@Slf4j
public class Sign {
    private static final BitSet URLENCODER = new BitSet(256);
    private static final String CONST_ENCODE = "0123456789ABCDEF";
    public static final Charset UTF_8 = StandardCharsets.UTF_8;
    private final String region;
    private final String service;
    private final String host;
    private final String path;
    private final String ak;
    private final String sk;
    static {
        int i;
        for (i = 97; i <= 122; ++i) {
            URLENCODER.set(i);
        }

        for (i = 65; i <= 90; ++i) {
            URLENCODER.set(i);
        }

        for (i = 48; i <= 57; ++i) {
            URLENCODER.set(i);
        }
        URLENCODER.set('-');
        URLENCODER.set('_');
        URLENCODER.set('.');
        URLENCODER.set('~');
    }

    public Sign(String region, String service, String host, String path, String ak, String sk) {
        this.region = region;
        this.service = service;
        this.host = host;
        this.path = path;
        this.ak = ak;
        this.sk = sk;
    }

    public Headers calcAuthorization(String method, Map<String, String> queryList, byte[] body,
                                     Date date, String action, String version) throws Exception {
        // 請(qǐng)求頭
        Map<String, String> headerMap = new HashMap<>();
        String contentType = "application/x-www-form-urlencoded; charset=utf-8";
        if (body == null) {
            body = new byte[0];
        } else {
            contentType = "application/json; charset=utf-8";
        }
        String xContentSha256 = hashSHA256(body);
        SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd'T'HHmmss'Z'");
        sdf.setTimeZone(TimeZone.getTimeZone("GMT"));
        // String xDate = "20240515T061353Z";
        String xDate = sdf.format(date);
        String shortXDate = xDate.substring(0, 8);
        String signHeader = "content-type;host;x-content-sha256;x-date";

        SortedMap<String, String> realQueryList = new TreeMap<>(queryList);
        realQueryList.put("Action", action);
        realQueryList.put("Version", version);
        StringBuilder querySB = new StringBuilder();
        for (String key : realQueryList.keySet()) {
            querySB.append(signStringEncoder(key)).append("=").append(signStringEncoder(realQueryList.get(key))).append("&");
        }
        querySB.deleteCharAt(querySB.length() - 1);
        String canonicalStringBuilder = method + "\n" + path + "\n" + querySB + "\n" +
                "content-type:" + contentType + "\n" +
                "host:" + host + "\n" +
                "x-content-sha256:" + xContentSha256 + "\n" +
                "x-date:" + xDate + "\n" +
                "\n" +
                signHeader + "\n" +
                xContentSha256;

        // log.info("canonicalStringBuilder is {}", canonicalStringBuilder);
        String hashcanonicalString = hashSHA256(canonicalStringBuilder.getBytes());
        String credentialScope = shortXDate + "/" + region + "/" + service + "/request";
        String signString = "HMAC-SHA256" + "\n" + xDate + "\n" + credentialScope + "\n" + hashcanonicalString;
        // log.info("signString is {}", signString);

        byte[] signKey = genSigningSecretKeyV4(sk, shortXDate, region, service);
        String signature = HexUtil.encodeHexStr(hmacSHA256(signKey, signString));
        String auth = "HMAC-SHA256" +
                " Credential=" + ak + "/" + credentialScope +
                ", SignedHeaders=" + signHeader +
                ", Signature=" + signature;
        headerMap.put("Authorization", auth);
        headerMap.put("X-Date", xDate);
        headerMap.put("X-Content-Sha256", xContentSha256);
        headerMap.put("Host", host);
        headerMap.put("Content-Type", contentType);
        headerMap.put("User-Agent", "volc-sdk-java/v");
        headerMap.put("Accept", "application/json");
        return Headers.of(headerMap);
    }

    private static String signStringEncoder(String source) {
        if (source == null) {
            return null;
        }
        StringBuilder buf = new StringBuilder(source.length());
        ByteBuffer bb = UTF_8.encode(source);
        while (bb.hasRemaining()) {
            int b = bb.get() & 255;
            if (URLENCODER.get(b)) {
                buf.append((char) b);
            } else if (b == 32) {
                buf.append("%20");
            } else {
                buf.append("%");
                char hex1 = CONST_ENCODE.charAt(b >> 4);
                char hex2 = CONST_ENCODE.charAt(b & 15);
                buf.append(hex1);
                buf.append(hex2);
            }
        }

        return buf.toString();
    }

    public static String hashSHA256(byte[] content) throws Exception {
        try {
            MessageDigest md = MessageDigest.getInstance("SHA-256");
            // return HexFormat.of().formatHex(md.digest(content));
            return HexUtil.encodeHexStr(md.digest(content));
        } catch (Exception e) {
            throw new Exception(
                    "Unable to compute hash while signing request: "
                            + e.getMessage(), e);
        }
    }

    public static byte[] hmacSHA256(byte[] key, String content) throws Exception {
        try {
            Mac mac = Mac.getInstance("HmacSHA256");
            mac.init(new SecretKeySpec(key, "HmacSHA256"));
            return mac.doFinal(content.getBytes());
        } catch (Exception e) {
            throw new Exception(
                    "Unable to calculate a request signature: "
                            + e.getMessage(), e);
        }
    }

    private byte[] genSigningSecretKeyV4(String secretKey, String date, String region, String service) throws Exception {
        byte[] kDate = hmacSHA256((secretKey).getBytes(), date);
        byte[] kRegion = hmacSHA256(kDate, region);
        byte[] kService = hmacSHA256(kRegion, service);
        return hmacSHA256(kService, "request");
    }
}