package com.bizzan.bitrade.util;

import org.apache.commons.codec.binary.Base32;
import org.apache.commons.codec.binary.Base64;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
/**
 * google验证工具类
 * @author shenzucai
 * @time 2018.04.05 8:51
 */
public class GoogleAuthenticatorUtil {

	
	    public static final int SECRET_SIZE = 10;  
	    
	    public static final String SEED = "g8GjEvTbW5oVSV7avLBdwIHqGlUYNzKFI7izOF8GwLDVKs2m0QN7vxRs2im5MDaNCWGmcD2rvcZx";
	      
	    public static final String RANDOM_NUMBER_ALGORITHM = "SHA1PRNG";  
	    public static final String  codes= "676526";  
	    public static final String  savedSecret= "5ODF2DGKUSMBZTHY";  
	      
	   /* int window_size = 17; // default 3 - max 17 (from google docs)最多可偏移的时间  
	    @Test 
	    public void setWindowSize(int s) {  
	        if (s >= 1 && s <= 17)  
	            window_size = s;  
	    }  */
	    //最大偏移时间
	    int window_size = 0;
	/*    @Test 
	    public void setWindowSize(int s) {  
	        if (s >= 1 && s <= 17)  
	            window_size = s;  
	    } */
	    
	    public static String generateSecretKey() {  
	        SecureRandom sr = null;  
	        try {  
	            sr = SecureRandom.getInstance(RANDOM_NUMBER_ALGORITHM);  
	            sr.setSeed(Base64.decodeBase64(SEED));  
	            byte[] buffer = sr.generateSeed(SECRET_SIZE);   
	            Base32 codec = new Base32();  
	            byte[] bEncodedKey = codec.encode(buffer);  
	            String encodedKey = new String(bEncodedKey);  
	            return encodedKey;  
	        }catch (NoSuchAlgorithmException e) {  
	            // should never occur... configuration error  
	        }  
	        return null;  
	    } 
	    
    
    
	    public static String getQRBarcodeURL(String user, String host, String secret) {
            String format = "otpauth://totp/%s@%s?secret=%s";
	        return String.format(format, user, host, secret);
	    }  
    
    
    
    public boolean check_code(String secret, long code, long timeMsec) {  
        Base32 codec = new Base32();  
        byte[] decodedKey = codec.decode(secret);  
        // convert unix msec time into a 30 second "window"  
        // this is per the TOTP spec (see the RFC for details)  
        long t = (timeMsec / 1000L) / 30L;  
        // Window is used to check codes generated in the near past.  
        // You can use this value to tune how far you're willing to go.  
        for (int i = -window_size; i <= window_size; ++i) {  
            long hash;  
            try {  
                hash = verify_code(decodedKey, t + i);  
                System.out.println("hash="+hash);
                System.out.println("code="+code);
            }catch (Exception e) {  
                // Yes, this is bad form - but  
                // the exceptions thrown would be rare and a static configuration problem  
                e.printStackTrace();  
                throw new RuntimeException(e.getMessage());  
                //return false;  
            }  
            if (hash == code) {  
                return true;  
            }  
        }  
        // The validation code is invalid.  
        return false;  
    }  
    
    
    
    
    private static int verify_code(byte[] key, long t) throws NoSuchAlgorithmException, InvalidKeyException {  
        byte[] data = new byte[8];  
        long value = t;  
        for (int i = 8; i-- > 0; value >>>= 8) {  
            data[i] = (byte) value;  
        }  
        SecretKeySpec signKey = new SecretKeySpec(key, "HmacSHA1");  
        Mac mac = Mac.getInstance("HmacSHA1");  
        mac.init(signKey);  
        byte[] hash = mac.doFinal(data);  
        int offset = hash[20 - 1] & 0xF;  
        // We're using a long because Java hasn't got unsigned int.  
        long truncatedHash = 0;  
        for (int i = 0; i < 4; ++i) {  
            truncatedHash <<= 8;  
            // We are dealing with signed bytes:  
            // we just keep the first byte.  
            truncatedHash |= (hash[offset + i] & 0xFF);  
        }  
        truncatedHash &= 0x7FFFFFFF;  
        truncatedHash %= 1000000;  
        return (int) truncatedHash;  
    }  
	

    
  
}
