package net.curisit.securis.utils;

import java.math.BigInteger;
import java.nio.charset.Charset;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.zip.CRC32;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

public class LicUtils {

    private static final Logger LOG = LogManager.getLogger(LicUtils.class);

    public static String md5(String str) {
        try {
            MessageDigest mDigest = MessageDigest.getInstance("MD5");
            mDigest.update(str.getBytes(DEFAULT_CHARSET), 0, str.length());
            BigInteger i = new BigInteger(1, mDigest.digest());
            return String.format("%1$032x", i);
        } catch (NoSuchAlgorithmException e) {
            LOG.error("Error generating MD5 for string: " + str, e);
        }
        return null;
    }

    public static String sha256(String str) {
        return sha256(str.getBytes(DEFAULT_CHARSET));
    }

    public static String sha256(byte[] bytes) {
        try {
            MessageDigest mDigest = MessageDigest.getInstance("SHA-256");
            mDigest.update(bytes, 0, bytes.length);
            BigInteger i = new BigInteger(1, mDigest.digest());
            return String.format("%1$064x", i);
        } catch (NoSuchAlgorithmException e) {
            LOG.error("Error generating SHA-256 for bytes: " + bytes, e);
        }
        return null;
    }

    public static String sha256(byte[]... bytes) {
        try {
            MessageDigest mDigest = MessageDigest.getInstance("SHA-256");
            for (byte[] bs : bytes) {
                mDigest.update(bs, 0, bs.length);
            }
            BigInteger i = new BigInteger(1, mDigest.digest());
            return String.format("%1$064x", i);
        } catch (NoSuchAlgorithmException e) {
            LOG.error("Error generating SHA-256 for bytes: " + bytes, e);
        }
        return null;
    }

    private final static Charset DEFAULT_CHARSET = Charset.forName("utf-8");

    public static String getLicenseCrc(String packCode, String licSufixCode) {
        CRC32 crc = new CRC32();
        crc.update(packCode.getBytes(DEFAULT_CHARSET));
        crc.update(licSufixCode.getBytes(DEFAULT_CHARSET));
        return String.format("%03d", crc.getValue() % 1000);
    }

    public static String getLicenseCrc(String packCode, Integer licSufixCode) {
        return getLicenseCrc(packCode, licSufixCode.toString());
    }

    public static Integer getLicenseCodeSuffix(String licCode) {
        String[] parts = splitLicCode(licCode);

        return new Integer(parts[parts.length - 1]);
    }

    public static String getLicenseCode(String packCode, Integer licSufixCode) {
        String crc = getLicenseCrc(packCode, licSufixCode);
        return String.format("%s-%s-%s", packCode, crc, licSufixCode);
    }

    /**
     * Check if the license code is valid according to the format, the CRC is
     * validated
     * 
     * @param licCode
     * @return true if license code format and its CRC are valid
     */
    public static boolean checkValidLicenseCodeCrc(String licCode) {
        String[] parts = splitLicCode(licCode);
        if (parts == null) {
            return false;
        }
        String crc = getLicenseCrc(parts[0], parts[2]);
        return crc.equals(parts[1]);
    }

    /**
     * We convert the license code in 3 parts: <br>
     * "P1-344-1 = ["P1", "344", "1"] <br>
     * "P1-OTHER-344-1 = ["P1-OTHER", "344", "1"] <br>
     * "P1-1 = null
     * 
     * @param code
     * @return The 2 license code packs or null if code is not valid
     */
    private static String[] splitLicCode(String code) {
        List<Integer> separators = new ArrayList<>();
        for (int i = 0; i < code.length(); i++) {
            if (code.charAt(i) == '-') {
                separators.add(i);
            }
        }
        if (separators.size() < 2) {
            return null;
        }

        int i0 = separators.get(separators.size() - 2);
        int i1 = separators.get(separators.size() - 1);
        String[] parts = new String[3];
        parts[0] = code.substring(0, i0);
        parts[1] = code.substring(i0 + 1, i1);
        parts[2] = code.substring(i1 + 1);

        return parts;
    }

    public static void main(String[] args) {
        String code = getLicenseCode("PC-K01", 5);
        System.out.println(code);
        System.out.println("Is valid ? " + checkValidLicenseCodeCrc(code));
        System.out.println("Is valid ? " + Arrays.asList(splitLicCode(code)));
    }
}