package com.walker.infrastructure.utils;

import java.io.ByteArrayOutputStream;
import java.nio.charset.Charset;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.Signature;
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 com.walker.infrastructure.utils.StringUtils;

public class RSAUtil {
	public static final Charset UTF8 = Charset.forName("UTF-8");
	
	public static final String DEFAULT_ALGORITHM = "RSA/ECB/PKCS1Padding";
	
	/**
	 * 加密算法RSA
	 */
	public static final String KEY_ALGORITHM = "RSA";

	/**
	 * 签名算法
	 */
	public static final String SIGNATURE_ALGORITHM = "MD5withRSA";
	public static final String SIGNaTURE_ALGORITHM_SHA1_RSA = "SHA1WithRSA";
	
	/**
	 * 获取公钥的key
	 */
	private static final String PUBLIC_KEY = "RSAPublicKey";

	/**
	 * 获取私钥的key
	 */
	private static final String PRIVATE_KEY = "RSAPrivateKey";

	/**
	 * 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 = 128;

	public static String privateKeyPath = "private_key.pem";
	public static String publicKeyPath = "public_key.pem";

	private static KeyFactory rsaKeyFactory = null;
	
	static {
		try {
			rsaKeyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		} catch (NoSuchAlgorithmException e) {
			throw new UnsupportedOperationException("未找到加密算法：" + KEY_ALGORITHM);
		}
	}
	
//	public RSAUtil(){
//		try {
//			rsaKeyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
//		} catch (NoSuchAlgorithmException e) {
//			throw new UnsupportedOperationException("未找到加密算法：" + KEY_ALGORITHM);
//		}
//	}
	
	/**
	 * 生成秘钥对
	 * 
	 * @return
	 * @throws NoSuchAlgorithmException
	 */
	public static KeyPair generateKey() throws NoSuchAlgorithmException {
		KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
		keyPairGen.initialize(1024, new SecureRandom());
		KeyPair keyPair = keyPairGen.generateKeyPair();
		return keyPair;
	}

	public static String toHexString(byte[] b) {
		StringBuilder sb = new StringBuilder(b.length * 2);
		for (int i = 0; i < b.length; i++) {
			sb.append(HEXCHAR[(b[i] & 0xf0) >>> 4]);
			sb.append(HEXCHAR[b[i] & 0x0f]);
		}
		return sb.toString();
	}

	public static final byte[] toBytes(String s) {
		byte[] bytes;
		bytes = new byte[s.length() / 2];
		for (int i = 0; i < bytes.length; i++) {
			bytes[i] = (byte) Integer.parseInt(s.substring(2 * i, 2 * i + 2),
					16);
		}
		return bytes;
	}

	private static char[] HEXCHAR = { '0', '1', '2', '3', '4', '5', '6', '7',
			'8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };

	/**
	 * <p>
	 * 生成密钥对(公钥和私钥)
	 * </p>
	 * 
	 * @return
	 * @throws Exception
	 */
	public static Map<String, Object> genKeyPair() throws Exception {
		KeyPair keyPair = generateKey();
		RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
		RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
		Map<String, Object> keyMap = new HashMap<String, Object>(2);
		keyMap.put(PUBLIC_KEY, publicKey);
		keyMap.put(PRIVATE_KEY, privateKey);
		return keyMap;
	}

	/**
	 * <p>
	 * 用私钥对信息生成数字签名
	 * </p>
	 * 
	 * @param data
	 *            已加密数据
	 * @param privateKey
	 *            私钥(BASE64编码)
	 * 
	 * @return
	 * @throws Exception
	 */
	public static String sign(byte[] data, String privateKey) throws Exception {
		byte[] keyBytes = Base64Utils.decode(privateKey);
		PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec);
		Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
		signature.initSign(privateK);
		signature.update(data);
		return Base64Utils.encode(signature.sign());
	}
	
	/**
	 * 签名算法，使用SHA1WithRSA，目前支付宝使用。
	 * @param content
	 * @param privateKey
	 * @return
	 */
	public static String signWithSha1Rsa(String content, String privateKey) {
		try {
			PKCS8EncodedKeySpec priPKCS8 = new PKCS8EncodedKeySpec(Base64Utils.decode(privateKey));
//			KeyFactory keyf = KeyFactory.getInstance(KEY_ALGORITHM);
			PrivateKey priKey = rsaKeyFactory.generatePrivate(priPKCS8);
			Signature signature = Signature.getInstance(SIGNaTURE_ALGORITHM_SHA1_RSA);

			signature.initSign(priKey);
			signature.update(content.getBytes(StringUtils.DEFAULT_CHARSET_UTF8));

			byte[] signed = signature.sign();
			return Base64Utils.encode(signed);
			
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}
	
	/**
	 * 验证签名，目前支付宝使用
	 * @param content
	 * @param sign
	 * @param alipay_public_key
	 * @param input_charset
	 * @return
	 * @throws Exception
	 */
	public static boolean verifyWithSha1Rsa(String content, String sign
			, String alipay_public_key, String input_charset) throws Exception{
//			KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        byte[] encodedKey = Base64Utils.decode(alipay_public_key);
        PublicKey pubKey = rsaKeyFactory.generatePublic(new X509EncodedKeySpec(encodedKey));

		Signature signature = Signature.getInstance(SIGNaTURE_ALGORITHM_SHA1_RSA);
		signature.initVerify(pubKey);
		signature.update(content.getBytes(input_charset));
	
		return signature.verify(Base64Utils.decode(sign) );
	}

	/**
	 * <p>
	 * 校验数字签名
	 * </p>
	 * 
	 * @param data
	 *            已加密数据
	 * @param publicKey
	 *            公钥(BASE64编码)
	 * @param sign
	 *            数字签名
	 * 
	 * @return
	 * @throws Exception
	 * 
	 */
	public static boolean verify(byte[] data, String publicKey, String sign)
			throws Exception {
		byte[] keyBytes = Base64Utils.decode(publicKey);
		X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		PublicKey publicK = keyFactory.generatePublic(keySpec);
		Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
		signature.initVerify(publicK);
		signature.update(data);
		return signature.verify(Base64Utils.decode(sign));
	}

	/**
	 * <P>
	 * 私钥解密
	 * </p>
	 * 
	 * @param encryptedData
	 *            已加密数据
	 * @param privateKey
	 *            私钥(BASE64编码)
	 * @return
	 * @throws Exception
	 */
	public static byte[] decryptByPrivateKey(byte[] encryptedData,
			String privateKey) throws Exception {
		byte[] keyBytes = Base64Utils.decode(privateKey);
		PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
//		String al = keyFactory.getAlgorithm();
		Cipher cipher = Cipher.getInstance(DEFAULT_ALGORITHM);
		cipher.init(Cipher.DECRYPT_MODE, privateK);
		int inputLen = encryptedData.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(encryptedData, offSet, MAX_DECRYPT_BLOCK);
			} else {
				cache = cipher
						.doFinal(encryptedData, offSet, inputLen - offSet);
			}
			out.write(cache, 0, cache.length);
			i++;
			offSet = i * MAX_DECRYPT_BLOCK;
		}
		byte[] decryptedData = out.toByteArray();
		out.close();
		return decryptedData;
	}

	/**
	 * <p>
	 * 公钥解密
	 * </p>
	 * 
	 * @param encryptedData
	 *            已加密数据
	 * @param publicKey
	 *            公钥(BASE64编码)
	 * @return
	 * @throws Exception
	 */
	public static byte[] decryptByPublicKey(byte[] encryptedData,
			String publicKey) throws Exception {
		byte[] keyBytes = Base64Utils.decode(publicKey);
		X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		Key publicK = keyFactory.generatePublic(x509KeySpec);
		Cipher cipher = Cipher.getInstance(DEFAULT_ALGORITHM);
		cipher.init(Cipher.DECRYPT_MODE, publicK);
		int inputLen = encryptedData.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(encryptedData, offSet, MAX_DECRYPT_BLOCK);
			} else {
				cache = cipher
						.doFinal(encryptedData, offSet, inputLen - offSet);
			}
			out.write(cache, 0, cache.length);
			i++;
			offSet = i * MAX_DECRYPT_BLOCK;
		}
		byte[] decryptedData = out.toByteArray();
		out.close();
		return decryptedData;
	}

	/**
	 * <p>
	 * 公钥加密
	 * </p>
	 * 
	 * @param data
	 *            源数据
	 * @param publicKey
	 *            公钥(BASE64编码)
	 * @return
	 * @throws Exception
	 */
	public static byte[] encryptByPublicKey(byte[] data, String publicKey)
			throws Exception {
		byte[] keyBytes = Base64Utils.decode(publicKey);
		X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		Key publicK = keyFactory.generatePublic(x509KeySpec);
		// 对数据加密
		Cipher cipher = Cipher.getInstance(DEFAULT_ALGORITHM);// keyFactory.getAlgorithm()解决javax.crypto.BadPaddingException:
																	// Blocktype异常的几种解决办法
		cipher.init(Cipher.ENCRYPT_MODE, publicK);
		int inputLen = data.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, offSet, MAX_ENCRYPT_BLOCK);
			} else {
				cache = cipher.doFinal(data, offSet, inputLen - offSet);
			}
			out.write(cache, 0, cache.length);
			i++;
			offSet = i * MAX_ENCRYPT_BLOCK;
		}
		byte[] encryptedData = out.toByteArray();
		out.close();
		return encryptedData;
	}

	/**
	 * <p>
	 * 私钥加密
	 * </p>
	 * 
	 * @param data
	 *            源数据
	 * @param privateKey
	 *            私钥(BASE64编码)
	 * @return
	 * @throws Exception
	 */
	public static byte[] encryptByPrivateKey(byte[] data, String privateKey)
			throws Exception {
		byte[] keyBytes = Base64Utils.decode(privateKey);
		PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
		Cipher cipher = Cipher.getInstance(DEFAULT_ALGORITHM);
		cipher.init(Cipher.ENCRYPT_MODE, privateK);
		int inputLen = data.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, offSet, MAX_ENCRYPT_BLOCK);
			} else {
				cache = cipher.doFinal(data, offSet, inputLen - offSet);
			}
			out.write(cache, 0, cache.length);
			i++;
			offSet = i * MAX_ENCRYPT_BLOCK;
		}
		byte[] encryptedData = out.toByteArray();
		out.close();
		return encryptedData;
	}

	/**
	 * <p>
	 * 获取私钥
	 * </p>
	 * 
	 * @param keyMap
	 *            密钥对
	 * @return
	 * @throws Exception
	 */
	public static String getPrivateKey(Map<String, Object> keyMap)
			throws Exception {
		Key key = (Key) keyMap.get(PRIVATE_KEY);
		return Base64Utils.encode(key.getEncoded());
	}

	/**
	 * <p>
	 * 获取公钥
	 * </p>
	 * 
	 * @param keyMap
	 *            密钥对
	 * @return
	 * @throws Exception
	 */
	public static String getPublicKey(Map<String, Object> keyMap)
			throws Exception {
		Key key = (Key) keyMap.get(PUBLIC_KEY);
		return Base64Utils.encode(key.getEncoded());
	}

	public static PublicKey getPublicKey(String key) throws Exception {
		byte[] keyBytes;
		keyBytes = Base64Utils.decode(key);
		X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		PublicKey publicKey = keyFactory.generatePublic(keySpec);
		return publicKey;
	}

	public static byte[] encrypt(PublicKey pubkey, String text) {
		try {
			Cipher rsa;
			rsa = Cipher.getInstance(DEFAULT_ALGORITHM);
			rsa.init(Cipher.ENCRYPT_MODE, pubkey);
			return rsa.doFinal(text.getBytes());
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}

	public static String decrypt(PrivateKey decryptionKey, byte[] buffer) {
		try {
			Cipher rsa;
			rsa = Cipher.getInstance(DEFAULT_ALGORITHM);
			rsa.init(Cipher.DECRYPT_MODE, decryptionKey);
			byte[] utf8 = rsa.doFinal(buffer);
			return new String(utf8, "UTF8");
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}

}