package com.ruoyi.system.utils;

import com.ruoyi.common.exception.ServiceException;
import org.apache.commons.codec.digest.DigestUtils;

import javax.crypto.Cipher;
import javax.crypto.spec.GCMParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.security.SecureRandom;
import java.util.Arrays;
import java.util.Base64;

/**
 * 门禁设备登录密码加解密工具。
 */
public final class DoorDeviceCredentialCrypto
{
    private static final String ENV_KEY = "DOOR_DEVICE_CREDENTIAL_KEY";
    private static final String SYSTEM_PROPERTY_KEY = "door.device.credential.key";
    private static final String PREFIX = "v1:";
    private static final byte[] AAD = "FangKeJiDoorDeviceCredential".getBytes(StandardCharsets.UTF_8);
    private static final SecureRandom SECURE_RANDOM = new SecureRandom();

    private DoorDeviceCredentialCrypto()
    {
    }

    public static String encrypt(String plainText)
    {
        if (plainText == null || plainText.length() == 0)
        {
            throw new ServiceException("设备登录密码不能为空");
        }
        try
        {
            byte[] nonce = new byte[12];
            SECURE_RANDOM.nextBytes(nonce);
            Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
            cipher.init(Cipher.ENCRYPT_MODE, secretKey(), new GCMParameterSpec(128, nonce));
            cipher.updateAAD(AAD);
            byte[] encrypted = cipher.doFinal(plainText.getBytes(StandardCharsets.UTF_8));
            byte[] payload = new byte[nonce.length + encrypted.length];
            System.arraycopy(nonce, 0, payload, 0, nonce.length);
            System.arraycopy(encrypted, 0, payload, nonce.length, encrypted.length);
            return PREFIX + Base64.getEncoder().encodeToString(payload);
        }
        catch (ServiceException e)
        {
            throw e;
        }
        catch (Exception e)
        {
            throw new ServiceException("设备登录密码加密失败");
        }
    }

    public static String decrypt(String cipherText)
    {
        if (cipherText == null || cipherText.length() == 0)
        {
            throw new ServiceException("设备未配置登录密码");
        }
        if (!cipherText.startsWith(PREFIX))
        {
            throw new ServiceException("设备登录密码密文版本不支持");
        }
        try
        {
            byte[] payload = Base64.getDecoder().decode(cipherText.substring(PREFIX.length()));
            if (payload.length <= 28)
            {
                throw new IllegalArgumentException("invalid payload");
            }
            byte[] nonce = Arrays.copyOfRange(payload, 0, 12);
            byte[] encrypted = Arrays.copyOfRange(payload, 12, payload.length);
            Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
            cipher.init(Cipher.DECRYPT_MODE, secretKey(), new GCMParameterSpec(128, nonce));
            cipher.updateAAD(AAD);
            return new String(cipher.doFinal(encrypted), StandardCharsets.UTF_8);
        }
        catch (ServiceException e)
        {
            throw e;
        }
        catch (Exception e)
        {
            throw new ServiceException("设备登录密码解密失败，请检查主密钥");
        }
    }

    private static SecretKeySpec secretKey()
    {
        String value = System.getProperty(SYSTEM_PROPERTY_KEY);
        if (value == null || value.trim().length() == 0)
        {
            value = System.getenv(ENV_KEY);
        }
        if (value == null || value.length() < 32)
        {
            throw new ServiceException(ENV_KEY + " 必须配置且长度不能少于32位");
        }
        return new SecretKeySpec(Arrays.copyOf(DigestUtils.sha256(value), 16), "AES");
    }
}