import java.util.Scanner;
import java.net.URL;
import java.io.PrintWriter;
import java.io.File;
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.util.HashSet;

/**
 * @author Moshe Kaplan [email protected]
 * @version 2011.03.26
 * @since 1.6
 *
 *      The purpose of this class is to download every picture on a thread
 */
public class Downloader {

    /**
     * A simple main class to test functionality.
     *
     * @param args [0] The first URL to download a comic from (oldest comic of the series, or the first one you're missing)
     */
    public static void main(String[] args)
            throws java.net.MalformedURLException, java.io.IOException {
        if (args.length < 1) {
            System.out.println("You must put in a URL as a source");
            System.exit(1);
        }
        Downloader test = new Downloader();
        String next = test.getPage(args[0]);
        while (!next.equals(""))
            next = test.getPage(next);
    }

    /**
     * Downloads a page, the image, and returns the URL of the next page
     *
     * Downloads page. Scans the page for the URL of the image. Parses out the
     * date of the comic, and calls gifURLtoFile to download and save the
     * picture. Scans the page for the URL of the Next button, and returns that
     *
     * @param surl A string representation of a URL to download
     * @return The next page.
     *
     */
    public String getPage(String surl) {
        String nextURL = "";
        try {
            URL url = new URL(surl);
            try {
                Scanner scan = new Scanner(url.openStream());
                while (scan.hasNextLine()) {
                    String data = scan.nextLine();
                    // find URL for next page
                    if (data.matches(".*title=\"Next Page.*")) {
                        // find last href=" , from there, till next "
                        int y = data.lastIndexOf("Next Page");
                        int x = data.substring(0,y).lastIndexOf("href=");

                        nextURL = data.substring(x+6);
                        nextURL = nextURL.substring(0,nextURL.indexOf("\""));
                    }
                    // now to find the URL of the image
                    while (data.matches(".*src=\".*\".*")) {
                        //System.out.println(data);
                        // extract URL
                        int x = data.indexOf("src=\"");
                        int y = data.indexOf("\"", x + 5);
                        String fileURL = data.substring(x + 5, y);
                        data = data.substring(y);
                        if( fileURL.matches(".*fohguild.org/forums/.*") || fileURL.matches(".*fohguild.org/forums/.*") ||
                            fileURL.matches(".*scorecardresearch.com.*")|| fileURL.matches(".*pixel.quantserve.com.*"))
                            break;
                        // extract format
                        String format = fileURL.substring(fileURL.lastIndexOf(".") + 1);
                        // Save picture to file
                        gifURLtoFile(new URL(fileURL), number.toString(), format);

                    }

                }

            } catch (java.io.IOException e) {
                System.out.println("Unable to connect to: " + surl);
            }

        } catch (java.net.MalformedURLException e) {
            System.out.println("Invalid URL");
            System.out.println(surl);
        }
        return nextURL;
    }

    /**
     * Saves a gif from a URL to a file
     *
     * @param url The URL of the gif picture
     * @param filename The name to save the gif as.
     */
    public void gifURLtoFile(URL url, String filename, String format) {
        try {
            BufferedImage temp = ImageIO.read(url);
            if(temp != null && !hashes.contains(url.hashCode()) ){
                System.out.println("Now Downloading: " + url + " as " + number);
                ImageIO.write(temp, format, new File(filename + "." + format));
                ++number;
                hashes.add(url.hashCode());
            }
        } catch (Exception e) {
            System.out.println("Error Saving file at: " + url + " as " + filename);
        }
    }

    private Integer number=0;
    private HashSet<Integer> hashes = new HashSet<Integer>();

}