package com.tangem.wallet;

import java.math.BigInteger;

/**
 * Created by Ilia on 15.02.2018.
 */

public class Base58 {
    private static final char[] BASE58 = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz".toCharArray();

    private static final int BASE58_CHUNK_DIGITS = 10;//how many base 58 digits fits in long
    private static final BigInteger BASE58_CHUNK_MOD = BigInteger.valueOf(0x5fa8624c7fba400L); //58^BASE58_CHUNK_DIGITS
    private static final byte[] BASE58_VALUES = new byte[]{-1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -2, -2, -2, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, -1, -1, -1, -1, -1, -1,
            -1, 9, 10, 11, 12, 13, 14, 15, 16, -1, 17, 18, 19, 20, 21, -1,
            22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, -1, -1, -1, -1, -1,
            -1, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, -1, 44, 45, 46,
            47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1};

    public static byte[] decodeBase58(String input) {
        if (input == null) {
            return null;
        }
        input = input.trim();
        if (input.length() == 0) {
            return new byte[0];
        }
        BigInteger resultNum = BigInteger.ZERO;
        int nLeadingZeros = 0;
        while (nLeadingZeros < input.length() && input.charAt(nLeadingZeros) == BASE58[0]) {
            nLeadingZeros++;
        }
        long acc = 0;
        int nDigits = 0;
        int p = nLeadingZeros;
        while (p < input.length()) {
            int v = BASE58_VALUES[input.charAt(p) & 0xff];
            if (v >= 0) {
                acc *= 58;
                acc += v;
                nDigits++;
                if (nDigits == BASE58_CHUNK_DIGITS) {
                    resultNum = resultNum.multiply(BASE58_CHUNK_MOD).add(BigInteger.valueOf(acc));
                    acc = 0;
                    nDigits = 0;
                }
                p++;
            } else {
                break;
            }
        }
        if (nDigits > 0) {
            long mul = 58;
            while (--nDigits > 0) {
                mul *= 58;
            }
            resultNum = resultNum.multiply(BigInteger.valueOf(mul)).add(BigInteger.valueOf(acc));
        }
        final int BASE58_SPACE = -2;
        while (p < input.length() && BASE58_VALUES[input.charAt(p) & 0xff] == BASE58_SPACE) {
            p++;
        }
        if (p < input.length()) {
            return null;
        }
        byte[] plainNumber = resultNum.toByteArray();
        int plainNumbersOffs = plainNumber[0] == 0 ? 1 : 0;
        byte[] result = new byte[nLeadingZeros + plainNumber.length - plainNumbersOffs];
        System.arraycopy(plainNumber, plainNumbersOffs, result, nLeadingZeros, plainNumber.length - plainNumbersOffs);
        return result;
    }

    public static String encodeBase58(byte[] input) {
        if (input == null) {
            return null;
        }
        StringBuilder str = new StringBuilder((input.length * 350) / 256 + 1);
        BigInteger bn = new BigInteger(1, input);
        long rem;
        while (true) {
            BigInteger[] divideAndRemainder = bn.divideAndRemainder(BASE58_CHUNK_MOD);
            bn = divideAndRemainder[0];
            rem = divideAndRemainder[1].longValue();
            if (bn.compareTo(BigInteger.ZERO) == 0) {
                break;
            }
            for (int i = 0; i < BASE58_CHUNK_DIGITS; i++) {
                str.append(BASE58[(int) (rem % 58)]);
                rem /= 58;
            }
        }
        while (rem != 0) {
            str.append(BASE58[(int) (rem % 58)]);
            rem /= 58;
        }
        str.reverse();
        int nLeadingZeros = 0;
        while (nLeadingZeros < input.length && input[nLeadingZeros] == 0) {
            str.insert(0, BASE58[0]);
            nLeadingZeros++;
        }
        return str.toString();
    }
}