package io.swagger.util;

import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;

public class AES {
//	public static void main(String[] args) throws Exception {
//		String content = "admin";
//		String key = "12345a78g2345678";
//		String encryptResult = encrypt(content, key);
//		String decryptResult = decrypt(encryptResult, key);
//		System.out.println("加密後：" + encryptResult);
//		System.out.println("解密後：" + new String(decryptResult));
//	}

	public static String decrypt(String data, String password) throws Exception {
		byte[] content = parseHexStr2Byte(data);
		Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
		KeyGenerator kgen = KeyGenerator.getInstance("AES"); // KeyGenerator提供（對稱）金鑰生成器的功能。使用getInstance 類方法構造金鑰生成器。
		kgen.init(128, new SecureRandom(password.getBytes("UTF-8")));// 使用使用者提供的隨機源初始化此金鑰生成器，使其具有確定的金鑰大小。
		SecretKey secretKey = kgen.generateKey();
		cipher.init(Cipher.DECRYPT_MODE, secretKey, new IvParameterSpec(password.getBytes("UTF-8")));// 使用解密模式初始化 金鑰
		byte[] decrypt = cipher.doFinal(content);
		return new String(decrypt, "UTF-8"); // 加密
	}

	public static String encrypt(String content, String password) throws Exception {
		Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
		KeyGenerator kgen = KeyGenerator.getInstance("AES");
		kgen.init(128, new SecureRandom(password.getBytes("UTF-8")));
		SecretKey secretKey = kgen.generateKey();
		cipher.init(Cipher.ENCRYPT_MODE, secretKey, new IvParameterSpec(password.getBytes("UTF-8")));// 使用加密模式初始化 金鑰
		byte[] encrypt = cipher.doFinal(content.getBytes("UTF-8")); // 按單部分操作加密或解密資料，或者結束一個多部分操作。
		return parseByte2HexStr(encrypt);
	}

	/**
	 * 將二進位制轉換成16進位制
	 * 
	 * @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();
	}

	/**
	 * 將16進位制轉換為二進位制
	 * 
	 * @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;
	}
}