/*
    * 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.commons.impl;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.math.BigDecimal;
  import java.math.BigInteger;
  import java.util.GregorianCalendar;
  
  import org.apache.chemistry.opencmis.commons.exceptions.CmisInvalidArgumentException;
  import org.apache.chemistry.opencmis.commons.exceptions.CmisRuntimeException;
  import org.w3c.dom.Document;
  import org.xmlpull.v1.XmlPullParser;
  import org.xmlpull.v1.XmlPullParserException;
  import org.xmlpull.v1.XmlSerializer;
  
  import android.util.Xml;
  
  public final class XMLUtils {
  
      private XMLUtils() {
      }
  
      // --------------
      // --- writer ---
      // --------------
  
      /**
       * Creates a new XML writer.
       */
      public static XmlSerializer createWriter(OutputStream out) throws IOException {
          assert out != null;
  
          XmlSerializer writer = Xml.newSerializer();
          writer.setOutput(out, IOUtils.UTF8);
          
          return writer;
      }
  
      /**
       * Starts a XML document.
       */
      public static void startXmlDocument(XmlSerializer writer) throws IOException {
          assert writer != null;
          
          writer.setPrefix(XMLConstants.PREFIX_ATOM, XMLConstants.NAMESPACE_ATOM);
          writer.setPrefix(XMLConstants.PREFIX_CMIS, XMLConstants.NAMESPACE_CMIS);
          writer.setPrefix(XMLConstants.PREFIX_RESTATOM, XMLConstants.NAMESPACE_RESTATOM);
          writer.setPrefix(XMLConstants.PREFIX_APACHE_CHEMISTY, XMLConstants.NAMESPACE_APACHE_CHEMISTRY);
  
          writer.startDocument("UTF-8", false);
      }
  
      /**
       * Ends a XML document.
       */
      public static void endXmlDocument(XmlSerializer writer) throws IOException {
          assert writer != null;
          
          // end document
          writer.endDocument();
          writer.flush();
          writer.toString();
      }
  
      /**
       * Writes a String tag.
       */
      public static void write(XmlSerializer writer, String prefix, String namespace, String tag, String value)
              throws IOException {
          assert writer != null;
  
          if (value == null) {
              return;
          }
  
          if (namespace == null) {
              writer.startTag(null, tag);
          } else {
              writer.startTag(namespace, tag);
          }
         writer.text(value);
         writer.endTag(namespace, tag);
     }
 
     /**
      * Writes an Integer tag.
      */
     public static void write(XmlSerializer writer, String prefix, String namespace, String tag, BigInteger value)
             throws IOException {
         assert writer != null;
 
         if (value == null) {
             return;
         }
 
         write(writer, prefix, namespace, tag, value.toString());
     }
 
     /**
      * Writes a Decimal tag.
      */
     public static void write(XmlSerializer writer, String prefix, String namespace, String tag, BigDecimal value)
             throws IOException {
         assert writer != null;
 
         if (value == null) {
             return;
         }
 
         write(writer, prefix, namespace, tag, value.toString());
     }
 
     /**
      * Writes a DateTime tag.
      */
     public static void write(XmlSerializer writer, String prefix, String namespace, String tag, GregorianCalendar value)
             throws IOException {
         assert writer != null;
 
         if (value == null) {
             return;
         }
 
         write(writer, prefix, namespace, tag, DateTimeHelper.formatXmlDateTime(value));
     }
 
     /**
      * Writes a Boolean tag.
      */
     public static void write(XmlSerializer writer, String prefix, String namespace, String tag, Boolean value)
             throws IOException {
         assert writer != null;
 
         if (value == null) {
             return;
         }
 
         write(writer, prefix, namespace, tag, value ? "true" : "false");
     }
 
     /**
      * Writes an Enum tag.
      */
     public static void write(XmlSerializer writer, String prefix, String namespace, String tag, Enum<?> value)
             throws IOException {
         assert writer != null;
 
         if (value == null) {
             return;
         }
 
         Object enumValue;
         try {
             enumValue = value.getClass().getMethod("value", new Class[0]).invoke(value, new Object[0]);
         } catch (Exception e) {
             throw new IllegalStateException("Cannot get enum value", e);
         }
 
         write(writer, prefix, namespace, tag, enumValue.toString());
     }
 
     // ---------------
     // ---- parser ---
     // ---------------
 
     /**
      * Creates a new XML parser with OpenCMIS default settings.
      */
     public static XmlPullParser createParser(InputStream stream) throws XmlPullParserException {
         XmlPullParser parser = Xml.newPullParser();
         parser.setInput(stream, IOUtils.UTF8);
         return parser;
     }
 
     /**
      * Moves the parser to the next element.
      */
     public static boolean next(XmlPullParser parser) {
         assert parser != null;
 
         try {
             if (hasNext(parser)) {
                 parser.next();
                 return true;
             }
             return false;
         } catch (Exception e) {
             // EOF exceptions
             return false;
         }
     }
 
     public static boolean hasNext(XmlPullParser parser) throws XmlPullParserException {
         assert parser != null;
 
         return parser.getEventType() != XmlPullParser.END_DOCUMENT;
     }
 
     /**
      * Skips a tag or subtree.
      */
     public static void skip(XmlPullParser parser) throws XmlPullParserException {
         assert parser != null;
 
         int level = 1;
         while (next(parser)) {
             int event = parser.getEventType();
             if (event == XmlPullParser.START_TAG) {
                 level++;
             } else if (event == XmlPullParser.END_TAG) {
                 level--;
                 if (level == 0) {
                     break;
                 }
             }
         }
 
         next(parser);
     }
 
     /**
      * Moves the parser to the next start element.
      * 
      * @return <code>true</code> if another start element has been found,
      *         <code>false</code> otherwise
      */
     public static boolean findNextStartElemenet(XmlPullParser parser) throws XmlPullParserException, IOException {
         assert parser != null;
 
         while (true) {
             int event = parser.getEventType();
 
             if (event == XmlPullParser.START_TAG) {
                 return true;
             }
 
             if (hasNext(parser)) {
                 parser.next();
             } else {
                 return false;
             }
         }
     }
 
     /**
      * Parses a tag that contains text.
      */
     public static String readText(XmlPullParser parser, int maxLength) throws XmlPullParserException {
         assert parser != null;
         assert maxLength >= 0;
 
         StringBuilder sb = new StringBuilder(128);
 
         next(parser);
 
         while (true) {
             int event = parser.getEventType();
             if (event == XmlPullParser.END_TAG) {
                 break;
             } else if (event == XmlPullParser.TEXT) {
                 int len = 0;
                 if (parser.getText() != null) {
                     len = parser.getText().length();
                 }
                 if (len > 0) {
                     if (sb.length() + len > maxLength) {
                         throw new CmisInvalidArgumentException("String limit exceeded!");
                     }
                     sb.append(parser.getText());
                 }
             } else if (event == XmlPullParser.START_TAG) {
                 throw new XmlPullParserException("Unexpected tag: " + parser.getName());
             }
 
             if (!next(parser)) {
                 break;
             }
         }
 
         next(parser);
 
         return sb.toString();
     }
 
     // ------------------
     // ---- DOM stuff ---
     // ------------------
     
     public static Document newDomDocument() {
         throw new CmisRuntimeException("This method should never be used on Android!");
     }
 }