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

public class URLLexer
	{
	// These are the 7 tokens in our simplified URL definition
	public static final int PROTOCOL = 0;
	public static final int NUMERICAL_ADDRESS = 1;
	public static final int NON_NUMERICAL_ADDRESS = 2;
	public static final int PORT = 3;
	public static final int FILE = 4;
	public static final int FRAGMENT = 5;
	public static final int QUERY = 6;
	
	// Here you place regular expressions, one per token.  Each is a string.
	public static final String[] REGULAR_EXPRESSION = 
		new String[]
			{
			"Not Defined Yet",  // protocol
			"Not Defined Yet.  This one will be very long.", // numerical address
			"Not Defined Yet", // non-numerical address
			"Not Defined Yet", // port
			"Not Defined Yet", // file
			"Not Defined Yet", // fragment
			"Not Defined Yet", // query
			};

	// This is an array of names for each of the tokens, which might be convenient for you to
	// use to print out stuff.
	public static final String[] NAME = new String[] { "protocol", "numerical address", "non-numerical address",
													   "port", "file", "fragment", "query" };
	
	/** Creates a Blank URLLexer set up to do pattern-matching on the given regular expressions. */
	public URLLexer()
		{
		// IMPLEMENT ME (ABOUT 5 LINES)
		}
	
	/** Resets the URLLexer to a new string as input. */
	public void reset(String input)
		{
		// IMPLEMENT ME (ABOUT 3 LINES)
		}
	
	public int getMatchingIndex()
		{
		// IMPLEMENT ME (ABOUT 1 LINE)
		}
		
	public int getPosition()
		{ 
		// IMPLEMENT ME (ABOUT 1 LINE)
		}
	
	public String nextToken()
		{
		// IMPLEMENT ME (ABOUT 10 LINES)
		}

	public static void main(String[] args) throws IOException
		{
		// IMPLEMENT ME.
		//
		// You will repeatedly request a URL by printing "URL: ".  Once the user has provided
		// a URL, you will trim it of whitespace, then tokenize it.  As you tokenize it you 
		// will print out the tokens one
		// by one, including their token types.  If you find a duplicate token type, you will
		// FAIL.  You will also FAIL if the tokenizer cannot recognize any further tokens but
		// you still have characters left to tokenize.  If you manage to finish tokenizing
		// a URL, you will pass the tokens to the fetch(...) function provided below.  Whenever
		// a failure occurs, you will indicate it, then loop again to request another URL.
		}



	// perhaps this function might come in use.
	// It takes various tokenized values, checks them for validity, then fetches the data
	// from a URL formed by them and prints it to the screen.
	public static void fetch(String protocol, String numericalAddress, String nonNumericalAddress,
							String port, String file, String query, String fragment)
		{
		String address = numericalAddress;
		int iport = 80;

		// verify the URL
		if (protocol == null || !protocol.equals("http://"))
			{
			System.out.println("ERROR. I don't know how to use protocol " + protocol);
			}
		else if (query != null)
			{
			System.out.println("ERROR. I'm not smart enough to issue queries, like " + query); 
			}
		else if (numericalAddress == null && nonNumericalAddress == null)
			{
			System.out.println("ERROR. No address was provided.");
			}
		else if (numericalAddress != null && nonNumericalAddress != null)
			{
			System.out.println("ERROR. Both types of addresses were provided.");
			}
		else
			{
			if (address == null)
				{
				address = nonNumericalAddress;
				}
			if (fragment != null)
				{
				System.out.println("NOTE. Fragment provided: I will not use it.");
				}
			if (port != null)
				{
				iport = Integer.parseInt(port.substring(1));  // strip off the ":"
				}
			else
				{
				System.out.println("NOTE. No port provided, defaulting to port 80.");
				}
			if (file == null)
				{
				System.out.println("NOTE. No file was provided.  Assuming it's just /");
				file = "/";
				}
			
			System.out.println("Downloading ADDRESS: " + address + " PORT: " + iport + " FILE: " + file);
			System.out.println("\n=======================================");
	
			java.io.InputStream stream = null;
			try
				{				
				java.net.URL url = new java.net.URL("http", address, iport, file);
				java.net.URLConnection connection = url.openConnection();
				connection.connect();
				stream = connection.getInputStream();
				final int BUFLEN = 1024;
				byte[] buffer = new byte[BUFLEN];
				while(true)
					{
					int len = stream.read(buffer, 0, BUFLEN);
					if (len <= 0) break;
					System.out.write(buffer, 0, len);
					}
				}
			catch (java.io.IOException e)
				{
				System.out.println("Error fetching data.");
				}
			try
				{
				if (stream != null) stream.close();
				}
			catch (java.io.IOException e) { }
			System.out.println("\n=======================================");
			}
		}
	}