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 * Copyright (c) 2001, 2022, 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
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package org.jdrupes.mdoclet.internal.doclets.formats.html;

import java.io.IOException;
import java.io.LineNumberReader;
import java.io.Reader;

import javax.lang.model.element.Element;
import javax.lang.model.element.ModuleElement;
import javax.lang.model.element.PackageElement;
import javax.lang.model.element.TypeElement;
import javax.tools.FileObject;

import org.jdrupes.mdoclet.internal.doclets.formats.html.markup.Head;
import org.jdrupes.mdoclet.internal.doclets.formats.html.markup.HtmlDocument;
import org.jdrupes.mdoclet.internal.doclets.formats.html.markup.HtmlId;
import org.jdrupes.mdoclet.internal.doclets.formats.html.markup.HtmlStyle;
import org.jdrupes.mdoclet.internal.doclets.formats.html.markup.HtmlTree;
import org.jdrupes.mdoclet.internal.doclets.formats.html.markup.TagName;
import org.jdrupes.mdoclet.internal.doclets.formats.html.markup.Text;
import org.jdrupes.mdoclet.internal.doclets.toolkit.Content;
import org.jdrupes.mdoclet.internal.doclets.toolkit.Messages;
import org.jdrupes.mdoclet.internal.doclets.toolkit.Resources;
import org.jdrupes.mdoclet.internal.doclets.toolkit.util.DocFile;
import org.jdrupes.mdoclet.internal.doclets.toolkit.util.DocFileIOException;
import org.jdrupes.mdoclet.internal.doclets.toolkit.util.DocPath;
import org.jdrupes.mdoclet.internal.doclets.toolkit.util.DocPaths;
import org.jdrupes.mdoclet.internal.doclets.toolkit.util.SimpleDocletException;
import org.jdrupes.mdoclet.internal.doclets.toolkit.util.Utils;

/**
 * Converts Java Source Code to HTML.
 */
public class SourceToHTMLConverter {

    /**
     * The number of trailing blank lines at the end of the page.
     * This is inserted so that anchors at the bottom of small pages
     * can be reached.
     */
    private static final int NUM_BLANK_LINES = 60;

    /**
     * New line to be added to the documentation.
     */
    private static final String NEW_LINE = Text.NL;

    private final HtmlConfiguration configuration;
    private final HtmlOptions options;
    private final Messages messages;
    private final Resources resources;
    private final Utils utils;

    private final DocPath outputdir;

    /**
     * Relative path from the documentation root to the file that is being
     * generated.
     */
    private DocPath relativePath = DocPath.empty;

    private SourceToHTMLConverter(HtmlConfiguration configuration,
            DocPath outputdir) {
        this.configuration = configuration;
        this.options = configuration.getOptions();
        this.messages = configuration.getMessages();
        this.resources = configuration.docResources;
        this.utils = configuration.utils;
        this.outputdir = outputdir;
    }

    /**
     * Translate the TypeElements in the given DocletEnvironment to HTML representation.
     *
     * @param configuration the configuration.
     * @param outputdir the name of the directory to output to.
     * @throws DocFileIOException if there is a problem generating an output file
     * @throws SimpleDocletException if there is a problem reading a source file
     */
    public static void convertRoot(HtmlConfiguration configuration,
            DocPath outputdir)
            throws DocFileIOException, SimpleDocletException {
        new SourceToHTMLConverter(configuration, outputdir).generate();
    }

    void generate() throws DocFileIOException, SimpleDocletException {
        if (outputdir == null) {
            return;
        }
        for (ModuleElement mdl : configuration.getSpecifiedModuleElements()) {
            // If -nodeprecated option is set and the module is marked as
            // deprecated,
            // do not convert the module files to HTML.
            if (!(options.noDeprecated() && utils.isDeprecated(mdl)))
                convertModule(mdl, outputdir);
        }
        for (PackageElement pkg : configuration.getSpecifiedPackageElements()) {
            // If -nodeprecated option is set and the package is marked as
            // deprecated,
            // do not convert the package files to HTML.
            if (!(options.noDeprecated() && utils.isDeprecated(pkg)))
                convertPackage(pkg, outputdir);
        }
        for (TypeElement te : configuration.getSpecifiedTypeElements()) {
            // If -nodeprecated option is set and the class is marked as
            // deprecated
            // or the containing package is deprecated, do not convert the
            // package files to HTML.
            if (!(options.noDeprecated() &&
                (utils.isDeprecated(te)
                    || utils.isDeprecated(utils.containingPackage(te)))))
                convertClass(te, outputdir);
        }
    }

    /**
     * Convert the Classes in the given Package to an HTML file.
     *
     * @param pkg the Package to convert.
     * @param outputdir the name of the directory to output to.
     * @throws DocFileIOException if there is a problem generating an output file
     * @throws SimpleDocletException if there is a problem reading a source file
     */
    public void convertPackage(PackageElement pkg, DocPath outputdir)
            throws DocFileIOException, SimpleDocletException {
        if (pkg == null) {
            return;
        }
        for (TypeElement te : utils.getAllClasses(pkg)) {
            // If -nodeprecated option is set and the class is marked as
            // deprecated,
            // do not convert the package files to HTML. We do not check for
            // containing package deprecation since it is already check in
            // the calling method above.
            if (!(options.noDeprecated() && utils.isDeprecated(te)))
                convertClass(te, outputdir);
        }
    }

    /**
     * Convert the documented packages contained in the given module to an HTML representation.
     *
     * @param mdl the module to convert.
     * @param outputdir the name of the directory to output to.
     * @throws DocFileIOException if there is a problem generating an output file
     * @throws SimpleDocletException if there is a problem reading a source file
     */
    public void convertModule(ModuleElement mdl, DocPath outputdir)
            throws DocFileIOException, SimpleDocletException {
        if (mdl == null) {
            return;
        }
        for (Element elem : mdl.getEnclosedElements()) {
            if (elem instanceof PackageElement pkg
                && configuration.docEnv.isIncluded(elem)
                && !(options.noDeprecated() && utils.isDeprecated(elem))) {
                convertPackage(pkg, outputdir);
            }
        }
    }

    /**
     * Convert the given Class to an HTML.
     *
     * @param te the class to convert.
     * @param outputdir the name of the directory to output to
     * @throws DocFileIOException if there is a problem generating the output file
     * @throws SimpleDocletException if there is a problem reading the source file
     */
    public void convertClass(TypeElement te, DocPath outputdir)
            throws DocFileIOException, SimpleDocletException {
        if (te == null) {
            return;
        }
        FileObject fo = utils.getFileObject(te);
        if (fo == null)
            return;

        try {
            Reader r = fo.openReader(true);
            int lineno = 1;
            String line;
            relativePath = DocPaths.SOURCE_OUTPUT
                .resolve(configuration.docPaths.forPackage(te))
                .invert();
            Content body = getHeader();
            var pre = new HtmlTree(TagName.PRE);
            try (var reader = new LineNumberReader(r)) {
                while ((line = reader.readLine()) != null) {
                    addLineNo(pre, lineno);
                    addLine(pre, line, lineno);
                    lineno++;
                }
            }
            addBlankLines(pre);
            var div = HtmlTree.DIV(HtmlStyle.sourceContainer, pre);
            body.add(HtmlTree.MAIN(div));
            writeToFile(body,
                outputdir.resolve(configuration.docPaths.forClass(te)), te);
        } catch (IOException e) {
            String message
                = resources.getText("doclet.exception.read.file", fo.getName());
            throw new SimpleDocletException(message, e);
        }
    }

    /**
     * Write the output to the file.
     *
     * @param body the documentation content to be written to the file.
     * @param path the path for the file.
     */
    private void writeToFile(Content body, DocPath path, TypeElement te)
            throws DocFileIOException {
        Head head = new Head(path, configuration.getDocletVersion(),
            configuration.getBuildDate())
//                .setTimestamp(!options.notimestamp) // temporary: compatibility!
                .setTitle(resources.getText("doclet.Window_Source_title"))
//                .setCharset(options.charset) // temporary: compatibility!
                .setDescription(HtmlDocletWriter.getDescription("source", te))
                .setGenerator(HtmlDocletWriter.getGenerator(getClass()))
                .addDefaultScript(false)
                .setStylesheets(configuration.getMainStylesheet(),
                    configuration.getAdditionalStylesheets());
        var html = HtmlTree.HTML(configuration.getLocale().getLanguage(), head,
            body);
        HtmlDocument document = new HtmlDocument(html);
        messages.notice("doclet.Generating_0", path.getPath());
        document.write(DocFile.createFileForOutput(configuration, path));
    }

    /**
     * Returns a link to the stylesheet file.
     *
     * @param head the content to which the stylesheet links will be added
     */
    public void addStyleSheetProperties(Content head) {
        String filename = options.stylesheetFile();
        DocPath stylesheet;
        if (filename.length() > 0) {
            DocFile file = DocFile.createFileForInput(configuration, filename);
            stylesheet = DocPath.create(file.getName());
        } else {
            stylesheet = DocPaths.STYLESHEET;
        }
        DocPath p = relativePath.resolve(stylesheet);
        var link
            = HtmlTree.LINK("stylesheet", "text/css", p.getPath(), "Style");
        head.add(link);
        addStylesheets(head);
    }

    protected void addStylesheets(Content head) {
        options.additionalStylesheets().forEach(css -> {
            DocFile file = DocFile.createFileForInput(configuration, css);
            DocPath cssPath = DocPath.create(file.getName());
            var slink = HtmlTree.LINK("stylesheet", "text/css",
                relativePath.resolve(cssPath).getPath(),
                "Style");
            head.add(slink);
        });
    }

    /**
     * Get the header.
     *
     * @return the header content for the HTML file
     */
    private static Content getHeader() {
        return new HtmlTree(TagName.BODY).setStyle(HtmlStyle.sourcePage);
    }

    /**
     * Add the line numbers for the source code.
     *
     * @param pre the content to which the line number will be added
     * @param lineno The line number
     */
    private static void addLineNo(Content pre, int lineno) {
        var span = HtmlTree.SPAN(HtmlStyle.sourceLineNo);
        if (lineno < 10) {
            span.add("00" + lineno);
        } else if (lineno < 100) {
            span.add("0" + lineno);
        } else {
            span.add(Integer.toString(lineno));
        }
        pre.add(span);
    }

    /**
     * Add a line from source to the HTML file that is generated.
     *
     * @param pre the content to which the line will be added.
     * @param line the string to format.
     * @param currentLineNo the current number.
     */
    private void addLine(HtmlTree pre, String line, int currentLineNo) {
        if (line != null) {
            var anchor = HtmlTree.SPAN_ID(
                HtmlIds.forLine(currentLineNo),
                Text.of(utils.replaceTabs(line)));
            pre.addUnchecked(anchor);
            pre.add(NEW_LINE);
        }
    }

    /**
     * Add trailing blank lines at the end of the page.
     *
     * @param pre the content to which the blank lines will be added.
     */
    private static void addBlankLines(Content pre) {
        for (int i = 0; i < NUM_BLANK_LINES; i++) {
            pre.add(NEW_LINE);
        }
    }

    /**
     * Given an element, return an anchor name for it.
     *
     * @param utils the utility class, used to get the line number of the element
     * @param e the element to check.
     * @return the name of the anchor.
     */
    public static HtmlId getAnchorName(Utils utils, Element e) {
        return HtmlIds.forLine((int) utils.getLineNumber(e));
    }
}