package com.tcm.training.admin.auth.service;
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import com.tcm.training.admin.auth.vo.CaptchaResponse;
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import org.springframework.stereotype.Service;
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import java.nio.charset.StandardCharsets;
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import java.util.Base64;
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import java.util.Map;
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import java.util.UUID;
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import java.util.concurrent.ConcurrentHashMap;
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import java.util.concurrent.ThreadLocalRandom;
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@Service
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public class CaptchaService {
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private static final long EXPIRE_MILLIS = 5 * 60 * 1000L;
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private static final char[] CAPTCHA_CHARS = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ".toCharArray();
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private final Map<String, CaptchaEntry> captchaStore = new ConcurrentHashMap<String, CaptchaEntry>();
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public CaptchaResponse createCaptcha() {
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clearExpired();
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String code = randomCode(4);
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String captchaId = UUID.randomUUID().toString().replace("-", "");
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captchaStore.put(captchaId, new CaptchaEntry(code, System.currentTimeMillis() + EXPIRE_MILLIS));
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String svg = buildSvg(code);
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String imageData = "data:image/svg+xml;base64,"
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+ Base64.getEncoder().encodeToString(svg.getBytes(StandardCharsets.UTF_8));
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return new CaptchaResponse(captchaId, imageData);
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}
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public void validate(String captchaId, String captchaCode) {
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clearExpired();
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CaptchaEntry entry = captchaStore.remove(captchaId);
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if (entry == null) {
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throw new IllegalArgumentException("验证码已失效，请刷新后重试");
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}
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if (entry.expireAt < System.currentTimeMillis()) {
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throw new IllegalArgumentException("验证码已过期，请刷新后重试");
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}
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if (!entry.code.equalsIgnoreCase(captchaCode)) {
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throw new IllegalArgumentException("验证码错误");
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}
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}
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private void clearExpired() {
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long now = System.currentTimeMillis();
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captchaStore.entrySet().removeIf(entry -> entry.getValue().expireAt < now);
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}
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private String randomCode(int length) {
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StringBuilder builder = new StringBuilder(length);
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ThreadLocalRandom random = ThreadLocalRandom.current();
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for (int i = 0; i < length; i++) {
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builder.append(CAPTCHA_CHARS[random.nextInt(CAPTCHA_CHARS.length)]);
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}
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return builder.toString();
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}
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private String buildSvg(String code) {
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ThreadLocalRandom random = ThreadLocalRandom.current();
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StringBuilder builder = new StringBuilder();
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builder.append("<svg xmlns='http://www.w3.org/2000/svg' width='132' height='44' viewBox='0 0 132 44'>");
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builder.append("<defs><linearGradient id='g' x1='0%' y1='0%' x2='100%' y2='100%'>");
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builder.append("<stop offset='0%' stop-color='#f7f9fc'/>");
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builder.append("<stop offset='100%' stop-color='#e6edf7'/></linearGradient></defs>");
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builder.append("<rect width='132' height='44' rx='10' fill='url(#g)'/>");
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for (int i = 0; i < 6; i++) {
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builder.append("<line x1='").append(random.nextInt(132)).append("' y1='").append(random.nextInt(44))
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.append("' x2='").append(random.nextInt(132)).append("' y2='").append(random.nextInt(44))
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.append("' stroke='rgba(100,116,139,0.35)' stroke-width='1'/>");
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}
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for (int i = 0; i < 16; i++) {
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builder.append("<circle cx='").append(random.nextInt(132)).append("' cy='").append(random.nextInt(44))
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.append("' r='").append(1 + random.nextInt(2)).append("' fill='rgba(59,130,246,0.18)'/>");
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}
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for (int i = 0; i < code.length(); i++) {
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int x = 18 + i * 24;
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int y = 29 + random.nextInt(6);
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int rotate = random.nextInt(-18, 19);
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String color = random.nextBoolean() ? "#1f2937" : "#2563eb";
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builder.append("<text x='").append(x).append("' y='").append(y)
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.append("' font-size='24' font-family='Arial' font-weight='700' fill='").append(color)
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.append("' transform='rotate(").append(rotate).append(" ").append(x).append(" ").append(y)
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.append(")'>").append(code.charAt(i)).append("</text>");
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}
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builder.append("</svg>");
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return builder.toString();
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}
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private static class CaptchaEntry {
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private final String code;
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private final long expireAt;
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private CaptchaEntry(String code, long expireAt) {
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this.code = code;
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this.expireAt = expireAt;
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}
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}
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}
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