gerrit-httpd/src/main/java/com/google/gerrit/httpd/raw/HostPageServlet.java - gerrit - Git at Google

 // Copyright (C) 2008 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.httpd.raw;

 import static com.google.gerrit.common.FileUtil.lastModified;
 import static java.nio.charset.StandardCharsets.UTF_8;

 import com.google.common.base.Strings;
 import com.google.common.hash.Hasher;
 import com.google.common.hash.Hashing;
 import com.google.common.primitives.Bytes;
 import com.google.gerrit.common.Version;
 import com.google.gerrit.common.data.HostPageData;
 import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import com.google.gerrit.extensions.registration.DynamicSet;
 import com.google.gerrit.extensions.restapi.AuthException;
 import com.google.gerrit.extensions.systemstatus.MessageOfTheDay;
 import com.google.gerrit.extensions.webui.WebUiPlugin;
 import com.google.gerrit.httpd.HtmlDomUtil;
 import com.google.gerrit.server.CurrentUser;
 import com.google.gerrit.server.IdentifiedUser;
 import com.google.gerrit.server.account.AccountResource;
 import com.google.gerrit.server.account.GetDiffPreferences;
 import com.google.gerrit.server.config.ConfigUtil;
 import com.google.gerrit.server.config.GerritServerConfig;
 import com.google.gerrit.server.config.SitePaths;
 import com.google.gerrit.server.notedb.NotesMigration;
 import com.google.gerrit.server.permissions.PermissionBackendException;
 import com.google.gwtexpui.server.CacheHeaders;
 import com.google.gwtjsonrpc.server.JsonServlet;
 import com.google.gwtjsonrpc.server.RPCServletUtils;
 import com.google.inject.Inject;
 import com.google.inject.Provider;
 import com.google.inject.Singleton;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.io.StringWriter;
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
 import javax.servlet.ServletContext;
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import org.eclipse.jgit.errors.ConfigInvalidException;
 import org.eclipse.jgit.lib.Config;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
 import org.w3c.dom.Node;

 /** Sends the Gerrit host page to clients. */
 @Singleton
 public class HostPageServlet extends HttpServlet {
   private static final long serialVersionUID = 1L;

   private static final Logger log = LoggerFactory.getLogger(HostPageServlet.class);

   private static final String HPD_ID = "gerrit_hostpagedata";
   private static final int DEFAULT_JS_LOAD_TIMEOUT = 5000;

   private final Provider<CurrentUser> currentUser;
   private final DynamicSet<WebUiPlugin> plugins;
   private final DynamicSet<MessageOfTheDay> messages;
   private final HostPageData.Theme signedOutTheme;
   private final HostPageData.Theme signedInTheme;
   private final SitePaths site;
   private final Document template;
   private final String noCacheName;
   private final boolean refreshHeaderFooter;
   private final SiteStaticDirectoryServlet staticServlet;
   private final boolean isNoteDbEnabled;
   private final Integer pluginsLoadTimeout;
   private final boolean canLoadInIFrame;
   private final GetDiffPreferences getDiff;
   private volatile Page page;

   @Inject
   HostPageServlet(
       Provider<CurrentUser> cu,
       SitePaths sp,
       ThemeFactory themeFactory,
       ServletContext servletContext,
       DynamicSet<WebUiPlugin> webUiPlugins,
       DynamicSet<MessageOfTheDay> motd,
       @GerritServerConfig Config cfg,
       SiteStaticDirectoryServlet ss,
       NotesMigration migration,
       GetDiffPreferences diffPref)
       throws IOException, ServletException {
     currentUser = cu;
     plugins = webUiPlugins;
     messages = motd;
     signedOutTheme = themeFactory.getSignedOutTheme();
     signedInTheme = themeFactory.getSignedInTheme();
     site = sp;
     refreshHeaderFooter = cfg.getBoolean("site", "refreshHeaderFooter", true);
     staticServlet = ss;
     isNoteDbEnabled = migration.readChanges();
     pluginsLoadTimeout = getPluginsLoadTimeout(cfg);
     canLoadInIFrame = cfg.getBoolean("gerrit", "canLoadInIFrame", false);
     getDiff = diffPref;

     String pageName = "HostPage.html";
     template = HtmlDomUtil.parseFile(getClass(), pageName);
     if (template == null) {
       throw new FileNotFoundException("No " + pageName + " in webapp");
     }

     if (HtmlDomUtil.find(template, "gerrit_module") == null) {
       throw new ServletException("No gerrit_module in " + pageName);
     }
     if (HtmlDomUtil.find(template, HPD_ID) == null) {
       throw new ServletException("No " + HPD_ID + " in " + pageName);
     }

     String src = "gerrit_ui/gerrit_ui.nocache.js";
     try (InputStream in = servletContext.getResourceAsStream("/" + src)) {
       if (in != null) {
         Hasher md = Hashing.murmur3_128().newHasher();
         byte[] buf = new byte[1024];
         int n;
         while ((n = in.read(buf)) > 0) {
           md.putBytes(buf, 0, n);
         }
         src += "?content=" + md.hash().toString();
       } else {
         log.debug("No " + src + " in webapp root; keeping noncache.js URL");
       }
     } catch (IOException e) {
       throw new IOException("Failed reading " + src, e);
     }

     noCacheName = src;
     page = new Page();
   }

   private static int getPluginsLoadTimeout(Config cfg) {
     long cfgValue =
         ConfigUtil.getTimeUnit(
             cfg, "plugins", null, "jsLoadTimeout", DEFAULT_JS_LOAD_TIMEOUT, TimeUnit.MILLISECONDS);
     if (cfgValue < 0) {
       return 0;
     }
     return (int) cfgValue;
   }

   private void json(Object data, StringWriter w) {
     JsonServlet.defaultGsonBuilder().create().toJson(data, w);
   }

   private Page get() {
     Page p = page;
     try {
       if (refreshHeaderFooter && p.isStale()) {
         p = new Page();
         page = p;
       }
     } catch (IOException e) {
       log.error("Cannot refresh site header/footer", e);
     }
     return p;
   }

   @Override
   protected void doGet(HttpServletRequest req, HttpServletResponse rsp) throws IOException {
     Page.Content page = select(req);
     StringWriter w = new StringWriter();
     CurrentUser user = currentUser.get();
     if (user.isIdentifiedUser()) {
       w.write(HPD_ID + ".accountDiffPref=");
       json(getDiffPreferences(user.asIdentifiedUser()), w);
       w.write(";");

       w.write(HPD_ID + ".theme=");
       json(signedInTheme, w);
       w.write(";");
     } else {
       w.write(HPD_ID + ".theme=");
       json(signedOutTheme, w);
       w.write(";");
     }
     plugins(w);
     messages(w);

     byte[] hpd = w.toString().getBytes(UTF_8);
     byte[] raw = Bytes.concat(page.part1, hpd, page.part2);
     byte[] tosend;
     if (RPCServletUtils.acceptsGzipEncoding(req)) {
       rsp.setHeader("Content-Encoding", "gzip");
       tosend = HtmlDomUtil.compress(raw);
     } else {
       tosend = raw;
     }

     CacheHeaders.setNotCacheable(rsp);
     rsp.setContentType("text/html");
     rsp.setCharacterEncoding(HtmlDomUtil.ENC.name());
     rsp.setContentLength(tosend.length);
     try (OutputStream out = rsp.getOutputStream()) {
       out.write(tosend);
     }
   }

   private DiffPreferencesInfo getDiffPreferences(IdentifiedUser user) {
     try {
       return getDiff.apply(new AccountResource(user));
     } catch (AuthException | ConfigInvalidException | IOException | PermissionBackendException e) {
       log.warn("Cannot query account diff preferences", e);
     }
     return DiffPreferencesInfo.defaults();
   }

   private void plugins(StringWriter w) {
     List<String> urls = new ArrayList<>();
     for (WebUiPlugin u : plugins) {
       urls.add(String.format("plugins/%s/%s", u.getPluginName(), u.getJavaScriptResourcePath()));
     }
     if (!urls.isEmpty()) {
       w.write(HPD_ID + ".plugins=");
       json(urls, w);
       w.write(";");
     }
   }

   private void messages(StringWriter w) {
     List<HostPageData.Message> list = new ArrayList<>(2);
     for (MessageOfTheDay motd : messages) {
       String html = motd.getHtmlMessage();
       if (!Strings.isNullOrEmpty(html)) {
         HostPageData.Message m = new HostPageData.Message();
         m.id = motd.getMessageId();
         m.redisplay = motd.getRedisplay();
         m.html = html;
         list.add(m);
       }
     }
     if (!list.isEmpty()) {
       w.write(HPD_ID + ".messages=");
       json(list, w);
       w.write(";");
     }
   }

   private Page.Content select(HttpServletRequest req) {
     Page pg = get();
     if ("1".equals(req.getParameter("dbg"))) {
       return pg.debug;
     }
     return pg.opt;
   }

   private void insertETags(Element e) {
     if ("img".equalsIgnoreCase(e.getTagName()) || "script".equalsIgnoreCase(e.getTagName())) {
       String src = e.getAttribute("src");
       if (src != null && src.startsWith("static/")) {
         String name = src.substring("static/".length());
         ResourceServlet.Resource r = staticServlet.getResource(name);
         if (r != null) {
           e.setAttribute("src", src + "?e=" + r.etag);
         }
       }
     }

     for (Node n = e.getFirstChild(); n != null; n = n.getNextSibling()) {
       if (n instanceof Element) {
         insertETags((Element) n);
       }
     }
   }

   private static class FileInfo {
     private final Path path;
     private final long time;

     FileInfo(Path p) {
       path = p;
       time = lastModified(path);
     }

     boolean isStale() {
       return time != lastModified(path);
     }
   }

   private class Page {
     private final FileInfo css;
     private final FileInfo header;
     private final FileInfo footer;
     private final Content opt;
     private final Content debug;

     Page() throws IOException {
       Document hostDoc = HtmlDomUtil.clone(template);

       css = injectCssFile(hostDoc, "gerrit_sitecss", site.site_css);
       header = injectXmlFile(hostDoc, "gerrit_header", site.site_header);
       footer = injectXmlFile(hostDoc, "gerrit_footer", site.site_footer);

       HostPageData pageData = new HostPageData();
       pageData.version = Version.getVersion();
       pageData.isNoteDbEnabled = isNoteDbEnabled;
       pageData.pluginsLoadTimeout = pluginsLoadTimeout;
       pageData.canLoadInIFrame = canLoadInIFrame;

       StringWriter w = new StringWriter();
       w.write("var " + HPD_ID + "=");
       json(pageData, w);
       w.write(";");

       Element data = HtmlDomUtil.find(hostDoc, HPD_ID);
       asScript(data);
       data.appendChild(hostDoc.createTextNode(w.toString()));
       data.appendChild(hostDoc.createComment(HPD_ID));

       Element nocache = HtmlDomUtil.find(hostDoc, "gerrit_module");
       asScript(nocache);
       nocache.removeAttribute("id");
       nocache.setAttribute("src", noCacheName);
       opt = new Content(hostDoc);

       nocache.setAttribute("src", "gerrit_ui/dbg_gerrit_ui.nocache.js");
       debug = new Content(hostDoc);
     }

     boolean isStale() {
       return css.isStale() || header.isStale() || footer.isStale();
     }

     private void asScript(Element scriptNode) {
       scriptNode.setAttribute("type", "text/javascript");
       scriptNode.setAttribute("language", "javascript");
     }

     class Content {
       final byte[] part1;
       final byte[] part2;

       Content(Document hostDoc) throws IOException {
         String raw = HtmlDomUtil.toString(hostDoc);
         int p = raw.indexOf("<!--" + HPD_ID);
         if (p < 0) {
           throw new IOException("No tag in transformed host page HTML");
         }
         part1 = raw.substring(0, p).getBytes(UTF_8);
         part2 = raw.substring(raw.indexOf('>', p) + 1).getBytes(UTF_8);
       }
     }

     private FileInfo injectCssFile(Document hostDoc, String id, Path src) throws IOException {
       FileInfo info = new FileInfo(src);
       Element banner = HtmlDomUtil.find(hostDoc, id);
       if (banner == null) {
         return info;
       }

       while (banner.getFirstChild() != null) {
         banner.removeChild(banner.getFirstChild());
       }

       String css = HtmlDomUtil.readFile(src.getParent(), src.getFileName().toString());
       if (css == null) {
         return info;
       }

       banner.appendChild(hostDoc.createCDATASection("\n" + css + "\n"));
       return info;
     }

     private FileInfo injectXmlFile(Document hostDoc, String id, Path src) throws IOException {
       FileInfo info = new FileInfo(src);
       Element banner = HtmlDomUtil.find(hostDoc, id);
       if (banner == null) {
         return info;
       }

       while (banner.getFirstChild() != null) {
         banner.removeChild(banner.getFirstChild());
       }

       Document html = HtmlDomUtil.parseFile(src);
       if (html == null) {
         return info;
       }

       Element content = html.getDocumentElement();
       insertETags(content);
       banner.appendChild(hostDoc.importNode(content, true));
       return info;
     }
   }
 }
	// Copyright (C) 2008 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.httpd.raw;

	import static com.google.gerrit.common.FileUtil.lastModified;
	import static java.nio.charset.StandardCharsets.UTF_8;

	import com.google.common.base.Strings;
	import com.google.common.hash.Hasher;
	import com.google.common.hash.Hashing;
	import com.google.common.primitives.Bytes;
	import com.google.gerrit.common.Version;
	import com.google.gerrit.common.data.HostPageData;
	import com.google.gerrit.extensions.client.DiffPreferencesInfo;
	import com.google.gerrit.extensions.registration.DynamicSet;
	import com.google.gerrit.extensions.restapi.AuthException;
	import com.google.gerrit.extensions.systemstatus.MessageOfTheDay;
	import com.google.gerrit.extensions.webui.WebUiPlugin;
	import com.google.gerrit.httpd.HtmlDomUtil;
	import com.google.gerrit.server.CurrentUser;
	import com.google.gerrit.server.IdentifiedUser;
	import com.google.gerrit.server.account.AccountResource;
	import com.google.gerrit.server.account.GetDiffPreferences;
	import com.google.gerrit.server.config.ConfigUtil;
	import com.google.gerrit.server.config.GerritServerConfig;
	import com.google.gerrit.server.config.SitePaths;
	import com.google.gerrit.server.notedb.NotesMigration;
	import com.google.gerrit.server.permissions.PermissionBackendException;
	import com.google.gwtexpui.server.CacheHeaders;
	import com.google.gwtjsonrpc.server.JsonServlet;
	import com.google.gwtjsonrpc.server.RPCServletUtils;
	import com.google.inject.Inject;
	import com.google.inject.Provider;
	import com.google.inject.Singleton;
	import java.io.FileNotFoundException;
	import java.io.IOException;
	import java.io.InputStream;
	import java.io.OutputStream;
	import java.io.StringWriter;
	import java.nio.file.Path;
	import java.util.ArrayList;
	import java.util.List;
	import java.util.concurrent.TimeUnit;
	import javax.servlet.ServletContext;
	import javax.servlet.ServletException;
	import javax.servlet.http.HttpServlet;
	import javax.servlet.http.HttpServletRequest;
	import javax.servlet.http.HttpServletResponse;
	import org.eclipse.jgit.errors.ConfigInvalidException;
	import org.eclipse.jgit.lib.Config;
	import org.slf4j.Logger;
	import org.slf4j.LoggerFactory;
	import org.w3c.dom.Document;
	import org.w3c.dom.Element;
	import org.w3c.dom.Node;

	/** Sends the Gerrit host page to clients. */
	@Singleton
	public class HostPageServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	private static final Logger log = LoggerFactory.getLogger(HostPageServlet.class);

	private static final String HPD_ID = "gerrit_hostpagedata";
	private static final int DEFAULT_JS_LOAD_TIMEOUT = 5000;

	private final Provider<CurrentUser> currentUser;
	private final DynamicSet<WebUiPlugin> plugins;
	private final DynamicSet<MessageOfTheDay> messages;
	private final HostPageData.Theme signedOutTheme;
	private final HostPageData.Theme signedInTheme;
	private final SitePaths site;
	private final Document template;
	private final String noCacheName;
	private final boolean refreshHeaderFooter;
	private final SiteStaticDirectoryServlet staticServlet;
	private final boolean isNoteDbEnabled;
	private final Integer pluginsLoadTimeout;
	private final boolean canLoadInIFrame;
	private final GetDiffPreferences getDiff;
	private volatile Page page;

	@Inject
	HostPageServlet(
	Provider<CurrentUser> cu,
	SitePaths sp,
	ThemeFactory themeFactory,
	ServletContext servletContext,
	DynamicSet<WebUiPlugin> webUiPlugins,
	DynamicSet<MessageOfTheDay> motd,
	@GerritServerConfig Config cfg,
	SiteStaticDirectoryServlet ss,
	NotesMigration migration,
	GetDiffPreferences diffPref)
	throws IOException, ServletException {
	currentUser = cu;
	plugins = webUiPlugins;
	messages = motd;
	signedOutTheme = themeFactory.getSignedOutTheme();
	signedInTheme = themeFactory.getSignedInTheme();
	site = sp;
	refreshHeaderFooter = cfg.getBoolean("site", "refreshHeaderFooter", true);
	staticServlet = ss;
	isNoteDbEnabled = migration.readChanges();
	pluginsLoadTimeout = getPluginsLoadTimeout(cfg);
	canLoadInIFrame = cfg.getBoolean("gerrit", "canLoadInIFrame", false);
	getDiff = diffPref;

	String pageName = "HostPage.html";
	template = HtmlDomUtil.parseFile(getClass(), pageName);
	if (template == null) {
	throw new FileNotFoundException("No " + pageName + " in webapp");
	}

	if (HtmlDomUtil.find(template, "gerrit_module") == null) {
	throw new ServletException("No gerrit_module in " + pageName);
	}
	if (HtmlDomUtil.find(template, HPD_ID) == null) {
	throw new ServletException("No " + HPD_ID + " in " + pageName);
	}

	String src = "gerrit_ui/gerrit_ui.nocache.js";
	try (InputStream in = servletContext.getResourceAsStream("/" + src)) {
	if (in != null) {
	Hasher md = Hashing.murmur3_128().newHasher();
	byte[] buf = new byte[1024];
	int n;
	while ((n = in.read(buf)) > 0) {
	md.putBytes(buf, 0, n);
	}
	src += "?content=" + md.hash().toString();
	} else {
	log.debug("No " + src + " in webapp root; keeping noncache.js URL");
	}
	} catch (IOException e) {
	throw new IOException("Failed reading " + src, e);
	}

	noCacheName = src;
	page = new Page();
	}

	private static int getPluginsLoadTimeout(Config cfg) {
	long cfgValue =
	ConfigUtil.getTimeUnit(
	cfg, "plugins", null, "jsLoadTimeout", DEFAULT_JS_LOAD_TIMEOUT, TimeUnit.MILLISECONDS);
	if (cfgValue < 0) {
	return 0;
	}
	return (int) cfgValue;
	}

	private void json(Object data, StringWriter w) {
	JsonServlet.defaultGsonBuilder().create().toJson(data, w);
	}

	private Page get() {
	Page p = page;
	try {
	if (refreshHeaderFooter && p.isStale()) {
	p = new Page();
	page = p;
	}
	} catch (IOException e) {
	log.error("Cannot refresh site header/footer", e);
	}
	return p;
	}

	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse rsp) throws IOException {
	Page.Content page = select(req);
	StringWriter w = new StringWriter();
	CurrentUser user = currentUser.get();
	if (user.isIdentifiedUser()) {
	w.write(HPD_ID + ".accountDiffPref=");
	json(getDiffPreferences(user.asIdentifiedUser()), w);
	w.write(";");

	w.write(HPD_ID + ".theme=");
	json(signedInTheme, w);
	w.write(";");
	} else {
	w.write(HPD_ID + ".theme=");
	json(signedOutTheme, w);
	w.write(";");
	}
	plugins(w);
	messages(w);

	byte[] hpd = w.toString().getBytes(UTF_8);
	byte[] raw = Bytes.concat(page.part1, hpd, page.part2);
	byte[] tosend;
	if (RPCServletUtils.acceptsGzipEncoding(req)) {
	rsp.setHeader("Content-Encoding", "gzip");
	tosend = HtmlDomUtil.compress(raw);
	} else {
	tosend = raw;
	}

	CacheHeaders.setNotCacheable(rsp);
	rsp.setContentType("text/html");
	rsp.setCharacterEncoding(HtmlDomUtil.ENC.name());
	rsp.setContentLength(tosend.length);
	try (OutputStream out = rsp.getOutputStream()) {
	out.write(tosend);
	}
	}

	private DiffPreferencesInfo getDiffPreferences(IdentifiedUser user) {
	try {
	return getDiff.apply(new AccountResource(user));
	} catch (AuthException \| ConfigInvalidException \| IOException \| PermissionBackendException e) {
	log.warn("Cannot query account diff preferences", e);
	}
	return DiffPreferencesInfo.defaults();
	}

	private void plugins(StringWriter w) {
	List<String> urls = new ArrayList<>();
	for (WebUiPlugin u : plugins) {
	urls.add(String.format("plugins/%s/%s", u.getPluginName(), u.getJavaScriptResourcePath()));
	}
	if (!urls.isEmpty()) {
	w.write(HPD_ID + ".plugins=");
	json(urls, w);
	w.write(";");
	}
	}

	private void messages(StringWriter w) {
	List<HostPageData.Message> list = new ArrayList<>(2);
	for (MessageOfTheDay motd : messages) {
	String html = motd.getHtmlMessage();
	if (!Strings.isNullOrEmpty(html)) {
	HostPageData.Message m = new HostPageData.Message();
	m.id = motd.getMessageId();
	m.redisplay = motd.getRedisplay();
	m.html = html;
	list.add(m);
	}
	}
	if (!list.isEmpty()) {
	w.write(HPD_ID + ".messages=");
	json(list, w);
	w.write(";");
	}
	}

	private Page.Content select(HttpServletRequest req) {
	Page pg = get();
	if ("1".equals(req.getParameter("dbg"))) {
	return pg.debug;
	}
	return pg.opt;
	}

	private void insertETags(Element e) {
	if ("img".equalsIgnoreCase(e.getTagName()) \|\| "script".equalsIgnoreCase(e.getTagName())) {
	String src = e.getAttribute("src");
	if (src != null && src.startsWith("static/")) {
	String name = src.substring("static/".length());
	ResourceServlet.Resource r = staticServlet.getResource(name);
	if (r != null) {
	e.setAttribute("src", src + "?e=" + r.etag);
	}
	}
	}

	for (Node n = e.getFirstChild(); n != null; n = n.getNextSibling()) {
	if (n instanceof Element) {
	insertETags((Element) n);
	}
	}
	}

	private static class FileInfo {
	private final Path path;
	private final long time;

	FileInfo(Path p) {
	path = p;
	time = lastModified(path);
	}

	boolean isStale() {
	return time != lastModified(path);
	}
	}

	private class Page {
	private final FileInfo css;
	private final FileInfo header;
	private final FileInfo footer;
	private final Content opt;
	private final Content debug;

	Page() throws IOException {
	Document hostDoc = HtmlDomUtil.clone(template);

	css = injectCssFile(hostDoc, "gerrit_sitecss", site.site_css);
	header = injectXmlFile(hostDoc, "gerrit_header", site.site_header);
	footer = injectXmlFile(hostDoc, "gerrit_footer", site.site_footer);

	HostPageData pageData = new HostPageData();
	pageData.version = Version.getVersion();
	pageData.isNoteDbEnabled = isNoteDbEnabled;
	pageData.pluginsLoadTimeout = pluginsLoadTimeout;
	pageData.canLoadInIFrame = canLoadInIFrame;

	StringWriter w = new StringWriter();
	w.write("var " + HPD_ID + "=");
	json(pageData, w);
	w.write(";");

	Element data = HtmlDomUtil.find(hostDoc, HPD_ID);
	asScript(data);
	data.appendChild(hostDoc.createTextNode(w.toString()));
	data.appendChild(hostDoc.createComment(HPD_ID));

	Element nocache = HtmlDomUtil.find(hostDoc, "gerrit_module");
	asScript(nocache);
	nocache.removeAttribute("id");
	nocache.setAttribute("src", noCacheName);
	opt = new Content(hostDoc);

	nocache.setAttribute("src", "gerrit_ui/dbg_gerrit_ui.nocache.js");
	debug = new Content(hostDoc);
	}

	boolean isStale() {
	return css.isStale() \|\| header.isStale() \|\| footer.isStale();
	}

	private void asScript(Element scriptNode) {
	scriptNode.setAttribute("type", "text/javascript");
	scriptNode.setAttribute("language", "javascript");
	}

	class Content {
	final byte[] part1;
	final byte[] part2;

	Content(Document hostDoc) throws IOException {
	String raw = HtmlDomUtil.toString(hostDoc);
	int p = raw.indexOf("<!--" + HPD_ID);
	if (p < 0) {
	throw new IOException("No tag in transformed host page HTML");
	}
	part1 = raw.substring(0, p).getBytes(UTF_8);
	part2 = raw.substring(raw.indexOf('>', p) + 1).getBytes(UTF_8);
	}
	}

	private FileInfo injectCssFile(Document hostDoc, String id, Path src) throws IOException {
	FileInfo info = new FileInfo(src);
	Element banner = HtmlDomUtil.find(hostDoc, id);
	if (banner == null) {
	return info;
	}

	while (banner.getFirstChild() != null) {
	banner.removeChild(banner.getFirstChild());
	}

	String css = HtmlDomUtil.readFile(src.getParent(), src.getFileName().toString());
	if (css == null) {
	return info;
	}

	banner.appendChild(hostDoc.createCDATASection("\n" + css + "\n"));
	return info;
	}

	private FileInfo injectXmlFile(Document hostDoc, String id, Path src) throws IOException {
	FileInfo info = new FileInfo(src);
	Element banner = HtmlDomUtil.find(hostDoc, id);
	if (banner == null) {
	return info;
	}

	while (banner.getFirstChild() != null) {
	banner.removeChild(banner.getFirstChild());
	}

	Document html = HtmlDomUtil.parseFile(src);
	if (html == null) {
	return info;
	}

	Element content = html.getDocumentElement();
	insertETags(content);
	banner.appendChild(hostDoc.importNode(content, true));
	return info;
	}
	}
	}