package com.qs.mp.common.utils;

import com.qs.mp.common.exception.ServiceException;
import java.nio.charset.StandardCharsets;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;
import javax.crypto.Cipher;
import org.apache.commons.codec.binary.Base64;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component
public class RSAUtil {

  private static String privateKey;

  @Value("${rsa.private-key}")
  public static void setPrivateKey(String priKey) {
    privateKey = priKey;
  }

  private static String publicKey;

  @Value("${rsa.public-key}")
  public static void setPublicKey(String pubKey) {
    publicKey = pubKey;
  }

  private static final Map<Integer, String> keyMap = new HashMap<Integer, String>();  //用于封装随机产生的公钥与私钥

  public static void main(String[] args) throws Exception {
    //生成公钥和私钥
    genKeyPair();
    //加密字符串
    String message = "5";
    System.out.println("随机生成的公钥为:" + keyMap.get(0));
    System.out.println("随机生成的私钥为:" + keyMap.get(1));
//    String messageEn = encrypt(message,keyMap.get(0));
//    System.out.println(message + "\t加密后的字符串为:" + messageEn);
//    String messageDe = decrypt(messageEn,keyMap.get(1));
//    System.out.println("还原后的字符串为:" + messageDe);
  }

  /**
   * 随机生成密钥对
   *
   * @throws NoSuchAlgorithmException
   */
  public static void genKeyPair() throws NoSuchAlgorithmException {
    // KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象
    KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
    // 初始化密钥对生成器，密钥大小为96-1024位
    keyPairGen.initialize(1024, new SecureRandom());
    // 生成一个密钥对，保存在keyPair中
    KeyPair keyPair = keyPairGen.generateKeyPair();
    RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();   // 得到私钥
    RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();  // 得到公钥
    String publicKeyString = new String(Base64.encodeBase64(publicKey.getEncoded()));
    // 得到私钥字符串
    String privateKeyString = new String(Base64.encodeBase64((privateKey.getEncoded())));
    // 将公钥和私钥保存到Map
    keyMap.put(0, publicKeyString);  //0表示公钥
    keyMap.put(1, privateKeyString);  //1表示私钥
  }

  /**
   * RSA公钥加密
   *
   * @param str       加密字符串
   * @param publicKey 公钥
   * @return 密文
   * @throws Exception 加密过程中的异常信息
   */
  public static String encrypt(String str) {
    try {

      //base64编码的公钥
      byte[] decoded = Base64.decodeBase64(publicKey);
      RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA")
          .generatePublic(new X509EncodedKeySpec(decoded));
      //RSA加密
      Cipher cipher = Cipher.getInstance("RSA");
      cipher.init(Cipher.ENCRYPT_MODE, pubKey);
      String outStr = Base64.encodeBase64String(
          cipher.doFinal(str.getBytes(StandardCharsets.UTF_8)));
      return outStr;
    } catch (Exception e) {
      throw new ServiceException("加密幸运数字异常，str:" + str, e);
    }
  }

  /**
   * RSA私钥解密
   *
   * @param str        加密字符串
   * @param privateKey 私钥
   * @return 铭文
   * @throws Exception 解密过程中的异常信息
   */
  public static String decrypt(String str) {
    try {

      //64位解码加密后的字符串
      byte[] inputByte = Base64.decodeBase64(str.getBytes(StandardCharsets.UTF_8));
      //base64编码的私钥
      byte[] decoded = Base64.decodeBase64(privateKey);
      RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA")
          .generatePrivate(new PKCS8EncodedKeySpec(decoded));
      //RSA解密
      Cipher cipher = Cipher.getInstance("RSA");
      cipher.init(Cipher.DECRYPT_MODE, priKey);
      String outStr = new String(cipher.doFinal(inputByte));
      return outStr;
    } catch (Exception e) {
      throw new ServiceException("解密幸运数字异常，str:" + str, e);
    }
  }

}