/*
 * Copyright (c) 2015, 2018, 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.
 */

 A utility class.
 
This is NOT part of any supported API.
 If you write code that depends on this, you do so at your own risk.
 This code and its internal interfaces are subject to change or
 deletion without notice.
/**
 *  A utility class.
 *
 *  <p><b>This is NOT part of any supported API.
 *  If you write code that depends on this, you do so at your own risk.
 *  This code and its internal interfaces are subject to change or
 *  deletion without notice.</b>
 */

package jdk.javadoc.internal.doclets.toolkit;

import java.net.URI;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import javax.lang.model.element.Element;
import javax.lang.model.element.ExecutableElement;
import javax.lang.model.element.Name;
import javax.lang.model.element.PackageElement;
import javax.lang.model.element.VariableElement;
import javax.lang.model.util.Elements;
import javax.tools.FileObject;
import javax.tools.JavaFileObject;
import javax.tools.SimpleJavaFileObject;

import com.sun.source.doctree.DocCommentTree;
import com.sun.source.doctree.DocTree;
import com.sun.source.doctree.IdentifierTree;
import com.sun.source.doctree.ReferenceTree;
import com.sun.source.doctree.TextTree;
import com.sun.source.util.DocTreeFactory;
import com.sun.source.util.DocTreePath;
import com.sun.source.util.DocTrees;
import com.sun.source.util.TreePath;
import com.sun.tools.javac.util.DefinedBy;
import com.sun.tools.javac.util.DefinedBy.Api;
import jdk.javadoc.internal.doclets.toolkit.util.Utils;

public class CommentUtils {

    final BaseConfiguration configuration;
    final Resources resources;
    final DocTreeFactory treeFactory;
    final HashMap<Element, DocCommentDuo> dcTreesMap = new HashMap<>();
    final DocTrees trees;
    final Elements elementUtils;

    protected CommentUtils(BaseConfiguration configuration) {
        this.configuration = configuration;
        resources = configuration.getResources();
        trees = configuration.docEnv.getDocTrees();
        treeFactory = trees.getDocTreeFactory();
        elementUtils = configuration.docEnv.getElementUtils();
    }

    public List<? extends DocTree> makePropertyDescriptionTree(List<? extends DocTree> content) {
        List<DocTree> out = new ArrayList<>();
        Name name = elementUtils.getName("propertyDescription");
        out.add(treeFactory.newUnknownBlockTagTree(name, content));
        return out;
    }

    public List<? extends DocTree> makePropertyDescriptionTree(String content) {
        List<DocTree> inlist = new ArrayList<>();
        inlist.add(treeFactory.newCommentTree(content));
        List<DocTree> out = new ArrayList<>();
        Name name = elementUtils.getName("propertyDescription");
        out.add(treeFactory.newUnknownBlockTagTree(name, inlist));
        return out;
    }

    public List<? extends DocTree> makeFirstSentenceTree(String content) {
        List<DocTree> out = new ArrayList<>();
        out.add(treeFactory.newTextTree(content));
        return out;
    }

    public DocTree makeSeeTree(String sig, Element e) {
        List<DocTree> list = new ArrayList<>();
        list.add(treeFactory.newReferenceTree(sig));
        return treeFactory.newSeeTree(list);
    }

    public DocTree makeTextTree(String content) {
        TextTree text = treeFactory.newTextTree(content);
        return (DocTree) text;
    }

    public void setEnumValuesTree(Element e) {
        Utils utils = configuration.utils;
        String klassName = utils.getSimpleName(utils.getEnclosingTypeElement(e));

        List<DocTree> fullBody = new ArrayList<>();
        fullBody.add(treeFactory.newTextTree(resources.getText("doclet.enum_values_doc.fullbody", klassName)));

        List<DocTree> descriptions = new ArrayList<>();
        descriptions.add(treeFactory.newTextTree(resources.getText("doclet.enum_values_doc.return")));

        List<DocTree> tags = new ArrayList<>();
        tags.add(treeFactory.newReturnTree(descriptions));
        DocCommentTree docTree = treeFactory.newDocCommentTree(fullBody, tags);
        dcTreesMap.put(e, new DocCommentDuo(null, docTree));
    }

    public void setEnumValueOfTree(Element e) {

        List<DocTree> fullBody = new ArrayList<>();
        fullBody.add(treeFactory.newTextTree(resources.getText("doclet.enum_valueof_doc.fullbody")));

        List<DocTree> tags = new ArrayList<>();

        List<DocTree> paramDescs = new ArrayList<>();
        paramDescs.add(treeFactory.newTextTree(resources.getText("doclet.enum_valueof_doc.param_name")));
        ExecutableElement ee = (ExecutableElement) e;
        java.util.List<? extends VariableElement> parameters = ee.getParameters();
        VariableElement param = parameters.get(0);
        IdentifierTree id = treeFactory.newIdentifierTree(elementUtils.getName(param.getSimpleName().toString()));
        tags.add(treeFactory.newParamTree(false, id, paramDescs));

        List<DocTree> returnDescs = new ArrayList<>();
        returnDescs.add(treeFactory.newTextTree(resources.getText("doclet.enum_valueof_doc.return")));
        tags.add(treeFactory.newReturnTree(returnDescs));

        List<DocTree> throwsDescs = new ArrayList<>();
        throwsDescs.add(treeFactory.newTextTree(resources.getText("doclet.enum_valueof_doc.throws_ila")));

        ReferenceTree ref = treeFactory.newReferenceTree("java.lang.IllegalArgumentException");
        tags.add(treeFactory.newThrowsTree(ref, throwsDescs));

        throwsDescs = new ArrayList<>();
        throwsDescs.add(treeFactory.newTextTree(resources.getText("doclet.enum_valueof_doc.throws_npe")));

        ref = treeFactory.newReferenceTree("java.lang.NullPointerException");
        tags.add(treeFactory.newThrowsTree(ref, throwsDescs));

        DocCommentTree docTree = treeFactory.newDocCommentTree(fullBody, tags);

        dcTreesMap.put(e, new DocCommentDuo(null, docTree));
    }

    /*
     * Returns the TreePath/DocCommentTree duo for synthesized element.
     */
    public DocCommentDuo getSyntheticCommentDuo(Element e) {
        return dcTreesMap.get(e);
    }

    /*
     * Returns the TreePath/DocCommentTree duo for html sources.
     */
    public DocCommentDuo getHtmlCommentDuo(Element e) {
        FileObject fo = null;
        PackageElement pe = null;
        switch (e.getKind()) {
            case OTHER:
                if (e instanceof DocletElement) {
                    DocletElement de = (DocletElement)e;
                    fo = de.getFileObject();
                    pe = de.getPackageElement();
                }
                break;
            case PACKAGE:
                fo = configuration.workArounds.getJavaFileObject((PackageElement)e);
                pe = (PackageElement)e;
                break;
            default:
                return null;
        }
        if (fo == null) {
            return null;
        }

        DocCommentTree dcTree = trees.getDocCommentTree(fo);
        if (dcTree == null) {
            return null;
        }
        DocTreePath treePath = trees.getDocTreePath(fo, pe);
        return new DocCommentDuo(treePath.getTreePath(), dcTree);
    }

    public DocCommentTree parse(URI uri, String text) {
        return trees.getDocCommentTree(new SimpleJavaFileObject(
                uri, JavaFileObject.Kind.SOURCE) {
            @Override @DefinedBy(Api.COMPILER)
            public CharSequence getCharContent(boolean ignoreEncoding) {
                return text;
            }
        });
    }

    public void setDocCommentTree(Element element, List<? extends DocTree> fullBody,
                                  List<? extends DocTree> blockTags, Utils utils) {
        DocCommentTree docTree = treeFactory.newDocCommentTree(fullBody, blockTags);
        dcTreesMap.put(element, new DocCommentDuo(null, docTree));
        // A method having null comment (no comment) that might need to be replaced
        // with a synthetic comment, remove such a comment from the cache.
        utils.removeCommentHelper(element);
    }

    
A simplistic container to transport a TreePath, DocCommentTree pair.
Here is why we need this:
a. not desirable to add javac's pair.
b. DocTreePath is not a viable  option either, as a null TreePath is required
to represent synthetic comments for Enum.values, valuesOf, javafx properties.
/**
     * A simplistic container to transport a TreePath, DocCommentTree pair.
     * Here is why we need this:
     * a. not desirable to add javac's pair.
     * b. DocTreePath is not a viable  option either, as a null TreePath is required
     * to represent synthetic comments for Enum.values, valuesOf, javafx properties.
     */
    public static class DocCommentDuo {
        public final TreePath treePath;
        public final DocCommentTree dcTree;

        public DocCommentDuo(TreePath treePath, DocCommentTree dcTree) {
            this.treePath = treePath;
            this.dcTree = dcTree;
        }
    }
}