/*

 * Copyright (c) 2012, 2017, 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.tools.doclint;

import java.io.IOException;

import java.io.StringWriter;

import java.net.URI;

import java.net.URISyntaxException;

import java.util.Deque;

import java.util.EnumSet;

import java.util.HashMap;

import java.util.HashSet;

import java.util.LinkedList;

import java.util.List;

import java.util.Map;

import java.util.Set;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

import javax.lang.model.element.Element;

import javax.lang.model.element.ElementKind;

import javax.lang.model.element.ExecutableElement;

import javax.lang.model.element.Name;

import javax.lang.model.element.VariableElement;

import javax.lang.model.type.TypeKind;

import javax.lang.model.type.TypeMirror;

import javax.tools.Diagnostic.Kind;

import javax.tools.JavaFileObject;

import com.sun.source.doctree.AttributeTree;

import com.sun.source.doctree.AuthorTree;

import com.sun.source.doctree.DocCommentTree;

import com.sun.source.doctree.DocRootTree;

import com.sun.source.doctree.DocTree;

import com.sun.source.doctree.EndElementTree;

import com.sun.source.doctree.EntityTree;

import com.sun.source.doctree.ErroneousTree;

import com.sun.source.doctree.IdentifierTree;

import com.sun.source.doctree.IndexTree;

import com.sun.source.doctree.InheritDocTree;

import com.sun.source.doctree.InlineTagTree;

import com.sun.source.doctree.LinkTree;

import com.sun.source.doctree.LiteralTree;

import com.sun.source.doctree.ParamTree;

import com.sun.source.doctree.ProvidesTree;

import com.sun.source.doctree.ReferenceTree;

import com.sun.source.doctree.ReturnTree;

import com.sun.source.doctree.SerialDataTree;

import com.sun.source.doctree.SerialFieldTree;

import com.sun.source.doctree.SinceTree;

import com.sun.source.doctree.StartElementTree;

import com.sun.source.doctree.SummaryTree;

import com.sun.source.doctree.SystemPropertyTree;

import com.sun.source.doctree.TextTree;

import com.sun.source.doctree.ThrowsTree;

import com.sun.source.doctree.UnknownBlockTagTree;

import com.sun.source.doctree.UnknownInlineTagTree;

import com.sun.source.doctree.UsesTree;

import com.sun.source.doctree.ValueTree;

import com.sun.source.doctree.VersionTree;

import com.sun.source.tree.Tree;

import com.sun.source.util.DocTreePath;

import com.sun.source.util.DocTreePathScanner;

import com.sun.source.util.TreePath;

import com.sun.tools.doclint.HtmlTag.AttrKind;

import com.sun.tools.javac.tree.DocPretty;

import com.sun.tools.javac.util.Assert;

import com.sun.tools.javac.util.DefinedBy;

import com.sun.tools.javac.util.DefinedBy.Api;

import com.sun.tools.javac.util.StringUtils;

import static com.sun.tools.doclint.Messages.Group.*;

/**

 * Validate a doc comment.

 *

 * <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></p>

 */

public class Checker extends DocTreePathScanner<Void, Void> {

    final Env env;

    Set<Element> foundParams = new HashSet<>();

    Set<TypeMirror> foundThrows = new HashSet<>();

    Map<Element, Set<String>> foundAnchors = new HashMap<>();

    boolean foundInheritDoc = false;

    boolean foundReturn = false;

    boolean hasNonWhitespaceText = false;

    public enum Flag {

        TABLE_HAS_CAPTION,

        HAS_ELEMENT,

        HAS_HEADING,

        HAS_INLINE_TAG,

        HAS_TEXT,

        REPORTED_BAD_INLINE

    }

    static class TagStackItem {

        final DocTree tree; // typically, but not always, StartElementTree

        final HtmlTag tag;

        final Set<HtmlTag.Attr> attrs;

        final Set<Flag> flags;

        TagStackItem(DocTree tree, HtmlTag tag) {

            this.tree = tree;

            this.tag = tag;

            attrs = EnumSet.noneOf(HtmlTag.Attr.class);

            flags = EnumSet.noneOf(Flag.class);

        }

        @Override

        public String toString() {

            return String.valueOf(tag);

        }

    }

    private final Deque<TagStackItem> tagStack; // TODO: maybe want to record starting tree as well

    private HtmlTag currHeaderTag;

    private final int implicitHeaderLevel;

    // <editor-fold defaultstate="collapsed" desc="Top level">

    Checker(Env env) {

        this.env = Assert.checkNonNull(env);

        tagStack = new LinkedList<>();

        implicitHeaderLevel = env.implicitHeaderLevel;

    }

    public Void scan(DocCommentTree tree, TreePath p) {

        env.initTypes();

        env.setCurrent(p, tree);

        boolean isOverridingMethod = !env.currOverriddenMethods.isEmpty();

        JavaFileObject fo = p.getCompilationUnit().getSourceFile();

        if (p.getLeaf().getKind() == Tree.Kind.PACKAGE) {

            // If p points to a package, the implied declaration is the

            // package declaration (if any) for the compilation unit.

            // Handle this case specially, because doc comments are only

            // expected in package-info files.

            boolean isPkgInfo = fo.isNameCompatible("package-info", JavaFileObject.Kind.SOURCE);

            if (tree == null) {

                if (isPkgInfo)

                    reportMissing("dc.missing.comment");

                return null;

            } else {

                if (!isPkgInfo)

                    reportReference("dc.unexpected.comment");

            }

        } else if (tree != null && fo.isNameCompatible("package", JavaFileObject.Kind.HTML)) {

            // a package.html file with a DocCommentTree

            if (tree.getFullBody().isEmpty()) {

                reportMissing("dc.missing.comment");

                return null;

            }

        } else {

            if (tree == null) {

                if (!isSynthetic() && !isOverridingMethod)

                    reportMissing("dc.missing.comment");

                return null;

            }

        }

        tagStack.clear();

        currHeaderTag = null;

        foundParams.clear();

        foundThrows.clear();

        foundInheritDoc = false;

        foundReturn = false;

        hasNonWhitespaceText = false;

        scan(new DocTreePath(p, tree), null);

        if (!isOverridingMethod) {

            switch (env.currElement.getKind()) {

                case METHOD:

                case CONSTRUCTOR: {

                    ExecutableElement ee = (ExecutableElement) env.currElement;

                    checkParamsDocumented(ee.getTypeParameters());

                    checkParamsDocumented(ee.getParameters());

                    switch (ee.getReturnType().getKind()) {

                        case VOID:

                        case NONE:

                            break;

                        default:

                            if (!foundReturn

                                    && !foundInheritDoc

                                    && !env.types.isSameType(ee.getReturnType(), env.java_lang_Void)) {

                                reportMissing("dc.missing.return");

                            }

                    }

                    checkThrowsDocumented(ee.getThrownTypes());

                }

            }

        }

        return null;

    }

    private void reportMissing(String code, Object... args) {

        env.messages.report(MISSING, Kind.WARNING, env.currPath.getLeaf(), code, args);

    }

    private void reportReference(String code, Object... args) {

        env.messages.report(REFERENCE, Kind.WARNING, env.currPath.getLeaf(), code, args);

    }

    @Override @DefinedBy(Api.COMPILER_TREE)

    public Void visitDocComment(DocCommentTree tree, Void ignore) {

        super.visitDocComment(tree, ignore);

        for (TagStackItem tsi: tagStack) {

            warnIfEmpty(tsi, null);

            if (tsi.tree.getKind() == DocTree.Kind.START_ELEMENT

                    && tsi.tag.endKind == HtmlTag.EndKind.REQUIRED) {

                StartElementTree t = (StartElementTree) tsi.tree;

                env.messages.error(HTML, t, "dc.tag.not.closed", t.getName());

            }

        }

        return null;

    }

    // </editor-fold>

    // <editor-fold defaultstate="collapsed" desc="Text and entities.">

    @Override @DefinedBy(Api.COMPILER_TREE)

    public Void visitText(TextTree tree, Void ignore) {

        hasNonWhitespaceText = hasNonWhitespace(tree);

        if (hasNonWhitespaceText) {

            checkAllowsText(tree);

            markEnclosingTag(Flag.HAS_TEXT);

        }

        return null;

    }

    @Override @DefinedBy(Api.COMPILER_TREE)

    public Void visitEntity(EntityTree tree, Void ignore) {

        checkAllowsText(tree);

        markEnclosingTag(Flag.HAS_TEXT);

        String name = tree.getName().toString();

        if (name.startsWith("#")) {

            int v = StringUtils.toLowerCase(name).startsWith("#x")

                    ? Integer.parseInt(name.substring(2), 16)

                    : Integer.parseInt(name.substring(1), 10);

            if (!Entity.isValid(v)) {

                env.messages.error(HTML, tree, "dc.entity.invalid", name);

            }

        } else if (!Entity.isValid(name)) {

            env.messages.error(HTML, tree, "dc.entity.invalid", name);

        }

        return null;

    }

    void checkAllowsText(DocTree tree) {

        TagStackItem top = tagStack.peek();

        if (top != null

                && top.tree.getKind() == DocTree.Kind.START_ELEMENT

                && !top.tag.acceptsText()) {

            if (top.flags.add(Flag.REPORTED_BAD_INLINE)) {

                env.messages.error(HTML, tree, "dc.text.not.allowed",

                        ((StartElementTree) top.tree).getName());

            }

        }

    }

    // </editor-fold>

    // <editor-fold defaultstate="collapsed" desc="HTML elements">

    @Override @DefinedBy(Api.COMPILER_TREE)

    public Void visitStartElement(StartElementTree tree, Void ignore) {

        final Name treeName = tree.getName();

        final HtmlTag t = HtmlTag.get(treeName);

        if (t == null) {

            env.messages.error(HTML, tree, "dc.tag.unknown", treeName);

        } else if (t.allowedVersion != HtmlVersion.ALL && t.allowedVersion != env.htmlVersion) {

            env.messages.error(HTML, tree, "dc.tag.not.supported", treeName);

        } else {

            boolean done = false;

            for (TagStackItem tsi: tagStack) {

                if (tsi.tag.accepts(t)) {

                    while (tagStack.peek() != tsi) {

                        warnIfEmpty(tagStack.peek(), null);

                        tagStack.pop();

                    }

                    done = true;

                    break;

                } else if (tsi.tag.endKind != HtmlTag.EndKind.OPTIONAL) {

                    done = true;

                    break;

                }

            }

            if (!done && HtmlTag.BODY.accepts(t)) {

                while (!tagStack.isEmpty()) {

                    warnIfEmpty(tagStack.peek(), null);

                    tagStack.pop();

                }

            }

            markEnclosingTag(Flag.HAS_ELEMENT);

            checkStructure(tree, t);

            // tag specific checks

            switch (t) {

                // check for out of sequence headers, such as <h1>...</h1>  <h3>...</h3>

                case H1: case H2: case H3: case H4: case H5: case H6:

                    checkHeader(tree, t);

                    break;

            }

            if (t.flags.contains(HtmlTag.Flag.NO_NEST)) {

                for (TagStackItem i: tagStack) {

                    if (t == i.tag) {

                        env.messages.warning(HTML, tree, "dc.tag.nested.not.allowed", treeName);

                        break;

                    }

                }

            }

        }

        // check for self closing tags, such as <a id="name"/>

        if (tree.isSelfClosing()) {

            env.messages.error(HTML, tree, "dc.tag.self.closing", treeName);

        }

        try {

            TagStackItem parent = tagStack.peek();

            TagStackItem top = new TagStackItem(tree, t);

            tagStack.push(top);

            super.visitStartElement(tree, ignore);

            // handle attributes that may or may not have been found in start element

            if (t != null) {

                switch (t) {

                    case CAPTION:

                        if (parent != null && parent.tag == HtmlTag.TABLE)

                            parent.flags.add(Flag.TABLE_HAS_CAPTION);

                        break;

                    case H1: case H2: case H3: case H4: case H5: case H6:

                        if (parent != null && (parent.tag == HtmlTag.SECTION || parent.tag == HtmlTag.ARTICLE)) {

                            parent.flags.add(Flag.HAS_HEADING);

                        }

                        break;

                    case IMG:

                        if (!top.attrs.contains(HtmlTag.Attr.ALT))

                            env.messages.error(ACCESSIBILITY, tree, "dc.no.alt.attr.for.image");

                        break;

                }

            }

            return null;

        } finally {

            if (t == null || t.endKind == HtmlTag.EndKind.NONE)

                tagStack.pop();

        }

    }

    private void checkStructure(StartElementTree tree, HtmlTag t) {

        Name treeName = tree.getName();

        TagStackItem top = tagStack.peek();

        switch (t.blockType) {

            case BLOCK:

                if (top == null || top.tag.accepts(t))

                    return;

                switch (top.tree.getKind()) {

                    case START_ELEMENT: {

                        if (top.tag.blockType == HtmlTag.BlockType.INLINE) {

                            Name name = ((StartElementTree) top.tree).getName();

                            env.messages.error(HTML, tree, "dc.tag.not.allowed.inline.element",

                                    treeName, name);

                            return;

                        }

                    }

                    break;

                    case LINK:

                    case LINK_PLAIN: {

                        String name = top.tree.getKind().tagName;

                        env.messages.error(HTML, tree, "dc.tag.not.allowed.inline.tag",

                                treeName, name);

                        return;

                    }

                }

                break;

            case INLINE:

                if (top == null || top.tag.accepts(t))

                    return;

                break;

            case LIST_ITEM:

            case TABLE_ITEM:

                if (top != null) {

                    // reset this flag so subsequent bad inline content gets reported

                    top.flags.remove(Flag.REPORTED_BAD_INLINE);

                    if (top.tag.accepts(t))

                        return;

                }

                break;

            case OTHER:

                switch (t) {

                    case SCRIPT:

                        // <script> may or may not be allowed, depending on --allow-script-in-comments

                        // but we allow it here, and rely on a separate scanner to detect all uses

                        // of JavaScript, including <script> tags, and use in attributes, etc.

                        break;

                    default:

                        env.messages.error(HTML, tree, "dc.tag.not.allowed", treeName);

                }

                return;

        }

        env.messages.error(HTML, tree, "dc.tag.not.allowed.here", treeName);

    }

    private void checkHeader(StartElementTree tree, HtmlTag tag) {

        // verify the new tag

        if (getHeaderLevel(tag) > getHeaderLevel(currHeaderTag) + 1) {

            if (currHeaderTag == null) {

                env.messages.error(ACCESSIBILITY, tree, "dc.tag.header.sequence.1", tag);

            } else {

                env.messages.error(ACCESSIBILITY, tree, "dc.tag.header.sequence.2",

                    tag, currHeaderTag);

            }

        }

        currHeaderTag = tag;

    }

    private int getHeaderLevel(HtmlTag tag) {

        if (tag == null)

            return implicitHeaderLevel;

        switch (tag) {

            case H1: return 1;

            case H2: return 2;

            case H3: return 3;

            case H4: return 4;

            case H5: return 5;

            case H6: return 6;

            default: throw new IllegalArgumentException();

        }

    }

    @Override @DefinedBy(Api.COMPILER_TREE)

    public Void visitEndElement(EndElementTree tree, Void ignore) {

        final Name treeName = tree.getName();

        final HtmlTag t = HtmlTag.get(treeName);

        if (t == null) {

            env.messages.error(HTML, tree, "dc.tag.unknown", treeName);

        } else if (t.endKind == HtmlTag.EndKind.NONE) {

            env.messages.error(HTML, tree, "dc.tag.end.not.permitted", treeName);

        } else {

            boolean done = false;

            while (!tagStack.isEmpty()) {

                TagStackItem top = tagStack.peek();

                if (t == top.tag) {

                    switch (t) {

                        case TABLE:

                            if (!top.attrs.contains(HtmlTag.Attr.SUMMARY)

                                    && !top.flags.contains(Flag.TABLE_HAS_CAPTION)) {

                                env.messages.error(ACCESSIBILITY, tree,

                                        "dc.no.summary.or.caption.for.table");

                            }

                            break;

                        case SECTION:

                        case ARTICLE:

                            if (env.htmlVersion == HtmlVersion.HTML5 && !top.flags.contains(Flag.HAS_HEADING)) {

                                env.messages.error(HTML, tree, "dc.tag.requires.heading", treeName);

                            }

                            break;

                    }

                    warnIfEmpty(top, tree);