/*******************************************************************************
 * Copyright (c) 2007, 2013 Wind River Systems, Inc. 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:
 *     Markus Schorn - initial API and implementation
 *******************************************************************************/
package org.eclipse.cdt.internal.core.parser.scanner;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;

import org.eclipse.cdt.core.dom.ast.IASTNodeLocation;
import org.eclipse.cdt.core.dom.ast.IASTTranslationUnit.IDependencyTree.IASTInclusionNode;

/**
 * Various location contexts which are suitable for interpreting local offsets. These offsets are
 * converted in a global sequence-number to make all AST nodes comparable with each other.
 * @since 5.0
 */
abstract class LocationCtx implements ILocationCtx {
	final LocationCtxContainer fParent;
	/**
	 * The first sequence number used by this context.
	 */
	final int fSequenceNumber;
	/**
	 * The offset of the denotation of this context in the parent's source. This is no sequence
	 * number.
	 */
	final int fOffsetInParent;
	/**
	 * The end-offset of the denotation of this context in the parent's source. This is no sequence
	 * number.
	 */
	final int fEndOffsetInParent;

	public LocationCtx(LocationCtxContainer parent, int parentOffset, int parentEndOffset, int sequenceNumber) {
		fParent= parent;
		fOffsetInParent= parentOffset;
		fEndOffsetInParent= parentEndOffset;
		fSequenceNumber= sequenceNumber;
		if (parent != null) {
			parent.addChild(this);
		}
	}

	@Override
	public String getFilePath() {
		return fParent.getFilePath();
	}

	@Override
	final public ILocationCtx getParent() {
		return fParent;
	}

	/**
	 * Returns the amount of sequence numbers occupied by this context including its children.
	 */
	public abstract int getSequenceLength();

	/**
	 * Converts an offset within this context to the sequence number. In case there are
	 * child-contexts behind the given offset, you need to set checkChildren to <code>true</code>.
	 */
	public int getSequenceNumberForOffset(int offset, boolean checkChildren) {
		return fSequenceNumber + offset;
	}

	/**
	 * When a child-context is finished it reports its total sequence length, such that offsets in
	 * this context can be converted to sequence numbers.
	 */
	public void addChildSequenceLength(int childLength) {
		assert false;
	}

	/**
	 * Returns the line number for an offset within this context. Not all contexts support line
	 * numbers, so this may return 0.
	 */
	public int getLineNumber(int offset) {
		return 0;
	}

	/**
	 * Returns the minimal context containing the specified range, assuming that it is contained in
	 * this context.
	 */
	public LocationCtx findSurroundingContext(int sequenceNumber, int length) {
		return this;
	}

	/**
	 * Returns the macro-expansion surrounding or augmenting the given range, or <code>null</code>.
	 */
	public LocationCtxMacroExpansion findEnclosingMacroExpansion(int sequenceNumber, int length) {
		return null;
	}

	public int convertToSequenceEndNumber(int sequenceNumber) {
		// if the sequence number is the beginning of this context, skip the denotation of this
		// context in the parent.
		if (sequenceNumber == fSequenceNumber)
			return sequenceNumber - fEndOffsetInParent + fOffsetInParent;
		return sequenceNumber;
	}

	/**
	 * Returns the minimal file location containing the specified sequence number range, assuming
	 * that it is contained in this context.
	 */
	public ASTFileLocation findMappedFileLocation(int sequenceNumber, int length) {
		return fParent.createMappedFileLocation(fOffsetInParent, fEndOffsetInParent - fOffsetInParent);
	}

	/**
	 * Returns the file location containing the specified offset range in this context.
	 */
	public ASTFileLocation createMappedFileLocation(int offset, int length) {
		return fParent.createMappedFileLocation(fOffsetInParent, fEndOffsetInParent - fOffsetInParent);
	}

	/**
	 * Returns the sequence of file locations spanning the given range.
	 * Assumes that the range starts within this context.
	 */
	public abstract void collectLocations(int sequenceNumber, int length,
			ArrayList<IASTNodeLocation> sofar);

	/**
	 * Support for the dependency tree, add inclusion statements found in this context.
	 */
	public void getInclusions(ArrayList<IASTInclusionNode> result) {
	}

	/**
	 * Support for the dependency tree, returns inclusion statement that created this context,
	 * or <code>null</code>.
	 */
	@Override
	public ASTInclusionStatement getInclusionStatement() {
		return null;
	}

	public Collection<LocationCtx> getChildren() {
		return Collections.emptySet();
	}

	public boolean isSourceFile() {
		if (fParent == null)
			return false;
		return fParent.isSourceFile();
	}
}