// GetPrice
//
// Copyright 2004 by Jeff Heaton (http://www.jeffheaton.com/)
//
// This is a very simple example program that shows how to use a Bot
// to look a price on Amazon.com. All you have to do is call the
// getPrice method with the ISBN of a book, and the program will
// query Amazon for the current price of that book.
//
// This program works as of December 14,2004. However, if Amazon
// changes the format of their HTML, this program will no longer
// work.
//
// This program is for educational purposes only. It is up to you
// to make sure that it is legal to use this program for what ever
// purpose you plan use it for. I offer no warranty nor do I accept
// any responsibility for the use of this program.
//

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

public class GetPrice
{
  double getPrice(String isbn)
    throws MalformedURLException,IOException
  {
    byte buffer[] = new byte[1024];
    String result = "";

    // construct the proper URL for the book
    URL url = new URL("http://www.amazon.com/exec/obidos/tg/detail/-/"+isbn);
    InputStream is = url.openStream();

    // now read the entire contents of the web page
    boolean done = false;
    while(!done)
    {
      int i = is.read(buffer);
      if( i!=-1 )
        result = result + new String(buffer,0,i);
      else
        done = true;
    }

    // find the price, it is enclosed by token1 and token2
    final String token1 = "<span class=listprice>$";
    final String token2 = "</span>";
    int indexToken1 = result.indexOf(token1);

    if( indexToken1==-1 )
      return 0;

    indexToken1+=token1.length();
    int indexToken2 = result.indexOf(token2,indexToken1);

    if( indexToken2==-1 )
      return 0;

    // Extract the price and convert to a double
    String strPrice = result.substring(indexToken1,indexToken2);
    double price = Double.parseDouble(strPrice);

    return price;
  }

  public static void main(String args[])
  {
    try
    {
      String isbn = "0782140408";
      GetPrice price = new GetPrice();
      System.out.println("The price for ISBN#" + isbn + " is: " + price.getPrice("0782140408") );
    }
    catch(Exception e)
    {
      e.printStackTrace();
    }
  }
}