//
// $Id$
// From Sijtsche de Jong (sy.de.jong@let.rug.nl)
//
// (c) COPYRIGHT 1995-2000  World Wide Web Consortium (MIT, INRIA, Keio University)
// Please first read the full copyright statement at
// http://www.w3.org/Consortium/Legal/copyright-software-19980720

package org.w3c.css.atsc;

import org.w3c.css.parser.CssStyle;
import org.w3c.css.values.CssIdent;
import org.w3c.css.values.CssValue;
import org.w3c.css.values.CssExpression;
import org.w3c.css.properties.CssProperty;
import org.w3c.css.util.Util;
import org.w3c.css.util.InvalidParamException;
import org.w3c.css.util.ApplContext;
import org.w3c.css.values.CssNumber;

/**
 *  <P>
 *  <EM>Value:</EM> &lt;integer&gt; || &lt;identifier&gt; ||
 *   &lt;identifier&gt;  &lt;integer&gt; <BR>
 *  <EM>Inherited:</EM>no<BR>
 *  <EM>Percentages:</EM>no<BR>
 *  <EM>Media:</EM>:visual
 *  <P>
 *  This property is used to effect explicit directional navigation control by
 *  associating specific styled elements with directional navigation events.
 */
public class ATSCNavUp extends CssProperty {

    CssValue navup;
    ApplContext ac;

    public ATSCNavUp() {
	// nothing to do
    }

    /**
     * Create a new ATSCNavUp
     * @param expression The expression for this property     
     * @exception InvalidParamException Values are incorrect
     */
    public ATSCNavUp (ApplContext ac, CssExpression expression) 
	throws InvalidParamException {
	
	this.ac = ac;
	setByUser(); // tell this property is set by the user
	CssValue val = expression.getValue();
	if (expression.getCount() == 1) {
	    if (val instanceof CssNumber) {
		if (((CssNumber)val).getValue() > 0 && 
		    ((CssNumber)val).getValue() < 32767 && 
		    ((CssNumber)val).isInteger()) {
		    navup = val;
		    expression.next();
		}
	    } 
	    else if (val instanceof CssIdent) {
		navup = val;
		expression.next();
	    } else {
		throw new InvalidParamException("value", val.toString(), 
						getPropertyName(), ac);
	    }
	} else if (expression.getCount() == 2) {
	    if (val instanceof CssIdent) {
		navup = val;
		expression.next();
	    } else {
		throw new InvalidParamException("value", val.toString(), 
						getPropertyName(), ac);
	    }

	    val = expression.getValue();

	    if (val instanceof CssNumber) {
		if (((CssNumber)val).getValue() > 0 && 
		    ((CssNumber)val).getValue() < 32767 && 
		    ((CssNumber)val).isInteger()) {
		    navup = val;
		    expression.next();
		} else {
		    throw new InvalidParamException("value", val.toString(), 
						    getPropertyName(), ac);
		}
	    } else {
		throw new InvalidParamException("value", val.toString(), 
						getPropertyName(), ac);
	    }
	}

    }

    /**
     * Add this property to the CssStyle.
     *
     * @param style The CssStyle
     */
    public void addToStyle(ApplContext ac, CssStyle style) {
	 if (((ATSCStyle) style).navup != null)
	     style.addRedefinitionWarning(ac, this);
	 ((ATSCStyle) style).navup = this;
    }
    
    /**
     * Get this property in the style.
     *
     * @param style The style where the property is
     * @param resolve if true, resolve the style to find this property
     */  
    public CssProperty getPropertyInStyle(CssStyle style, boolean resolve) {
	if (resolve) {
	    return ((ATSCStyle) style).getNavUp();
	} else {
	    return ((ATSCStyle) style).navup;
	}
    }
    
    /**
     * Compares two properties for equality.
     *
     * @param value The other property.
     */  
    public boolean equals(CssProperty property) {
	return (property instanceof ATSCNavUp && 
                navup.equals( ((ATSCNavUp) property).navup));
    }
    
    /**
     * Returns the name of this property
     */
    public String getPropertyName() {
	return "atsc-nav-up";
    }
    
    /**
     * Returns the value of this property
     */
    public Object get() {
	return navup;
    }
    
    /**
     * Returns true if this property is "softly" inherited
     */
    public boolean isSoftlyInherited() {
	return false;
    }
    
    /**
     * Returns a string representation of the object
     */
    public String toString() {
	return navup.toString();
    }
    
    /**
     * Is the value of this property a default value
     * It is used by all macro for the function <code>print</code>
     */
    public boolean isDefault() {	
	return false;
    }
    
}
