package HashCracker;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.concurrent.CountDownLatch;

public class Cracker {
    // Array of chars used to produce strings
    public static final char[] CHARS = "abcdefghijklmnopqrstuvwxyz0123456789.,-!".toCharArray();

    public Cracker(){

    }
    /*
     Given a byte[] array, produces a hex String,
     such as "234a6f". with 2 chars for each byte in the array.
     (provided code)
    */
    public static String hexToString(byte[] bytes) {
        StringBuffer buff = new StringBuffer();
        for (int i=0; i<bytes.length; i++) {
            int val = bytes[i];
            val = val & 0xff;  // remove higher bits, sign
            if (val<16) buff.append('0'); // leading 0
            buff.append(Integer.toString(val, 16));
        }
        return buff.toString();
    }

    /*
     Given a string of hex byte values such as "24a26f", creates
     a byte[] array of those values, one byte value -128..127
     for each 2 chars.
     (provided code)
    */
    public static byte[] hexToArray(String hex) {
        byte[] result = new byte[hex.length()/2];
        for (int i=0; i<hex.length(); i+=2) {
            result[i/2] = (byte) Integer.parseInt(hex.substring(i, i+2), 16);
        }
        return result;
    }

    // possible test values:
    // a 86f7e437faa5a7fce15d1ddcb9eaeaea377667b8
    // fm adeb6f2a18fe33af368d91b09587b68e3abcb9a7
    // a! 34800e15707fae815d7c90d49de44aca97e2d759
    // xyz 66b27417d37e024c46526c2f6d358a754fc552f3

    public String generateHash(String string) throws NoSuchAlgorithmException {
        MessageDigest md = MessageDigest.getInstance("SHA");

        string = hexToString(string.getBytes());
        byte[] byteArray = md.digest(hexToArray(string));
        string = hexToString(byteArray);
        return string;
    }

    public static void main(String[] args) throws NoSuchAlgorithmException, InterruptedException {

        String result = "";
        Cracker cracker = new Cracker();

        if(args.length == 1) {
            result = cracker.generateHash(args[0]);
            System.out.println(result);
        }
        else if(args.length == 3) {
            String hashValue = args[0];
            Integer maxChars = Integer.parseInt(args[1]);
            Integer numWorkers = Integer.parseInt(args[2]);
            Integer workNumber;
            CountDownLatch doneSignal = new CountDownLatch(numWorkers);

            for(int i = 0; i < numWorkers; i++) {
                workNumber = i;
                new Worker(cracker, hashValue, maxChars, numWorkers, workNumber, CHARS, doneSignal).start();
                doneSignal.await();
            }
            System.out.println("All Done");
        }
    }
}