/*******************************************************************************
 * Copyright (c) 2004 Actuate Corporation.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *  Actuate Corporation  - initial API and implementation
 *******************************************************************************/

package org.eclipse.birt.report.model.command;

import org.eclipse.birt.report.model.activity.AbstractElementCommand;
import org.eclipse.birt.report.model.api.StyleHandle;
import org.eclipse.birt.report.model.api.command.StyleException;
import org.eclipse.birt.report.model.api.metadata.PropertyValueException;
import org.eclipse.birt.report.model.api.util.StringUtil;
import org.eclipse.birt.report.model.core.DesignElement;
import org.eclipse.birt.report.model.core.Module;
import org.eclipse.birt.report.model.core.StyledElement;
import org.eclipse.birt.report.model.elements.Theme;
import org.eclipse.birt.report.model.elements.interfaces.IStyledElementModel;
import org.eclipse.birt.report.model.metadata.ElementPropertyDefn;
import org.eclipse.birt.report.model.metadata.ElementRefValue;

/**
 * Sets the style property of an element.
 * 
 */

public class StyleCommand extends AbstractElementCommand
{

	/**
	 * Constructor.
	 * 
	 * @param module
	 *            the root of <code>obj</code>
	 * @param obj
	 *            the element to modify.
	 */

	public StyleCommand( Module module, DesignElement obj )
	{
		super( module, obj );
	}

	/**
	 * Sets the style of an element.
	 * 
	 * @param name
	 *            the name of the style to set.
	 * @throws StyleException
	 *             if the element can not have style or the style is not found.
	 */

	public void setStyle( String name ) throws StyleException
	{
		name = StringUtil.trimString( name );

		// Ensure that the element can have a style.

		if ( !element.getDefn( ).hasStyle( ) )
			throw new StyleException( element, name,
					StyleException.DESIGN_EXCEPTION_FORBIDDEN );
		StyledElement obj = (StyledElement) element;

		// Ensure that the style exists.

		ElementPropertyDefn propDefn = obj
				.getPropertyDefn( IStyledElementModel.STYLE_PROP );

		if ( name == null && obj.getStyleName( ) == null )
			return;

		Object retValue = null;

		try
		{
			retValue = propDefn.validateValue( module, name );
		}
		catch ( PropertyValueException e )
		{
			assert false;
		}

		// Make the change.

		doSetStyleRefValue( (ElementRefValue) retValue );
	}

	/**
	 * Sets the style of an element given the style itself.
	 * 
	 * @param style
	 *            the style element to set.
	 * @throws StyleException
	 *             if the element can not have style or the style is not found.
	 */

	public void setStyleElement( DesignElement style ) throws StyleException
	{
		// Make the change starting with the name. This will handle the
		// case where the application is trying to set a style that is
		// not part of the design.

		String name = null;
		if ( style != null )
			name = style.getName( );
		setStyle( name );
	}

	/**
	 * Sets the extends attribute for an element given the new parent element.
	 * 
	 * @param parent
	 *            the new parent element.
	 * @throws StyleException
	 *             if the element can not be extended or the base element is not
	 *             on component slot, or the base element has no name.
	 */

	public void setStyleElement( StyleHandle parent ) throws StyleException
	{
		if ( parent == null )
		{
			setStyle( null );
			return;
		}

		setStyle( parent.getName( ) );
	}

	/**
	 * Sets the theme with the given element reference value. Call this method
	 * when the theme name or theme element has been validated. Otherwise, uses
	 * {@link #setStyle(String)} or {@link #setStyleElement(Theme)}.
	 * 
	 * @param refValue
	 *            the validated reference value
	 * @throws StyleException
	 *             if the style is not found.
	 */

	protected void setStyleRefValue( ElementRefValue refValue )
			throws StyleException
	{

		if ( refValue == null )
		{
			if ( ( element instanceof StyledElement )
					&& ( ( (StyledElement) element ).getStyleName( ) == null ) )
			{
				return;
			}
		}

		doSetStyleRefValue( refValue );
	}

	/**
	 * Does the work to set the new style with the given
	 * <code>newStyleValue</code>.
	 * 
	 * @param newStyleValue
	 *            the validated <code>ElementRefValue</code>
	 */

	private void doSetStyleRefValue( ElementRefValue newStyleValue )
			throws StyleException
	{
		if ( newStyleValue != null && !newStyleValue.isResolved( ) )
			throw new StyleException( element, newStyleValue.getName( ),
					StyleException.DESIGN_EXCEPTION_NOT_FOUND );

		if ( newStyleValue != null && newStyleValue.isResolved( )
				&& newStyleValue.getElement( ) == element.getStyle( ) )
			return;

		// Make the change.

		StyledElement obj = (StyledElement) element;

		StyleRecord record = new StyleRecord( obj, newStyleValue );
		getActivityStack( ).execute( record );

	}
}