package com.software.util;

import java.util.*;
import java.text.*;
import java.security.*;

public class CryptCode {

    private final static String sMappingList = "$6kl!784mx~HIp?qr/s@tu;v[bw%JKL:oMV^cyz{eWX&gY>fZ-01#23.ST(Un5<AB)9NO+PQ]RC}DEF|G_da,hi*j";
    private final static int nMappingLength = 89;

    // This function uses to encrypt a string to an encrypted string.
    public CryptCode(){
    }

    public static String Encrypt( String sInputText ) {
        String sBeforeMapping = "";
        String sAfterMapping = "";
        String sEncrypted_string = "";
        int nRotation = getRotationNo();

        int i = 0, j = 0, k = 0;

        sBeforeMapping = sInputText; //.toUpperCase();
        int nEndIndex = sBeforeMapping.length();
        char a;
        char b[] = new char[nEndIndex];

        // Search matching patterns.
        while (i < nEndIndex){
            a = sBeforeMapping.charAt(i);
            j = 0;
            while (j < nMappingLength) {
                if (a == sMappingList.charAt(j)) {
                    k = j + nRotation;
                    if (k >= nMappingLength) {
                        a = sMappingList.charAt(k - nMappingLength);
                    } else {
                        a = sMappingList.charAt(k);
                    }
                    break;
                }
                j++;
            }
            b[i] = a;
            i++;
        }

        String x = sMappingList;
        String y = x.substring(nRotation, nRotation + 1);
        int nTemp = nRotation + 5;
        String z = x.substring(nTemp, nTemp + 1);

        sEncrypted_string = sEncrypted_string.concat(y).concat(z);

        for ( int m = 0; m < nEndIndex; m++ ) {
            sEncrypted_string = sEncrypted_string.concat(sAfterMapping.valueOf(b[m]) );
        }

        return sEncrypted_string;
    }


    // This function uses to decrypt an encrypted string to a decrypted string.

    public static String Decrypt( String sInputText ) {
        String sBeforeMapping = "";
        String sAfterMapping = "";
        String sDecrypted_string = "";

        int i = 0, j = 0, k = 0;

        sBeforeMapping = sInputText;   //.toUpperCase();
        int nEndIndex = sBeforeMapping.length();

        String x = sMappingList;
        int nRotation = x.indexOf(sBeforeMapping.substring(0, 1));

        char a;
        char b[] = new char[nEndIndex];

        // Search matching patterns.
        while (i < nEndIndex){
            a = sBeforeMapping.charAt(i);
            j = 0;
            while (j < nMappingLength) {
                if (a == sMappingList.charAt(j)) {
                    k = j - nRotation;
                    if (k >= 0) {
                        a = sMappingList.charAt(k);
                    } else {
                        a = sMappingList.charAt(k + nMappingLength);
                    }
                    break;
                }
                j++;
                if (j == nMappingLength) {
                    a = ' ';
                }
            }
            b[i] = a;
            i++;
        }

        for ( int m = 2; m < nEndIndex; m++ ) {
            sDecrypted_string = sDecrypted_string.concat(sAfterMapping.valueOf(b[m]) );
        }

        return sDecrypted_string;
    }


    // This function uses to get a rotation number randomly (Between 1 to 30).

    private static int getRotationNo() {
        Date dDate = new Date();
        SimpleDateFormat dDateTime = new SimpleDateFormat("ss");
        dDateTime.setTimeZone(TimeZone.getTimeZone("CTT"));
        int nSec = Integer.parseInt(dDateTime.format(dDate));

        return Math.abs((nSec / 2) + 1);
    }

    public static String encrypt2(String password) {
        password = password.toUpperCase();
        MessageDigest md5 = null;
        try {
            md5 = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
            throw new RuntimeException("Unable to use MD5 algorithm for encryption.");
        }
        byte[] digest = md5.digest(password.getBytes());
        char[] hex = new char[digest.length * 2];
        for (int i = 0; i < digest.length; i++) {
            char c;
            c = (char)((digest[i] >> 4) & 0xf);
            if (c > 9) {
                c = (char)((c - 10) + 'a');
            } else {
                c = (char)(c + '0');
            }
            hex[2 * i] = c;
            c = (char)(digest[i] & 0xf);
            if (c > 9) {
                c = (char)((c - 10) + 'a');
            } else {
                c = (char)(c + '0');
            }
            hex[2 * i + 1] = c;
        }
        return String.valueOf(hex);
    }
}