/* StringContent.java --
   Copyright (C) 2005 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath 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, or (at your option)
any later version.

GNU Classpath 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 GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so.  If you do not wish to do so, delete this
exception statement from your version. */


package javax.swing.text;

import java.io.Serializable;
import java.util.Iterator;
import java.util.Vector;

import javax.swing.undo.AbstractUndoableEdit;
import javax.swing.undo.CannotRedoException;
import javax.swing.undo.CannotUndoException;
import javax.swing.undo.UndoableEdit;

/**
 * An implementation of the <code>AbstractDocument.Content</code>
 * interface useful for small documents or debugging. The character
 * content is a simple character array. It's not really efficient.
 * 
 * <p>Do not use this class for large size.</p>
 */
public final class StringContent implements AbstractDocument.Content, Serializable
{
  private char[] content;

  private int count;

  private Vector positions = new Vector();

  private class InsertUndo extends AbstractUndoableEdit
  {
    private int start;
    
    private int length;

    private String redoContent;

    public InsertUndo(int start, int length)
    {
      super();
      this.start = start;
      this.length = length;
    }

    public void undo()
    {
      super.undo();
      try
        {
          StringContent.this.checkLocation(this.start, this.length);
          this.redoContent = new String(StringContent.this.content, this.start, this.length);
          StringContent.this.remove(this.start, this.length);
        }
      catch (BadLocationException b)
        {
          throw new CannotUndoException();
        }
    }
    
    public void redo()
    {
      super.redo();
      try
        {
          StringContent.this.insertString(this.start, this.redoContent);
        }
      catch (BadLocationException b)
        {
          throw new CannotRedoException();
        }
    }
  }

  private class RemoveUndo extends AbstractUndoableEdit
  {
    private int start;

    private String undoString;

    public RemoveUndo(int start, String str)
    {
      super();
      this.start = start;
      this.undoString = str;
    }

    public void undo()
    {
      super.undo();
      try
        {
          StringContent.this.insertString(this.start, this.undoString);
        }
      catch (BadLocationException bad)
        {
          throw new CannotUndoException();
        }
    }

    public void redo()
    {
      super.redo();
      try
        {
          int end = this.undoString.length();
          StringContent.this.remove(this.start, end);
        }
      catch (BadLocationException bad)
        {
          throw new CannotRedoException();
        }
    }
  }

  private class StickyPosition implements Position
  {
    private int offset = -1;

    public StickyPosition(int offset)
    {
      this.offset = offset;
    }

    private void setOffset(int offset)
    {
      this.offset = this.offset >= 0 ? offset : -1;
    }

    /**
     * Should be >=0.
     */
    public int getOffset()
    {
      return offset < 0 ? 0 : offset;
    }
  }

  public StringContent()
  {
    this(1);
  }

  public StringContent(int initialLength)
  {
    super();
    if (initialLength < 1)
      initialLength = 1;
    this.content = new char[initialLength];
    this.content[0] = '\n';
    this.count = 1;
  }

  protected Vector getPositionsInRange(Vector v,
                                       int offset,
                                       int length)
  {
    Vector refPos = new Vector();
    Iterator iter = this.positions.iterator();
    while(iter.hasNext())
      {
        Position p = (Position)iter.next();
        if ((offset <= p.getOffset())
            && (p.getOffset() <= (offset + length)))
          refPos.add(p);
      }
    return refPos;
  }

  public Position createPosition(int offset) throws BadLocationException
  {
    if (offset < this.count || offset > this.count)
      checkLocation(offset, 0);
    StickyPosition sp = new StickyPosition(offset);
    this.positions.add(sp);
    return sp;
  }
  
  public int length()
  {
    return this.count;
  }
  
  public UndoableEdit insertString(int where, String str)
    throws BadLocationException
  {
    checkLocation(where, 0);
    if (where == this.count)
      throw new BadLocationException("Invalid location", 1);
    if (str == null)
      throw new NullPointerException();
    char[] insert = str.toCharArray();
    char[] temp = new char[this.content.length + insert.length];
    this.count += insert.length;
    // Copy array and insert the string.
    if (where > 0)
      System.arraycopy(this.content, 0, temp, 0, where);
    System.arraycopy(insert, 0, temp, where, insert.length);
    System.arraycopy(this.content, where, temp, (where + insert.length), (temp.length - where - insert.length));
    if (this.content.length < temp.length)
      this.content = new char[temp.length];
    // Copy the result in the original char array.
    System.arraycopy(temp, 0, this.content, 0, temp.length);
    // Move all the positions.
    Vector refPos = getPositionsInRange(this.positions, where, temp.length - where);
    Iterator iter = refPos.iterator();
    while (iter.hasNext())
      {
        StickyPosition p = (StickyPosition)iter.next();
        p.setOffset(p.getOffset() + str.length());
      }
    InsertUndo iundo = new InsertUndo(where, insert.length);
    return iundo;
  }
  
  public UndoableEdit remove(int where, int nitems) throws BadLocationException
  {
    checkLocation(where, nitems);
    char[] temp = new char[(this.content.length - nitems)];
    this.count = this.count - nitems;
    RemoveUndo rundo = new RemoveUndo(where, new String(this.content, where, nitems));
    // Copy array.
    System.arraycopy(this.content, 0, temp, 0, where);
    System.arraycopy(this.content, where + nitems, temp, where, this.content.length - where - nitems);
    this.content = new char[temp.length];
    // Then copy the result in the original char array.
    System.arraycopy(temp, 0, this.content, 0, this.content.length);
    // Move all the positions.
    Vector refPos = getPositionsInRange(this.positions, where, this.content.length + nitems - where);
    Iterator iter = refPos.iterator();
    while (iter.hasNext())
      {
        StickyPosition p = (StickyPosition)iter.next();
        int result = p.getOffset() - nitems;
        p.setOffset(result);
        if (result < 0)
          this.positions.remove(p);
      }
    return rundo;
  }
  
  public String getString(int where, int len) throws BadLocationException
  {
    checkLocation(where, len);
    return new String (this.content, where, len);
  }
  
  public void getChars(int where, int len, Segment txt) throws BadLocationException
  {
    checkLocation(where, len);
    if (txt != null)
      {
        txt.array = this.content;
        txt.offset = where;
        txt.count = len;
      }
  }

  private void checkLocation(int where, int len) throws BadLocationException
  {
    if (where < 0)
      throw new BadLocationException("Invalid location", 1);
    else if (where > this.count)
      throw new BadLocationException("Invalid location", this.count);
    else if ((where + len)>this.count)
      throw new BadLocationException("Invalid range", this.count);
  }
  
}