package com.whyc.util;

import com.whyc.constant.YamlProperties;
import org.apache.commons.codec.binary.Base64;

import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.security.*;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.LinkedList;
import java.util.List;

public class RSAUtil {

    /**
     * 固定公私钥
     */
    private static final  String publicKey = YamlProperties.publicKey;
    private static final  String privateKey = YamlProperties.privateKey;
    /**
     * RSA最大加密明文大小
     */
    private static final int MAX_ENCRYPT_BLOCK = 117;
    /**
     * RSA最大解密密文大小
     */
    private static final int MAX_DECRYPT_BLOCK = 384;

    public static final String fontSeparator = "&&&&&&&&&&";
    /**
     * 获取密钥对
     *
     * @return 密钥对
     */
    public static List<String> getKeyPair() throws Exception {
        LinkedList<String> list = new LinkedList<>();
        KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA");
        generator.initialize(3072);
        KeyPair keyPair = generator.generateKeyPair();
        String publicKey = Base64.encodeBase64String(keyPair.getPublic().getEncoded());
        String privateKey = Base64.encodeBase64String(keyPair.getPrivate().getEncoded());
        System.out.println("公钥:"+publicKey);
        System.out.println("私钥:"+privateKey);
        list.add(publicKey);
        list.add(privateKey);
        return list;
    }
    /**
     * 获取私钥
     *
     * @param privateKey 私钥字符串
     * @return
     */
    public static PrivateKey getPrivateKey(String privateKey) {
        try {
            KeyFactory keyFactory = null;
            keyFactory = KeyFactory.getInstance("RSA");

            byte[] decodedKey = Base64.decodeBase64(privateKey.getBytes());
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(decodedKey);
            return keyFactory.generatePrivate(keySpec);
        }catch (NoSuchAlgorithmException | InvalidKeySpecException e){
            return null;
        }
    }

    /**
     * 获取私钥
     *
     * @return
     */
    public static PrivateKey getPrivateKey() {
        try {
            KeyFactory keyFactory = null;
            keyFactory = KeyFactory.getInstance("RSA");

            byte[] decodedKey = Base64.decodeBase64(privateKey.getBytes());
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(decodedKey);
            return keyFactory.generatePrivate(keySpec);
        }catch (NoSuchAlgorithmException | InvalidKeySpecException e){
            return null;
        }
    }
    /**
     * 获取公钥
     *
     * @param publicKey 公钥字符串
     * @return
     */
    public static PublicKey getPublicKey(String publicKey) throws Exception {
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        byte[] decodedKey = Base64.decodeBase64(publicKey.getBytes());
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(decodedKey);
        return keyFactory.generatePublic(keySpec);
    }

    /**
     * 获取公钥
     *
     * @return
     */
    public static PublicKey getPublicKey(){
        try {
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            byte[] decodedKey = Base64.decodeBase64(publicKey.getBytes());
            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(decodedKey);
            return keyFactory.generatePublic(keySpec);
        }catch (Exception e){
            return null;
        }
    }

    /**
     * RSA加密
     *
     * @param data 待加密数据
     * @param publicKey 公钥
     * @return
     */
    public static String encrypt(String data, PublicKey publicKey) {
        try {
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            int inputLen = data.getBytes().length;
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            int offset = 0;
            byte[] cache;
            int i = 0;
            // 对数据分段加密
            while (inputLen - offset > 0) {
                if (inputLen - offset > MAX_ENCRYPT_BLOCK) {
                    cache = cipher.doFinal(data.getBytes(), offset, MAX_ENCRYPT_BLOCK);
                } else {
                    cache = cipher.doFinal(data.getBytes(), offset, inputLen - offset);
                }
                out.write(cache, 0, cache.length);
                i++;
                offset = i * MAX_ENCRYPT_BLOCK;
            }
            byte[] encryptedData = out.toByteArray();
            out.close();
            // 获取加密内容使用base64进行编码,并以UTF-8为标准转化成字符串
            // 加密后的字符串
            return new String(Base64.encodeBase64String(encryptedData));
        }catch (Exception e){
            return null;
        }
    }
    /**
     * RSA解密
     *
     * @param data 待解密数据
     * @param privateKey 私钥
     * @return
     */
    public static String decrypt(String data, PrivateKey privateKey) {
        try {
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            byte[] dataBytes = Base64.decodeBase64(data);
            int inputLen = dataBytes.length;
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            int offset = 0;
            byte[] cache;
            int i = 0;
            // 对数据分段解密
            while (inputLen - offset > 0) {
                if (inputLen - offset > MAX_DECRYPT_BLOCK) {
                    cache = cipher.doFinal(dataBytes, offset, MAX_DECRYPT_BLOCK);
                } else {
                    cache = cipher.doFinal(dataBytes, offset, inputLen - offset);
                }
                out.write(cache, 0, cache.length);
                i++;
                offset = i * MAX_DECRYPT_BLOCK;
            }
            byte[] decryptedData = out.toByteArray();
            out.close();
            // 解密后的内容
            return new String(decryptedData, "UTF-8");
        }catch (Exception e){
            return null;
        }
    }
    /**
     * RSA解密
     *
     * @param data 待解密数据
     * @return
     */
    public static String decrypt(String data) {
        try {
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.DECRYPT_MODE, getPrivateKey());
            byte[] dataBytes = Base64.decodeBase64(data);
            int inputLen = dataBytes.length;
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            int offset = 0;
            byte[] cache;
            int i = 0;
            // 对数据分段解密
            while (inputLen - offset > 0) {
                if (inputLen - offset > MAX_DECRYPT_BLOCK) {
                    cache = cipher.doFinal(dataBytes, offset, MAX_DECRYPT_BLOCK);
                } else {
                    cache = cipher.doFinal(dataBytes, offset, inputLen - offset);
                }
                out.write(cache, 0, cache.length);
                i++;
                offset = i * MAX_DECRYPT_BLOCK;
            }
            byte[] decryptedData = out.toByteArray();
            out.close();
            // 解密后的内容
            return new String(decryptedData, "UTF-8");
        }catch (Exception e){
            return null;
        }
    }

    /**
     * 前端加密数据RSA[明文+MD5(明文)]解密为明文和MD5[明文]
     * @param frontEncryptData
     * @return
     */
    public static String[] decryptFront(String frontEncryptData,String separatorStr){
        String[] dataArr = new String[2];
        String dataMD5Mix = RSAUtil.decrypt(frontEncryptData, RSAUtil.getPrivateKey());
        int index = dataMD5Mix.lastIndexOf(separatorStr);
        String data = dataMD5Mix.substring(0, index);
        String dataMD5 = dataMD5Mix.substring(index+separatorStr.length());
        dataArr[0] = data;
        dataArr[1] = dataMD5;
        return dataArr;
    }

    /**
     * 先URL解码,再进行密文解析[rsa(明文+md5)]
     */
    public static String[] decryptFrontP(String frontEncryptData,String separatorStr){
        try {
            frontEncryptData = URLDecoder.decode(frontEncryptData, "utf-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        String[] dataArr = new String[2];
        String dataMD5Mix = RSAUtil.decrypt(frontEncryptData, RSAUtil.getPrivateKey());
        if(dataMD5Mix!=null){
            int index = dataMD5Mix.lastIndexOf(separatorStr);
            String data = dataMD5Mix.substring(0, index);
            String dataMD5 = dataMD5Mix.substring(index+separatorStr.length());
            dataArr[0] = data;
            dataArr[1] = dataMD5;
        }
        return dataArr;
    }

    public static void main(String[] args) {
        try {
            //String word = "123456";
            //String publicKey = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCPpJ3j+SHQ69lqq+ShV7deA40Y+8rYra6rr4ReOJ+UE7ek8tsJJrcy1xMO1SophJdHXXwSNbZWhnJW9GlIq1Um6IplkwFc/AtyoeJDP3EJtUZgI5H6fSz0BPLFHn18C0Nxz1Br109U07DqQdMsarcBmKXYQw+2oZOz0KpA5b0FawIDAQAB";
            //String privateKey = "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";

            //List<String> keyPair = getKeyPair();
            //String encryptWord = encrypt(word, getPublicKey(keyPair.get(0)));
            //System.out.println("加密后的字符串:"+encryptWord);

            //String encryptWord = "NTDEt29l3QqDjgbK5AToix14GQNMi2qPDgsIy7JQf0586wEhOr6LgQ3YuZo9gEYLgmRxdOtxTcVCMugIJnXr6xukoopYfdH7epnQlszMYcM73a7mOrI1DJQA8%2B7AnMkm0s3X3GR7CdpT2OHrdogOAywFWhBirETaeY36ZH%2FOrXQ%3D";
            //encryptWord=URLDecoder.decode(encryptWord, "utf-8");
            String encrypt = encrypt("hELEEWWEEr9Lu6HgEvttjj8vYhy3ID+PqPbumuXhcHhe", getPublicKey());
            System.out.println(encrypt);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}