DamnDownloader7

//This program is used to essentially download every image from DamnLOL.com
//By entering the first link of a damnlol page, the program will save that image to your computer
//then go to the previous page and download that picture
//It will continue until you stop the program
//DamnDownloader7 Fixes: Ability to stop if repeats are found
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.net.URL;
import java.nio.channels.Channels;
import java.nio.channels.ReadableByteChannel;
import java.util.Scanner;


public class DamnDownloader7 {


    public static void main(String[] args) throws IOException {
        System.out.println("About DamnDownloader:");
        System.out.println("This program will essentially download every image from DamnLOL");
        System.out.println("It will start at your link, then move to PREVIOUS pages");
        System.out.println("Enter the DamnLOL URL to start with. Include http and www:");
        Scanner userInput = new Scanner(System.in);
        String theURL = userInput.next();
        System.out.println("Stop the program when a duplicate is found? Yes or No");
        String repeatQuit = userInput.next();
        System.out.println("Press Ctrl + C to stop the program");

        URL link = new URL(theURL);//Created the first URL using the link above

        //Sets up the first filename
        String damnLOLFront = "";
        damnLOLFront = theURL.substring(23, theURL.length()-5);

        String nextURL = "";//Sets up nextURL
        boolean finished = false;//Stops the program when the last page is reached
        boolean startFinish = false;//Stops the program when the last page is reached
        while(finished == false){

            //Stops the program when the last page is reached
            if( nextURL.equals("http://www.damnlol.com/gonna-buy-my-girl-one-of-these-1.html")){//The comic ends at comic 15. This if statement will stop the program
                startFinish = true;
            }

            //This section downloads the HTML page
            ReadableByteChannel rbc = Channels.newChannel(link.openStream());//Gets the html page
            FileOutputStream fos = new FileOutputStream("page.html");//Creates the output name of the html page to be saved to the computer
            fos.getChannel().transferFrom(rbc, 0, 1 << 24);
            Scanner sc = new Scanner(new FileReader("page.html"));//Takes the downloaded HTML page and sends it to a scanner




            //This section converts the html page to the string
            String contents = "";
            while(sc.hasNextLine() || sc.hasNext()){
                contents = contents + sc.nextLine() + "\n"; //Contents is the html page as a string!
            }
            sc.close();//Closes the scanner file



            //This finds the next url to scan!
            Scanner sc2 = new Scanner(contents);//Takes the string version of the html page and sends it to a new scanner
            int counter = 0;//The previous page's url is on line 8, so I use this int as a counter
            while((sc2.hasNext() || sc2.hasNextLine()) && (counter != 8)){
            nextURL = sc2.findWithinHorizon("http://www.damnlol.com/.*[.]html", 0);//This grabs the url and saves it to a string
            theURL = nextURL;
            counter += 1;//Adds one to the counter so it will stop at 8
            }
            link = new URL(nextURL);//This now sets link as the newly found url so when the program starts back at the top it will now download this HTML page
            //Ends next url!


            //This section finds the image to download
            sc2 = new Scanner(contents);//Sends the html to a scanner
            String theImage = "";
            int counter2 = 0;//I think that the image url is on line 2 so I need a counter
            while((sc2.hasNext() || sc2.hasNextLine()) && (counter2 != 2)){
            theImage = sc2.findWithinHorizon("http://www.damnlol.com/.*[.][jJpPgG][pPnNiI][eE]?[gGfF]", 0);//This finds the image's url and saves it to a string
            counter2 += 1;//Adds one to my counter
            }
            //Ends finding image



            //This section determines the file extension

                String imageType = "";
                if(theImage.matches("[h][t][t][p][:][/][/][w][w][w][.][d][a][m][n][l][o][l][.][c][o][m][/].*[.][jJ][pP][gG]")){
                    imageType = ".jpg";
                }
                if(theImage.matches("[h][t][t][p][:][/][/][w][w][w][.][d][a][m][n][l][o][l][.][c][o][m][/].*[.][jJ][pP][eE][gG]")){
                    imageType = ".jpeg";
                }
                if(theImage.matches("[h][t][t][p][:][/][/][w][w][w][.][d][a][m][n][l][o][l][.][c][o][m][/].*[.][pP][nN][gG]")){
                    imageType = ".png";
                }
                if(theImage.matches("[h][t][t][p][:][/][/][w][w][w][.][d][a][m][n][l][o][l][.][c][o][m][/].*[.][gG][iI][Ff]")){
                    imageType = ".gif";
                }




            //This section saves the image itself
            URL link2 = new URL(theImage);//A new URL is created with the image's url that was found
            String damnLOLLinkFinal = damnLOLFront + imageType;//The string that will be used to name the file

            //Skips the file if it exists
            boolean exists = (new File(damnLOLLinkFinal)).exists();
            if(exists){
                if(repeatQuit.equals("Yes") || repeatQuit.equals("yes")){
                    System.out.println("Duplicate found. Program Stopped.");
                    System.exit(0);
                }
                else{
                    System.out.println(damnLOLLinkFinal + " already exists. Skipping.");
                }
            }
            else{
                ReadableByteChannel rbc2 = Channels.newChannel(link2.openStream());//Gets the image
                FileOutputStream fos2 = new FileOutputStream(damnLOLLinkFinal);//The output of the file name
                fos2.getChannel().transferFrom(rbc2, 0, 1 << 24);
                System.out.println("Image Saved: " + damnLOLLinkFinal);//Prints the name of the file that is saved
                //Ends saving the image
            }

            //Sets up new file
            damnLOLFront = nextURL.substring(23, nextURL.length()-5);

            //Quits program when at last page
            if(startFinish == true){
                System.out.println("All images downloaded!");
                System.exit(0);
            }

        }
    }

}