package jnpf.util;

import lombok.Cleanup;

import javax.imageio.ImageIO;
import jakarta.servlet.ServletOutputStream;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.util.Objects;
import java.util.Random;

/**
 *
 * @author JNPF开发平台组
 * @version V3.1.0
 * @copyright 引迈信息技术有限公司
 * @date 2021/3/16 10:45
 */
public class CodeUtil {
    /**
     *放到session中的key
     */
    public static final String RANDOMCODEKEY = "RANDOMCODEKEY";
    private Random random = new Random();
    /**
     *随机产生的字符串
     */
    private String randString = "abcdefghjklmnopqrstuvwxyz23456789ABCDEFGHJKLMNPQRSTUVWXYZ";
    /**
     *图片宽
     */
    private int width = 120;
    /**
     *图片高
     */
    private int height = 40;
    /**
     *干扰线数量
     */
    private int lineSize = 10;
    /**
     *随机产生字符数量
     */
    private int stringNum = 4;

    /**
     * 获得字体
     */
    private Font getFont(){
        return new Font("Fixedsys", Font.CENTER_BASELINE,18);
    }

    /**
     * 获得颜色
     */
    private Color getRandColor(int fc, int bc){
        if(fc > 255) {
            fc = 255;
        }
        if(bc > 255) {
            bc = 255;
        }
        int r = fc + random.nextInt(bc-fc-16);
        int g = fc + random.nextInt(bc-fc-14);
        int b = fc + random.nextInt(bc-fc-18);
        return new Color(r,g,b);
    }

    /**
     * 生成随机图片
     */
    public void getRandcode(HttpServletResponse response, Integer stringLength) {
        try {
            HttpSession session = ServletUtil.getSession();
            //BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
            BufferedImage image = new BufferedImage(width,height, BufferedImage.TYPE_INT_BGR);
            //产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作
            Graphics g = image.getGraphics();
            g.fillRect(0, 0, width, height);
            g.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE,20));
            g.setColor(getRandColor(110, 133));
            //绘制干扰线
            for(int i=0;i<=lineSize;i++){
                drowLine(g);
            }
            //绘制随机字符
            String randomString = "";
            if (Objects.nonNull(stringLength)) {
                stringNum = stringLength;
            }
            for(int i = 1; i <= stringNum; i++){
                randomString=drowString(g,randomString,i);
            }
            session.removeAttribute(RANDOMCODEKEY);
            session.setAttribute(RANDOMCODEKEY, randomString);
            System.out.println("后台代码"+randomString);
            g.dispose();
            @Cleanup ServletOutputStream outputStream = response.getOutputStream();
            //将内存中的图片通过流动形式输出到客户端
            ImageIO.write(image, "JPEG", outputStream);
        }catch (Exception e){
            e.getStackTrace();
        }
    }

    /**
     * 绘制字符串
     */
    private String drowString(Graphics g, String randomString, int i){
        g.setFont(getFont());
        g.setColor(new Color(random.nextInt(101),random.nextInt(111),random.nextInt(121)));
        String rand = String.valueOf(getRandomString(random.nextInt(randString.length())));
        randomString +=rand;
        g.translate(random.nextInt(3), random.nextInt(3));
        g.drawString(rand, 15*i, 22);
        return randomString;
    }

    /**
     * 绘制干扰线
     */
    private void drowLine(Graphics g){
        int x = random.nextInt(width);
        int y = random.nextInt(height);
        int xl = random.nextInt(13);
        int yl = random.nextInt(15);
        g.drawLine(x, y, x+xl, y+yl);
    }

    /**
     * 获取随机的字符
     */
    public String getRandomString(int num){
        return String.valueOf(randString.charAt(num));
    }
}