import java.net.*;
import java.io.*;
import java.util.*;

/*
 * <em>EasyWebServer</em> is a simple web server that can provide limited
 * service. Specifically, it can return one of the three pages:<p>
 * <ol>
 *   <li> the main home page which contains a couple real links,
 *   <li> a <em>sample.html</em> page which contains other forms of html
 *   components such as images and lists, and
 *   <li> a <em>search</em> page that can take input data from the browser
 * </ol>
 *
 * @author Xiannong Meng xmeng@bucknell.edu
 *  Fall 2002
 * Revised Fall 2003, 2004, 2006
 *
 */
public class EasyWebServer 
{

    public static void main(String[] args)
	throws IOException
    {
	if (args.length != 1)
	    {
		System.out.println("usage java EasyWebServer port");
		System.exit(-1);
	    }

	PORT = Integer.parseInt(args[0]);
	/* open a server socket at the given port */
	ServerSocket server = new ServerSocket(PORT);

	String inBuffer;

	/* the server is running forever (when not crashed :0) */
	for (;;) 
	{
	    try 
	    {
		/* accept an incoming connection request */
		Socket sock = server.accept();

                /* prepare for input and output stream */
                BufferedReader sockIn = new BufferedReader
		                          (new InputStreamReader
                                          (sock.getInputStream()));
		DataOutputStream sockOut = 
                    new DataOutputStream(sock.getOutputStream());

		inBuffer = readAll(sockIn);

		http_data = Http.ParseToken(inBuffer);

		// echo the command, for debug purposes
		System.out.print("inBuffer : " + inBuffer);
		System.out.println();
		System.out.println("!"+http_data.get("content-length")+"!");

		// now process the command, return results when required
		processHTTPCmd(inBuffer, sockIn, sockOut);

		/* close the connection */
		sock.close();
	    } catch (IOException ignored) {}
	}
    }


    /*
     * Reads and returns all the information from a client (browser).
     * This typically is a request (get or post) from a client.<p>
     *
     * @param fileIn a pointer to the buffered reader where the client 
     *               sends in the information.
     * @author Xiannong Meng
     */
    public static String readAll(BufferedReader fileIn)
    {
       String inBuffer = "";
       try
       {

          String line;
	  do 
	  {
              line = fileIn.readLine();
	      inBuffer += line + "\r\n";
	      //	  System.out.print("in readAll -> " + line + "<-");
              if (line.length() == 2 && line.compareTo("\r\n") == 0)
              {
                System.out.println("we hit the break in readAll");
                break;
              }
	  } while (line.length() > 0);
	}
	catch (IOException ignored) {};
	  System.out.println("\n end of readAll -> " + inBuffer + "<-");
	return inBuffer;
    }

    /*
     * Process the request (cmd) by a client. Determine what to
     * do based on the parsing result. <p>
     * 
     * The results are directly written to the output stream back
     * to the client.<p>
     *
     * @param cmd the client request
     * @param sockIn socket input stream
     * @param sockOut socket output stream
     *
     * @author Xiannong Meng
     *
     */

    public static void processHTTPCmd(String cmd,
                                      BufferedReader sockIn,
                                      DataOutputStream sockOut)
    {
	String operation;       // the operation requested
	String path;            // the path to the HTML doc
	String version;         // version of http
	int    returnStatus = 200;   
	                        // status of operation
	long   returnLength = 0;   
                                // length of the doc to return
	boolean isForm = false; // by default it is not a form input

	/* take the input command and split it into tokens */
	/* here is an example of the command               */
        /* get /path http/1.0 \r\n                         */
	StringTokenizer tokens = new StringTokenizer(cmd, " \r\n");
	operation = (tokens.nextToken()).toUpperCase();
	path      = tokens.nextToken();
	version   = (tokens.nextToken()).toUpperCase();

	/* for debugging purpose */
	System.out.println("operation: " + operation);
	System.out.println("path: " + path);
	System.out.println("version: " + version);

	/* check for a request that we dont' understand */
	if ((operation.compareTo("GET") != 0 && 
	    operation.compareTo("POST") != 0) || 
	    ((version.compareTo("HTTP/1.0") != 0) 
	     && (version.compareTo("HTTP/1.1") != 0)))
        {
	    returnStatus = 400;
	    returnLength = ERROR_400.length();
	}
	else /* the request is trying to get some HTML page */
	    if (path.compareTo("/") == 0)
	    {
		returnStatus = 200;
		returnLength = HOME_PAGE.length();
	    }
	    else if (path.compareTo("/sample.html") == 0)
	    {
		returnStatus = 200;
		File f = new File("sample.html");
		returnLength = f.length();
	    }
	    else if (path.compareTo("/search") == 0)
	    {
		returnStatus = 200;
		File f = new File("form.html");
		returnLength = f.length();
	    }
	    else if (path.compareTo("/cross.gif") == 0)
	    {
		returnStatus = 200;
		File f = new File("cross.gif");
		returnLength = f.length();
	    }
	    else if (path.compareTo("/form") == 0)
		isForm = true;
	    else /* the page is unknown */
	    {
		returnStatus = 404;
		returnLength = ERROR_404.length();
	    }

	/* now that we know what to do, send the result back */
	if (isForm == true)  // this is a form request
        {
	    processForm(sockIn, sockOut);
	}
	else
	    try
	    {
		if (path.compareTo("/cross.gif") == 0)
		   sendHeader(sockOut, returnStatus, returnLength, "image/gif");
                else
		   sendHeader(sockOut, returnStatus, returnLength, "text/html");
		switch (returnStatus) 
		{
		case 200:      // send the page requested
		    if (path.compareTo("/") == 0)
			sockOut.writeBytes(HOME_PAGE);  // short page
		    else if (path.compareTo("/sample.html") == 0)
			openAndSendFile(sockOut, "sample.html"); // long page
		    else if (path.compareTo("/cross.gif") == 0)
			openAndSendFile(sockOut, "cross.gif"); // image page
		    else 
			openAndSendFile(sockOut, "form.html");   // a test form
		    break;
		case 400:
		    sockOut.writeBytes(ERROR_400);
		    break;
		case 404:
		    sockOut.writeBytes(ERROR_404);
		    break;
		}
	    } catch (IOException ignored) {}
	
    }

    /*
     * Send the returning header to the client, based on the return
     * status. The response must follow the HTTP protocol.<p>
     *
     * @param out output stream of the socket
     * @param returnStatus the numerical code for the returning status
     * @param contentLength the length of the content (not the header)
     * @param contentType the type of the return content
     *
     * @author Xiannong Meng
     *
     */
    static void sendHeader(DataOutputStream out, 
			   int returnStatus,
			   long contentLength,
                           String contentType)
    {
	String statusStr;
	String returnContent;

	switch (returnStatus)
	{
	case 200: 
	    statusStr = "OK";
	    break;
	case 400: 
	    statusStr = "Bad Request";
	    break;
	case 404: 
	    statusStr = "Not Found";
	    break;
	default:  
	    statusStr = "Unknown";
	    break;
	}
	
	/*
	 * send an HTTP/1.0 response with Server, Content-Length,
	 * and Content-Type headers.
	 */
        try
        {
	returnContent = "HTTP/1.0 " + returnStatus + " " + statusStr + "\r\n";
	out.writeBytes(returnContent);

	returnContent = "Server: " + SERVER_NAME + "\r\n";
	out.writeBytes(returnContent);

	returnContent = "Content-Length: " + contentLength + "\r\n";
	out.writeBytes(returnContent);

	returnContent = "Content-Type: " + contentType + "\r\n";
	out.writeBytes(returnContent);

	returnContent = "\r\n";
	out.writeBytes(returnContent);
        }
        catch (IOException ignored){}
    }


    /*
     * Send the file requested to the output stream (client).<p>
     * 
     * @param out output stream to the client.
     * @param fileToSend string name of the file to be sent.
     *
     * @author Xiannong Meng
     *
     */
    static void openAndSendFile(DataOutputStream out, String fileToSend)
    {
	try
	{
	    DataInputStream fileIn = new DataInputStream
					   (new FileInputStream
					    (new File(fileToSend)));
	    
            File f = new File(fileToSend);
            long length = f.length();
	    byte[] content = new byte[(int)length];

	    fileIn.readFully(content);
            out.write(content);
	} catch (IOException ignored) {};
    }

    /*
     * Process the form sent from the client. The content of the form 
     * has been stored in http_data, a member of the class.<p>
     *
     * @param sockIn input stream from the client.
     * @param sockOut output stream to the client
     *
     */
  public static void processForm(BufferedReader sockIn,
                                 DataOutputStream sockOut)
  {
      try
      {

	  String inBuffer;
	  String returnString = "";

	  int returnStatus;
	  int returnLength;

	  int dataLength = Integer.parseInt
	      (((String)http_data.get("content-length")).trim());

          System.out.println("data length " + dataLength);

	  char[] inChars = new char[dataLength];

	  sockIn.read(inChars, 0, dataLength);

          inBuffer = new String(inChars);


	  // for debugging only
	  System.out.print(inBuffer);

	  //
	  // Parse the CGI input string
	  //
	  Hashtable form_data = Html.ParseToken(inBuffer);
	  
	  //
	  //  Print out each of the name/value pairs
	  //  from sent from the browser.
	  //
	  returnString += Html.Variables(form_data);
	  returnString += "<hr>";
	  
	  //
	  // Create the Bottom of the returned HTML page - which closes it cleanly.
	  //
	  returnString += Html.HtmlBot();

	  //
	  // Print the required CGI header.
	  //
	  returnStatus = 200;
	  returnLength = returnString.length();

	  sendHeader(sockOut, returnStatus, returnLength, "text/html");

	  // 
	  // Send back the contents
	  //
	  sockOut.writeBytes(returnString);
      }
      catch (IOException ignored) {};
  }

    /* this is the class data segments */

    static int PORT;  // the port used for communication

    static Hashtable http_data;  // HTTP header infromation from client
    

    // name of the server
    static String SERVER_NAME	= "CSCI 335 Project Web Server";

    // error message 400
    static String ERROR_400	= "<head></head><body><html><h1>Error 400</h1><p>The server couldn't understand your request.</html></body>\n";

    // error message 404
    static String ERROR_404	= "<head></head><body><html><h1>Error 404</h1><p>Document not found.</html></body>\n";

    // a simple, short home page
    static String HOME_PAGE	= "<head></head><body><html><h1>Welcome to the CSCI 335 Demo Server</h1><p>Why not visit: <ul><li><a href=\"http://www.eg.bucknell.edu/\">Bucknell College of Engineering Home Page</a><li><a href=\"http://www.orgs.bucknell.edu/acm/\">Bucknell ACM Home Page<a></ul></html></body>\n";
}