package com.sinata.appointment.util;

import java.nio.charset.StandardCharsets;
import java.util.Base64;

/**
 * 敏感字段占位处理：生产环境应替换为 KMS + 对称加密。
 */
public final class SensitiveDataUtil {

    private static final String PREFIX = "ENC:";

    private SensitiveDataUtil() {}

    public static String maskIdCard(String plain) {
        if (plain == null || plain.length() < 8) {
            return "****";
        }
        int starLen = plain.length() - 8;
        String stars = "*".repeat(Math.max(starLen, 1));
        return plain.substring(0, 4) + stars + plain.substring(plain.length() - 4);
    }

    public static String encryptIdCard(String plain) {
        if (plain == null || plain.isBlank()) {
            return null;
        }
        return PREFIX + Base64.getEncoder().encodeToString(plain.getBytes(StandardCharsets.UTF_8));
    }

    public static String decryptIdCard(String cipher) {
        if (cipher == null || cipher.isBlank()) {
            return null;
        }
        String t = cipher.trim();
        if (t.startsWith(PREFIX)) {
            String raw = t.substring(PREFIX.length());
            return new String(Base64.getDecoder().decode(raw), StandardCharsets.UTF_8);
        }
        return t;
    }
}