/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.apache.chemistry.opencmis.server.impl.atompub;
  
  import org.apache.chemistry.opencmis.commons.impl.Constants;
  
  import org.apache.commons.codec.binary.Base64;
  
  import java.io.UnsupportedEncodingException;
  
  import java.math.BigInteger;
  
  import java.net.URLEncoder;
  
  import java.text.SimpleDateFormat;
  
  import java.util.GregorianCalendar;
  import java.util.Locale;
  import java.util.TimeZone;
  
  import javax.xml.stream.XMLStreamException;
  import javax.xml.stream.XMLStreamWriter;
  
  
  /**
   * Atom base class.
   */
  public abstract class AtomDocumentBase extends XMLDocumentBase
  {
      private static final String ID_PREFIX = "http://chemistry.apache.org/";
      private static final String ID_DUMMY = "http://chemistry.apache.org/no-id";
      private SimpleDateFormat dateFormater;
  
      /**
       * Formats a DateTime.
       */
      public String formatDate( long millis )
      {
          if ( dateFormater == null )
          {
              dateFormater = new SimpleDateFormat( "yyyy-MM-dd'T'HH:mm:ss'Z'", Locale.US );
              dateFormater.setTimeZone( TimeZone.getTimeZone( "UTC" ) );
          }
  
          return dateFormater.format( millis );
      }
  
      /**
       * Generates a valid Atom id.
       */
      public String generateAtomId( String input )
      {
          if ( input == null )
          {
              return ID_DUMMY;
          }
  
          try
          {
              return ID_PREFIX + ( new String( Base64.encodeBase64( input.getBytes( "UTF-8" ) ) ) );
          }
          catch ( UnsupportedEncodingException e )
          {
              return ID_DUMMY;
          }
      }
  
      /**
       * Writes a simple tag.
       */
      public void writeSimpleTag( String namespace, String name, String value )
          throws XMLStreamException
      {
          if ( value == null )
          {
              return;
          }
  
          XMLStreamWriter xsw = getWriter(  );
  
          xsw.writeStartElement( namespace, name );
          xsw.writeCharacters( value );
          xsw.writeEndElement(  );
     }
 
     /**
      * Writes a simple date tag.
      */
     public void writeSimpleDate( String namespace, String name, GregorianCalendar value )
         throws XMLStreamException
     {
         if ( value == null )
         {
             return;
         }
 
         writeSimpleTag( namespace, name, formatDate( value.getTimeInMillis(  ) ) );
     }
 
     /**
      * Writes a simple date tag.
      */
     public void writeSimpleDate( String namespace, String name, long millis )
         throws XMLStreamException
     {
         writeSimpleTag( namespace, name, formatDate( millis ) );
     }
 
     /**
      * Writes an Atom id tag.
      */
     public void writeId( String id ) throws XMLStreamException
     {
         writeSimpleTag( Constants.NAMESPACE_ATOM, "id", id );
     }
 
     /**
      * Writes an Atom title tag.
      */
     public void writeTitle( String title ) throws XMLStreamException
     {
         writeSimpleTag( Constants.NAMESPACE_ATOM, "title", title );
     }
 
     /**
      * Writes an Atom author tag.
      */
     public void writeAuthor( String author ) throws XMLStreamException
     {
         XMLStreamWriter xsw = getWriter(  );
 
         xsw.writeStartElement( Constants.NAMESPACE_ATOM, "author" );
         writeSimpleTag( Constants.NAMESPACE_ATOM, "name", author );
         xsw.writeEndElement(  );
     }
 
     /**
      * Writes an Atom updated tag.
      */
     public void writeUpdated( GregorianCalendar updated )
         throws XMLStreamException
     {
         writeSimpleDate( Constants.NAMESPACE_APP, "edited", updated );
         writeSimpleDate( Constants.NAMESPACE_ATOM, "updated", updated );
     }
 
     /**
      * Writes an Atom updated tag.
      */
     public void writeUpdated( long updated ) throws XMLStreamException
     {
         writeSimpleDate( Constants.NAMESPACE_APP, "edited", updated );
         writeSimpleDate( Constants.NAMESPACE_ATOM, "updated", updated );
     }
 
     /**
      * Writes an Atom published tag.
      */
     public void writePublished( GregorianCalendar published )
         throws XMLStreamException
     {
         writeSimpleDate( Constants.NAMESPACE_ATOM, "published", published );
     }
 
     /**
      * Writes an Atom published tag.
      */
     public void writePublished( long published ) throws XMLStreamException
     {
         writeSimpleDate( Constants.NAMESPACE_ATOM, "published", published );
     }
 
     /**
      * Writes a CMIS pathSegment tag.
      */
     public void writePathSegment( String pathSegment )
         throws XMLStreamException
     {
         writeSimpleTag( Constants.NAMESPACE_RESTATOM, "pathSegment", pathSegment );
     }
 
     /**
      * Writes a CMIS relativePathSegment tag.
      */
     public void writeRelativePathSegment( String relativePathSegment )
         throws XMLStreamException
     {
         writeSimpleTag( Constants.NAMESPACE_RESTATOM, "relativePathSegment", relativePathSegment );
     }
 
     /**
      * Writes an Atom collection.
      */
     public void writeCollection( String href, String collectionType, String text, String... accept )
         throws XMLStreamException
     {
         XMLStreamWriter xsw = getWriter(  );
 
         xsw.writeStartElement( Constants.NAMESPACE_APP, "collection" );
         xsw.writeAttribute( "href", href );
 
         if ( collectionType != null )
         {
             xsw.writeStartElement( Constants.NAMESPACE_RESTATOM, "collectionType" );
             xsw.writeCharacters( collectionType );
             xsw.writeEndElement(  );
         }
 
         xsw.writeStartElement( Constants.NAMESPACE_ATOM, "title" );
         xsw.writeAttribute( "type", "text" );
         xsw.writeCharacters( text );
         xsw.writeEndElement(  );
 
         for ( String ct : accept )
         {
             xsw.writeStartElement( Constants.NAMESPACE_APP, "accept" );
             xsw.writeCharacters( ct );
             xsw.writeEndElement(  );
         }
 
         xsw.writeEndElement(  );
     }
 
     /**
      * Writes a link.
      */
     public void writeLink( String rel, String href, String type, String id )
         throws XMLStreamException
     {
         XMLStreamWriter xsw = getWriter(  );
 
         xsw.writeStartElement( Constants.NAMESPACE_ATOM, "link" );
 
         xsw.writeAttribute( "rel", rel );
         xsw.writeAttribute( "href", href );
 
         if ( type != null )
         {
             xsw.writeAttribute( "type", type );
         }
 
         if ( id != null )
         {
             xsw.writeAttribute( Constants.NAMESPACE_RESTATOM, "id", id );
         }
 
         xsw.writeEndElement(  );
     }
 
     public void writeServiceLink( String href, String repositoryId )
         throws XMLStreamException
     {
         try
         {
             writeLink( Constants.REL_SERVICE, href + "?repositoryId=" + URLEncoder.encode( repositoryId, "UTF-8" ),
                 Constants.MEDIATYPE_SERVICE, null );
         }
         catch ( UnsupportedEncodingException e )
         {
         }
     }
 
     public void writeSelfLink( String href, String id )
         throws XMLStreamException
     {
         writeLink( Constants.REL_SELF, href, Constants.MEDIATYPE_ENTRY, id );
     }
 
     public void writeEnclosureLink( String href ) throws XMLStreamException
     {
         writeLink( Constants.REL_ENCLOSURE, href, Constants.MEDIATYPE_ENTRY, null );
     }
 
     public void writeEditLink( String href ) throws XMLStreamException
     {
         writeLink( Constants.REL_EDIT, href, Constants.MEDIATYPE_ENTRY, null );
     }
 
     public void writeAlternateLink( String href, String type, String kind, String title, BigInteger length )
         throws XMLStreamException
     {
         XMLStreamWriter xsw = getWriter(  );
 
         xsw.writeStartElement( Constants.NAMESPACE_ATOM, "link" );
 
         xsw.writeAttribute( "rel", Constants.REL_ALTERNATE );
         xsw.writeAttribute( "href", href );
 
         if ( type != null )
         {
             xsw.writeAttribute( "type", type );
         }
 
         if ( kind != null )
         {
             xsw.writeAttribute( Constants.NAMESPACE_RESTATOM, "renditionKind", kind );
         }
 
         if ( title != null )
         {
             xsw.writeAttribute( "title", title );
         }
 
         if ( length != null )
         {
             xsw.writeAttribute( "length", length.toString(  ) );
         }
 
         xsw.writeEndElement(  );
     }
 
     public void writeWorkingCopyLink( String href ) throws XMLStreamException
     {
         writeLink( Constants.REL_WORKINGCOPY, href, Constants.MEDIATYPE_ENTRY, null );
     }
 
     public void writeUpLink( String href, String type )
         throws XMLStreamException
     {
         writeLink( Constants.REL_UP, href, type, null );
     }
 
     public void writeDownLink( String href, String type )
         throws XMLStreamException
     {
         writeLink( Constants.REL_DOWN, href, type, null );
     }
 
     public void writeVersionHistoryLink( String href )
         throws XMLStreamException
     {
         writeLink( Constants.REL_VERSIONHISTORY, href, Constants.MEDIATYPE_FEED, null );
     }
 
     public void writeCurrentVerionsLink( String href )
         throws XMLStreamException
     {
         writeLink( Constants.REL_CURRENTVERSION, href, Constants.MEDIATYPE_ENTRY, null );
     }
 
     public void writeEditMediaLink( String href, String type )
         throws XMLStreamException
     {
         writeLink( Constants.REL_EDITMEDIA, href, type, null );
     }
 
     public void writeDescribedByLink( String href ) throws XMLStreamException
     {
         writeLink( Constants.REL_DESCRIBEDBY, href, Constants.MEDIATYPE_ENTRY, null );
     }
 
     public void writeAllowableActionsLink( String href )
         throws XMLStreamException
     {
         writeLink( Constants.REL_ALLOWABLEACTIONS, href, Constants.MEDIATYPE_ALLOWABLEACTION, null );
     }
 
     public void writeAclLink( String href ) throws XMLStreamException
     {
         writeLink( Constants.REL_ACL, href, Constants.MEDIATYPE_ACL, null );
     }
 
     public void writePoliciesLink( String href ) throws XMLStreamException
     {
         writeLink( Constants.REL_POLICIES, href, Constants.MEDIATYPE_FEED, null );
     }
 
     public void writeRelationshipsLink( String href ) throws XMLStreamException
     {
         writeLink( Constants.REL_RELATIONSHIPS, href, Constants.MEDIATYPE_FEED, null );
     }
 
     public void writeRelationshipSourceLink( String href )
         throws XMLStreamException
     {
         writeLink( Constants.REL_SOURCE, href, Constants.MEDIATYPE_ENTRY, null );
     }
 
     public void writeRelationshipTargetLink( String href )
         throws XMLStreamException
     {
         writeLink( Constants.REL_TARGET, href, Constants.MEDIATYPE_ENTRY, null );
     }
 
     public void writeFolderTreeLink( String href ) throws XMLStreamException
     {
         writeLink( Constants.REL_FOLDERTREE, href, Constants.MEDIATYPE_DESCENDANTS, null );
     }
 
     public void writeTypeUpLink( String href, String type )
         throws XMLStreamException
     {
         writeLink( Constants.REL_UP, href, type, null );
     }
 
     public void writeTypeDownLink( String href, String type )
         throws XMLStreamException
     {
         writeLink( Constants.REL_DOWN, href, type, null );
     }
 
     public void writeViaLink( String href ) throws XMLStreamException
     {
         writeLink( Constants.REL_VIA, href, Constants.MEDIATYPE_ENTRY, null );
     }
 
     public void writeFirstLink( String href ) throws XMLStreamException
     {
         writeLink( Constants.REL_FIRST, href, Constants.MEDIATYPE_FEED, null );
     }
 
     public void writeLastLink( String href ) throws XMLStreamException
     {
         writeLink( Constants.REL_LAST, href, Constants.MEDIATYPE_FEED, null );
     }
 
     public void writePreviousLink( String href ) throws XMLStreamException
     {
         writeLink( Constants.REL_PREV, href, Constants.MEDIATYPE_FEED, null );
     }
 
     public void writeNextLink( String href ) throws XMLStreamException
     {
         writeLink( Constants.REL_NEXT, href, Constants.MEDIATYPE_FEED, null );
     }
 }