/*
 * JBoss, Home of Professional Open Source.
 *
 * See the LEGAL.txt file distributed with this work for information regarding copyright ownership and licensing.
 *
 * See the AUTHORS.txt file distributed with this work for a full listing of individual contributors.
 */
package org.teiid.query.ui.sqleditor.sql;

import org.eclipse.jface.text.rules.ICharacterScanner;
import org.eclipse.jface.text.rules.IToken;
import org.eclipse.jface.text.rules.IWordDetector;
import org.eclipse.jface.text.rules.Token;
import org.eclipse.jface.text.rules.WordRule;

/**
 * @author SDelap
 * Extends Word Rule by upper case-ing the token before attempting to get it from the map
 * thus returning tokens for all cases
 *
 * @since 8.0
 */
public class CaseInsensitiveWordRule extends WordRule {
	/**
	 * Creates a rule which, with the help of an word detector, will return the token
	 * associated with the detected word. If no token has been associated, the scanner 
	 * will be rolled back and an undefined token will be returned in order to allow 
	 * any subsequent rules to analyze the characters.
	 *
	 * @param detector the word detector to be used by this rule, may not be <code>null</code>
	 *
	 * @see #addWord
	 */
    protected StringBuffer fBuffer= new StringBuffer();
    
	public CaseInsensitiveWordRule(IWordDetector detector) {
		this(detector, Token.UNDEFINED);
	}

	/**
	 * Creates a rule which, with the help of an word detector, will return the token
	 * associated with the detected word. If no token has been associated, the
	 * specified default token will be returned.
	 *
	 * @param detector the word detector to be used by this rule, may not be <code>null</code>
	 * @param defaultToken the default token to be returned on success 
	 *		if nothing else is specified, may not be <code>null</code>
	 *
	 * @see #addWord
	 */
	public CaseInsensitiveWordRule(IWordDetector detector, IToken defaultToken) {
	    super(detector, defaultToken);
	}    
    
	
	//Upper cases word before attempting to get out of the map
	@Override
    public IToken evaluate(ICharacterScanner scanner) {
		int c= scanner.read();
		if (fDetector.isWordStart((char) c)) {
			if (fColumn == UNDEFINED || (fColumn == scanner.getColumn() - 1)) {
				
				fBuffer.setLength(0);
				do {
					fBuffer.append((char) c);
					c= scanner.read();
				} while (c != ICharacterScanner.EOF && fDetector.isWordPart((char) c));
				scanner.unread();
				
				IToken token= (IToken) fWords.get(fBuffer.toString().toUpperCase());
				if (token != null)
					return token;
					
				if (fDefaultToken.isUndefined())
					unreadBuffer(scanner);
					
				return fDefaultToken;
			}
		}
		
		scanner.unread();
		return Token.UNDEFINED;
	}
	
	/*
	 * Returns the characters in the buffer to the scanner.
	 * Had to override since fBuffer is not protected
	 * @param scanner the scanner to be used
	 */
	@Override
    protected void unreadBuffer(ICharacterScanner scanner) {
		for (int i= fBuffer.length() - 1; i >= 0; i--)
			scanner.unread();
	}
	
}