/*

 * Copyright (c) 2006, 2016, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package com.sun.source.util;

import com.sun.source.doctree.DocCommentTree;

import com.sun.source.doctree.DocTree;

import java.util.Iterator;

import java.util.Objects;

/**

 * A path of tree nodes, typically used to represent the sequence of ancestor

 * nodes of a tree node up to the top level DocCommentTree node.

 *

 * @since 1.8

 */

public class DocTreePath implements Iterable<DocTree> {

    /**

     * Returns a documentation tree path for a tree node within a compilation unit,

     * or {@code null} if the node is not found.

     * @param treePath the path for the node with which the doc comment is associated

     * @param doc the doc comment associated with the node

     * @param target a node within the doc comment

     * @return a path identifying the target within the tree

     */

    public static DocTreePath getPath(TreePath treePath, DocCommentTree doc, DocTree target) {

        return getPath(new DocTreePath(treePath, doc), target);

    }

    /**

     * Returns a documentation tree path for a tree node within a subtree

     * identified by a DocTreePath object, or {@code null} if the node is not found.

     * @param path a path identifying a node within a doc comment tree

     * @param target a node to be located within the given node

     * @return a path identifying the target node

     */

    public static DocTreePath getPath(DocTreePath path, DocTree target) {

        Objects.requireNonNull(path); //null check

        Objects.requireNonNull(target); //null check

        class Result extends Error {

            static final long serialVersionUID = -5942088234594905625L;

            DocTreePath path;

            Result(DocTreePath path) {

                this.path = path;

            }

        }

        class PathFinder extends DocTreePathScanner<DocTreePath,DocTree> {

            @Override

            public DocTreePath scan(DocTree tree, DocTree target) {

                if (tree == target) {

                    throw new Result(new DocTreePath(getCurrentPath(), target));

                }

                return super.scan(tree, target);

            }

        }

        if (path.getLeaf() == target) {

            return path;

        }

        try {

            new PathFinder().scan(path, target);

        } catch (Result result) {

            return result.path;

        }

        return null;

    }

    /**

     * Creates a DocTreePath for a root node.

     *

     * @param treePath the TreePath from which the root node was created.

     * @param t the DocCommentTree to create the path for.

     */

    public DocTreePath(TreePath treePath, DocCommentTree t) {

        this.treePath = treePath;

        this.docComment = Objects.requireNonNull(t);

        this.parent = null;

        this.leaf = t;

    }

    /**

     * Creates a DocTreePath for a child node.

     * @param p the parent node

     * @param t the child node

     */

    public DocTreePath(DocTreePath p, DocTree t) {

        if (t.getKind() == DocTree.Kind.DOC_COMMENT) {

            throw new IllegalArgumentException("Use DocTreePath(TreePath, DocCommentTree) to construct DocTreePath for a DocCommentTree.");

        } else {

            treePath = p.treePath;

            docComment = p.docComment;

            parent = p;

        }

        leaf = t;

    }

    /**

     * Returns the TreePath associated with this path.

     * @return the TreePath for this DocTreePath

     */

    public TreePath getTreePath() {

        return treePath;

    }

    /**

     * Returns the DocCommentTree associated with this path.

     * @return the DocCommentTree for this DocTreePath

     */

    public DocCommentTree getDocComment() {

        return docComment;

    }

    /**

     * Returns the leaf node for this path.

     * @return the DocTree for this DocTreePath

     */

    public DocTree getLeaf() {

        return leaf;

    }

    /**

     * Returns the path for the enclosing node, or {@code null} if there is no enclosing node.

     * @return DocTreePath of parent

     */

    public DocTreePath getParentPath() {

        return parent;

    }

    @Override

    public Iterator<DocTree> iterator() {

        return new Iterator<DocTree>() {

            @Override

            public boolean hasNext() {

                return next != null;

            }

            @Override

            public DocTree next() {

                DocTree t = next.leaf;

                next = next.parent;

                return t;

            }

            @Override

            public void remove() {

                throw new UnsupportedOperationException();

            }

            private DocTreePath next = DocTreePath.this;

        };

    }

    private final TreePath treePath;

    private final DocCommentTree docComment;

    private final DocTree leaf;

    private final DocTreePath parent;

}