/**
 * Description: 微信小程序工具类
 *
 * @author : laughing
 * DateTime: 2021-03-16 11:10
 */
@Slf4j
public class WeChatUtils {

    public static String httpRequest(String requestUrl, String requestMethod, String output) {
        try {
            URL url = new URL(requestUrl);
            HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();
            connection.setDoOutput(true);
            connection.setDoInput(true);
            connection.setUseCaches(false);
            connection.setRequestMethod(requestMethod);
            if (null != output) {
                OutputStream outputStream = connection.getOutputStream();
                outputStream.write(output.getBytes(StandardCharsets.UTF_8));
                outputStream.close();
            }
            // 从输入流读取返回内容
            InputStream inputStream = connection.getInputStream();
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream, StandardCharsets.UTF_8);
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
            String str;
            StringBuilder buffer = new StringBuilder();
            while ((str = bufferedReader.readLine()) != null) {
                buffer.append(str);
            }
            bufferedReader.close();
            inputStreamReader.close();
            inputStream.close();
            connection.disconnect();
            return buffer.toString();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "";
    }

    public static String decryptData(String encryptDataB64, String sessionKeyB64, String ivB64) {
        log.info("encryptDataB64:" + encryptDataB64);
        log.info("sessionKeyB64:" + sessionKeyB64);
        log.info("ivB64:" + ivB64);
        return new String(
                decryptOfDiyIv(
                        Base64.decode(encryptDataB64),
                        Base64.decode(sessionKeyB64),
                        Base64.decode(ivB64)
                )
        );
    }

    private static final String KEY_ALGORITHM = "AES";
    private static final String ALGORITHM_STR = "AES/CBC/PKCS7Padding";
    private static Key key;
    private static Cipher cipher;

    private static void init(byte[] keyBytes) {
        // 如果密钥不足16位，那么就补足.  这个if 中的内容很重要
        int base = 16;
        if (keyBytes.length % base != 0) {
            int groups = keyBytes.length / base + 1;
            byte[] temp = new byte[groups * base];
            Arrays.fill(temp, (byte) 0);
            System.arraycopy(keyBytes, 0, temp, 0, keyBytes.length);
            keyBytes = temp;
        }
        // 初始化
        Security.addProvider(new BouncyCastleProvider());
        // 转化成JAVA的密钥格式
        key = new SecretKeySpec(keyBytes, KEY_ALGORITHM);
        try {
            // 初始化cipher
            cipher = Cipher.getInstance(ALGORITHM_STR, "BC");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 解密方法
     *
     * @param encryptedData 要解密的字符串
     * @param keyBytes      解密密钥
     * @param ivs           自定义对称解密算法初始向量 iv
     * @return 解密后的字节数组
     */
    private static byte[] decryptOfDiyIv(byte[] encryptedData, byte[] keyBytes, byte[] ivs) {
        byte[] encryptedText = null;
        init(keyBytes);
        try {
            cipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(ivs));
            encryptedText = cipher.doFinal(encryptedData);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return encryptedText;
    }

    /**
     * 向指定 URL 发送POST方法的请求
     *
     * @param url  发送请求的 URL
     * @param json 请求参数，请求参数应该是 json 的形式。
     * @return 所代表远程资源的响应结果
     */
    public static String httpPost(String url, JSONObject json) {
        PrintWriter out = null;
        BufferedReader in = null;
        String result = "";
        try {
            URL realUrl = new URL(url);
            // 打开和URL之间的连接
            URLConnection conn = realUrl.openConnection();
            // 设置通用的请求属性
            conn.setRequestProperty("accept", "*/*");
            conn.setRequestProperty("connection", "Keep-Alive");
            conn.setRequestProperty("user-agent",
                    "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            // 发送POST请求必须设置如下两行
            conn.setDoOutput(true);
            conn.setDoInput(true);
            // 获取URLConnection对象对应的输出流
            out = new PrintWriter(conn.getOutputStream());
            // 发送请求参数

            out.print(json);
            // flush输出流的缓冲
            out.flush();
            // 定义BufferedReader输入流来读取URL的响应
            in = new BufferedReader(
                    new InputStreamReader(conn.getInputStream()));
            String line;
            while ((line = in.readLine()) != null) {
                result=result.concat(line);
            }
        } catch (Exception e) {
            System.out.println("发送 POST 请求出现异常！" + e);
            e.printStackTrace();
        }
        //使用finally块来关闭输出流、输入流
        finally {
            try {
                if (out != null) {
                    out.close();
                }
                if (in != null) {
                    in.close();
                }
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        return result;
    }