/*******************************************************************************
 * 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.tools;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.KeyEvent;
import org.eclipse.swt.graphics.Cursor;

import org.eclipse.core.runtime.Platform;

import org.eclipse.draw2d.IFigure;
import org.eclipse.draw2d.PositionConstants;
import org.eclipse.draw2d.geometry.Dimension;
import org.eclipse.draw2d.geometry.Point;
import org.eclipse.draw2d.geometry.PrecisionPoint;
import org.eclipse.draw2d.geometry.PrecisionRectangle;

import org.eclipse.gef.AutoexposeHelper;
import org.eclipse.gef.EditPart;
import org.eclipse.gef.EditPartViewer;
import org.eclipse.gef.GraphicalEditPart;
import org.eclipse.gef.LayerConstants;
import org.eclipse.gef.Request;
import org.eclipse.gef.RequestConstants;
import org.eclipse.gef.SharedCursors;
import org.eclipse.gef.SnapToHelper;
import org.eclipse.gef.commands.Command;
import org.eclipse.gef.commands.CompoundCommand;
import org.eclipse.gef.commands.UnexecutableCommand;
import org.eclipse.gef.editparts.LayerManager;
import org.eclipse.gef.handles.HandleBounds;
import org.eclipse.gef.requests.ChangeBoundsRequest;

/**
 * A DragTracker that moves {@link org.eclipse.gef.EditPart EditParts}.
 */
public class DragEditPartsTracker extends SelectEditPartTracker {

	/**
	 * Key modifier for cloning. It's ALT on Mac, and CTRL on all other
	 * platforms.
	 */
	static final int MODIFIER_CLONE;

	static {
		if (Platform.OS_MACOSX.equals(Platform.getOS()))
			MODIFIER_CLONE = SWT.ALT;
		else
			MODIFIER_CLONE = SWT.CTRL;
	}

	/**
	 * Key modifier for constrained move. It's SHIFT on all platforms.
	 */
	static final int MODIFIER_CONSTRAINED_MOVE = SWT.SHIFT;

	private static final int FLAG_SOURCE_FEEDBACK = SelectEditPartTracker.MAX_FLAG << 1;
	/** Max flag */
	protected static final int MAX_FLAG = FLAG_SOURCE_FEEDBACK;
	private List exclusionSet;
	private PrecisionPoint sourceRelativeStartPoint;
	private SnapToHelper snapToHelper;
	private PrecisionRectangle sourceRectangle, compoundSrcRect;
	private boolean cloneActive;

	/**
	 * Constructs a new DragEditPartsTracker with the given source edit part.
	 * 
	 * @param sourceEditPart
	 *            the source edit part
	 */
	public DragEditPartsTracker(EditPart sourceEditPart) {
		super(sourceEditPart);

		cloneActive = false;
		setDisabledCursor(SharedCursors.NO);
	}

	/**
	 * Returns true if the control key was the key in the key event and the tool
	 * is in an acceptable state for this event.
	 * 
	 * @param e
	 *            the key event
	 * @return true if the key was control and can be accepted.
	 */
	private boolean acceptClone(KeyEvent e) {
		int key = e.keyCode;
		if (!(isInState(STATE_DRAG_IN_PROGRESS | STATE_ACCESSIBLE_DRAG
				| STATE_ACCESSIBLE_DRAG_IN_PROGRESS)))
			return false;
		return (key == MODIFIER_CLONE);
	}

	private boolean acceptSHIFT(KeyEvent e) {
		return isInState(STATE_DRAG_IN_PROGRESS | STATE_ACCESSIBLE_DRAG
				| STATE_ACCESSIBLE_DRAG_IN_PROGRESS)
				&& e.keyCode == SWT.SHIFT;
	}

	/**
	 * Returns the cursor used under normal conditions.
	 * 
	 * @see #setDefaultCursor(Cursor)
	 * @return the default cursor
	 */
	protected Cursor getDefaultCursor() {
		if (isCloneActive())
			return SharedCursors.CURSOR_TREE_ADD;
		return super.getDefaultCursor();
	}

	/**
	 * Erases feedback and calls {@link #performDrag()}. Sets the state to
	 * terminal.
	 * 
	 * @see org.eclipse.gef.tools.AbstractTool#commitDrag()
	 */
	public void commitDrag() {
		eraseSourceFeedback();
		eraseTargetFeedback();
		performDrag();
		setState(STATE_TERMINAL);
	}

	/**
	 * Captures the bounds of the source being dragged, and the unioned bounds
	 * of all figures being dragged. These bounds are used for snapping by the
	 * snap strategies in <code>updateTargetRequest()</code>.
	 */
	private void captureSourceDimensions() {
		List editparts = getOperationSet();
		for (int i = 0; i < editparts.size(); i++) {
			GraphicalEditPart child = (GraphicalEditPart) editparts.get(i);
			IFigure figure = child.getFigure();
			PrecisionRectangle bounds = null;
			if (figure instanceof HandleBounds)
				bounds = new PrecisionRectangle(
						((HandleBounds) figure).getHandleBounds());
			else
				bounds = new PrecisionRectangle(figure.getBounds());
			figure.translateToAbsolute(bounds);

			if (compoundSrcRect == null)
				compoundSrcRect = new PrecisionRectangle(bounds);
			else
				compoundSrcRect = compoundSrcRect.union(bounds);
			if (child == getSourceEditPart())
				sourceRectangle = bounds;
		}
		if (sourceRectangle == null) {
			IFigure figure = ((GraphicalEditPart) getSourceEditPart())
					.getFigure();
			if (figure instanceof HandleBounds)
				sourceRectangle = new PrecisionRectangle(
						((HandleBounds) figure).getHandleBounds());
			else
				sourceRectangle = new PrecisionRectangle(figure.getBounds());
			figure.translateToAbsolute(sourceRectangle);
		}
	}

	/**
	 * Returns a List of top-level edit parts excluding dependants (by calling
	 * {@link ToolUtilities#getSelectionWithoutDependants(EditPartViewer)} that
	 * understand the current target request (by calling
	 * {@link ToolUtilities#filterEditPartsUnderstanding(List, Request)}.
	 * 
	 * @see org.eclipse.gef.tools.AbstractTool#createOperationSet()
	 */
	protected List createOperationSet() {
		if (getCurrentViewer() != null) {
			List list = ToolUtilities
					.getSelectionWithoutDependants(getCurrentViewer());
			ToolUtilities
					.filterEditPartsUnderstanding(list, getTargetRequest());
			return list;
		}

		return new ArrayList();
	}

	/**
	 * Creates a {@link ChangeBoundsRequest}. By default, the type is
	 * {@link RequestConstants#REQ_MOVE}. Later on when the edit parts are asked
	 * to contribute to the overall command, the request type will be either
	 * {@link RequestConstants#REQ_MOVE} or {@link RequestConstants#REQ_ORPHAN},
	 * depending on the result of {@link #isMove()}.
	 * 
	 * @see org.eclipse.gef.tools.TargetingTool#createTargetRequest()
	 */
	protected Request createTargetRequest() {
		if (isCloneActive())
			return new ChangeBoundsRequest(REQ_CLONE);
		else
			return new ChangeBoundsRequest(REQ_MOVE);
	}

	/**
	 * Erases source feedback and sets the autoexpose helper to
	 * <code>null</code>.
	 * 
	 * @see org.eclipse.gef.Tool#deactivate()
	 */
	public void deactivate() {
		eraseSourceFeedback();
		super.deactivate();
		exclusionSet = null;
		sourceRelativeStartPoint = null;
		sourceRectangle = null;
		compoundSrcRect = null;
		snapToHelper = null;
	}

	/**
	 * Asks the edit parts in the {@link AbstractTool#getOperationSet()
	 * operation set} to erase their source feedback.
	 */
	protected void eraseSourceFeedback() {
		if (!getFlag(FLAG_SOURCE_FEEDBACK))
			return;
		setFlag(FLAG_SOURCE_FEEDBACK, false);
		List editParts = getOperationSet();
		for (int i = 0; i < editParts.size(); i++) {
			EditPart editPart = (EditPart) editParts.get(i);
			editPart.eraseSourceFeedback(getTargetRequest());
		}
	}

	/**
	 * Asks each edit part in the {@link AbstractTool#getOperationSet()
	 * operation set} to contribute to a {@link CompoundCommand} after first
	 * setting the request type to either {@link RequestConstants#REQ_MOVE} or
	 * {@link RequestConstants#REQ_ORPHAN}, depending on the result of
	 * {@link #isMove()}.
	 * 
	 * @see org.eclipse.gef.tools.AbstractTool#getCommand()
	 */
	protected Command getCommand() {
		CompoundCommand command = new CompoundCommand();
		command.setDebugLabel("Drag Object Tracker");//$NON-NLS-1$

		Iterator iter = getOperationSet().iterator();

		Request request = getTargetRequest();

		if (isCloneActive())
			request.setType(REQ_CLONE);
		else if (isMove())
			request.setType(REQ_MOVE);
		else
			request.setType(REQ_ORPHAN);

		if (!isCloneActive()) {
			while (iter.hasNext()) {
				EditPart editPart = (EditPart) iter.next();
				command.add(editPart.getCommand(request));
			}
		}

		if (!isMove() || isCloneActive()) {
			if (!isCloneActive())
				request.setType(REQ_ADD);

			if (getTargetEditPart() == null)
				command.add(UnexecutableCommand.INSTANCE);
			else
				command.add(getTargetEditPart().getCommand(getTargetRequest()));
		}

		return command.unwrap();
	}

	/**
	 * @see org.eclipse.gef.tools.AbstractTool#getCommandName()
	 */
	protected String getCommandName() {
		if (isCloneActive())
			return REQ_CLONE;
		else if (isMove())
			return REQ_MOVE;
		else
			return REQ_ADD;
	}

	/**
	 * @see org.eclipse.gef.tools.AbstractTool#getDebugName()
	 */
	protected String getDebugName() {
		return "DragEditPartsTracker:" + getCommandName();//$NON-NLS-1$
	}

	/**
	 * Returns a list of all the edit parts in the
	 * {@link AbstractTool#getOperationSet() operation set}, plus the
	 * {@link org.eclipse.draw2d.ConnectionLayer}.
	 * 
	 * @see org.eclipse.gef.tools.TargetingTool#getExclusionSet()
	 */
	protected Collection getExclusionSet() {
		if (exclusionSet == null) {
			List set = getOperationSet();
			exclusionSet = new ArrayList(set.size() + 1);
			for (int i = 0; i < set.size(); i++) {
				GraphicalEditPart editpart = (GraphicalEditPart) set.get(i);
				exclusionSet.add(editpart.getFigure());
			}
			LayerManager layerManager = (LayerManager) getCurrentViewer()
					.getEditPartRegistry().get(LayerManager.ID);
			if (layerManager != null) {
				exclusionSet.add(layerManager
						.getLayer(LayerConstants.CONNECTION_LAYER));
			}
		}
		return exclusionSet;
	}

	/**
	 * @see org.eclipse.gef.tools.TargetingTool#handleAutoexpose()
	 */
	protected void handleAutoexpose() {
		updateTargetRequest();
		updateTargetUnderMouse();
		showTargetFeedback();
		showSourceFeedback();
		setCurrentCommand(getCommand());
	}

	/**
	 * Erases feedback and calls {@link #performDrag()}.
	 * 
	 * @see org.eclipse.gef.tools.AbstractTool#handleButtonUp(int)
	 */
	protected boolean handleButtonUp(int button) {
		if (stateTransition(STATE_DRAG_IN_PROGRESS, STATE_TERMINAL)) {
			eraseSourceFeedback();
			eraseTargetFeedback();
			performDrag();
			return true;
		}
		return super.handleButtonUp(button);
	}

	/**
	 * Updates the target request and mouse target, asks to show feedback, and
	 * sets the current command.
	 * 
	 * @see org.eclipse.gef.tools.AbstractTool#handleDragInProgress()
	 */
	protected boolean handleDragInProgress() {
		if (isInDragInProgress()) {
			updateTargetRequest();
			if (updateTargetUnderMouse())
				updateTargetRequest();
			showTargetFeedback();
			showSourceFeedback();
			setCurrentCommand(getCommand());
		}
		return true;
	}

	/**
	 * Calls {@link TargetingTool#updateAutoexposeHelper()} if a drag is in
	 * progress.
	 * 
	 * @see org.eclipse.gef.tools.TargetingTool#handleHover()
	 */
	protected boolean handleHover() {
		if (isInDragInProgress())
			updateAutoexposeHelper();
		return true;
	}

	/**
	 * Erases source feedback.
	 * 
	 * @see org.eclipse.gef.tools.TargetingTool#handleInvalidInput()
	 */
	protected boolean handleInvalidInput() {
		super.handleInvalidInput();
		eraseSourceFeedback();
		return true;
	}

	/**
	 * Processes arrow keys used to move edit parts.
	 * 
	 * @see org.eclipse.gef.tools.AbstractTool#handleKeyDown(org.eclipse.swt.events.KeyEvent)
	 */
	protected boolean handleKeyDown(KeyEvent e) {
		setAutoexposeHelper(null);
		if (acceptArrowKey(e)) {
			accStepIncrement();
			if (stateTransition(STATE_INITIAL,
					STATE_ACCESSIBLE_DRAG_IN_PROGRESS))
				setStartLocation(getLocation());
			switch (e.keyCode) {
			case SWT.ARROW_DOWN:
				placeMouseInViewer(getLocation().getTranslated(0, accGetStep()));
				break;
			case SWT.ARROW_UP:
				placeMouseInViewer(getLocation()
						.getTranslated(0, -accGetStep()));
				break;
			case SWT.ARROW_RIGHT:
				int stepping = accGetStep();
				if (isCurrentViewerMirrored())
					stepping = -stepping;
				placeMouseInViewer(getLocation().getTranslated(stepping, 0));
				break;
			case SWT.ARROW_LEFT:
				int step = -accGetStep();
				if (isCurrentViewerMirrored())
					step = -step;
				placeMouseInViewer(getLocation().getTranslated(step, 0));
				break;
			}
			return true;
		} else if (acceptClone(e)) {
			setCloneActive(true);
			handleDragInProgress();
			return true;
		} else if (acceptSHIFT(e)) {
			handleDragInProgress();
			return true;
		}

		return false;
	}

	/**
	 * Interprets and processes clone deactivation, constrained move
	 * deactivation, and accessibility navigation reset.
	 * 
	 * @see org.eclipse.gef.tools.AbstractTool#handleKeyUp(org.eclipse.swt.events.KeyEvent)
	 */
	protected boolean handleKeyUp(KeyEvent e) {
		if (acceptArrowKey(e)) {
			accStepReset();
			return true;
		} else if (acceptClone(e)) {
			setCloneActive(false);
			handleDragInProgress();
			return true;
		} else if (acceptSHIFT(e)) {
			handleDragInProgress();
			return true;
		}
		return false;
	}

	/**
	 * Returns true if the current drag is a clone operation.
	 * 
	 * @return true if cloning is enabled and is currently active.
	 */
	protected boolean isCloneActive() {
		return cloneActive;
	}

	/**
	 * Returns <code>true</code> if the source edit part is being moved within
	 * its parent. If the source edit part is being moved to another parent,
	 * this returns <code>false</code>.
	 * 
	 * @return <code>true</code> if the source edit part is not being reparented
	 */
	protected boolean isMove() {
		EditPart part = getSourceEditPart();
		while (part != getTargetEditPart() && part != null) {
			if (part.getParent() == getTargetEditPart()
					&& part.getSelected() != EditPart.SELECTED_NONE)
				return true;
			part = part.getParent();
		}
		return false;
	}

	/**
	 * Calls {@link AbstractTool#executeCurrentCommand()}.
	 */
	protected void performDrag() {
		executeCurrentCommand();
	}

	/**
	 * If auto scroll (also called auto expose) is being performed, the start
	 * location moves during the scroll. This method updates that location.
	 */
	protected void repairStartLocation() {
		if (sourceRelativeStartPoint == null)
			return;
		IFigure figure = ((GraphicalEditPart) getSourceEditPart()).getFigure();
		PrecisionPoint newStart = (PrecisionPoint) sourceRelativeStartPoint
				.getCopy();
		figure.translateToAbsolute(newStart);
		Point delta = new Point(newStart.x - getStartLocation().x, newStart.y
				- getStartLocation().y);
		setStartLocation(newStart);
		// sourceRectangle and compoundSrcRect need to be updated as well when
		// auto-scrolling
		if (sourceRectangle != null)
			sourceRectangle.translate(delta);
		if (compoundSrcRect != null)
			compoundSrcRect.translate(delta);
	}

	/**
	 * @see org.eclipse.gef.tools.TargetingTool#setAutoexposeHelper(org.eclipse.gef.AutoexposeHelper)
	 */
	protected void setAutoexposeHelper(AutoexposeHelper helper) {
		super.setAutoexposeHelper(helper);
		if (helper != null && sourceRelativeStartPoint == null
				&& isInDragInProgress()) {
			IFigure figure = ((GraphicalEditPart) getSourceEditPart())
					.getFigure();
			sourceRelativeStartPoint = new PrecisionPoint(getStartLocation());
			figure.translateToRelative(sourceRelativeStartPoint);
		}
	}

	/**
	 * Enables cloning if the value is true.
	 * 
	 * @param cloneActive
	 *            <code>true</code> if cloning should be active
	 */
	protected void setCloneActive(boolean cloneActive) {
		if (this.cloneActive == cloneActive)
			return;
		eraseSourceFeedback();
		eraseTargetFeedback();
		this.cloneActive = cloneActive;
	}

	/**
	 * Extended to update the current snap-to strategy.
	 * 
	 * @see org.eclipse.gef.tools.TargetingTool#setTargetEditPart(org.eclipse.gef.EditPart)
	 */
	protected void setTargetEditPart(EditPart editpart) {
		if (getTargetEditPart() == editpart)
			return;
		super.setTargetEditPart(editpart);
		snapToHelper = null;
		if (getTargetEditPart() != null && getOperationSet().size() > 0)
			snapToHelper = (SnapToHelper) getTargetEditPart().getAdapter(
					SnapToHelper.class);
	}

	/**
	 * Asks the edit parts in the {@link AbstractTool#getOperationSet()
	 * operation set} to show source feedback.
	 */
	protected void showSourceFeedback() {
		List editParts = getOperationSet();
		for (int i = 0; i < editParts.size(); i++) {
			EditPart editPart = (EditPart) editParts.get(i);
			editPart.showSourceFeedback(getTargetRequest());
		}
		setFlag(FLAG_SOURCE_FEEDBACK, true);
	}

	/**
	 * Extended to activate cloning and to update the captured source dimensions
	 * when applicable.
	 * 
	 * @see org.eclipse.gef.tools.AbstractTool#setState(int)
	 */
	protected void setState(int state) {
		boolean check = isInState(STATE_INITIAL);
		super.setState(state);

		if (isInState(STATE_ACCESSIBLE_DRAG | STATE_DRAG_IN_PROGRESS
				| STATE_ACCESSIBLE_DRAG_IN_PROGRESS)) {
			if (getCurrentInput().isModKeyDown(MODIFIER_CLONE)) {
				setCloneActive(true);
				handleDragInProgress();
			}
		}

		if (check
				&& isInState(STATE_DRAG | STATE_ACCESSIBLE_DRAG
						| STATE_ACCESSIBLE_DRAG_IN_PROGRESS))
			captureSourceDimensions();
	}

	/**
	 * Calls {@link #repairStartLocation()} in case auto scroll is being
	 * performed. Updates the request with the current
	 * {@link AbstractTool#getOperationSet() operation set}, move delta,
	 * location and type.
	 * 
	 * @see org.eclipse.gef.tools.TargetingTool#updateTargetRequest()
	 */
	protected void updateTargetRequest() {
		repairStartLocation();
		ChangeBoundsRequest request = (ChangeBoundsRequest) getTargetRequest();
		request.setEditParts(getOperationSet());
		Dimension delta = getDragMoveDelta();

		request.setConstrainedMove(getCurrentInput().isModKeyDown(
				MODIFIER_CONSTRAINED_MOVE));
		request.setSnapToEnabled(!getCurrentInput().isModKeyDown(
				MODIFIER_NO_SNAPPING));

		// constrains the move to dx=0, dy=0, or dx=dy if shift is depressed
		if (request.isConstrainedMove()) {
			float ratio = 0;

			if (delta.width != 0)
				ratio = (float) delta.height / (float) delta.width;

			ratio = Math.abs(ratio);
			if (ratio > 0.5 && ratio < 1.5) {
				if (Math.abs(delta.height) > Math.abs(delta.width)) {
					if (delta.height > 0)
						delta.height = Math.abs(delta.width);
					else
						delta.height = -Math.abs(delta.width);
				} else {
					if (delta.width > 0)
						delta.width = Math.abs(delta.height);
					else
						delta.width = -Math.abs(delta.height);
				}
			} else {
				if (Math.abs(delta.width) > Math.abs(delta.height))
					delta.height = 0;
				else
					delta.width = 0;
			}
		}

		Point moveDelta = new Point(delta.width, delta.height);
		request.getExtendedData().clear();
		request.setMoveDelta(moveDelta);
		snapPoint(request);

		request.setLocation(getLocation());
		request.setType(getCommandName());
	}

	/**
	 * This method can be overridden by clients to customize the snapping
	 * behavior.
	 * 
	 * @param request
	 *            the <code>ChangeBoundsRequest</code> from which the move delta
	 *            can be extracted and updated
	 * @since 3.4
	 */
	protected void snapPoint(ChangeBoundsRequest request) {
		Point moveDelta = request.getMoveDelta();
		if (snapToHelper != null && request.isSnapToEnabled()) {
			PrecisionRectangle baseRect = sourceRectangle.getPreciseCopy();
			PrecisionRectangle jointRect = compoundSrcRect.getPreciseCopy();
			baseRect.translate(moveDelta);
			jointRect.translate(moveDelta);

			PrecisionPoint preciseDelta = new PrecisionPoint(moveDelta);
			snapToHelper.snapPoint(request, PositionConstants.HORIZONTAL
					| PositionConstants.VERTICAL, new PrecisionRectangle[] {
					baseRect, jointRect }, preciseDelta);
			request.setMoveDelta(preciseDelta);
		}
	}

}