package com.example.demo.util;

import lombok.extern.slf4j.Slf4j;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.security.SecureRandom;

/**
 * 驗證碼工具類
 *
 * @author wangbo
 * @since 2024/10/29
 */
@Slf4j
public class CaptchaGeneratorUtil {

    private CaptchaGeneratorUtil() {
        // ...
    }

    public static void main(String[] args) throws IOException {
        // 生成4位隨機數(shù)字驗證碼
        String text = generateRandomCode();
        // 創(chuàng)建驗證碼圖片
        BufferedImage image = createImage(text);
        // 保存圖片到文件
        ImageIO.write(image, "png", new File("captcha.png"));
    }

    private static final SecureRandom RANDOM = new SecureRandom();

    /**
     * 生成4位隨機數(shù)字字母驗證碼
     */
    public static String generateRandomCode() {
        StringBuilder code = new StringBuilder();
        for (int i = 0; i < 4; i++) {
            int i1 = RANDOM.nextInt(3);
            if (i1 == 0) {
                code.append((char) (RANDOM.nextInt(26) + 65));
            } else if (i1 == 1) {
                code.append((char) (RANDOM.nextInt(26) + 97));
            } else {
                code.append(RANDOM.nextInt(10));
            }
        }
        log.info("生成的驗證碼文本 text = {}", code);
        return code.toString();
    }

    /**
     * 創(chuàng)建驗證碼圖片
     */
    public static BufferedImage createImage(String text) {
        log.info("待生成驗證碼圖片的文本 text = {}", text);
        int width = 75;
        int height = 25;
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        // 使用Graphics2D以獲得更好的圖形控制
        Graphics2D g2d = image.createGraphics();

        try {
            // 設(shè)置背景顏色
            g2d.setColor(new Color(0xDCDCDC));
            g2d.fillRect(0, 0, width, height);

            // 設(shè)置字體和顏色
            g2d.setFont(new Font("Arial", Font.BOLD, 20));
            g2d.setColor(new Color(0x004000));

            // 確保文本不會超出圖像邊界
            FontMetrics fm = g2d.getFontMetrics();
            int textWidth = fm.stringWidth(text);
            // 居中文本
            int x = (width - textWidth) / 2;
            // 居中文本（基線對齊）
            int y = (height - fm.getHeight()) / 2 + fm.getAscent();

            g2d.drawString(text, x, y);

            // 添加噪聲線
            for (int i = 0; i < 5; i++) {
                g2d.setColor(new Color(RANDOM.nextInt(255), RANDOM.nextInt(255), RANDOM.nextInt(255)));
                g2d.drawLine(RANDOM.nextInt(width), RANDOM.nextInt(height), RANDOM.nextInt(width), RANDOM.nextInt(height));
            }

            // 設(shè)置渲染提示以提高圖像質(zhì)量（可選）
            g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        } finally {
            // 確保在try塊之后釋放Graphics2D資源
            g2d.dispose();
        }

        return image;
    }

    private static final String CAPTCHA_PREFIX = "captcha:";

    public static String generateCaptchaRedisKey(String key) {
        return CAPTCHA_PREFIX + key;
    }
}

/**
 * 生成圖片驗證碼
 *
 * @param key UUID字符串
 */
@GetMapping("/captcha/generator/{key}")
public void captchaGenerator(@PathVariable("key") String key, HttpServletResponse response) throws BaseException {
    userService.captchaGenerator(key, response);
}

public void captchaGenerator(String key, HttpServletResponse response) throws BaseException {
    //查看key的驗證碼是否已存在
    String captchaRedisKey = CaptchaGeneratorUtil.generateCaptchaRedisKey(key);
    boolean hasKey = Boolean.TRUE.equals(redisTemplate.hasKey(captchaRedisKey));
    if (hasKey) {
        throw new BaseException(ErrorCode.USER_KEY_REPETITION);
    }
    String captcha = CaptchaGeneratorUtil.generateRandomCode();
    BufferedImage image = CaptchaGeneratorUtil.createImage(captcha);
    //設(shè)置驗證碼，有效期1分鐘
    redisTemplate.opsForValue().set(captchaRedisKey, captcha, 60L, TimeUnit.SECONDS);
    response.setContentType("image/jpeg");
    try (ServletOutputStream out = response.getOutputStream()) {
        ImageIO.write(image, "JPEG", out);
    } catch (IOException e) {
        throw new RuntimeException(e);
    }
}

//校驗驗證碼
String key = loginPage.getKey();
String captcha = loginPage.getCaptcha();
if (StringUtils.isNullOrEmpty(key) || StringUtils.isNullOrEmpty(captcha)) {
    throw new BaseException(ErrorCode.USER_KEY_OR_CAPTCHA_NOT_FOUND);
}
String captchaRedisKey = CaptchaGeneratorUtil.generateCaptchaRedisKey(key);
String redisCaptcha = redisTemplate.opsForValue().get(captchaRedisKey);
if (StringUtils.isNullOrEmpty(redisCaptcha) || !captcha.equalsIgnoreCase(redisCaptcha)) {
    throw new BaseException(ErrorCode.USER_CAPTCHA_ERROR);
} else {
    //刪除驗證碼緩存
    redisTemplate.delete(captchaRedisKey);
}