import java.io.*; 
import javax.servlet.*; 
import javax.servlet.http.*; 
import java.sql.*;
import java.util.Date;
import java.util.*;

// Servlet - implements a guest book.
public class GuestBook extends HttpServlet { 
	Connection con;
	Statement stmt;
	Properties props;

	// Init gets called once and thats it.
	// Loads the properties (using the base.dir redirection) and
	// connects to the DB.
	public void init(ServletConfig conf) throws ServletException { 
		super.init(conf); 
		try {
			loadProperties();
			Class.forName( props.getProperty( "login.jdbc" ));
			con = DriverManager.getConnection( props.getProperty( "login.url"), 
				props.getProperty( "login.user" ), props.getProperty( "login.passwd" ));
			stmt = con.createStatement();
		}
		catch( Exception e ) {
			throw new ServletException( e.toString());
		}
	} 

	// Get a new key value
	// Perform work in a transaction - commit at the end.
	private int getKey( int id ) throws Exception {
		con.setAutoCommit(false );
		ResultSet rs = stmt.executeQuery( "select val from key_table where id = "+id );
		int val = 0;
		 
		if( rs.next()) {
			val = rs.getInt( "val" ) + 1;
			stmt.executeUpdate( "update key_table set val = "+val+" where id = "+id );
		}
		else {
			stmt.executeUpdate( "insert into key_table values( "+id+", 0)" );
		}
		con.commit();
		con.setAutoCommit( true );
		return val;
	}
		
	// Handle individual requests
	public void service(HttpServletRequest req, HttpServletResponse res) 
		throws IOException{ 
		//Get a channel to the Web browser, so we can send output 
		ServletOutputStream out = res.getOutputStream(); 
		res.setContentType("text/html"); // Required for HTTP 

		try {
			out.print( props.getProperty( "html.title" )); 

			if( req.getParameter( "enter" ) != null ) {
				out.print( props.getProperty( "html.header.form" ));
				showForm( req, out );
			}
			else if( req.getParameter( "name" ) != null ) {
				addEntries( req );
				out.print( props.getProperty( "html.header.list" ));
				listEntries( req, out );
			}
			else {
				out.print( props.getProperty( "html.header.list" ));
				listEntries( req, out );
			}
		}
		catch( Exception e ) {
			throw new IOException( e.toString());
		}								 
		finally {
			out.print( props.getProperty( "html.footer" ));
			out.close();
		}
	}


	// Load the properties - use the "base.dir" property to locate property file.
	// The 'base.dir' directory is a public readable/writable directory wherein 
	// servlet developers may place their property files.
	private void loadProperties( ) throws IOException {
		props = new Properties();
		props.load( new FileInputStream( System.getProperty( "base.dir" )+
			"GuestBook.properties" ));
	}


	// Contruct a URL to this Servlet - for <A HREF's later.
	private String getURL( HttpServletRequest req ) {
		return req.getRequestURI();
	}
	
	
	// Print the DB guestbook entries.
	private void listEntries( HttpServletRequest req, ServletOutputStream out ) throws Exception {
		ResultSet rs = stmt.executeQuery( "select * from guest_book");

		out.print( "<TABLE>" );
		while( rs.next()) {
			String email = rs.getString( "email" );
			String comment = rs.getString( "comment" );
			String name = rs.getString( "name" );
			String addr = rs.getString( "addr" );
			String tnbgColor = props.getProperty( "table.name.bgcolor" )!=null?
				(" BGCOLOR="+props.getProperty( "table.name.bgcolor" )) :
				"";

			out.print( "<TR"+tnbgColor+"><TD>" );
			if( email != null && email.length() > 1 )
				out.print( "<A HREF=\"mailto:"+email+"\">"+name+"</A>" );
			else
				out.print( name );

			out.print( "</TD><TD>"+rs.getString( "time" )+"</TD></TR>" );
			out.print( "</TR>" );

			if( addr != null ) 
				out.print( "<TR><TD COLSPAN=2><EM>"+addr+"</EM></TD></TR>" );

			if( comment != null ) 
				out.print( "<TR><TD COLSPAN=2>"+comment+"</TD></TR>" );

			out.print( "<TR><TD COLSPAN=2><BR></TD></TR>" );
		}
		out.print( "</TABLE>" );
	}


	// Display the form
	private void showForm( HttpServletRequest req, ServletOutputStream out ) throws Exception {
		out.print( "<FORM METHOD=post ACTION=\""+getURL( req )+"\">");
		out.print( "<TABLE VALIGN=TOP>" );
		out.print( "<TR><TD>Name</TD><TD><INPUT TYPE=text NAME=name SIZE=30></TD></TR>" );
		out.print( "<TR><TD>Address</TD><TD><INPUT TYPE=text NAME=addr SIZE=30></TD></TR>" );
		out.print( "<TR><TD>Email</TD><TD><INPUT TYPE=text NAME=email SIZE=30></TD></TR>" );
		out.print( "<TR><TD VALIGN=TOP>Comment</TD><TD><TEXTAREA NAME=comment COLS=40 ROWS=5></TEXTAREA></TD></TR><BR>" );
		out.print( "</TABLE>" );
		out.print( "<INPUT TYPE=submit VALUE=\"Submit\"></FORM>" );
	}
	

	// Replace 'from's in the comment text with 'to's
	private String replace( String s, String from, String to ) {
		StringBuffer sb = new StringBuffer();
		int idx = 0;
		int ldx = 0;

		// copy the fragments between 'from's
		while(( idx = s.indexOf( from, ldx )) != -1 ) {
			sb.append( s.substring( ldx, idx ));
			sb.append( to );
			ldx = idx+1;
		}

		// No more 'from's - make sure to copy the rest
		if( ldx < s.length()) {
			sb.append( s.substring( ldx ));
		}

		return new String( sb );
	}


	// Add the new comment to the guestbook table. Only proceed if the length of the name supplied
	// is longer than 0 chars.
	private void addEntries( HttpServletRequest req ) throws Exception {
		String name = req.getParameter( "name" );
		
		if( name.length() > 0 ) {
			String comment = (req.getParameter( "comment")!=null)?req.getParameter( "comment"):"";
			String email = (req.getParameter( "email" )!=null)?req.getParameter( "email" ):"";
			String addr = (req.getParameter( "addr" )!=null)?req.getParameter( "addr" ):"";

			stmt.executeUpdate( "insert into guest_book values( "+getKey( 1 )+",'','"+
				name+"','"+addr+"','"+email+"','now','"+
				replace( replace( comment, "\n", "<BR>" ), "'", "''" )+"')"); 
		}
	}
}