package info.frostfs.sdk;

import com.google.protobuf.ByteString;
import com.google.protobuf.Message;
import info.frostfs.sdk.exceptions.ValidationFrostFSException;
import org.apache.commons.lang3.StringUtils;

import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import static info.frostfs.sdk.constants.ErrorConst.INPUT_PARAM_IS_MISSING;
import static java.util.Objects.isNull;

public class Helper {
    private static final String SHA256 = "SHA-256";
    private static final int HEX_RADIX = 16;

    private Helper() {
    }

    public static MessageDigest getSha256Instance() {
        try {
            return MessageDigest.getInstance(SHA256);
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        }
    }

    public static byte[] getSha256(byte[] value) {
        if (isNull(value)) {
            throw new ValidationFrostFSException(INPUT_PARAM_IS_MISSING);
        }

        return getSha256Instance().digest(value);
    }

    public static ByteString getSha256(Message value) {
        if (isNull(value)) {
            throw new ValidationFrostFSException(INPUT_PARAM_IS_MISSING);
        }

        return ByteString.copyFrom(getSha256(value.toByteArray()));
    }

    public static String getHexString(byte[] value) {
        if (isNull(value) || value.length == 0) {
            throw new ValidationFrostFSException(INPUT_PARAM_IS_MISSING);
        }

        return String.format("%0" + (value.length << 1) + "x", new BigInteger(1, value));
    }

    public static byte[] getByteArrayFromHex(String hex) {
        if (StringUtils.isBlank(hex)) {
            throw new ValidationFrostFSException(INPUT_PARAM_IS_MISSING);
        }

        return new BigInteger(hex, HEX_RADIX).toByteArray();
    }
}