/*
 * @(#)PlainDocument.java	1.34 00/02/02
 *
 * Copyright 1997-2000 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 */
package javax.swing.text;

import java.util.Vector;
import javax.swing.event.*;

/**
 * A plain document that maintains no character attributes.  The 
 * default element structure for this document is a map of the lines in
 * the text.  The Element returned by getDefaultRootElement is
 * a map of the lines, and each child element represents a line.
 * This model does not maintain any character level attributes,
 * but each line can be tagged with an arbitrary set of attributes.
 * Line to offset, and offset to line translations can be quickly
 * performed using the default root element.  The structure information
 * of the DocumentEvent's fired by edits will indicate the line
 * structure changes.
 * <p>
 * The default content storage management is performed by a
 * gapped buffer implementation (GapContent).  It supports 
 * editing reasonably large documents with good efficiency when
 * the edits are contiguous or clustered, as is typical.
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with
 * future Swing releases.  The current serialization support is appropriate
 * for short term storage or RMI between applications running the same
 * version of Swing.  A future release of Swing will provide support for
 * long term persistence.
 *
 * @author  Timothy Prinzing
 * @version 1.34 02/02/00
 * @see     Document
 * @see     AbstractDocument
 */
public class PlainDocument extends AbstractDocument {

    /**
     * Name of the attribute that specifies the tab
     * size for tabs contained in the content.  The
     * type for the value is Integer.
     */
    public static final String tabSizeAttribute = "tabSize";

    /**
     * Name of the attribute that specifies the maximum
     * length of a line, if there is a maximum length.
     * The type for the value is Integer.
     */
    public static final String lineLimitAttribute = "lineLimit";

    /**
     * Constructs a plain text document.  A default model using StringContent
     * is constructed and set.
     */
    public PlainDocument() {
	this(new GapContent());
    }

    /**
     * Constructs a plain text document.  A default root element is created,
     * and the tab size set to 8.
     *
     * @param c  the container for the content
     */
    protected PlainDocument(Content c) {
	super(c);
	putProperty(tabSizeAttribute, new Integer(8));
	defaultRoot = createDefaultRoot();
    }

    /**
     * Gets the default root element for the document model.
     *
     * @return the root
     * @see Document#getDefaultRootElement
     */
    public Element getDefaultRootElement() {
	return defaultRoot;
    }

    /**
     * Creates the root element to be used to represent the
     * default document structure.
     *
     * @return the element base
     */
    protected AbstractElement createDefaultRoot() {
	BranchElement map = (BranchElement) createBranchElement(null, null);
	Element line = createLeafElement(map, null, 0, 1);
	Element[] lines = new Element[1];
	lines[0] = line;
	map.replace(0, 0, lines);
	return map;
    }

    /**
     * Get the paragraph element containing the given position.  Since this
     * document only models lines, it returns the line instead.
     */
    public Element getParagraphElement(int pos){
        Element lineMap = getDefaultRootElement();
        return lineMap.getElement( lineMap.getElementIndex( pos ) );
    }
    
    /**
     * Updates document structure as a result of text insertion.  This
     * will happen within a write lock.  Since this document simply
     * maps out lines, we refresh the line map.
     *
     * @param chng the change event describing the dit
     * @param attr the set of attributes for the inserted text
     */
    protected void insertUpdate(DefaultDocumentEvent chng, AttributeSet attr) {
	removed.removeAllElements();
	added.removeAllElements();
	BranchElement lineMap = (BranchElement) getDefaultRootElement();
	int offset = chng.getOffset();
	int length = chng.getLength();
	if (offset > 0) {
	  offset -= 1;
	  length += 1;
	}
	int index = lineMap.getElementIndex(offset);
	Element rmCandidate = lineMap.getElement(index);
	int rmOffs0 = rmCandidate.getStartOffset();
	int rmOffs1 = rmCandidate.getEndOffset();
	int lastOffset = rmOffs0;
	try {
	    String str = getText(offset, length);
	    boolean hasBreaks = false;
	    for (int i = 0; i < length; i++) {
		char c = str.charAt(i);
		if (c == '\n') {
		    int breakOffset = offset + i + 1;
		    added.addElement(createLeafElement(lineMap, null, lastOffset, breakOffset));
		    lastOffset = breakOffset;
		    hasBreaks = true;
		}
	    }
	    if (hasBreaks) {
		int rmCount = 1;
		removed.addElement(rmCandidate);
		if ((offset + length == rmOffs1) && (lastOffset != rmOffs1) &&
		    ((index+1) < lineMap.getElementCount())) {
		    rmCount += 1;
		    Element e = lineMap.getElement(index+1);
		    removed.addElement(e);
		    rmOffs1 = e.getEndOffset();
		}
		if (lastOffset < rmOffs1) {
		    added.addElement(createLeafElement(lineMap, null, lastOffset, rmOffs1));
		}

		Element[] aelems = new Element[added.size()];
		added.copyInto(aelems);
		Element[] relems = new Element[removed.size()];
		removed.copyInto(relems);
		ElementEdit ee = new ElementEdit(lineMap, index, relems, aelems);
		chng.addEdit(ee);
		lineMap.replace(index, relems.length, aelems);
	    }
	    if (Utilities.isComposedTextAttributeDefined(attr)) {
	        insertComposedTextUpdate(chng, attr);
	    }
	} catch (BadLocationException e) {
	    throw new Error("Internal error: " + e.toString());
	}
	super.insertUpdate(chng, attr);
    }
    
    /**
     * Updates any document structure as a result of text removal.
     * This will happen within a write lock. Since the structure
     * represents a line map, this just checks to see if the 
     * removal spans lines.  If it does, the two lines outside
     * of the removal area are joined together.
     *
     * @param chng the change event describing the edit
     */
    protected void removeUpdate(DefaultDocumentEvent chng) {
	removed.removeAllElements();
	BranchElement map = (BranchElement) getDefaultRootElement();
	int offset = chng.getOffset();
	int length = chng.getLength();
	int line0 = map.getElementIndex(offset);
	int line1 = map.getElementIndex(offset + length);
	if (line0 != line1) {
	    // a line was removed
	    for (int i = line0; i <= line1; i++) {
		removed.addElement(map.getElement(i));
	    }
	    int p0 = map.getElement(line0).getStartOffset();
	    int p1 = map.getElement(line1).getEndOffset();
	    Element[] aelems = new Element[1];
	    aelems[0] = createLeafElement(map, null, p0, p1);
	    Element[] relems = new Element[removed.size()];
	    removed.copyInto(relems);
	    ElementEdit ee = new ElementEdit(map, line0, relems, aelems);
	    chng.addEdit(ee);
	    map.replace(line0, relems.length, aelems);
	} else {
	    //Check for the composed text element
	    Element line = map.getElement(line0);
	    if (!line.isLeaf()) {
	        Element leaf = line.getElement(line.getElementIndex(offset));
		if (Utilities.isComposedTextElement(leaf)) {
	            Element[] aelem = new Element[1];
	            aelem[0] = createLeafElement(map, null, 
		        line.getStartOffset(), line.getEndOffset());
	            Element[] relem = new Element[1];
	            relem[0] = line;
	            ElementEdit ee = new ElementEdit(map, line0, relem, aelem);
	            chng.addEdit(ee);
	            map.replace(line0, 1, aelem);
		}
	    }
	}
	super.removeUpdate(chng);
    }
  
    //
    // Inserts the composed text of an input method. The line element 
    // where the composed text is inserted into becomes an branch element
    // which contains leaf elements of the composed text and the text
    // backing store.
    //
    private void insertComposedTextUpdate(DefaultDocumentEvent chng, AttributeSet attr) {
	added.removeAllElements();
	BranchElement lineMap = (BranchElement) getDefaultRootElement();
	int offset = chng.getOffset();
	int length = chng.getLength();
	int index = lineMap.getElementIndex(offset);
	Element elem = lineMap.getElement(index);
	int elemStart = elem.getStartOffset();
	int elemEnd = elem.getEndOffset();
	BranchElement[] abelem = new BranchElement[1];
	abelem[0] = (BranchElement) createBranchElement(lineMap, null);
	Element[] relem = new Element[1];
	relem[0] = elem;
	if (elemStart != offset) 
	    added.addElement(createLeafElement(abelem[0], null, elemStart, offset));
	added.addElement(createLeafElement(abelem[0], attr, offset, offset+length));
	if (elemEnd != offset+length) 
	    added.addElement(createLeafElement(abelem[0], null, offset+length, elemEnd));
	Element[] alelem = new Element[added.size()];
	added.copyInto(alelem);
	ElementEdit ee = new ElementEdit(lineMap, index, relem, abelem);
	chng.addEdit(ee);

	abelem[0].replace(0, 0, alelem);
	lineMap.replace(index, 1, abelem);
    }

    private AbstractElement defaultRoot;
    private Vector added = new Vector();     // Vector<Element>
    private Vector removed = new Vector();   // Vector<Element>
}