package com.project.common.utils.sign;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Md5加密方法
 *
 * @author project
 */
public class Md5Utils
{
    private static final Logger log = LoggerFactory.getLogger(Md5Utils.class);

    private static byte[] md5(String s)
    {
        MessageDigest algorithm;
        try
        {
            algorithm = MessageDigest.getInstance("MD5");
            algorithm.reset();
            algorithm.update(s.getBytes("UTF-8"));
            byte[] messageDigest = algorithm.digest();
            return messageDigest;
        }
        catch (Exception e)
        {
            log.error("MD5 Error...", e);
        }
        return null;
    }

    private static final String toHex(byte hash[])
    {
        if (hash == null)
        {
            return null;
        }
        StringBuffer buf = new StringBuffer(hash.length * 2);
        int i;

        for (i = 0; i < hash.length; i++)
        {
            if ((hash[i] & 0xff) < 0x10)
            {
                buf.append("0");
            }
            buf.append(Long.toString(hash[i] & 0xff, 16));
        }
        return buf.toString();
    }

    public static String hash(String s)
    {
        try
        {
            return new String(toHex(md5(s)).getBytes(StandardCharsets.UTF_8), StandardCharsets.UTF_8);
        }
        catch (Exception e)
        {
            log.error("not supported charset...{}", e);
            return s;
        }
    }

    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){
            System.err.println(Md5Utils.class.getName()+"初始化失败，MessageDigest不支持MD5Util。");
            nsaex.printStackTrace();
        }
    }


    public static String getFileMD5String(File file) throws IOException
    {
        FileInputStream in = new FileInputStream(file);
        FileChannel ch = in.getChannel();
        MappedByteBuffer byteBuffer = ch.map(FileChannel.MapMode.READ_ONLY, 0, file.length());
        messagedigest.update(byteBuffer);
        return bufferToHex(messagedigest.digest());
    }

    public static String getMD5String(String s)
    {

        return getMD5String(s.getBytes());
    }

    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];
        char c1 = hexDigits[bt & 0xf];
        stringbuffer.append(c0);
        stringbuffer.append(c1);
    }

    public static boolean checkPassword(String password, String md5PwdStr)
    {
        String s = getMD5String(password);
        return s.equals(md5PwdStr);
    }
}