.SAXParserFactory;
  
  /**
   * Parser implementation for mpeg-7 files. Note that this implementation does by far not cover the full mpeg-7 standard
   * but only deals with those parts relevant to Opencast, mainly temporal decompositions.
   */
  public class Mpeg7Parser extends DefaultHandler {
  
    /** the logging facility */
    private static final Logger logger = LoggerFactory.getLogger(Mpeg7Parser.class.getName());
  
    /** The current parser state */
    enum ParserState {
      Document, MultimediaContent, Segment, VideoText
    };
  
    /**
     * Number formatter, used to deal with relevance values in a locale
     * independent way
     */
    private static DecimalFormatSymbols standardSymbols = new DecimalFormatSymbols(Locale.US);
  
    /** The manifest */
    private Mpeg7CatalogImpl mpeg7Doc = null;
  
    /** The element content */
    private StringBuffer tagContent = new StringBuffer();
  
    /** The multimedia content */
    private MultimediaContentType multimediaContent = null;
  
    /** Current multimedia content type (audio, video, audiovisual) */
    private MultimediaContentType.Type contentType = null;
  
    /** The multimedia content identifier */
    private String contentId = null;
  
    /** The media locator */
    private MediaLocator mediaLocator = null;
  
    /** The content media time point (will usually refer to 0:00:00) */
    private MediaTimePoint contentTimePoint = null;
  
    /** The time point (relative to the content time point) */
    private MediaTimePoint mediaTimePoint = null;
  
    /** The duration */
    private MediaDuration mediaDuration = null;
  
    /** The media time and duration */
    private MediaTime mediaTime = null;
  
    /** The temporal decomposition container */
    private TemporalDecomposition<?> temporalDecomposition = null;
  
   /** The temporal segment */
   private Segment segment = null;
 
   /** The spatio temporal decomposition container */
   private SpatioTemporalDecomposition spatioTemporalDecomposition = null;
 
   /** The text annoation */
   private TextAnnotation textAnnotation = null;
 
   /** The videotext element */
   private VideoText videoText = null;
 
   /** The videotext text */
   private Textual textual = null;
 
   /** The current parser state */
   private Mpeg7Parser.ParserState state = ParserState.Document;
 
   /** Flag to check if this is not just an arbitrary xml document */
   private boolean isMpeg7 = false;
 
   private DecimalFormat floatFormat = new DecimalFormat();
 
   /**
    * Creates a new parser for mpeg-7 files.
    */
   public Mpeg7Parser() {
     floatFormat.setDecimalFormatSymbols(standardSymbols);
   }
 
   public Mpeg7Parser(Mpeg7CatalogImpl catalog) {
     this.mpeg7Doc = catalog;
     floatFormat.setDecimalFormatSymbols(standardSymbols);
   }
 
   /**
    * Parses the mpeg-7 catalog file and returns its object representation.
    *
    * @param is
    *          the input stream containing the catalog
    * @return the catalog representation
    * @throws ParserConfigurationException
    *           if setting up the parser failed
    * @throws SAXException
    *           if an error occured while parsing the document
    * @throws IOException
    *           if the file cannot be accessed in a proper way
    * @throws IllegalArgumentException
    *           if the provided file does not contain mpeg-7 data
    */
   public Mpeg7CatalogImpl parse(InputStream is) throws ParserConfigurationException, SAXException, IOException {
     if (mpeg7Doc == null)
       mpeg7Doc = new Mpeg7CatalogImpl();
     SAXParserFactory factory = XmlSafeParser.newSAXParserFactory();
     // REPLAY does not use a DTD here
     factory.setValidating(false);
     factory.setNamespaceAware(true);
     SAXParser parser = factory.newSAXParser();
     parser.parse(is, this);
 
     // Did we parse an mpeg-7 document?
     if (!isMpeg7)
       throw new IllegalArgumentException("Content of input stream is not mpeg-7");
     return mpeg7Doc;
   }
 
   /**
    * Read <code>type</code> attribute from track or catalog element.
    *
    * @see org.xml.sax.helpers.DefaultHandler#startElement(java.lang.String, java.lang.String, java.lang.String,
    *      org.xml.sax.Attributes)
    */
   @Override
   public void startElement(String uri, String localName, String name, Attributes attributes) throws SAXException {
     super.startElement(uri, localName, name, attributes);
     tagContent = new StringBuffer();
 
     // Make sure this is an mpeg-7 catalog
     // TODO: Improve this test, add namespace awareness
     if (!isMpeg7 && "Mpeg7".equals(name))
       isMpeg7 = true;
 
     // Handle parser state
     if ("MultimediaContent".equals(localName)) {
       state = ParserState.MultimediaContent;
     }
 
     // Content type
     if ("Audio".equals(localName) || "Video".equals(localName) || "AudioVisual".equals(localName)) {
       contentType = MultimediaContentType.Type.valueOf(localName);
       contentId = attributes.getValue("id");
       if (MultimediaContentType.Type.Audio.equals(contentType))
         multimediaContent = mpeg7Doc.addAudioContent(contentId, mediaTime, mediaLocator);
       else if (MultimediaContentType.Type.Video.equals(contentType))
         multimediaContent = mpeg7Doc.addVideoContent(contentId, mediaTime, mediaLocator);
       else if (MultimediaContentType.Type.AudioVisual.equals(contentType))
         multimediaContent = mpeg7Doc.addAudioVisualContent(contentId, mediaTime, mediaLocator);
     }
 
     // Temporal decomposition
     if ("TemporalDecomposition".equals(localName)) {
       String hasGap = attributes.getValue("gap");
       String isOverlapping = attributes.getValue("overlap");
       String criteria = attributes.getValue("criteria");
       if (!"temporal".equals(criteria))
         throw new IllegalStateException("Decompositions other than temporal are not supported");
       temporalDecomposition = multimediaContent.getTemporalDecomposition();
       temporalDecomposition.setGap("true".equals(hasGap));
       temporalDecomposition.setOverlapping("overlap".equals(isOverlapping));
     }
 
     // Segment
     if ("AudioSegment".equals(localName) || "VideoSegment".equals(localName) || "AudioVisualSegment".equals(localName)) {
       String segmentId = attributes.getValue("id");
       segment = temporalDecomposition.createSegment(segmentId);
       state = ParserState.Segment;
     }
 
     // TextAnnotation
     if ("TextAnnotation".equals(localName)) {
       String language = attributes.getValue("xml:lang");
       float confidence = -1.0f;
       float relevance = -1.0f;
       try {
         confidence = floatFormat.parse(attributes.getValue("confidence")).floatValue();
       } catch (Exception e) {
         confidence = -1.0f;
       }
       try {
         relevance = floatFormat.parse(attributes.getValue("relevance")).floatValue();
       } catch (Exception e) {
         relevance = -1.0f;
       }
       textAnnotation = segment.createTextAnnotation(confidence, relevance, language);
     }
 
     // Spatiotemporal decomposition
     if ("SpatioTemporalDecomposition".equals(localName)) {
       String hasGap = attributes.getValue("gap");
       String isOverlapping = attributes.getValue("overlap");
       if (!(segment instanceof VideoSegment))
         throw new IllegalStateException("Can't have a spatio temporal decomposition outside of a video segment");
       boolean gap = "true".equalsIgnoreCase(attributes.getValue("gap"));
       boolean overlap = "true".equalsIgnoreCase(attributes.getValue("overlap"));
       spatioTemporalDecomposition = ((VideoSegment) segment).createSpatioTemporalDecomposition(gap, overlap);
       spatioTemporalDecomposition.setGap("true".equals(hasGap));
       spatioTemporalDecomposition.setOverlapping("overlap".equals(isOverlapping));
     }
 
     // Video Text
     if ("VideoText".equals(localName)) {
       String id = attributes.getValue("id");
       videoText = new VideoTextImpl(id);
       state = ParserState.VideoText;
     }
 
     // Textual
     if ("Text".equals(localName)) {
       String language = attributes.getValue("xml:lang");
       textual = new TextualImpl();
       textual.setLanguage(language);
     }
 
   }
 
   /**
    * @see org.xml.sax.helpers.DefaultHandler#endElement(java.lang.String, java.lang.String, java.lang.String)
    */
   @Override
   public void endElement(String uri, String localName, String name) throws SAXException {
     super.endElement(uri, localName, name);
 
     // Handle parser state
     if ("MultimediaContent".equals(localName))
       state = ParserState.Document;
     else if ("AudioSegment".equals(localName) || "VideoSegment".equals(localName)
             || "AudioVisualSegment".equals(localName))
       state = ParserState.MultimediaContent;
 
     // Media locator uri
     if ("MediaUri".equals(localName)) {
       MediaLocatorImpl locator = new MediaLocatorImpl();
       URI mediaUri = URI.create(getTagContent());
       locator.setMediaURI(mediaUri);
       if (ParserState.MultimediaContent.equals(state)) {
         multimediaContent.setMediaLocator(locator);
       }
     }
 
     // Media/Segment time
     if ("MediaTime".equals(localName)) {
       if (ParserState.MultimediaContent.equals(state)) {
         mediaTime = new MediaTimeImpl(mediaTimePoint, mediaDuration);
         multimediaContent.setMediaTime(mediaTime);
       } else if (ParserState.Segment.equals(state)) {
         mediaTime = new MediaTimeImpl(mediaTimePoint, mediaDuration);
         segment.setMediaTime(mediaTime);
       } else if (ParserState.VideoText.equals(state)) {
         SpatioTemporalLocator spatioTemporalLocator = new SpatioTemporalLocatorImpl(mediaTime);
         videoText.setSpatioTemporalLocator(spatioTemporalLocator);
       }
     }
 
     // Media/Segment time point
     if ("MediaTimePoint".equals(localName)) {
       mediaTimePoint = MediaTimePointImpl.parseTimePoint(getTagContent());
       if (ParserState.MultimediaContent.equals(state)) {
         contentTimePoint = mediaTimePoint;
       }
     }
 
     // Media/Segment time point
     if ("MediaRelTimePoint".equals(localName)) {
       MediaRelTimePointImpl tp = MediaRelTimePointImpl.parseTimePoint(getTagContent());
       mediaTimePoint = tp;
       if (ParserState.MultimediaContent.equals(state))
         contentTimePoint = tp;
       else if (ParserState.Segment.equals(state)) {
         tp.setReferenceTimePoint(contentTimePoint);
       }
     }
 
     // Media/Segment duration
     if ("MediaDuration".equals(localName)) {
       mediaDuration = MediaDurationImpl.parseDuration(getTagContent());
     }
 
     // Keyword
     if ("Keyword".equals(localName)) {
       KeywordAnnotation keyword = new KeywordAnnotationImpl(tagContent.toString());
       textAnnotation.addKeywordAnnotation(keyword);
     }
 
     // Free text
     if ("FreeTextAnnotation".equals(localName)) {
       FreeTextAnnotation freeText = new FreeTextAnnotationImpl(tagContent.toString());
       textAnnotation.addFreeTextAnnotation(freeText);
     }
 
     // Video Text
     if ("VideoText".equals(localName)) {
       spatioTemporalDecomposition.addVideoText(videoText);
     }
 
     // SpatioTemporalLocator
     if ("SpatioTemporalLocator".equals(localName)) {
       videoText.setSpatioTemporalLocator(new SpatioTemporalLocatorImpl(mediaTime));
     }
 
     // Videotext text
     if ("Text".equals(localName)) {
       textual.setText(tagContent.toString());
       videoText.setText(textual);
     }
 
     // Videotext bouding box
     if ("Box".equals(localName)) {
       String[] coords = tagContent.toString().trim().split(" ");
       if (coords.length != 4)
         throw new IllegalStateException("Box coordinates '" + tagContent + "' is malformatted");
       int[] coordsL = new int[4];
       for (int i = 0; i < 4; i++)
         try {
           coordsL[i] = (int) floatFormat.parse(coords[i]).floatValue();
         } catch (ParseException e) {
           throw new SAXException(e);
         }
       videoText.setBoundary(new Rectangle(coordsL[0], coordsL[1], (coordsL[2] - coordsL[0]), coordsL[3] - coordsL[1]));
     }
 
   }
 
   /**
    * @see org.xml.sax.helpers.DefaultHandler#characters(char[], int, int)
    */
   @Override
   public void characters(char[] ch, int start, int length) throws SAXException {
     super.characters(ch, start, length);
     tagContent.append(ch, start, length);
   }
 
   /**
    * Returns the element content.
    *
    * @return the element content
    */
   private String getTagContent() {
     String str = tagContent.toString().trim();
     return str;
   }
 
   /**
    * @see org.xml.sax.helpers.DefaultHandler#error(org.xml.sax.SAXParseException)
    */
   @Override
   public void error(SAXParseException e) throws SAXException {
     logger.warn("Error while parsing mpeg-7 catalog: " + e.getMessage());
     super.error(e);
   }
 
   /**
    * @see org.xml.sax.helpers.DefaultHandler#fatalError(org.xml.sax.SAXParseException)
    */
   @Override
   public void fatalError(SAXParseException e) throws SAXException {
     logger.warn("Fatal error while parsing mpeg-7 catalog: " + e.getMessage());
     super.fatalError(e);
   }
 
   /**
    * @see org.xml.sax.helpers.DefaultHandler#warning(org.xml.sax.SAXParseException)
    */
   @Override
   public void warning(SAXParseException e) throws SAXException {
     logger.warn("Warning while parsing mpeg-7 catalog: " + e.getMessage());
     super.warning(e);
   }
 
 }