/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2006, Red Hat Middleware LLC, and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.jboss.web;

import EDU.oswego.cs.dl.util.concurrent.ConcurrentReaderHashMap;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.InetAddress;
import java.net.MalformedURLException;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.URL;
import java.security.AccessController;
import java.util.Properties;
import java.util.concurrent.Executor;
import org.jboss.logging.Logger;
import org.jboss.util.loading.ContextClassLoaderSwitcher;
import org.jboss.util.loading.ContextClassLoaderSwitcher.SwitchContext;

/**
 * A mini webserver that should be embedded in another application. It can
 * server any file that is available from classloaders that are registered with
 * it, including class-files.
 *
 * Its primary purpose is to simplify dynamic class-loading in RMI. Create an
 * instance of it, register a classloader with your classes, start it, and
 * you'll be able to let RMI-clients dynamically download classes from it.
 *
 * It is configured by calling any methods programmatically prior to startup.
 * @author <a href="mailto:marc@jboss.org">Marc Fleury</a>
 * @author <a href="mailto:Scott.Stark@org.jboss">Scott Stark</a>
 * @authro <a href="mailto:dimitris@jboss.org">Dimitris Andreadis</a>
 * @version $Revision: 99507 $
 * @see WebClassLoader
 */
public class WebServer
   implements Runnable
{
   // Constants -----------------------------------------------------

   // Attributes ----------------------------------------------------
   private static Logger log = Logger.getLogger(WebServer.class);
   
   /**
    * The port the web server listens on
    */
   private int port = 8083;

   /**
    * The interface to bind to. This is useful for multi-homed hosts that want
    * control over which interfaces accept connections.
    */
   private InetAddress bindAddress;
   
   /**
    * The serverSocket listen queue depth
    */
   private int backlog = 50;

   /**
    * The map of class loaders registered with the web server
    */
   private final ConcurrentReaderHashMap loaderMap = new ConcurrentReaderHashMap();
   
   /**
    * The web server http listening socket
    */
   private ServerSocket server = null;
   
   /**
    * A flag indicating if the server should attempt to download classes from
    * thread context class loader when a request arrives that does not have a
    * class loader key prefix.
    */
   private boolean downloadServerClasses = true;
   
   /**
    * A flag indicating if the server should attempt to download resources,
    * i.e. resource paths that don't end in .class
    */
   private boolean downloadResources = false;
   
   /**
    * The class wide mapping of type suffixes(class, txt) to their mime type
    * string used as the Content-Type header for the vended classes/resources
    */
   private static final Properties mimeTypes = new Properties();
   
   /**
    * The thread pool used to manage listening threads
    */
   private Executor executor;
   
   private final ContextClassLoaderSwitcher tclSwitcher;
   
   // Constructors --------------------------------------------------

   public WebServer()
   {
      @SuppressWarnings("unchecked")
      ContextClassLoaderSwitcher clSwitcher = (ContextClassLoaderSwitcher) AccessController.doPrivileged(ContextClassLoaderSwitcher.INSTANTIATOR);
      this.tclSwitcher = clSwitcher;
   }
   // Public --------------------------------------------------------

   /**
    * Set the http listening port
    */
   public void setPort(int port)
   {
      this.port = port;
   }

   /**
    * Get the http listening port
    * @return the http listening port
    */
   public int getPort()
   {
      return port;
   }

   /**
    * Set the http server bind address
    * @param bindAddress
    */
   public void setBindAddress(InetAddress bindAddress)
   {
      this.bindAddress = bindAddress;
      
   }
   
   /**
    * Get the address the http server binds to
    * @return the http bind address
    */
   public InetAddress getBindAddress()
   {
      return bindAddress;
   }

   /**
    * Get the server sockets listen queue depth
    * @return the listen queue depth
    */
   public int getBacklog()
   {
      return backlog;
   }

   /**
    * Set the server sockets listen queue depth
    */
   public void setBacklog(int backlog)
   {
      if (backlog <= 0)
         backlog = 50;
      
      this.backlog = backlog;
   }

   public boolean getDownloadServerClasses()
   {
      return downloadServerClasses;
   }

   public void setDownloadServerClasses(boolean flag)
   {
      downloadServerClasses = flag;
   }

   public boolean getDownloadResources()
   {
      return downloadResources;
   }

   public void setDownloadResources(boolean flag)
   {
      downloadResources = flag;
   }

   public Executor getThreadPool()
   {
      return executor;
   }

   public void setThreadPool(Executor executor)
   {
      this.executor = executor;
   }

   /**
    * Augment the type suffix to mime type mappings
    * @param extension - the type extension without a period(class, txt)
    * @param type - the mime type string
    */
   public void addMimeType(String extension, String type)
   {
      mimeTypes.put(extension, type);
   }

   /**
    * Start the web server on port and begin listening for requests.
    */
   public void start() throws Exception
   {
      if (executor == null)
         throw new IllegalArgumentException("Required property 'executor' not specified");
      
      try
      {
         server = new ServerSocket(port, backlog, bindAddress);
         log.debug("Started server: " + server);
         
         listen();
      }
      catch(java.net.BindException be)
      {
           throw new Exception("Port "+port+" already in use.",be);
      }
      catch (IOException e)
      {
         throw e;
      }
   }

   /**
    * Close the web server listening socket
    */
   public void stop()
   {
      try
      {
         ServerSocket srv = server;
         server = null;
         srv.close();
      }
      catch (Exception ignore) {}
   }

   /**
    * Add a class loader to the web server map and return the URL that should be
    * used as the annotated codebase for classes that are to be available via
    * RMI dynamic classloading. The codebase URL is formed by taking the
    * java.rmi.server.codebase system property and adding a subpath unique for
    * the class loader instance.
    * @param cl - the ClassLoader instance to begin serving download requests
    * for
    * @return the annotated codebase to use if java.rmi.server.codebase is set,
    *         null otherwise.
    * @see #getClassLoaderKey(ClassLoader)
    */
   public URL addClassLoader(ClassLoader cl)
   {
      String key = (cl instanceof WebClassLoader) ?
         ((WebClassLoader) cl).getKey() :
         getClassLoaderKey(cl);
      loaderMap.put(key, cl);
      URL loaderURL = null;
      String codebase = System.getProperty("java.rmi.server.codebase");
      if (codebase != null)
      {
         if (codebase.endsWith("/") == false)
            codebase += '/';
         codebase += key;
         codebase += '/';
         try
         {
            loaderURL = new URL(codebase);
         }
         catch (MalformedURLException e)
         {
            log.error("invalid url", e);
         }
      }
      log.trace("Added ClassLoader: " + cl + " URL: " + loaderURL);
      return loaderURL;
   }

   /**
    * Remove a class loader previously added via addClassLoader
    * @param cl - the ClassLoader previously added via addClassLoader
    */
   public void removeClassLoader(ClassLoader cl)
   {
      String key = getClassLoaderKey(cl);
      loaderMap.remove(key);
   }

   // Runnable implementation ---------------------------------------
   /**
    * Listen threads entry point. Here we accept a client connection and located
    * requested classes/resources using the class loader specified in the http
    * request.
    */
   public void run()
   {
      // Return if the server has been stopped
      if (server == null)
         return;

      // Accept a connection
      Socket socket = null;
      try
      {
         socket = server.accept();
      }
      catch (IOException e)
      {
         // If the server is not null meaning we were not stopped report the err
         if (server != null)
            log.error("Failed to accept connection", e);
         return;
      }

      // Create a new thread to accept the next connection
      listen();

      try
      {
         // Get the request socket output stream
         DataOutputStream out = new DataOutputStream(socket.getOutputStream());
         try
         {
            String httpCode = "200 OK";
            // Get the requested item from the HTTP header
            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            String rawPath = getPath(in);

            // Parse the path into the class loader key and file path.
            //
            // The class loader key is a string whose format is
            // "ClassName[oid]",  where the oid substring may contain '/'
            // chars. The expected form of the raw path is:
            //
            //     "SomeClassName[some/object/id]/some/file/path"
            //
            // The class loader key is "SomeClassName[some/object/id]"
            // and the file path is "some/file/path"

            int endOfKey = rawPath.indexOf(']');
            String filePath = rawPath.substring(endOfKey + 2);
            String loaderKey = rawPath.substring(0, endOfKey + 1);
            log.trace("loaderKey = " + loaderKey);
            log.trace("filePath = " + filePath);
            ClassLoader loader = (ClassLoader) loaderMap.get(loaderKey);
            /* If we did not find a class loader check to see if the raw path
               begins with className + '[' + class loader key + ']' by looking for
               an '[' char. If it does not and downloadServerClasses is true use
               the thread context class loader and set filePath to the rawPath
            */
            if (loader == null && rawPath.indexOf('[') < 0 && downloadServerClasses)
            {
               filePath = rawPath;
               log.trace("No loader, reset filePath = " + filePath);
               loader = Thread.currentThread().getContextClassLoader();
            }
            log.trace("loader = " + loader);
            byte[] bytes = {};
            SwitchContext tclSwitchContext = null; 
            try
            {
               tclSwitchContext = this.tclSwitcher.getSwitchContext(this.getClass().getClassLoader());
               if (loader != null && filePath.endsWith(".class"))
               {
                  // A request for a class file
                  String className = filePath.substring(0, filePath.length() - 6).replace('/', '.');
                  log.trace("loading className = " + className);
                  Class<?> clazz = loader.loadClass(className);
                  URL clazzUrl = clazz.getProtectionDomain().getCodeSource().getLocation();
                  log.trace("clazzUrl = " + clazzUrl);
                  if (clazzUrl == null)
                  {
                     // Does the WebClassLoader of clazz
                     // have the ability to obtain the bytecodes of clazz?
                     bytes = ((WebClassLoader) clazz.getClassLoader()).getBytes(clazz);
                     if (bytes == null)
                        throw new Exception("Class not found: " + className);
                  }
                  else
                  {
                     if (clazzUrl.getFile().endsWith("/") == false)
                     {
                        clazzUrl = new URL("jar:" + clazzUrl + "!/" + filePath);
                     }
                     // this is a hack for the AOP ClassProxyFactory
                     else if (clazzUrl.getFile().indexOf("/org_jboss_aop_proxy$") < 0)
                     {
                        clazzUrl = new URL(clazzUrl, filePath);
                     }
   
                     // Retrieve bytecodes
                     log.trace("new clazzUrl: " + clazzUrl);
                     bytes = getBytes(clazzUrl);
                  }
               }
               else if (loader != null && filePath.length() > 0 && downloadServerClasses && downloadResources)
               {
                  // Try getting resource
                  log.trace("loading resource = " + filePath);
                  URL resourceURL = loader.getResource(filePath);
                  if (resourceURL == null)
                     httpCode = "404 Resource not found:" + filePath;
                  else
                  {
                     // Retrieve bytes
                     log.trace("resourceURL = " + resourceURL);
                     bytes = getBytes(resourceURL);
                  }
               }
               else
               {
                  httpCode = "404 Not Found";
               }
            }
            finally
            {
               if (tclSwitchContext != null)
               {
                  tclSwitchContext.reset();
               }
            }


            // Send bytecodes/resource data in response (assumes HTTP/1.0 or later)
            try
            {
               log.trace("HTTP code=" + httpCode + ", Content-Length: " + bytes.length);
               // The HTTP 1.0 header
               out.writeBytes("HTTP/1.0 " + httpCode + "\r\n");
               out.writeBytes("Content-Length: " + bytes.length + "\r\n");
               out.writeBytes("Content-Type: " + getMimeType(filePath));
               out.writeBytes("\r\n\r\n");
               // The response body
               out.write(bytes);
               out.flush();
            }
            catch (IOException ie)
            {
               return;
            }
         }
         catch (Throwable e)
         {
            try
            {
               log.trace("HTTP code=404, " + e.getMessage());
               // Write out error response
               out.writeBytes("HTTP/1.0 404 Not Found\r\n");
               out.writeBytes("Content-Type: text/html\r\n\r\n");
               out.flush();
            }
            catch (IOException ex)
            {
               // Ignore
            }
         }
         finally
         {
            
         }
      }
      catch (IOException ex)
      {
         log.error("error writting response", ex);
      }
      finally
      {
         // Close the client request socket
         try
         {
            socket.close();
         }
         catch (IOException e)
         {
         }
      }
   }

   // Protected -----------------------------------------------------
   /**
    * Create the string key used as the key into the loaderMap.
    * @return The class loader instance key.
    */
   protected String getClassLoaderKey(ClassLoader cl)
   {
      String className = cl.getClass().getName();
      int dot = className.lastIndexOf('.');
      if (dot >= 0)
         className = className.substring(dot + 1);
      String key = className + '[' + cl.hashCode() + ']';
      return key;
   }

   protected void listen()
   {
      executor.execute(this);
   }

   /**
    * @return the path portion of the HTTP request header.
    */
   protected String getPath(BufferedReader in) throws IOException
   {
      String line = in.readLine();
      log.trace("raw request=" + line);
      // Find the request path by parsing the 'REQUEST_TYPE filePath HTTP_VERSION' string
      int start = line.indexOf(' ') + 1;
      int end = line.indexOf(' ', start + 1);
      // The file minus the leading '/'
      String filePath = line.substring(start + 1, end);
      return filePath;
   }

   /**
    * Read the local class/resource contents into a byte array.
    */
   protected byte[] getBytes(URL url) throws IOException
   {
      InputStream in = new BufferedInputStream(url.openStream());
      log.debug("Retrieving " + url);
      ByteArrayOutputStream out = new ByteArrayOutputStream();
      byte[] tmp = new byte[1024];
      int bytes;
      while ((bytes = in.read(tmp)) != -1)
      {
         out.write(tmp, 0, bytes);
      }
      in.close();
      return out.toByteArray();
   }

   /**
    * Lookup the mime type for the suffix of the path argument.
    * @return the mime-type string for path.
    */
   protected String getMimeType(String path)
   {
      int dot = path.lastIndexOf(".");
      String type = "text/html";
      if (dot >= 0)
      {
         // The suffix is the type extension without the '.'
         String suffix = path.substring(dot + 1);
         String mimeType = mimeTypes.getProperty(suffix);
         if (mimeType != null)
            type = mimeType;
      }
      return type;
   }

}
