/*
 *                 Sun Public License Notice
 * 
 * The contents of this file are subject to the Sun Public License
 * Version 1.0 (the "License"). You may not use this file except in
 * compliance with the License. A copy of the License is available at
 * http://www.sun.com/
 * 
 * The Original Code is NetBeans. The Initial Developer of the Original
 * Code is Sun Microsystems, Inc. Portions Copyright 1997-2003 Sun
 * Microsystems, Inc. All Rights Reserved.
 */

package org.netbeans.modules.xml.text.syntax;

import java.lang.ref.*;
import java.util.*;
import java.io.*;

import javax.swing.text.*;
import javax.swing.event.DocumentListener;
import javax.swing.event.DocumentEvent;

import org.netbeans.editor.*;
import org.netbeans.editor.ext.*;

import org.netbeans.modules.xml.text.syntax.dom.*;
import org.openide.ErrorManager;
import org.openide.util.WeakListeners;

/**
 * Creates higher level syntax elements (DOM nodes) above token chain.
 * 

 * It also defines rules for auto code completion poping up (Editor architecture issue).
 *
 * @author  Petr Nejedly - original HTML code
 * @author  Sandeep S. Randhawa - XML port
 * @author  Petr Kuzel - use before strategy, use tokens whenever possible
 * @version 0.8
 */
public class XMLSyntaxSupport extends ExtSyntaxSupport implements XMLTokenIDs {
    
    private Reference reference = new SoftReference(null);  // cached helper
    private String systemId = null;  // cached refernce to DTD
    private String publicId = null;  // cached refernce to DTD
    private volatile boolean requestedAutoCompletion = false;

    /** Holds last character user have typed. */
    private char lastInsertedChar = 'X';  // NOI18N

    private final DocumentMonitor documentMonitor;

    /** Creates new XMLSyntaxSupport */
    public XMLSyntaxSupport(BaseDocument doc) {
        super(doc);

        // listener has same lifetime as this class
        documentMonitor = new DocumentMonitor();
        DocumentListener l = WeakListeners.document(documentMonitor, doc);
        doc.addDocumentListener(l);

    }

    /**
     * Get token at given offet or previous one if at token boundary.
     * It does not lock the document.
     * @param offset valid position in document
     * @return TokenItem or null at the document beginning.
     */
    public TokenItem getPreviousToken( int offset) throws BadLocationException {
        
        if (offset == 0) return null;
        if (offset < 0) throw new BadLocationException("Offset " + offset + " cannot be less than 0.", offset);  //NOI18N
        
        // find first token item at the offset
        
        TokenItem item = null;        
        int step = 11;
        int len = getDocument().getLength();  //??? read lock
        if (offset > len) throw new BadLocationException("Offset " + offset + " cannot be higher that document length " + len + " .", offset );  //NOI18N
        int from = Math.min(len, offset);
        int to = Math.min(len, offset);                

        // go ahead to document beginning
        
        while ( item == null) {
            from = Math.max( from - step, 0);
            if ( from == 0) {
                to = Math.min(to + step, len);
            }
            item = getTokenChain( from, to);
            if ( from == 0 && to == len && item == null) {
                throw new IllegalStateException("Token at " + offset + " cannot be located!\nInspected range:[" + from + ", " + to + "].");  //NOI18N
            }
        }
        
        // if we are are at token boundary or at the fist document tokem all is OK
        // otherwise the offset actually resides in some next token
        
        while (item.getOffset() + item.getImage().length() < offset) {  // it must cross or touch it
            TokenItem next = item.getNext();
            if (next == null) {
                if (item.getOffset() + item.getImage().length() >= len) {
                    return item;  // we are at boundary at the end of document
                } else {
                    throw new IllegalStateException("Token at " + offset + " cannot be located!\nPrevious token: " + item);  //NOI18N
                }
            }
            item = next;
        }

        return item;
    }
    
    /** 
     * Returns SyntaxElement instance for block of tokens, which is either
     * surrounding given offset, or is just before the offset.
     * @param offset Offset in document where to search for SyntaxElement.
     * @return SyntaxElement Element surrounding or laying BEFORE the offset
     * or null at document begining.
     */
    public SyntaxElement getElementChain( int offset ) throws BadLocationException {

        TokenItem item = getPreviousToken( offset);
        if (item == null) return null;
    
        // locate SyntaxElement start boundary by traversing previous tokens
        // then create element starting from that boundary
        
        TokenID id = item.getTokenID();
        TokenItem first = item;
        
        // reference can be in attribute or in content
        
        if( id == CHARACTER ) {
            while( id == CHARACTER ) {                
                item = item.getPrevious();
                if (item == null) break;
                id = item.getTokenID();
                first = item;
            }
            
            // now item is either XMLSyntax.VALUE or we're in text, or at BOF
            if( id != VALUE && id != TEXT && id != CDATA_SECTION ) {

                // #34453 it may start of element tag or end of start tag (skip attributtes)
                if( id == XMLDefaultTokenContext.TAG ) {
                    if( item.getImage().startsWith( "<" ) ) {
                        return createElement( item );  // TAGO/ETAGO
                    } else {
                        do {
                            item = item.getPrevious();
                            id = item.getTokenID();
                        } while( id != XMLDefaultTokenContext.TAG );
                        return createElement( item );       // TAGC
                    }
                }

                return createElement( first );
            } // else ( for VALUE or TEXT ) fall through
        }
        
        // these are possible only in containers (tags or doctype)
        if ( id == XMLDefaultTokenContext.WS 
          || id == XMLDefaultTokenContext.ARGUMENT 
          || id == XMLDefaultTokenContext.OPERATOR
          || id == XMLDefaultTokenContext.VALUE)  // or doctype
        {
            while (true) {
                item = item.getPrevious();
                id = item.getTokenID();
                if (id == XMLDefaultTokenContext.TAG) break;
                if (id == XMLDefaultTokenContext.DECLARATION 
                    && item.getImage().trim().length() > 0) break;
                if (isInPI(id, false)) break;
            };
        }
                
        if( id == TEXT || id == CDATA_SECTION) {
            
            while( id == TEXT || id == CHARACTER || id == CDATA_SECTION) {
                first = item;
                item = item.getPrevious();                
                if (item == null)  break;                
                id = item.getTokenID();                
            }
            return createElement( first ); // from start of continuous text
        }

        //
        // it may start of element tag or end of start tag (skip attributtes)
        //
        if( id == XMLDefaultTokenContext.TAG ) {
            if( item.getImage().startsWith( "<" ) ) {
                return createElement( item );  // TAGO/ETAGO
            } else {
                do {
                    item = item.getPrevious();
                    id = item.getTokenID();
                } while( id != XMLDefaultTokenContext.TAG );
                return createElement( item );       // TAGC
            }
        }
        
        if( id == XMLDefaultTokenContext.ERROR )
            return new SyntaxElement.Error( this, item, getTokenEnd( item ) );
        
        if( id == XMLDefaultTokenContext.BLOCK_COMMENT ) {
            while( id == XMLDefaultTokenContext.BLOCK_COMMENT && !item.getImage().startsWith( "