package com.eighteengray.commonutil;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;

/**
 * 加密解密工具类
 */
public class EncryptUtils
{
	public static String encryptMd5(String string)
	{
		byte[] hash;
		try
		{
			hash = MessageDigest.getInstance("MD5").digest(string.getBytes("UTF-8"));
		} catch (NoSuchAlgorithmException e) {
			throw new RuntimeException("Huh, MD5 should be supported?", e);
		} catch (UnsupportedEncodingException e) {
			throw new RuntimeException("Huh, UTF-8 should be supported?", e);
		}

		StringBuilder hex = new StringBuilder(hash.length * 2);
		for (byte b : hash)
		{
			if ((b & 0xFF) < 0x10)
			{
				hex.append("0");
			}
			hex.append(Integer.toHexString(b & 0xFF));
		}
		return hex.toString();
	}

	public static String decryptMD5(String source)
	{
		char[] a = source.toCharArray();
		for (int i = 0; i < a.length; i++){
			a[i] = (char) (a[i] ^ 't');
		}
		String s = new String(a);
		return s;
	}


	private final static String DES = "DES";
	private static byte[] encryptDES(byte[] data, byte[] key) throws Exception
	{
		// 生成一个可信任的随机数源
		SecureRandom sr = new SecureRandom();
		// 从原始密钥数据创建DESKeySpec对象
		DESKeySpec dks = new DESKeySpec(key);
		// 创建一个密钥工厂，然后用它把DESKeySpec转换成SecretKey对象
		SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
		SecretKey securekey = keyFactory.generateSecret(dks);
		// Cipher对象实际完成加密操作
		Cipher cipher = Cipher.getInstance(DES);
		// 用密钥初始化Cipher对象
		cipher.init(Cipher.ENCRYPT_MODE, securekey, sr);
		return cipher.doFinal(data);
	}


	private static byte[] decryptDES(byte[] data, byte[] key) throws Exception
	{
		// 生成一个可信任的随机数源
		SecureRandom sr = new SecureRandom();
		// 从原始密钥数据创建DESKeySpec对象
		DESKeySpec dks = new DESKeySpec(key);
		// 创建一个密钥工厂，然后用它把DESKeySpec转换成SecretKey对象
		SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
		SecretKey securekey = keyFactory.generateSecret(dks);
		// Cipher对象实际完成解密操作
		Cipher cipher = Cipher.getInstance(DES);
		// 用密钥初始化Cipher对象
		cipher.init(Cipher.DECRYPT_MODE, securekey, sr);
		return cipher.doFinal(data);
	}


	//Base64
	public static String encryptBase64(String data, String key) throws Exception
	{
		byte[] bt = encryptDES(data.getBytes(), key.getBytes());
		String strs = Base64.encode(bt);
		return strs;
	}

	public static String decryptBase64(String data, String key) throws Exception
	{
		if (data == null) {
			return null;
		}
		byte[] buf = Base64.decode(data);
		byte[] bt = decryptDES(buf, key.getBytes());
		return new String(bt);
	}

	public static class Base64
	{
		/**
		 * Base64编码表。
		 */
		private static final char[] BASE64CODE =
				{'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V',
						'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q',
						'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/',};

		/**
		 * Base64解码表。
		 */
		private static final byte[] BASE64DECODE =
				{-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
						-1, -1, -1,
						-1,
						-1, // 注意两个63，为兼容SMP，
						-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, 63,
						-1,
						63, // “/”和“-”都翻译成63。
						52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, 0, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
						12, 13,
						14, // 注意两个0：
						15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1,
						-1, // “A”和“=”都翻译成0。
						-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,
						-1, -1, -1, -1, -1,};

		private static final int HEX_255 = 0x0000ff;
		private static final int HEX_16515072 = 0xfc0000;
		private static final int HEX_258048 = 0x3f000;
		private static final int HEX_4032 = 0xfc0;
		private static final int HEX_63 = 0x3f;
		private static final int HEX_16711680 = 0xff0000;
		private static final int HEX_65280 = 0x00ff00;
		private static final int NUMBER_TWO = 2;
		private static final int NUMBER_THREE = 3;
		private static final int NUMBER_FOUR = 4;
		private static final int NUMBER_SIX = 6;
		private static final int NUMBER_EIGHT = 8;
		private static final int NUMBER_TWELVE = 12;
		private static final int NUMBER_SIXTEEN = 16;
		private static final int NUMBER_EIGHTEEN = 18;

		/**
		 * 构造方法私有化，防止实例化。
		 */
		private Base64()
		{
		}

		/**
		 * Base64编码。将字节数组中字节3个一组编码成4个可见字符。
		 * @param b 需要被编码的字节数据。
		 * @return 编码后的Base64字符串。
		 */
		public static String encode(byte[] b)
		{
			int code = 0;

			// 按实际编码后长度开辟内存，加快速度
			StringBuffer sb = new StringBuffer(((b.length - 1) / NUMBER_THREE) << NUMBER_TWO + NUMBER_FOUR);
			// 进行编码
			for (int i = 0; i < b.length; i++)
			{
				code |=
						(b[i] << (NUMBER_SIXTEEN - i % NUMBER_THREE * NUMBER_EIGHT))
								& (HEX_255 << (NUMBER_SIXTEEN - i % NUMBER_THREE * NUMBER_EIGHT));
				if (i % NUMBER_THREE == NUMBER_TWO || i == b.length - 1)
				{
					sb.append(BASE64CODE[(code & HEX_16515072) >>> NUMBER_EIGHTEEN]);
					sb.append(BASE64CODE[(code & HEX_258048) >>> NUMBER_TWELVE]);
					sb.append(BASE64CODE[(code & HEX_4032) >>> NUMBER_SIX]);
					sb.append(BASE64CODE[code & HEX_63]);
					code = 0;
				}
			}

			// 对于长度非3的整数倍的字节数组，编码前先补0，编码后结尾处编码用=代替，
			// =的个数和短缺的长度一致，以此来标识出数据实际长度
			if (b.length % NUMBER_THREE > 0)
			{
				sb.setCharAt(sb.length() - 1, '=');
			}
			if (b.length % NUMBER_THREE == 1)
			{
				sb.setCharAt(sb.length() - NUMBER_TWO, '=');
			}
			return sb.toString();
		}

		/**
		 * Base64解码。
		 *
		 * @param code 用Base64编码的ASCII字符串
		 * @return 解码后的字节数据
		 */
		public static byte[] decode(String code)
		{
			// 检查参数合法性
			if (code == null)
			{
				return null;
			}
			int len = code.length();
			if (len % NUMBER_FOUR != 0)
			{
				throw new IllegalArgumentException("Base64 string length must be 4*n");
			}
			if (code.length() == 0)
			{
				return new byte[0];
			}

			// 统计填充的等号个数
			int pad = 0;
			if (code.charAt(len - 1) == '=')
			{
				pad++;
			}
			if (code.charAt(len - NUMBER_TWO) == '=')
			{
				pad++;
			}

			// 根据填充等号的个数来计算实际数据长度
			int retLen = len / NUMBER_FOUR * NUMBER_THREE - pad;

			// 分配字节数组空间
			byte[] ret = new byte[retLen];

			// 查表解码
			char ch1, ch2, ch3, ch4;
			int i;
			for (i = 0; i < len; i += NUMBER_FOUR)
			{
				int j = i / NUMBER_FOUR * NUMBER_THREE;
				ch1 = code.charAt(i);
				ch2 = code.charAt(i + 1);
				ch3 = code.charAt(i + NUMBER_TWO);
				ch4 = code.charAt(i + NUMBER_THREE);
				int tmp =
						(BASE64DECODE[ch1] << NUMBER_EIGHTEEN) | (BASE64DECODE[ch2] << NUMBER_TWELVE)
								| (BASE64DECODE[ch3] << NUMBER_SIX) | (BASE64DECODE[ch4]);
				ret[j] = (byte)((tmp & HEX_16711680) >> NUMBER_SIXTEEN);
				if (i < len - NUMBER_FOUR)
				{
					ret[j + 1] = (byte)((tmp & HEX_65280) >> NUMBER_EIGHT);
					ret[j + NUMBER_TWO] = (byte)((tmp & HEX_255));

				}
				else
				{
					if (j + 1 < retLen)
					{
						ret[j + 1] = (byte)((tmp & HEX_65280) >> NUMBER_EIGHT);
					}
					if (j + NUMBER_TWO < retLen)
					{
						ret[j + NUMBER_TWO] = (byte)((tmp & HEX_255));
					}
				}
			}
			return ret;
		}
	}

}
