java/com/google/gerrit/server/documentation/MarkdownFormatter.java - gerrit - Git at Google

 // Copyright (C) 2012 The Android Open Source Project
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 // http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 package com.google.gerrit.server.documentation;

 import static com.vladsch.flexmark.profiles.pegdown.Extensions.ALL;
 import static com.vladsch.flexmark.profiles.pegdown.Extensions.HARDWRAPS;
 import static com.vladsch.flexmark.profiles.pegdown.Extensions.SUPPRESS_ALL_HTML;
 import static java.nio.charset.StandardCharsets.UTF_8;

 import com.google.common.base.Strings;
 import com.google.common.flogger.FluentLogger;
 import com.vladsch.flexmark.ast.Block;
 import com.vladsch.flexmark.ast.Heading;
 import com.vladsch.flexmark.ast.Node;
 import com.vladsch.flexmark.ast.util.TextCollectingVisitor;
 import com.vladsch.flexmark.html.HtmlRenderer;
 import com.vladsch.flexmark.parser.Parser;
 import com.vladsch.flexmark.profiles.pegdown.PegdownOptionsAdapter;
 import com.vladsch.flexmark.util.options.MutableDataHolder;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.UnsupportedEncodingException;
 import java.net.URL;
 import java.nio.charset.Charset;
 import java.util.concurrent.atomic.AtomicBoolean;
 import org.apache.commons.lang.StringEscapeUtils;
 import org.eclipse.jgit.util.RawParseUtils;
 import org.eclipse.jgit.util.TemporaryBuffer;

 public class MarkdownFormatter {
   private static final FluentLogger logger = FluentLogger.forEnclosingClass();

   private static final String defaultCss;

   static {
     AtomicBoolean file = new AtomicBoolean();
     String src;
     try {
       src = readFlexMarkJavaCss(file);
     } catch (IOException err) {
       logger.atWarning().withCause(err).log("Cannot load flexmark-java.css");
       src = "";
     }
     defaultCss = file.get() ? null : src;
   }

   private static String readCSS() {
     if (defaultCss != null) {
       return defaultCss;
     }
     try {
       return readFlexMarkJavaCss(new AtomicBoolean());
     } catch (IOException err) {
       logger.atWarning().withCause(err).log("Cannot load flexmark-java.css");
       return "";
     }
   }

   private boolean suppressHtml;
   private String css;

   public MarkdownFormatter suppressHtml() {
     suppressHtml = true;
     return this;
   }

   public MarkdownFormatter setCss(String css) {
     this.css = StringEscapeUtils.escapeHtml(css);
     return this;
   }

   private MutableDataHolder markDownOptions() {
     int options = ALL & ~(HARDWRAPS);
     if (suppressHtml) {
       options |= SUPPRESS_ALL_HTML;
     }

     MutableDataHolder optionsExt =
         PegdownOptionsAdapter.flexmarkOptions(
                 options, MarkdownFormatterHeader.HeadingExtension.create())
             .toMutable();

     return optionsExt;
   }

   public byte[] markdownToDocHtml(String md, String charEnc) throws UnsupportedEncodingException {
     Node root = parseMarkdown(md);
     HtmlRenderer renderer = HtmlRenderer.builder(markDownOptions()).build();
     String title = findTitle(root);

     StringBuilder html = new StringBuilder();
     html.append("<html>");
     html.append("<head>");
     if (!Strings.isNullOrEmpty(title)) {
       html.append("<title>").append(title).append("</title>");
     }
     html.append("<style type=\"text/css\">\n");
     if (css != null) {
       html.append(css);
     } else {
       html.append(readCSS());
     }
     html.append("\n</style>");
     html.append("</head>");
     html.append("<body>\n");
     html.append(renderer.render(root));
     html.append("\n</body></html>");
     return html.toString().getBytes(charEnc);
   }

   public String extractTitleFromMarkdown(byte[] data, String charEnc) {
     String md = RawParseUtils.decode(Charset.forName(charEnc), data);
     return findTitle(parseMarkdown(md));
   }

   private String findTitle(Node root) {
     if (root instanceof Heading) {
       Heading h = (Heading) root;
       if (h.getLevel() == 1 && h.hasChildren()) {
         TextCollectingVisitor collectingVisitor = new TextCollectingVisitor();
         return collectingVisitor.collectAndGetText(h);
       }
     }

     if (root instanceof Block && root.hasChildren()) {
       Node child = root.getFirstChild();
       while (child != null) {
         String title = findTitle(child);
         if (title != null) {
           return title;
         }
         child = child.getNext();
       }
     }

     return null;
   }

   private Node parseMarkdown(String md) {
     Parser parser = Parser.builder(markDownOptions()).build();
     Node document = parser.parse(md);
     return document;
   }

   private static String readFlexMarkJavaCss(AtomicBoolean file) throws IOException {
     String name = "flexmark-java.css";
     URL url = MarkdownFormatter.class.getResource(name);
     if (url == null) {
       throw new FileNotFoundException("Resource " + name);
     }
     file.set("file".equals(url.getProtocol()));
     try (InputStream in = url.openStream();
         TemporaryBuffer.Heap tmp = new TemporaryBuffer.Heap(128 * 1024)) {
       tmp.copy(in);
       return new String(tmp.toByteArray(), UTF_8);
     }
   }
 }
	// Copyright (C) 2012 The Android Open Source Project
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	package com.google.gerrit.server.documentation;

	import static com.vladsch.flexmark.profiles.pegdown.Extensions.ALL;
	import static com.vladsch.flexmark.profiles.pegdown.Extensions.HARDWRAPS;
	import static com.vladsch.flexmark.profiles.pegdown.Extensions.SUPPRESS_ALL_HTML;
	import static java.nio.charset.StandardCharsets.UTF_8;

	import com.google.common.base.Strings;
	import com.google.common.flogger.FluentLogger;
	import com.vladsch.flexmark.ast.Block;
	import com.vladsch.flexmark.ast.Heading;
	import com.vladsch.flexmark.ast.Node;
	import com.vladsch.flexmark.ast.util.TextCollectingVisitor;
	import com.vladsch.flexmark.html.HtmlRenderer;
	import com.vladsch.flexmark.parser.Parser;
	import com.vladsch.flexmark.profiles.pegdown.PegdownOptionsAdapter;
	import com.vladsch.flexmark.util.options.MutableDataHolder;
	import java.io.FileNotFoundException;
	import java.io.IOException;
	import java.io.InputStream;
	import java.io.UnsupportedEncodingException;
	import java.net.URL;
	import java.nio.charset.Charset;
	import java.util.concurrent.atomic.AtomicBoolean;
	import org.apache.commons.lang.StringEscapeUtils;
	import org.eclipse.jgit.util.RawParseUtils;
	import org.eclipse.jgit.util.TemporaryBuffer;

	public class MarkdownFormatter {
	private static final FluentLogger logger = FluentLogger.forEnclosingClass();

	private static final String defaultCss;

	static {
	AtomicBoolean file = new AtomicBoolean();
	String src;
	try {
	src = readFlexMarkJavaCss(file);
	} catch (IOException err) {
	logger.atWarning().withCause(err).log("Cannot load flexmark-java.css");
	src = "";
	}
	defaultCss = file.get() ? null : src;
	}

	private static String readCSS() {
	if (defaultCss != null) {
	return defaultCss;
	}
	try {
	return readFlexMarkJavaCss(new AtomicBoolean());
	} catch (IOException err) {
	logger.atWarning().withCause(err).log("Cannot load flexmark-java.css");
	return "";
	}
	}

	private boolean suppressHtml;
	private String css;

	public MarkdownFormatter suppressHtml() {
	suppressHtml = true;
	return this;
	}

	public MarkdownFormatter setCss(String css) {
	this.css = StringEscapeUtils.escapeHtml(css);
	return this;
	}

	private MutableDataHolder markDownOptions() {
	int options = ALL & ~(HARDWRAPS);
	if (suppressHtml) {
	options \|= SUPPRESS_ALL_HTML;
	}

	MutableDataHolder optionsExt =
	PegdownOptionsAdapter.flexmarkOptions(
	options, MarkdownFormatterHeader.HeadingExtension.create())
	.toMutable();

	return optionsExt;
	}

	public byte[] markdownToDocHtml(String md, String charEnc) throws UnsupportedEncodingException {
	Node root = parseMarkdown(md);
	HtmlRenderer renderer = HtmlRenderer.builder(markDownOptions()).build();
	String title = findTitle(root);

	StringBuilder html = new StringBuilder();
	html.append("<html>");
	html.append("<head>");
	if (!Strings.isNullOrEmpty(title)) {
	html.append("<title>").append(title).append("</title>");
	}
	html.append("<style type=\"text/css\">\n");
	if (css != null) {
	html.append(css);
	} else {
	html.append(readCSS());
	}
	html.append("\n</style>");
	html.append("</head>");
	html.append("<body>\n");
	html.append(renderer.render(root));
	html.append("\n</body></html>");
	return html.toString().getBytes(charEnc);
	}

	public String extractTitleFromMarkdown(byte[] data, String charEnc) {
	String md = RawParseUtils.decode(Charset.forName(charEnc), data);
	return findTitle(parseMarkdown(md));
	}

	private String findTitle(Node root) {
	if (root instanceof Heading) {
	Heading h = (Heading) root;
	if (h.getLevel() == 1 && h.hasChildren()) {
	TextCollectingVisitor collectingVisitor = new TextCollectingVisitor();
	return collectingVisitor.collectAndGetText(h);
	}
	}

	if (root instanceof Block && root.hasChildren()) {
	Node child = root.getFirstChild();
	while (child != null) {
	String title = findTitle(child);
	if (title != null) {
	return title;
	}
	child = child.getNext();
	}
	}

	return null;
	}

	private Node parseMarkdown(String md) {
	Parser parser = Parser.builder(markDownOptions()).build();
	Node document = parser.parse(md);
	return document;
	}

	private static String readFlexMarkJavaCss(AtomicBoolean file) throws IOException {
	String name = "flexmark-java.css";
	URL url = MarkdownFormatter.class.getResource(name);
	if (url == null) {
	throw new FileNotFoundException("Resource " + name);
	}
	file.set("file".equals(url.getProtocol()));
	try (InputStream in = url.openStream();
	TemporaryBuffer.Heap tmp = new TemporaryBuffer.Heap(128 * 1024)) {
	tmp.copy(in);
	return new String(tmp.toByteArray(), UTF_8);
	}
	}
	}