/*******************************************************************************
 * Copyright (c) 2000, 2010 IBM Corporation and others.
 * 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:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.gef.ui.actions;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import org.eclipse.ui.IEditorPart;
import org.eclipse.ui.IWorkbenchPart;

import org.eclipse.draw2d.PositionConstants;
import org.eclipse.draw2d.geometry.PrecisionRectangle;
import org.eclipse.draw2d.geometry.Rectangle;

import org.eclipse.gef.EditPart;
import org.eclipse.gef.GraphicalEditPart;
import org.eclipse.gef.Request;
import org.eclipse.gef.RequestConstants;
import org.eclipse.gef.commands.Command;
import org.eclipse.gef.commands.CompoundCommand;
import org.eclipse.gef.internal.GEFMessages;
import org.eclipse.gef.internal.InternalImages;
import org.eclipse.gef.requests.AlignmentRequest;
import org.eclipse.gef.tools.ToolUtilities;

/**
 * An action to align the selected parts.
 * 
 * @author hudsonr
 */
public final class AlignmentAction extends SelectionAction {

	/**
	 * Indicates that the bottom edges should be aligned.
	 */
	public static final String ID_ALIGN_BOTTOM = GEFActionConstants.ALIGN_BOTTOM;

	/**
	 * Indicates that the horizontal centers should be aligned.
	 */
	public static final String ID_ALIGN_CENTER = GEFActionConstants.ALIGN_CENTER;

	/**
	 * Indicates that the left edges should be aligned.
	 */
	public static final String ID_ALIGN_LEFT = GEFActionConstants.ALIGN_LEFT;

	/**
	 * Indicates that the vertical midpoints should be aligned.
	 */
	public static final String ID_ALIGN_MIDDLE = GEFActionConstants.ALIGN_MIDDLE;

	/**
	 * Indicates that the right edges should be aligned.
	 */
	public static final String ID_ALIGN_RIGHT = GEFActionConstants.ALIGN_RIGHT;

	/**
	 * Indicates that the top edges should be aligned.
	 */
	public static final String ID_ALIGN_TOP = GEFActionConstants.ALIGN_TOP;
	private int alignment;

	private List operationSet;

	/**
	 * @deprecated use AlignmentAction(IWorkbenchPart, int align)
	 * @param editor
	 *            the editor
	 * @param align
	 *            the alignment ID
	 */
	public AlignmentAction(IEditorPart editor, int align) {
		this((IWorkbenchPart) editor, align);
	}

	/**
	 * Constructs an AlignmentAction with the given part and alignment ID. The
	 * alignment ID must by one of:
	 * <UL>
	 * <LI>GEFActionConstants.ALIGN_LEFT
	 * <LI>GEFActionConstants.ALIGN_RIGHT
	 * <LI>GEFActionConstants.ALIGN_CENTER
	 * <LI>GEFActionConstants.ALIGN_TOP
	 * <LI>GEFActionConstants.ALIGN_BOTTOM
	 * <LI>GEFActionConstants.ALIGN_MIDDLE
	 * </UL>
	 * 
	 * @param part
	 *            the workbench part used to obtain context
	 * @param align
	 *            the aligment ID.
	 */
	public AlignmentAction(IWorkbenchPart part, int align) {
		super(part);
		alignment = align;
		initUI();
	}

	/**
	 * Returns the alignment rectangle to which all selected parts should be
	 * aligned.
	 * 
	 * @param request
	 *            the alignment Request
	 * @return the alignment rectangle
	 */
	protected Rectangle calculateAlignmentRectangle(Request request) {
		List editparts = getOperationSet(request);
		if (editparts == null || editparts.isEmpty())
			return null;
		GraphicalEditPart part = (GraphicalEditPart) editparts.get(editparts
				.size() - 1);
		Rectangle rect = new PrecisionRectangle(part.getFigure().getBounds());
		part.getFigure().translateToAbsolute(rect);
		return rect;
	}

	/**
	 * @see org.eclipse.gef.ui.actions.WorkbenchPartAction#calculateEnabled()
	 */
	protected boolean calculateEnabled() {
		operationSet = null;
		Command cmd = createAlignmentCommand();
		if (cmd == null)
			return false;
		return cmd.canExecute();
	}

	private Command createAlignmentCommand() {
		AlignmentRequest request = new AlignmentRequest(
				RequestConstants.REQ_ALIGN);
		request.setAlignmentRectangle(calculateAlignmentRectangle(request));
		request.setAlignment(alignment);
		List editparts = getOperationSet(request);
		if (editparts.size() < 2)
			return null;

		CompoundCommand command = new CompoundCommand();
		command.setDebugLabel(getText());
		for (int i = 0; i < editparts.size(); i++) {
			EditPart editpart = (EditPart) editparts.get(i);
			command.add(editpart.getCommand(request));
		}
		return command;
	}

	/**
	 * @see org.eclipse.gef.Disposable#dispose()
	 */
	public void dispose() {
		operationSet = Collections.EMPTY_LIST;
		super.dispose();
	}

	/**
	 * Returns the list of editparts which will participate in alignment.
	 * 
	 * @param request
	 *            the alignment request
	 * @return the list of parts which will be aligned
	 */
	protected List getOperationSet(Request request) {
		if (operationSet != null)
			return operationSet;
		List editparts = new ArrayList(getSelectedObjects());
		if (editparts.isEmpty()
				|| !(editparts.get(0) instanceof GraphicalEditPart))
			return Collections.EMPTY_LIST;
		Object primary = editparts.get(editparts.size() - 1);
		editparts = ToolUtilities.getSelectionWithoutDependants(editparts);
		ToolUtilities.filterEditPartsUnderstanding(editparts, request);
		if (editparts.size() < 2 || !editparts.contains(primary))
			return Collections.EMPTY_LIST;
		EditPart parent = ((EditPart) editparts.get(0)).getParent();
		for (int i = 1; i < editparts.size(); i++) {
			EditPart part = (EditPart) editparts.get(i);
			if (part.getParent() != parent)
				return Collections.EMPTY_LIST;
		}
		return editparts;
	}

	/**
	 * Initializes the actions UI presentation.
	 */
	protected void initUI() {
		switch (alignment) {
		case PositionConstants.LEFT:
			setId(GEFActionConstants.ALIGN_LEFT);
			setText(GEFMessages.AlignLeftAction_Label);
			setToolTipText(GEFMessages.AlignLeftAction_Tooltip);
			setImageDescriptor(InternalImages.DESC_HORZ_ALIGN_LEFT);
			setDisabledImageDescriptor(InternalImages.DESC_HORZ_ALIGN_LEFT_DIS);
			break;

		case PositionConstants.RIGHT:
			setId(GEFActionConstants.ALIGN_RIGHT);
			setText(GEFMessages.AlignRightAction_Label);
			setToolTipText(GEFMessages.AlignRightAction_Tooltip);
			setImageDescriptor(InternalImages.DESC_HORZ_ALIGN_RIGHT);
			setDisabledImageDescriptor(InternalImages.DESC_HORZ_ALIGN_RIGHT_DIS);
			break;

		case PositionConstants.TOP:
			setId(GEFActionConstants.ALIGN_TOP);
			setText(GEFMessages.AlignTopAction_Label);
			setToolTipText(GEFMessages.AlignTopAction_Tooltip);
			setImageDescriptor(InternalImages.DESC_VERT_ALIGN_TOP);
			setDisabledImageDescriptor(InternalImages.DESC_VERT_ALIGN_TOP_DIS);
			break;

		case PositionConstants.BOTTOM:
			setId(GEFActionConstants.ALIGN_BOTTOM);
			setText(GEFMessages.AlignBottomAction_Label);
			setToolTipText(GEFMessages.AlignBottomAction_Tooltip);
			setImageDescriptor(InternalImages.DESC_VERT_ALIGN_BOTTOM);
			setDisabledImageDescriptor(InternalImages.DESC_VERT_ALIGN_BOTTOM_DIS);
			break;

		case PositionConstants.CENTER:
			setId(GEFActionConstants.ALIGN_CENTER);
			setText(GEFMessages.AlignCenterAction_Label);
			setToolTipText(GEFMessages.AlignCenterAction_Tooltip);
			setImageDescriptor(InternalImages.DESC_HORZ_ALIGN_CENTER);
			setDisabledImageDescriptor(InternalImages.DESC_HORZ_ALIGN_CENTER_DIS);
			break;

		case PositionConstants.MIDDLE:
			setId(GEFActionConstants.ALIGN_MIDDLE);
			setText(GEFMessages.AlignMiddleAction_Label);
			setToolTipText(GEFMessages.AlignMiddleAction_Tooltip);
			setImageDescriptor(InternalImages.DESC_VERT_ALIGN_MIDDLE);
			setDisabledImageDescriptor(InternalImages.DESC_VERT_ALIGN_MIDDLE_DIS);
			break;
		}
	}

	/**
	 * @see org.eclipse.jface.action.IAction#run()
	 */
	public void run() {
		operationSet = null;
		execute(createAlignmentCommand());
	}

}