package com.sxd.yfl;

import android.util.Base64;

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

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

/**
 * Created by wujie on 2016/5/7.
 */
public class ISecurity {
    public static final String APP_ID = Global.APP_ID;
    public static final String APP_KEY = Global.APP_KEY;

    public static String encrypt(String clear, String key, String iv) {
        try {
            byte[] encrypted = encrypt(clear.getBytes(), md5(key), md5(iv));
            return Base64.encodeToString(encrypted, Base64.DEFAULT);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "";
    }

    public static String decrypt(String encrypted, String key, String iv) {
        try {
            byte[] decrypted = decrypt(Base64.decode(encrypted, Base64.DEFAULT), md5(key), md5(iv));
            return new String(decrypted).trim();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "";
    }

    private static byte[] encrypt(byte[] clear, byte[] key, byte[] iv) throws Exception {
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        SecretKeySpec skeySpec = new SecretKeySpec(key, "AES");
        IvParameterSpec ivParamSpec = new IvParameterSpec(iv);
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec, ivParamSpec);
        return cipher.doFinal(clear);
    }

    private static byte[] decrypt(byte[] encrypted, byte[] key, byte[] iv) throws Exception {
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        SecretKeySpec skeySpec = new SecretKeySpec(key, "AES");
        IvParameterSpec ivParamSpec = new IvParameterSpec(iv);
        cipher.init(Cipher.DECRYPT_MODE, skeySpec, ivParamSpec);
        return cipher.doFinal(encrypted);
    }

    public static byte[] md5(String str) {
        try {
            return md5(str.getBytes("utf-8"));
        } catch (UnsupportedEncodingException e) {
            return md5(str.getBytes());
        }
    }

    public static byte[] md5(byte[] bytes) {
        try {
            MessageDigest md5 = MessageDigest.getInstance("MD5");
            md5.update(bytes);
            return md5.digest();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return bytes;
    }

    public static String MD5(String str) {
        try {
            return MD5(str.getBytes("utf-8"));
        } catch (UnsupportedEncodingException e) {
            return MD5(str.getBytes());
        }
    }

    private static String MD5(byte[] bytes) {
        try {
            MessageDigest md5 = MessageDigest.getInstance("MD5");
            md5.update(bytes);
            byte[] digested = md5.digest();
            char hexDigits[] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
                    'A', 'B', 'C', 'D', 'E', 'F'};
//            byte tmp[] = bytes;// MD5 的计算结果是一个 128 位的长整数，
            // 用字节表示就是 16 个字节
            char str[] = new char[16 * 2];// 每个字节用 16 进制表示的话，使用两个字符， 所以表示成 16
            // 进制需要 32 个字符
            int k = 0;// 表示转换结果中对应的字符位置
            for (int i = 0; i < 16; i++) {// 从第一个字节开始，对 MD5 的每一个字节// 转换成 16
                // 进制字符的转换
                byte byte0 = digested[i];// 取第 i 个字节
                str[k++] = hexDigits[byte0 >>> 4 & 0xf];// 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
                str[k++] = hexDigits[byte0 & 0xf];// 取字节中低 4 位的数字转换

            }
            return new String(str);// 换后的结果转换为字符串
        } catch (Exception e) {
            e.printStackTrace();
        }
        return new String(bytes);
    }

    public static String sha1(byte[] bytes) {
        try {
            MessageDigest md5 = MessageDigest.getInstance("SHA-1");
            md5.update(bytes);
            byte[] digested = md5.digest();
            return hexDigits(digested, digested.length);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return new String(bytes);
    }

    private static String hexDigits(byte[] bytes, int length) {
        char hexChars[] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
                'a', 'b', 'c', 'd', 'e', 'f'};
        char str[] = new char[length * 2];
        int k = 0;
        for (int i = 0; i < length; i++) {
            byte byte0 = bytes[i];
            str[k++] = hexChars[byte0 >>> 4 & 0xf];
            str[k++] = hexChars[byte0 & 0xf];
        }
        return new String(str);
    }
}