import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.util.Base64;

/**
 * 微信解密工具
 */
public class WXDecryptUtils {
    /**
     * 解密微信加密数据
     *
     * @param encryptedData 加密数据（Base64编码）
     * @param sessionKey    会话密钥（Base64编码）
     * @param iv            初始向量（Base64编码）
     * @return 解密后的JSON字符串
     * {
     * "phoneNumber": "13800000000",
     * "purePhoneNumber": "13800000000",
     * "countryCode": "86",
     * "watermark": {
     * "appid": "wx1234567890abcdef",
     * "timestamp": 1601234567
     * }
     * }
     */
    public static String decryptData(String encryptedData, String sessionKey, String iv) {
        try {
            // Base64 解码
            byte[] encryptedBytes = Base64.getDecoder().decode(encryptedData);
            byte[] keyBytes = Base64.getDecoder().decode(sessionKey);
            byte[] ivBytes = Base64.getDecoder().decode(iv);

            // 初始化AES解密器
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
            SecretKeySpec keySpec = new SecretKeySpec(keyBytes, "AES");
            IvParameterSpec ivSpec = new IvParameterSpec(ivBytes);
            cipher.init(Cipher.DECRYPT_MODE, keySpec, ivSpec);

            // 解密并转成字符串
            byte[] decryptedBytes = cipher.doFinal(encryptedBytes);
            return new String(decryptedBytes, StandardCharsets.UTF_8);
        } catch (Exception e) {
            // 添加详细的错误日志，便于调试
            Log.error("微信解密失败 - encryptedData: {}, sessionKey: {}, iv: {}, 错误: {}",
                    encryptedData,
                    sessionKey,
                    iv,
                    e.getMessage());
            throw new RuntimeException("解密失败: " + e.getMessage(), e);
        }
    }
}