Copyright (c) 2000, 2018 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2018 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.internal.corext.dom;

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

import org.eclipse.core.runtime.Assert;

import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.Region;

import org.eclipse.jdt.core.dom.ASTNode;
import org.eclipse.jdt.core.dom.Expression;


Maps a selection to a set of AST nodes.
/**
 * Maps a selection to a set of AST nodes.
 */
public class SelectionAnalyzer extends GenericVisitor {

	private Selection fSelection;
	private boolean fTraverseSelectedNode;
	private ASTNode fLastCoveringNode;

	// Selected nodes
	private List<ASTNode> fSelectedNodes;

	public SelectionAnalyzer(Selection selection, boolean traverseSelectedNode) {
		super(true);
		Assert.isNotNull(selection);
		fSelection= selection;
		fTraverseSelectedNode= traverseSelectedNode;
	}

	protected void setSelection(Selection selection) {
		fSelection= selection;
	}

	public boolean hasSelectedNodes() {
		return fSelectedNodes != null && !fSelectedNodes.isEmpty();
	}

	public ASTNode[] getSelectedNodes() {
		if (fSelectedNodes == null || fSelectedNodes.isEmpty())
			return new ASTNode[0];
		return fSelectedNodes.toArray(new ASTNode[fSelectedNodes.size()]);
	}

	public ASTNode getFirstSelectedNode() {
		if (fSelectedNodes == null || fSelectedNodes.isEmpty())
			return null;
		return fSelectedNodes.get(0);
	}

	public ASTNode getLastSelectedNode() {
		if (fSelectedNodes == null || fSelectedNodes.isEmpty())
			return null;
		return fSelectedNodes.get(fSelectedNodes.size() - 1);
	}

	public boolean isExpressionSelected() {
		if (!hasSelectedNodes())
			return false;
		return fSelectedNodes.get(0) instanceof Expression;
	}

	public IRegion getSelectedNodeRange() {
		if (fSelectedNodes == null || fSelectedNodes.isEmpty())
			return null;
		ASTNode firstNode= fSelectedNodes.get(0);
		ASTNode lastNode= fSelectedNodes.get(fSelectedNodes.size() - 1);
		int start= firstNode.getStartPosition();
		return new Region(start, lastNode.getStartPosition() + lastNode.getLength() - start);
	}

	public ASTNode getLastCoveringNode() {
		return fLastCoveringNode;
	}

	public Selection getSelection() {
		return fSelection;
	}

	//--- node management ---------------------------------------------------------

	@Override
	protected boolean visitNode(ASTNode node) {
		// The selection lies behind the node.
		if (fSelection.liesOutside(node)) {
			return false;
		} else if (fSelection.covers(node)) {
			if (isFirstNode()) {
				handleFirstSelectedNode(node);
			} else {
				handleNextSelectedNode(node);
			}
			return fTraverseSelectedNode;
		} else if (fSelection.coveredBy(node)) {
			fLastCoveringNode= node;
			return true;
		} else if (fSelection.endsIn(node)) {
			return handleSelectionEndsIn(node);
		}
		// There is a possibility that the user has selected trailing semicolons that don't belong
		// to the statement. So dive into it to check if sub nodes are fully covered.
		return true;
	}

	protected void reset() {
		fSelectedNodes= null;
	}

	protected void handleFirstSelectedNode(ASTNode node) {
		fSelectedNodes= new ArrayList<>(5);
		fSelectedNodes.add(node);
	}

	protected void handleNextSelectedNode(ASTNode node) {
		if (getFirstSelectedNode().getParent() == node.getParent()) {
			fSelectedNodes.add(node);
		}
	}

	protected boolean handleSelectionEndsIn(ASTNode node) {
		return false;
	}

	protected List<ASTNode> internalGetSelectedNodes() {
		return fSelectedNodes;
	}

	private boolean isFirstNode() {
		return fSelectedNodes == null;
	}
}