// Copyright (C) 2009 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.pgm.http.jetty;

import static java.util.concurrent.TimeUnit.MILLISECONDS;
import static java.util.concurrent.TimeUnit.SECONDS;

import com.google.common.base.Strings;
import com.google.gerrit.extensions.events.LifecycleListener;
import com.google.gerrit.pgm.http.jetty.HttpLog.HttpLogFactory;
import com.google.gerrit.reviewdb.client.AuthType;
import com.google.gerrit.server.config.GerritServerConfig;
import com.google.gerrit.server.config.SitePaths;
import com.google.inject.Inject;
import com.google.inject.Injector;
import com.google.inject.Singleton;
import com.google.inject.servlet.GuiceFilter;
import com.google.inject.servlet.GuiceServletContextListener;

import org.eclipse.jetty.http.HttpScheme;
import org.eclipse.jetty.jmx.MBeanContainer;
import org.eclipse.jetty.server.Connector;
import org.eclipse.jetty.server.ForwardedRequestCustomizer;
import org.eclipse.jetty.server.Handler;
import org.eclipse.jetty.server.HttpConfiguration;
import org.eclipse.jetty.server.HttpConnectionFactory;
import org.eclipse.jetty.server.Request;
import org.eclipse.jetty.server.SecureRequestCustomizer;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.server.ServerConnector;
import org.eclipse.jetty.server.SslConnectionFactory;
import org.eclipse.jetty.server.handler.ContextHandler;
import org.eclipse.jetty.server.handler.ContextHandlerCollection;
import org.eclipse.jetty.server.handler.RequestLogHandler;
import org.eclipse.jetty.server.session.SessionHandler;
import org.eclipse.jetty.servlet.DefaultServlet;
import org.eclipse.jetty.servlet.FilterHolder;
import org.eclipse.jetty.servlet.ServletContextHandler;
import org.eclipse.jetty.servlet.ServletHolder;
import org.eclipse.jetty.util.BlockingArrayQueue;
import org.eclipse.jetty.util.log.Log;
import org.eclipse.jetty.util.ssl.SslContextFactory;
import org.eclipse.jetty.util.thread.QueuedThreadPool;
import org.eclipse.jetty.util.thread.ThreadPool;
import org.eclipse.jgit.lib.Config;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.lang.management.ManagementFactory;
import java.net.URI;
import java.net.URISyntaxException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.EnumSet;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import javax.servlet.DispatcherType;
import javax.servlet.Filter;

@Singleton
public class JettyServer {
  private static final Logger log = LoggerFactory.getLogger(JettyServer.class);

  static class Lifecycle implements LifecycleListener {
    private final JettyServer server;
    private final Config cfg;

    @Inject
    Lifecycle(final JettyServer server, @GerritServerConfig final Config cfg) {
      this.server = server;
      this.cfg = cfg;
    }

    @Override
    public void start() {
      try {
        String origUrl = cfg.getString("httpd", null, "listenUrl");
        boolean rewrite = !Strings.isNullOrEmpty(origUrl)
            && origUrl.endsWith(":0/");
        server.httpd.start();
        if (rewrite) {
          Connector con = server.httpd.getConnectors()[0];
          if (con instanceof ServerConnector) {
            @SuppressWarnings("resource")
            ServerConnector serverCon = (ServerConnector)con;
            String host = serverCon.getHost();
            int port = serverCon.getLocalPort();
            String url = String.format("http://%s:%d", host, port);
            cfg.setString("gerrit", null, "canonicalWebUrl", url);
            cfg.setString("httpd", null, "listenUrl", url);
          }
        }
      } catch (Exception e) {
        throw new IllegalStateException("Cannot start HTTP daemon", e);
      }
    }

    @Override
    public void stop() {
      try {
        server.httpd.stop();
        server.httpd.join();
      } catch (Exception e) {
        throw new IllegalStateException("Cannot stop HTTP daemon", e);
      }
    }
  }

  private final SitePaths site;
  private final Server httpd;

  private boolean reverseProxy;

  @Inject
  JettyServer(@GerritServerConfig final Config cfg, final SitePaths site,
      final JettyEnv env, final HttpLogFactory httpLogFactory) {
    this.site = site;

    httpd = new Server(threadPool(cfg));
    httpd.setConnectors(listen(httpd, cfg));

    Handler app = makeContext(env, cfg);
    if (cfg.getBoolean("httpd", "requestLog", !reverseProxy)) {
      RequestLogHandler handler = new RequestLogHandler();
      handler.setRequestLog(httpLogFactory.get());
      handler.setHandler(app);
      app = handler;
    }
    if (cfg.getBoolean("httpd", "registerMBeans", false)) {
      MBeanContainer mbean =
          new MBeanContainer(ManagementFactory.getPlatformMBeanServer());
      httpd.addEventListener(mbean);
      httpd.addBean(Log.getRootLogger());
      httpd.addBean(mbean);
    }

    httpd.setHandler(app);
    httpd.setStopAtShutdown(false);
  }

  private Connector[] listen(Server server, Config cfg) {
    // OpenID and certain web-based single-sign-on products can cause
    // some very long headers, especially in the Referer header. We
    // need to use a larger default header size to ensure we have
    // the space required.
    //
    final int requestHeaderSize =
        cfg.getInt("httpd", "requestheadersize", 16386);
    final URI[] listenUrls = listenURLs(cfg);
    final boolean reuseAddress = cfg.getBoolean("httpd", "reuseaddress", true);
    final int acceptors = cfg.getInt("httpd", "acceptorThreads", 2);
    final AuthType authType = cfg.getEnum("auth", null, "type", AuthType.OPENID);

    reverseProxy = isReverseProxied(listenUrls);
    final Connector[] connectors = new Connector[listenUrls.length];
    for (int idx = 0; idx < listenUrls.length; idx++) {
      final URI u = listenUrls[idx];
      final int defaultPort;
      final ServerConnector c;
      HttpConfiguration config = defaultConfig(requestHeaderSize);

      if (AuthType.CLIENT_SSL_CERT_LDAP.equals(authType) && ! "https".equals(u.getScheme())) {
        throw new IllegalArgumentException("Protocol '" + u.getScheme()
            + "' " + " not supported in httpd.listenurl '" + u
            + "' when auth.type = '" + AuthType.CLIENT_SSL_CERT_LDAP.name()
            + "'; only 'https' is supported");
      }

      if ("http".equals(u.getScheme())) {
        defaultPort = 80;
        c = newServerConnector(server, acceptors, config);

      } else if ("https".equals(u.getScheme())) {
        SslContextFactory ssl = new SslContextFactory();
        final Path keystore = getFile(cfg, "sslkeystore", "etc/keystore");
        String password = cfg.getString("httpd", null, "sslkeypassword");
        if (password == null) {
          password = "gerrit";
        }
        ssl.setKeyStorePath(keystore.toAbsolutePath().toString());
        ssl.setTrustStorePath(keystore.toAbsolutePath().toString());
        ssl.setKeyStorePassword(password);
        ssl.setTrustStorePassword(password);

        if (AuthType.CLIENT_SSL_CERT_LDAP.equals(authType)) {
          ssl.setNeedClientAuth(true);

          Path crl = getFile(cfg, "sslcrl", "etc/crl.pem");
          if (Files.exists(crl)) {
            ssl.setCrlPath(crl.toAbsolutePath().toString());
            ssl.setValidatePeerCerts(true);
          }
        }

        defaultPort = 443;

        config.addCustomizer(new SecureRequestCustomizer());
        c = new ServerConnector(server,
            null, null, null, 0, acceptors,
            new SslConnectionFactory(ssl, "http/1.1"),
            new HttpConnectionFactory(config));

      } else if ("proxy-http".equals(u.getScheme())) {
        defaultPort = 8080;
        config.addCustomizer(new ForwardedRequestCustomizer());
        c = newServerConnector(server, acceptors, config);

      } else if ("proxy-https".equals(u.getScheme())) {
        defaultPort = 8080;
        config.addCustomizer(new ForwardedRequestCustomizer());
        config.addCustomizer(new HttpConfiguration.Customizer() {
          @Override
          public void customize(Connector connector,
              HttpConfiguration channelConfig, Request request) {
            request.setScheme(HttpScheme.HTTPS.asString());
            request.setSecure(true);
          }
        });
        c = newServerConnector(server, acceptors, config);

      } else {
        throw new IllegalArgumentException("Protocol '" + u.getScheme() + "' "
            + " not supported in httpd.listenurl '" + u + "';"
            + " only 'http', 'https', 'proxy-http, 'proxy-https'"
            + " are supported");
      }

      try {
        if (u.getHost() == null && (u.getAuthority().equals("*") //
            || u.getAuthority().startsWith("*:"))) {
          // Bind to all local addresses. Port wasn't parsed right by URI
          // due to the illegal host of "*" so replace with a legal name
          // and parse the URI.
          //
          final URI r =
              new URI(u.toString().replace('*', 'A')).parseServerAuthority();
          c.setHost(null);
          c.setPort(0 < r.getPort() ? r.getPort() : defaultPort);
        } else {
          final URI r = u.parseServerAuthority();
          c.setHost(r.getHost());
          c.setPort(0 <= r.getPort() ? r.getPort() : defaultPort);
        }
      } catch (URISyntaxException e) {
        throw new IllegalArgumentException("Invalid httpd.listenurl " + u, e);
      }

      c.setReuseAddress(reuseAddress);
      connectors[idx] = c;
    }
    return connectors;
  }

  private static ServerConnector newServerConnector(Server server,
      int acceptors, HttpConfiguration config) {
    return new ServerConnector(server, null, null, null, 0, acceptors,
        new HttpConnectionFactory(config));
  }

  private HttpConfiguration defaultConfig(int requestHeaderSize) {
    HttpConfiguration config = new HttpConfiguration();
    config.setRequestHeaderSize(requestHeaderSize);
    config.setSendServerVersion(false);
    config.setSendDateHeader(true);
    return config;
  }

  static boolean isReverseProxied(final URI[] listenUrls) {
    for (URI u : listenUrls) {
      if ("http".equals(u.getScheme()) || "https".equals(u.getScheme())) {
        return false;
      }
    }
    return true;
  }

  static URI[] listenURLs(final Config cfg) {
    String[] urls = cfg.getStringList("httpd", null, "listenurl");
    if (urls.length == 0) {
      urls = new String[] {"http://*:8080/"};
    }

    final URI[] r = new URI[urls.length];
    for (int i = 0; i < r.length; i++) {
      final String s = urls[i];
      try {
        r[i] = new URI(s);
      } catch (URISyntaxException e) {
        throw new IllegalArgumentException("Invalid httpd.listenurl " + s, e);
      }
    }
    return r;
  }

  private Path getFile(Config cfg, String name, String def) {
    String path = cfg.getString("httpd", null, name);
    if (path == null || path.length() == 0) {
      path = def;
    }
    return site.resolve(path);
  }

  private ThreadPool threadPool(Config cfg) {
    int maxThreads = cfg.getInt("httpd", null, "maxthreads", 25);
    int minThreads = cfg.getInt("httpd", null, "minthreads", 5);
    int maxQueued = cfg.getInt("httpd", null, "maxqueued", 200);
    int idleTimeout = (int)MILLISECONDS.convert(60, SECONDS);
    int maxCapacity = maxQueued == 0
        ? Integer.MAX_VALUE
        : Math.max(minThreads, maxQueued);
    QueuedThreadPool pool = new QueuedThreadPool(
        maxThreads,
        minThreads,
        idleTimeout,
        new BlockingArrayQueue<Runnable>(
            minThreads, // capacity,
            minThreads, // growBy,
            maxCapacity // maxCapacity
    ));
    pool.setName("HTTP");
    return pool;
  }

  private Handler makeContext(final JettyEnv env, final Config cfg) {
    final Set<String> paths = new HashSet<>();
    for (URI u : listenURLs(cfg)) {
      String p = u.getPath();
      if (p == null || p.isEmpty()) {
        p = "/";
      }
      while (1 < p.length() && p.endsWith("/")) {
        p = p.substring(0, p.length() - 1);
      }
      paths.add(p);
    }

    final List<ContextHandler> all = new ArrayList<>();
    for (String path : paths) {
      all.add(makeContext(path, env, cfg));
    }

    if (all.size() == 1) {
      // If we only have one context path in our web space, return it
      // without any wrapping so Jetty has less work to do per-request.
      //
      return all.get(0);
    } else {
      // We have more than one path served out of this container so
      // combine them in a handler which supports dispatching to the
      // individual contexts.
      //
      final ContextHandlerCollection r = new ContextHandlerCollection();
      r.setHandlers(all.toArray(new Handler[0]));
      return r;
    }
  }

  private ContextHandler makeContext(final String contextPath,
      final JettyEnv env, final Config cfg) {
    final ServletContextHandler app = new ServletContextHandler();

    // This enables the use of sessions in Jetty, feature available
    // for Gerrit plug-ins to enable user-level sessions.
    //
    app.setSessionHandler(new SessionHandler());
    app.setErrorHandler(new HiddenErrorHandler());

    // This is the path we are accessed by clients within our domain.
    //
    app.setContextPath(contextPath);

    // HTTP front-end filter to be used as surrogate of Apache HTTP
    // reverse-proxy filtering.
    // It is meant to be used as simpler tiny deployment of custom-made
    // security enforcement (Security tokens, IP-based security filtering, others)
    String filterClassName = cfg.getString("httpd", null, "filterClass");
    if (filterClassName != null) {
      try {
        @SuppressWarnings("unchecked")
        Class<? extends Filter> filterClass =
            (Class<? extends Filter>) Class.forName(filterClassName);
        Filter filter = env.webInjector.getInstance(filterClass);
        app.addFilter(new FilterHolder(filter), "/*",
            EnumSet.of(DispatcherType.REQUEST, DispatcherType.ASYNC));
      } catch (Throwable e) {
        String errorMessage =
            "Unable to instantiate front-end HTTP Filter " + filterClassName;
        log.error(errorMessage, e);
        throw new IllegalArgumentException(errorMessage, e);
      }
    }

    // Perform the same binding as our web.xml would do, but instead
    // of using the listener to create the injector pass the one we
    // already have built.
    //
    GuiceFilter filter = env.webInjector.getInstance(GuiceFilter.class);
    app.addFilter(new FilterHolder(filter), "/*", EnumSet.of(
        DispatcherType.REQUEST,
        DispatcherType.ASYNC));
    app.addEventListener(new GuiceServletContextListener() {
      @Override
      protected Injector getInjector() {
        return env.webInjector;
      }
    });

    // Jetty requires at least one servlet be bound before it will
    // bother running the filter above. Since the filter has all
    // of our URLs except the static resources, the only servlet
    // we need to bind is the default static resource servlet from
    // the Jetty container.
    //
    final ServletHolder ds = app.addServlet(DefaultServlet.class, "/");
    ds.setInitParameter("dirAllowed", "false");
    ds.setInitParameter("redirectWelcome", "false");
    ds.setInitParameter("useFileMappedBuffer", "false");
    ds.setInitParameter("gzip", "true");

    app.setWelcomeFiles(new String[0]);
    return app;
  }
}