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

// This "Web server" will return HTML files (only) that it finds in
// the directory where it is run (or its subdirectories).

// You must specify port 8080 in the URL entered into your browser.


public class TrivialHTTPD {

    public static void main(String [] args) throws Exception {

        ServerSocket server = new ServerSocket(8080);

        while (true) {
            Socket sock = server.accept() ;

            BufferedReader in =
              new BufferedReader(new InputStreamReader(sock.getInputStream()));

            String req = in.readLine();
            readRemainder(in) ;

            System.out.println("Got request header: " + req) ;

            String fileName = getFileName(req) ;

            DataOutputStream out =
                    new DataOutputStream(sock.getOutputStream());

            byte [] fileContents = readBytes("." + fileName) ;
            if(getExtension(fileName).equals("html") && fileContents != null) {
                out.writeBytes("HTTP/1.0 200 OK\r\n");
                out.writeBytes("Content-Length: " + fileContents.length + "\r\n");
                out.writeBytes("Content-Type: text/html\r\n\r\n");
                out.write(fileContents);
            } else
                out.writeBytes("HTTP/1.0 404 Not Found\r\n\r\n");
            out.close();
        }
    }

    /**
      * Skips over remaining lines of HTTP header, till empty line.
      */

    static void readRemainder(BufferedReader in) throws IOException {
	while(true) {
	    String line = in.readLine();
	    if(line == null || line.length() == 0 ||
	       line.charAt(0) == '\r' || line.charAt(0) == '\n') break ;
	}
    }

    /**
      * Gets the file name from the method field.
      */

    static String getFileName(String header) {
	String result = header.substring(4);  // Strip off "GET "

	int i = result.indexOf(' ');
	return result.substring(0, i);     // Strip off protocol version
    }

    /**
      * Naively extracts extension from a filename
      */

    static String getExtension(String fileName) {
       int j = fileName.indexOf('.');
       return fileName.substring(j + 1);   // file extension
    }

    /**
      * Reads all bytes in a file.
      */

    static byte [] readBytes(String name) {
	try {
	    File f = new File(name) ;

	    DataInputStream din =
		new DataInputStream(new FileInputStream(f));

	    byte[] bytes = new byte[(int) f.length()];
	    din.readFully(bytes);
	    din.close();

	    return bytes ;
	} catch (IOException e) {
	    return null ;
	}
   }

}