/*
 * SimplyHTML, a word processor based on Java, HTML and CSS
 * Copyright (C) 2002 Ulrich Hilger
 * Copyright (C) 2006 Dimitri Polivaev
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

package com.lightdev.app.shtm;

import java.awt.Color;
import java.io.File;
import java.io.IOException;
import java.io.StringWriter;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashSet;
import java.util.Set;

import javax.swing.event.DocumentEvent;
import javax.swing.event.UndoableEditEvent;
import javax.swing.text.AbstractDocument;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
import javax.swing.text.Element;
import javax.swing.text.GapContent;
import javax.swing.text.MutableAttributeSet;
import javax.swing.text.SimpleAttributeSet;
import javax.swing.text.StyleConstants;
import javax.swing.text.html.HTML;
import javax.swing.text.html.HTMLDocument;
import javax.swing.text.html.HTMLEditorKit;
import javax.swing.text.html.StyleSheet;
import javax.swing.text.html.HTML.Tag;
import javax.swing.undo.CompoundEdit;
import javax.swing.undo.UndoableEdit;


/**
 * Extends <code>HTMLDocument</code> by a custom reader which supports
 * the SPAN tag.
 *
 * @author Ulrich Hilger
 * @author Light Development
 * @author <a href="http://www.lightdev.com">http://www.lightdev.com</a>
 * @author <a href="mailto:info@lightdev.com">info@lightdev.com</a>
 * @author published under the terms and conditions of the
 *      GNU General Public License,
 *      for details see file gpl.txt in the distribution
 *      package of this software
 *
 * 
 */

public class SHTMLDocument extends HTMLDocument {

  public static final String SUFFIX = "&nbsp;";

  private static Set paragraphElements;

  private AttributeContext context;
  private CompoundEdit compoundEdit;
  private int compoundEditDepth;
  private boolean inSetParagraphAttributes = false;
  private boolean baseDirChecked = false;
  private boolean keepSpanTag = Util.preferenceIsTrue("keepSpanTag");
  
  /**
   * Constructs an SHTMLDocument.
   */
  public SHTMLDocument() {
    this(new GapContent(BUFFER_SIZE_DEFAULT), new StyleSheet());
  }

  /**
   * Constructs an SHTMLDocument with the default content
   * storage implementation and the given style/attribute
   * storage mechanism.
   *
   * @param styles  the styles
   */
  public SHTMLDocument(StyleSheet styles) {
    this(new GapContent(BUFFER_SIZE_DEFAULT), styles);
  }

  /**
   * Constructs an SHTMLDocument with the given content
   * storage implementation and the given style/attribute
   * storage mechanism.
   *
   * @param c  the container for the content
   * @param styles the styles
   */
  public SHTMLDocument(Content c, StyleSheet styles) {
    super(c, styles);
    compoundEdit = null;
  }

  /**
   * apply a set of attributes to a given document element
   *
   * @param e  the element to apply attributes to
   * @param a  the set of attributes to apply
   */
  public void addAttributes(Element e, AttributeSet a) {
    if ((e != null) && (a != null)) {
      try {
        writeLock();
        //System.out.println("SHTMLDocument addAttributes e=" + e);
        //System.out.println("SHTMLDocument addAttributes a=" + a);
        int start = e.getStartOffset();
        DefaultDocumentEvent changes = new DefaultDocumentEvent(start,
            e.getEndOffset() - start, DocumentEvent.EventType.CHANGE);
        AttributeSet sCopy = a.copyAttributes();
        MutableAttributeSet attr = (MutableAttributeSet) e.getAttributes();
        changes.addEdit(new AttributeUndoableEdit(e, sCopy, false));
        attr.addAttributes(a);
        changes.end();
        fireChangedUpdate(changes);
        fireUndoableEditUpdate(new UndoableEditEvent(this, changes));
      }
      finally {
        writeUnlock();
      }
    }
  }

  /**
   * Removes a consecutive group of child elements.
   *
   * @param element  the parent element to remove child elements from
   * @param index  the index of the first child element to remove
   * @param count  the number of child elements to remove
   */
  public void removeElements(Element element, int index, int count)
  throws BadLocationException
  {
    writeLock();
    int start = element.getElement(index).getStartOffset();
    int end = element.getElement(index + count - 1).getEndOffset();
    try {
      Element[] removed = new Element[count];
      Element[] added = new Element[0];
      for (int counter = 0; counter < count; counter++) {
        removed[counter] = element.getElement(counter + index);
      }
      DefaultDocumentEvent defaultDocumentEvent = new DefaultDocumentEvent(
          start, end - start, DocumentEvent.EventType.REMOVE);
      ((AbstractDocument.BranchElement)element).replace(index, removed.length,
          added);
      defaultDocumentEvent.addEdit(new ElementEdit(element, index, removed, added));
      UndoableEdit undoableEdit = getContent().remove(start, end - start);
      if (undoableEdit != null) {
        defaultDocumentEvent.addEdit(undoableEdit);
      }
      postRemoveUpdate(defaultDocumentEvent);
      defaultDocumentEvent.end();
      fireRemoveUpdate(defaultDocumentEvent);
      if (undoableEdit != null) {
        fireUndoableEditUpdate(new UndoableEditEvent(this, defaultDocumentEvent));
      }
    }
    finally {
      writeUnlock();
    }
  }

  /* (non-Javadoc)
   * @see javax.swing.text.html.HTMLDocument#setOuterHTML(javax.swing.text.Element, java.lang.String)
   */
  public void setOuterHTML(Element paragraphElement, String htmlText) throws BadLocationException, IOException {
    try{
      startCompoundEdit();
      if (paragraphElement.getName().equalsIgnoreCase("p-implied")) {
        //What has to be replaced is the HTML of the parent of this implied element.
        Element parentElement = paragraphElement.getParentElement();
        SHTMLWriter writer = new SHTMLWriter(this);
        int indexOfElement = parentElement.getElementIndex(paragraphElement.getStartOffset());
        writer.writeStartTag(parentElement);        
        for (int i=0;i<indexOfElement;i++)
          writer.write(parentElement.getElement(i));
        writer.write(htmlText);
        for (int i=indexOfElement+1;i<parentElement.getElementCount();i++)
          writer.write(parentElement.getElement(i));        
        writer.writeEndTag(parentElement);
        super.setOuterHTML(parentElement, writer.toString());
      }
      else
        super.setOuterHTML(paragraphElement, htmlText);
    }
    finally{
      endCompoundEdit();
    }
  }

  /* (non-Javadoc)
   * @see javax.swing.text.html.HTMLDocument#insertAfterEnd(javax.swing.text.Element, java.lang.String)
   */
  public void insertAfterEnd(Element elem, String htmlText) throws BadLocationException, IOException {
    try{
      startCompoundEdit();
      super.insertAfterEnd(elem, htmlText);
    }
    finally{
      endCompoundEdit();
    }
  }

  /* (non-Javadoc)
   * @see javax.swing.text.html.HTMLDocument#insertAfterStart(javax.swing.text.Element, java.lang.String)
   */
  public void insertAfterStart(Element elem, String htmlText) throws BadLocationException, IOException {
    try{
      startCompoundEdit();
      super.insertAfterStart(elem, htmlText);
    }
    finally{
      endCompoundEdit();
    }
  }

  /* (non-Javadoc)
   * @see javax.swing.text.html.HTMLDocument#insertBeforeEnd(javax.swing.text.Element, java.lang.String)
   */
  public void insertBeforeEnd(Element elem, String htmlText) throws BadLocationException, IOException {
    try{
      startCompoundEdit();
      super.insertBeforeEnd(elem, htmlText);
    }
    finally{
      endCompoundEdit();
    }
  }

  /* (non-Javadoc)
   * @see javax.swing.text.html.HTMLDocument#insertBeforeStart(javax.swing.text.Element, java.lang.String)
   */
  public void insertBeforeStart(Element elem, String htmlText) throws BadLocationException, IOException {
    try{
      startCompoundEdit();
      super.insertBeforeStart(elem, htmlText);
    }
    finally{
      endCompoundEdit();
    }
  }

  /** */
  public void replaceHTML(Element firstElement, int number, String htmlText) throws
  BadLocationException, IOException {
    if(number > 1){
      if (firstElement != null && firstElement.getParentElement() != null &&
          htmlText != null) {
        int start = firstElement.getStartOffset();
        Element parent = firstElement.getParentElement();
        int removeIndex = parent.getElementIndex(start);
        try{
          startCompoundEdit();
          removeElements(parent, removeIndex, number - 1);
          setOuterHTML(parent.getElement(removeIndex), htmlText);
        }
        finally{
          endCompoundEdit();
        }
      }
    }
    else if (number == 1) {
      setOuterHTML(firstElement, htmlText);
    }
  }

  public void startCompoundEdit() {
    compoundEditDepth++;
  }

  public void endCompoundEdit() {
    if(compoundEditDepth != 0){
      compoundEditDepth--;
      if(compoundEditDepth == 0 && compoundEdit != null){
        compoundEdit.end();
        super.fireUndoableEditUpdate(new UndoableEditEvent(this, compoundEdit));
        compoundEdit = null;
      }
    }
  }

  protected void fireUndoableEditUpdate(UndoableEditEvent e) {
    if(compoundEditDepth == 0){
      super.fireUndoableEditUpdate(e);
    }
    else{
      if(compoundEdit == null){
        compoundEdit = new CompoundEdit();;
      }
      compoundEdit.addEdit(e.getEdit());
    }
  }
  /* ------------------ custom document title handling start -------------------- */

  /**
   * set the title of this SHTMLDocument
   *
   * @param title  the title this document shall have
   */
  public void setDocumentTitle(String title) {
    try {
      String titleHTML = "<title></title>";
      Element defaultRoot = getDefaultRootElement();
      Element head = Util.findElementDown(HTML.Tag.HEAD.toString(), defaultRoot);
      if(head != null) {
        Element pImpl = Util.findElementDown(HTML.Tag.IMPLIED.toString(), head);
        if(pImpl != null) {
          Element tElem = Util.findElementDown(HTML.Tag.TITLE.toString(), pImpl);
          if(tElem == null) {
            insertBeforeEnd(pImpl, titleHTML);
          }
        }
      }
      else {
        Element body = Util.findElementDown(HTML.Tag.BODY.toString(), defaultRoot);
        insertBeforeStart(body, "<head>" + titleHTML + "</head>");
      }
      putProperty(Document.TitleProperty, title);
    }
    catch(Exception e) {
      Util.errMsg(null, "An exception occurred while trying to insert the title", e);
    }
  }

  /**
   * get the title of this SHTMLDocument
   *
   * @return  the title of this document or null if none was set so far
   */
  public String getDocumentTitle() {
    Object title = getProperty(Document.TitleProperty);
    if(title != null) {
      return title.toString();
    }
    else {
      return null;
    }
  }

  /* ------------------ custom document title handling end -------------------- */

  /* ------------------ custom style sheet reference handling start -------------------- */

  /**
   * insert a style sheet reference into the head of this SHTMLDocument
   */
  public void insertStyleRef() {
    try {
      String styleRef = "  <link rel=stylesheet type=\"text/css\" href=\"" +
      DocumentPane.DEFAULT_STYLE_SHEET_NAME + "\">";
      Element defaultRoot = getDefaultRootElement();
      Element head = Util.findElementDown(HTML.Tag.HEAD.toString(), defaultRoot);
      if(head != null) {
        Element pImpl = Util.findElementDown(HTML.Tag.IMPLIED.toString(), head);
        if(pImpl != null) {
          Element link = Util.findElementDown(HTML.Tag.LINK.toString(), pImpl);
          if(link != null) {
            setOuterHTML(link, styleRef);
          }
          else {
            insertBeforeEnd(pImpl, styleRef);
          }
        }
      }
      else {
        Element body = Util.findElementDown(HTML.Tag.BODY.toString(), defaultRoot);
        insertBeforeStart(body, "<head>" + styleRef + "</head>");
      }
    }
    catch(Exception e) {
      Util.errMsg(null, "An exception occurred while trying to insert the style sheet reference link", e);
    }
  }

  /**
   * check whether or not this SHTMLDocument has an explicit style sheet reference
   *
   * @return true, if a style sheet reference was found, false if not
   */
  public boolean hasStyleRef() {
    return (getStyleRef() != null);
  }

  /**
   * get the style sheet reference of the document in this
   * <code>DocumentPane</code>.
   *
   * @return the reference to this document's style sheet or
   *    null if none is found
   */
  public String getStyleRef() {
    String linkName = null;
    Element link = Util.findElementDown(HTML.Tag.LINK.toString(),
        getDefaultRootElement());
    if(link != null) {
      Object href = link.getAttributes().getAttribute(HTML.Attribute.HREF);
      if(href != null) {
        linkName = href.toString();
      }
    }
    return linkName;
  }

  /* ------------------ custom style sheet reference handling end -------------------- */

  /* -------- custom reader implementation start ------ */

  /**
   * Fetches the reader for the parser to use to load the document
   * with HTML.  This is implemented to return an instance of
   * SHTMLDocument.SHTMLReader.
   */
  public HTMLEditorKit.ParserCallback getReader(int pos) {
    Object desc = getProperty(Document.StreamDescriptionProperty);
    if (desc instanceof URL) {
      setBase((URL)desc);
    }
    SHTMLReader reader = new SHTMLReader(pos, getLength() == 0);
    return reader;
  }







  /**
   * This reader extends HTMLDocument.HTMLReader by the capability
   * to handle SPAN tags
   */
  public class SHTMLReader extends HTMLDocument.HTMLReader {

    /** action needed to handle SPAN tags */
    SHTMLCharacterAction characterAction = new SHTMLCharacterAction();

    /** the attributes found in a STYLE attribute */
    AttributeSet styleAttributes;

    /** indicates whether we're inside a SPAN tag */
    boolean inSpan = false;
    boolean emptyDocument;

    private int paragraphLevel;
    private boolean inBody;
    private boolean paragraphCreated;

    private boolean isParagraphTag;

    /**
     * Constructor
     * 
     */
    public SHTMLReader(int offset, boolean emptyDocument) {
      super(offset, 0, 0, null);
      this.emptyDocument = emptyDocument;
      inBody = false;
      paragraphLevel = 0;
      paragraphCreated = false;
    }

    /**
     * Handles the start tag received by the parser.
     *
     * If it is a SPAN tag, converts the contents of the STYLE
     * attribute to an AttributeSet, and adds it to the contents
     * of this tag.
     *
     * Otherwise lets HTMLDocument.HTMLReader do the work.
     */
    public void handleStartTag(HTML.Tag tag, MutableAttributeSet attributeSet, int pos) {
      if(tag == HTML.Tag.BODY)
        inBody = true;
      else if(inBody){
        isParagraphTag = isParagraphTag(tag);
        if(isParagraphTag){
          if(paragraphCreated && paragraphLevel == 0)
            insertParagraphEndTag(pos);		
          paragraphLevel++; }
        else if(! paragraphCreated && paragraphLevel == 0)
          insertParagraphStartTag(pos); }

      if (tag == HTML.Tag.SPAN && !keepSpanTag) 
        handleStartSpan(attributeSet);
      else {
        super.handleStartTag(tag, attributeSet, pos);
        if(tag == HTML.Tag.FONT)
          charAttr.removeAttribute(tag);	
      }
    }

    private void insertParagraphStartTag(int pos) {
      super.handleStartTag(HTML.Tag.P, new SimpleAttributeSet(), pos);
      paragraphCreated = true;
    }

    private void insertParagraphEndTag(int pos) {
      super.handleEndTag(HTML.Tag.P, pos);
      paragraphCreated = false;
    }

    private boolean isParagraphTag(Tag t) {
      if(paragraphElements == null){
        paragraphElements = new HashSet();
        Object[] elementList = new Object[] {
            HTML.Tag.BLOCKQUOTE,
            HTML.Tag.DIR,
            HTML.Tag.DIV,
            HTML.Tag.DL,
            HTML.Tag.DT,
            HTML.Tag.FRAMESET,
            HTML.Tag.H1,
            HTML.Tag.H2,
            HTML.Tag.H3,
            HTML.Tag.H4,
            HTML.Tag.H5,
            HTML.Tag.H6,
            HTML.Tag.HR,
            HTML.Tag.LI,
            HTML.Tag.MENU,
            HTML.Tag.OL,
            HTML.Tag.P,
            HTML.Tag.PRE,
            HTML.Tag.TABLE,
            HTML.Tag.TD,
            HTML.Tag.TH,
            HTML.Tag.TR,
            HTML.Tag.UL };
        for (int i=0; i<elementList.length;i++)
          paragraphElements.add(elementList[i]);
      }
      return paragraphElements.contains(t);
    }

    private void handleStartSpan(MutableAttributeSet attributeSet) {
      if(attributeSet.isDefined(HTML.Attribute.STYLE)) {
        String styleAttributeValue = (String)attributeSet.getAttribute(HTML.Attribute.STYLE);
        attributeSet.removeAttribute(HTML.Attribute.STYLE);
        styleAttributes = getStyleSheet().getDeclaration(styleAttributeValue);
        attributeSet.addAttributes(styleAttributes);
      }
      else {
        styleAttributes = null;
      }
      TagAction action = (TagAction)characterAction;

      if (action != null) {
        /** Remembers which part we're in for handleSimpleTag. */
        inSpan = true;
        action.start(HTML.Tag.SPAN, attributeSet);
      }
    }

    /**
     * SPAN tags are directed to handleSimpleTag by the parser.
     * If a SPAN tag is detected in this method, it gets redirected
     * to handleStartTag and handleEndTag respectively.
     */
    public void handleSimpleTag(HTML.Tag t, MutableAttributeSet a, int pos) {
      if(inBody && ! paragraphCreated && paragraphLevel == 0){
        insertParagraphStartTag(pos);
      }
      if(t == HTML.Tag.SPAN && !keepSpanTag) {
        if(inSpan) {
          handleEndTag(t, pos);
        }
        else {
          handleStartTag(t, a, pos);
        }
      }
      else {
        super.handleSimpleTag(t, a, pos);
      }
    }

    /**
     * Handles end tag. If a SPAN tag is directed to this method, end its action,
     * otherwise, let HTMLDocument.HTMLReader do the work
     */
    public void handleEndTag(HTML.Tag t, int pos) {
      if (t == HTML.Tag.BODY ){
        if (paragraphCreated){
          insertParagraphEndTag(pos);
        }
        inBody = false;
        if(emptyDocument) {
          super.handleStartTag(HTML.Tag.P, getEndingAttributeSet(), pos);  
          super.handleText(" ".toCharArray(), pos);
          super.handleEndTag(HTML.Tag.P, pos);  
        }
        super.handleEndTag(t, pos);
      }
      else if(t == HTML.Tag.SPAN && !keepSpanTag) {
        handleEndSpan();
      }
      else {           
        super.handleEndTag(t, pos);
      }
    }

    /* (non-Javadoc)
     * @see javax.swing.text.html.HTMLDocument.HTMLReader#handleComment(char[], int)
     */
    public void handleComment(char[] data, int pos) {
      if(emptyDocument){
        super.handleComment(data, pos);
      }
    }

    /* (non-Javadoc)
     * @see javax.swing.text.html.HTMLDocument.HTMLReader#handleText(char[], int)
     */

    private void handleEndSpan() {
      TagAction action = (TagAction) characterAction;
      if (action != null) {
        /**
         * remember which part we're in for handleSimpleTag
         */
        inSpan = false;

        action.end(HTML.Tag.SPAN);
      }
    }

    /**
     * Is used to read the style attribute from
     * a SPAN tag and to map from HTML to Java attributes.
     */
    class SHTMLCharacterAction extends HTMLDocument.HTMLReader.CharacterAction {
      public void start(HTML.Tag tag, MutableAttributeSet attr) {
        pushCharacterStyle();
        if (attr.isDefined(IMPLIED)) {
          attr.removeAttribute(IMPLIED);
        }
        charAttr.addAttribute(tag, attr.copyAttributes());
        if (styleAttributes != null) {
          charAttr.addAttributes(styleAttributes);
        }
        if(charAttr.isDefined(HTML.Tag.SPAN)) {
          charAttr.removeAttribute(HTML.Tag.SPAN);
        }
        //System.out.println("mapping attributes");
        charAttr = (MutableAttributeSet) new AttributeMapper(charAttr).
        getMappedAttributes(AttributeMapper.toJava);
      }

      public void end(HTML.Tag t) {
        popCharacterStyle();
      }
    }

  }

  /* -------- custom reader implementation end -------- */
  public Element getParagraphElement(int pos) {
    return getParagraphElement(pos, inSetParagraphAttributes);
  }

  /** Gets the current paragraph element, retracing out of p-implied if the parameter
   * noImplied is true.
   * @see javax.swing.text.DefaultStyledDocument#getParagraphElement(int)
   */
  public Element getParagraphElement(int pos, boolean noPImplied) {
    Element element = super.getParagraphElement(pos);
    if(noPImplied){
      while(element != null && element.getName().equalsIgnoreCase("p-implied")){
        element = element.getParentElement();
      }
    }
    return element;
  }

  public int getLastDocumentPosition(){
    final int length = getLength();
    final int suffixLength = 1;
    return length > suffixLength ? length - suffixLength : length;
  }
  /* (non-Javadoc)
   * @see javax.swing.text.html.HTMLDocument#setParagraphAttributes(int, int, javax.swing.text.AttributeSet, boolean)
   */
  public void setParagraphAttributes(int offset, int length, AttributeSet s, boolean replace) {
    startCompoundEdit();
    super.setParagraphAttributes(offset, length, s, replace);
    inSetParagraphAttributes  = true;
    super.setParagraphAttributes(offset, length, s, replace);
    inSetParagraphAttributes = false;
    endCompoundEdit();
  }
  public void removeParagraphAttributes(int offset, int length) {
    startCompoundEdit();
    // clear all paragraph attributes in selection
    for(int i = offset; i < offset + length; ) {
      final Element paragraphElement = super.getParagraphElement(i);
      removeParagraphAtributes(paragraphElement);
      final int endOffset = paragraphElement.getEndOffset();
      i = endOffset;
    }
    endCompoundEdit();
  }

  private void removeParagraphAtributes(final Element paragraphElement) {
    if(paragraphElement != null && paragraphElement.getName().equalsIgnoreCase("p-implied")){
      removeParagraphAtributes(paragraphElement.getParentElement());
      return;
    }
    StringWriter writer = new StringWriter();
    SHTMLWriter htmlStartWriter = new SHTMLWriter(writer, this);
    try {
      htmlStartWriter.writeStartTag(paragraphElement.getName(), null);
      htmlStartWriter.writeChildElements(paragraphElement);
      htmlStartWriter.writeEndTag(paragraphElement.getName());
      setOuterHTML(paragraphElement, writer.toString());
    } catch (IOException e) {
      e.printStackTrace();
    } catch (BadLocationException e) {
      e.printStackTrace();
    }
  }

  private SimpleAttributeSet getEndingAttributeSet() {
    final SimpleAttributeSet set = new SimpleAttributeSet();
    if(Util.preferenceIsTrue("gray_row_below_end")) {
      StyleConstants.setBackground(set, Color.GRAY);
    }
    return set;
  }

  /* (non-Javadoc)
   * @see javax.swing.text.html.HTMLDocument#getBase()
   */
  public URL getBase() {
    URL url = super.getBase();
    if(false == baseDirChecked){
      baseDirChecked = true;
      File docDir = new File (url.getFile());
      if(!docDir.exists()) {
        docDir.mkdirs();
      }
      try {
        url = docDir.toURI().toURL();
        super.setBase(url);
        return url;
      } catch (MalformedURLException e) {
      }
    }
    return url;
  }

  /* (non-Javadoc)
   * @see javax.swing.text.html.HTMLDocument#setBase(java.net.URL)
   */
  public void setBase(URL u) {
    baseDirChecked = false;
    super.setBase(u);
  }

}