package tech.easyflow.common.util;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.util.Base64;
import java.util.concurrent.ThreadLocalRandom;

public class HashUtil {
    private static final char[] HEX_DIGITS = "0123456789abcdef".toCharArray();
    private static final char[] CHAR_ARRAY = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ".toCharArray();

    public static String md5(String srcStr) {
        return hash("MD5", srcStr);
    }


    public static String sha256(String srcStr) {
        return hash("SHA-256", srcStr);
    }

    public static String macHha256(String srcStr, String secret) {
        try {
            Mac hmacSHA256 = Mac.getInstance("HmacSHA256");
            SecretKeySpec secretKey = new SecretKeySpec(secret.getBytes(StandardCharsets.UTF_8), "HmacSHA256");
            hmacSHA256.init(secretKey);
            byte[] bytes = hmacSHA256.doFinal(srcStr.getBytes(StandardCharsets.UTF_8));
            return Base64.getEncoder().encodeToString(bytes);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    public static String hash(String algorithm, String srcStr) {
        try {
            MessageDigest md = MessageDigest.getInstance(algorithm);
            byte[] bytes = md.digest(srcStr.getBytes(StandardCharsets.UTF_8));
            return bytesToHex(bytes);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    public static String bytesToHex(byte[] bytes) {
        StringBuilder ret = new StringBuilder(bytes.length * 2);
        for (int i = 0; i < bytes.length; i++) {
            ret.append(HEX_DIGITS[(bytes[i] >> 4) & 0x0f]);
            ret.append(HEX_DIGITS[bytes[i] & 0x0f]);
        }
        return ret.toString();
    }


    public static String generateSalt(int saltLength) {
        StringBuilder salt = new StringBuilder(saltLength);
        ThreadLocalRandom random = ThreadLocalRandom.current();
        for (int i = 0; i < saltLength; i++) {
            salt.append(CHAR_ARRAY[random.nextInt(CHAR_ARRAY.length)]);
        }
        return salt.toString();
    }

}
