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

public class WebSearch {
    /**
     * The string which is input by the user to end the search.
     */
    protected static final String QUITSTRING = "quit";

    /**
     * The Vector of URLs initialized by the constructor.
     */
    protected Vector urlWords;

    /** 
     * Creates a WebSearch object for the specified URLs.
     *
     * @param urls  is a vector of URL objects.
     */
    public WebSearch(Vector urls) {
	urlWords = new Vector();
	Iterator i = urls.iterator();
	while (i.hasNext()) {
	    urlWords.add(new URLWords((URL) i.next()));
	}
    }

    /**
     * Determines if the user wants to end the web search.
     *
     * @param line  is a String to be tested.
     * @return      true if the user wants to end the web search, otherwise
     *              false. 
     */
    public boolean isStopCondition(String line) {
	return line.equals(QUITSTRING);
    }

    /**
     * Extracts words from the given string.
     *
     * @param line  is a String to be processed. 
     * @return      a Vector of Strings containing the words in the input
     *              String. 
     */
    public Vector parseLine(String line) {
	StringTokenizer st = new StringTokenizer(line);
	Vector words = new Vector();

	while (st.hasMoreTokens())
	    words.add(st.nextToken().toLowerCase());

	return words;
    }

    /**
     * Prints the URLs in the instance variable urlWords which contain all of
     * the given words.
     *
     * @param searchWords  is a Vector of Strings to be searched for. 
     */
    public void printURLsContainingWords(Vector searchWords) {
	Iterator i = urlWords.iterator();
	while (i.hasNext()) {
	    URLWords current = (URLWords) i.next();
	    if (current.containsWords(searchWords))
		System.out.println(current.getURL());
	}
    }

    /**
     * Until the user types quit, prompts the user to enter words to search for
     * and then outputs, on separate lines, the URLs of all the web pages in the
     * instance variable urlWords that contain all of the search words.
     */
    public void start() {
	if (urlWords.size() == 0) {
	    System.out.println("No valid URLs to search.");
	    return;
	}

	String prompt = getClass().getName() +"> ";
	BufferedReader br
	    = new BufferedReader(new InputStreamReader(System.in));

	try {
	    System.out.print(prompt);
	    String line = br.readLine();

	    while (!isStopCondition(line)) {
		Vector searchWords = parseLine(line);
		printURLsContainingWords(searchWords);

		System.out.println();
		System.out.print(prompt);
		line = br.readLine();
	    }
	}

	catch (IOException e) {
	}
    }

    /**
     * Takes a list of URLs from the command line, attempts to create
     * corresponding URL objects for them and starts the web search.
     *
     * @param args  a list URLs as an array of Strings.
     */
    public static void main(String args[]) {
	Vector urls = new Vector();
	int arg = 0;

	while (arg < args.length) {
	    try {
		urls.add(new URL(args[arg]));
	    }
	    catch (MalformedURLException e) {
		System.out.println("Ignoring bad URL: " + args[arg]);
	    }
	    arg++;
	}

	WebSearch webSearch = new WebSearch(urls);
	webSearch.start();
    }
}