package com.cowr.common.utils;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.io.UnsupportedEncodingException;
import java.security.GeneralSecurityException;
import java.util.Arrays;

public class AESUtil {
    public static byte[] encrypt(String key, byte[] origData) throws GeneralSecurityException {
        byte[] keyBytes = getKeyBytes(key);
        byte[] buf = new byte[16];
        System.arraycopy(keyBytes, 0, buf, 0, keyBytes.length > buf.length ? keyBytes.length : buf.length);
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(buf, "AES"), new IvParameterSpec(keyBytes));
        return cipher.doFinal(origData);

    }

    public static byte[] decrypt(String key, byte[] crypted) throws GeneralSecurityException {
        byte[] keyBytes = getKeyBytes(key);
        byte[] buf = new byte[16];
        System.arraycopy(keyBytes, 0, buf, 0, keyBytes.length > buf.length ? keyBytes.length : buf.length);
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(buf, "AES"), new IvParameterSpec(keyBytes));
        return cipher.doFinal(crypted);
    }

    private static byte[] getKeyBytes(String key) {
        byte[] bytes = key.getBytes();
        return bytes.length == 16 ? bytes : Arrays.copyOf(bytes, 16);
    }

    public static String encrypt(String key, String val) throws GeneralSecurityException {
        byte[] origData = val.getBytes();
        byte[] crypted = encrypt(key, origData);
        return parseByte2HexStr(crypted);
    }

    public static String decrypt(String key, String val) throws GeneralSecurityException, UnsupportedEncodingException {
        byte[] crypted = parseHexStr2Byte(val);
        byte[] origData = decrypt(key, crypted);
        return new String(origData, "utf-8");
    }


    /**
     *  将二进制转换成16进制
     *
     * @param buf
     * @return
     */
    public static String parseByte2HexStr(byte buf[]) {
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < buf.length; i++) {
            String hex = Integer.toHexString(buf[i] & 0xFF);
            if (hex.length() == 1) {
                hex = '0' + hex;
            }
            sb.append(hex.toUpperCase());
        }
        return sb.toString();
    }

    /**
     * 将16进制转换为二进制
     *
     * @param hexStr
     * @return
     */
    public static byte[] parseHexStr2Byte(String hexStr) {
        if (hexStr.length() < 1)
            return null;
        byte[] result = new byte[hexStr.length() / 2];
        for (int i = 0; i < hexStr.length() / 2; i++) {
            int high = Integer.parseInt(hexStr.substring(i * 2, i * 2 + 1), 16);
            int low = Integer.parseInt(hexStr.substring(i * 2 + 1, i * 2 + 2), 16);
            result[i] = (byte) (high * 16 + low);
        }
        return result;
    }

    public static void main(String[] args) throws Exception {
        String content  = "加密之前加密之前加密之前";
        String password = "21";
        System.out.println("加密之前：" + content);

        String hexStrResult = encrypt(password, content);
        System.out.println("加密之后：" + hexStrResult);
        System.out.println("解密后的内容：" + decrypt(password, hexStrResult));
    }

}