/*
    * Copyright 2015 Data Archiving and Networked Services (an institute of
    * Koninklijke Nederlandse Akademie van Wetenschappen), King's College London,
    * Georg-August-Universitaet Goettingen Stiftung Oeffentlichen Rechts
    *
    * Licensed under the EUPL, Version 1.1 or – as soon they will be approved by
    * the European Commission - subsequent versions of the EUPL (the "Licence");
    * You may not use this work except in compliance with the Licence.
    * You may obtain a copy of the Licence at:
   *
   * https://joinup.ec.europa.eu/software/page/eupl
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the Licence is distributed on an "AS IS" basis,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the Licence for the specific language governing
   * permissions and limitations under the Licence.
   */
  
  package eu.ehri.project.exporters.xml;
  
  import javax.xml.namespace.NamespaceContext;
  import javax.xml.stream.XMLStreamException;
  import javax.xml.stream.XMLStreamWriter;
  import java.util.Stack;
  
  /**
   * Derived from JDK6 Sun internal implementation.
   */
  public class IndentingXMLStreamWriter implements XMLStreamWriter, AutoCloseable {
  
      private enum State {
          SEEN_NOTHING, SEEN_ELEMENT, SEEN_DATA
      }
  
      private State state = State.SEEN_NOTHING;
      private Stack<State> stateStack = new Stack<>();
  
      private final String indentStep;
      private int depth = 0;
  
      private final XMLStreamWriter writer;
  
      public IndentingXMLStreamWriter(XMLStreamWriter writer, String indentStep) {
          this.writer = writer;
          this.indentStep = indentStep;
      }
  
      public IndentingXMLStreamWriter(XMLStreamWriter writer) {
          this(writer, "  ");
      }
  
      private void onStartElement() throws XMLStreamException {
          stateStack.push(State.SEEN_ELEMENT);
          state = State.SEEN_NOTHING;
          if (depth > 0) {
              writer.writeCharacters("\n");
          }
          doIndent();
          depth++;
      }
  
      private void onEndElement() throws XMLStreamException {
          depth--;
          if (state == State.SEEN_ELEMENT) {
              writer.writeCharacters("\n");
              doIndent();
          }
          state = stateStack.pop();
      }
  
      private void onEmptyElement() throws XMLStreamException {
          state = State.SEEN_ELEMENT;
          if (depth > 0) {
              writer.writeCharacters("\n");
          }
          doIndent();
      }
  
      private void doIndent() throws XMLStreamException {
          if (depth > 0) {
              for (int i = 0; i < depth; i++)
                  writer.writeCharacters(indentStep);
          }
      }
  
      @Override
      public void writeStartDocument() throws XMLStreamException {
          writer.writeStartDocument();
          writer.writeCharacters("\n");
      }
  
      @Override
      public void writeStartDocument(String version) throws XMLStreamException {
          writer.writeStartDocument(version);
          writer.writeCharacters("\n");
      }
  
      @Override
     public void writeStartDocument(String encoding, String version) throws XMLStreamException {
         writer.writeStartDocument(encoding, version);
         writer.writeCharacters("\n");
     }
 
     @Override
     public void writeStartElement(String localName) throws XMLStreamException {
         onStartElement();
         writer.writeStartElement(localName);
     }
 
     @Override
     public void writeStartElement(String namespaceURI, String localName) throws XMLStreamException {
         onStartElement();
         writer.writeStartElement(namespaceURI, localName);
     }
 
     @Override
     public void writeStartElement(String prefix, String localName, String namespaceURI) throws XMLStreamException {
         onStartElement();
         writer.writeStartElement(prefix, localName, namespaceURI);
     }
 
     @Override
     public void writeEmptyElement(String namespaceURI, String localName) throws XMLStreamException {
         onEmptyElement();
         writer.writeEmptyElement(namespaceURI, localName);
     }
 
     @Override
     public void writeEmptyElement(String prefix, String localName, String namespaceURI) throws XMLStreamException {
         onEmptyElement();
         writer.writeEmptyElement(prefix, localName, namespaceURI);
     }
 
     @Override
     public void writeEmptyElement(String localName) throws XMLStreamException {
         onEmptyElement();
         writer.writeEmptyElement(localName);
     }
 
     @Override
     public void writeEndElement() throws XMLStreamException {
         onEndElement();
         writer.writeEndElement();
     }
 
     @Override
     public void writeEndDocument() throws XMLStreamException {
         writer.writeEndDocument();
     }
 
     @Override
     public void close() throws XMLStreamException {
         writer.close();
     }
 
     @Override
     public void flush() throws XMLStreamException {
         writer.flush();
     }
 
     @Override
     public void writeAttribute(String localName, String value) throws XMLStreamException {
         writer.writeAttribute(localName, value);
     }
 
     @Override
     public void writeAttribute(String prefix, String namespaceURI, String localName, String value) throws XMLStreamException {
         writer.writeAttribute(prefix, namespaceURI, localName, value);
     }
 
     @Override
     public void writeAttribute(String namespaceURI, String localName, String value) throws XMLStreamException {
         writer.writeAttribute(namespaceURI, localName, value);
     }
 
     @Override
     public void writeNamespace(String prefix, String namespaceURI) throws XMLStreamException {
         writer.writeNamespace(prefix, namespaceURI);
     }
 
     @Override
     public void writeDefaultNamespace(String namespaceURI) throws XMLStreamException {
         writer.writeDefaultNamespace(namespaceURI);
     }
 
     @Override
     public void writeComment(String data) throws XMLStreamException {
         writer.writeComment(data);
     }
 
     @Override
     public void writeProcessingInstruction(String target) throws XMLStreamException {
         writer.writeProcessingInstruction(target);
     }
 
     @Override
     public void writeProcessingInstruction(String target, String data) throws XMLStreamException {
         writer.writeProcessingInstruction(target, data);
     }
 
     @Override
     public void writeCharacters(String text) throws XMLStreamException {
         state = State.SEEN_DATA;
         writer.writeCharacters(text);
     }
 
     @Override
     public void writeCharacters(char[] text, int start, int len) throws XMLStreamException {
         state = State.SEEN_DATA;
         writer.writeCharacters(text, start, len);
     }
 
     @Override
     public String getPrefix(String uri) throws XMLStreamException {
         return null;
     }
 
     @Override
     public void setPrefix(String prefix, String uri) throws XMLStreamException {
 
     }
 
     @Override
     public void setDefaultNamespace(String uri) throws XMLStreamException {
 
     }
 
     @Override
     public void setNamespaceContext(NamespaceContext context) throws XMLStreamException {
 
     }
 
     @Override
     public NamespaceContext getNamespaceContext() {
         return null;
     }
 
     @Override
     public Object getProperty(String name) throws IllegalArgumentException {
         return null;
     }
 
     @Override
     public void writeCData(String data) throws XMLStreamException {
         state = State.SEEN_DATA;
         writer.writeCData(data);
     }
 
     @Override
     public void writeDTD(String dtd) throws XMLStreamException {
 
     }
 
     @Override
     public void writeEntityRef(String name) throws XMLStreamException {
 
     }
 }