package com.example.attendance.util;

import com.example.attendance.entity.Teacher;
import io.jsonwebtoken.Claims;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;
import io.jsonwebtoken.security.Keys;

import javax.crypto.SecretKey;
import java.util.Date;

public class JWTUtil {

    private static final SecretKey SECRET_KEY = Keys.secretKeyFor(SignatureAlgorithm.HS256);

    public static String generateToken(Teacher teacher) {
        return Jwts.builder()
                .setSubject(teacher.getUsername())
                .setIssuedAt(new Date())
                .setExpiration(new Date(System.currentTimeMillis() + 60 * 60 * 1000))  // Token 有效期 1 小时
                .signWith(SignatureAlgorithm.HS256, SECRET_KEY)
                .compact();
    }

    public static Claims extractClaims(String token) {
        try {
            return Jwts.parser()
                    .setSigningKey(SECRET_KEY)
                    .parseClaimsJws(token)
                    .getBody();
        } catch (Exception e) {
            throw new RuntimeException("Invalid JWT token", e); // 捕获并抛出异常
        }
    }

    public static String getUsernameFromToken(String token) {
        return extractClaims(token).getSubject();
    }

    public static boolean isTokenExpired(String token) {
        return extractClaims(token).getExpiration().before(new Date());
    }
}