package com.nationalelectric.greenH5.utils;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.*;

public class MD5Util {

	private static String kk = "greenh5";

	public static String encrypt(String data) {

		try {
			java.security.MessageDigest md = java.security.MessageDigest.getInstance("MD5");
			byte[] array = md.digest((data + kk).getBytes());

			StringBuffer sb = new StringBuffer();
			for (int i = 0; i < array.length; ++i) {
				sb.append(Integer.toHexString((array[i] & 0xFF) | 0x100).substring(1, 3));
			}
			return sb.toString().toUpperCase();
		} catch (NoSuchAlgorithmException e) {
			// TODO Auto-generated catch block
			
			return null;
		}
	}

	/**
	 * 签名加密
	 * 
	 * @param map
	 * @return
	 */
	public static String MD5(Map map) {
		// 参数按键名升序排序
		List list = new ArrayList();
		Iterator iter = map.entrySet().iterator();
		while (iter.hasNext()) {
			Map.Entry entry = (Map.Entry) iter.next();
			list.add(entry.getKey());
		}
		Collections.sort(list);
		// 拼接参数
		StringBuilder param = new StringBuilder();
		for (int i = 0; i < list.size(); i++) {
			if (i == 0) {
				param.append(list.get(i) + "=" + map.get(list.get(i)));
			} else {
				param.append("&" + list.get(i) + "=" + map.get(list.get(i)));
			}
		}
		// 测试默认密匙，正式上线会约定修改
		param.append("&secretkey=xxxxxxxxx");
		try {
			// MD5加密
			java.security.MessageDigest md = java.security.MessageDigest.getInstance("MD5");
			byte[] array = md.digest(param.toString().getBytes());
			StringBuffer sb = new StringBuffer();
			for (int i = 0; i < array.length; ++i) {
				sb.append(Integer.toHexString((array[i] & 0xFF) | 0x100).substring(1, 3));
			}
			return sb.toString().toUpperCase();
		} catch (java.security.NoSuchAlgorithmException e) {
			
		}
		return null;
	}

	public static String getMD5(String param) throws NoSuchAlgorithmException {
		// MD5加密
		java.security.MessageDigest md = java.security.MessageDigest.getInstance("MD5");
		byte[] array = md.digest(param.toString().getBytes());
		StringBuffer sb = new StringBuffer();
		for (int i = 0; i < array.length; ++i) {
			sb.append(Integer.toHexString((array[i] & 0xFF) | 0x100).substring(1, 3));
		}
		return sb.toString();

	}

	// ==========================================
	/**
	 * 默认的密码字符串组合，用来将字节转换成 16 进制表示的字符,apache校验下载的文件的正确性用的就是默认的这个组合
	 */
	protected static char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e',
			'f' };

	protected static MessageDigest messagedigest = null;
	static {
		try {
			messagedigest = MessageDigest.getInstance("MD5");
		} catch (NoSuchAlgorithmException nsaex) {
			
			nsaex.printStackTrace();
		}
	}

	/**
	 * 生成字符串的md5校验值
	 * 
	 * @param s
	 * @return
	 */
	public static String getMD5String(String s) {
		return getMD5String(s.getBytes());
	}

	/**
	 * 判断字符串的md5校验码是否与一个已知的md5码相匹配
	 * 
	 * @param possword
	 *            要校验的字符串
	 * @param md5PwdStr
	 *            已知的md5校验码
	 * @return
	 */
	public static boolean checkPossword(String possword, String md5PwdStr) {
		String s = getMD5String(possword);
		return s.equals(md5PwdStr);
	}

	/**
	 * 生成文件的md5校验值
	 * 
	 * @param file
	 * @return
	 * @throws IOException
	 */
	public static String getFileMD5String(File file) throws IOException {
		InputStream fis = null;
		try {
			fis = new FileInputStream(file);
			byte[] buffer = new byte[1024];
			int numRead = 0;
			while ((numRead = fis.read(buffer)) > 0) {
				messagedigest.update(buffer, 0, numRead);
			}
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			if (fis != null) {
				fis.close();
			}
		}
		
		
		return bufferToHex(messagedigest.digest());
	}

	/**
	 * JDK1.4中不支持以MappedByteBuffer类型为参数update方法，并且网上有讨论要慎用MappedByteBuffer，
	 * 原因是当使用 FileChannel.map 方法时，MappedByteBuffer 已经在系统内占用了一个句柄， 而使用
	 * FileChannel.close 方法是无法释放这个句柄的，且FileChannel有没有提供类似 unmap 的方法，
	 * 因此会出现无法删除文件的情况。
	 * 
	 * 不推荐使用
	 * 
	 * @param file
	 * @return
	 * @throws IOException
	 */
	public static String getFileMD5String_old(File file) throws IOException {
		FileInputStream in = null;
		try {
			in = new FileInputStream(file);
			FileChannel ch = in.getChannel();
			MappedByteBuffer byteBuffer = ch.map(FileChannel.MapMode.READ_ONLY, 0, file.length());
			messagedigest.update(byteBuffer);
			
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			if (in != null) {
				in.close();
			}
		}
		
		return bufferToHex(messagedigest.digest());
	}

	public static String getMD5String(byte[] bytes) {
		messagedigest.update(bytes);
		return bufferToHex(messagedigest.digest());
	}

	private static String bufferToHex(byte bytes[]) {
		return bufferToHex(bytes, 0, bytes.length);
	}

	private static String bufferToHex(byte bytes[], int m, int n) {
		StringBuffer stringbuffer = new StringBuffer(2 * n);
		int k = m + n;
		for (int l = m; l < k; l++) {
			appendHexPair(bytes[l], stringbuffer);
		}
		return stringbuffer.toString();
	}

	private static void appendHexPair(byte bt, StringBuffer stringbuffer) {
		char c0 = hexDigits[(bt & 0xf0) >> 4];// 取字节中高 4 位的数字转换, >>>
												// 为逻辑右移，将符号位一起右移,此处未发现两种符号有何不同
		char c1 = hexDigits[bt & 0xf];// 取字节中低 4 位的数字转换
		stringbuffer.append(c0);
		stringbuffer.append(c1);
	}



}