gc-guide-api/src/main/java/com/gcsc/guide/auth/JwtTokenProvider.java

package com.gcsc.guide.auth;

import io.jsonwebtoken.Claims;
import io.jsonwebtoken.JwtException;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.security.Keys;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import javax.crypto.SecretKey;
import java.nio.charset.StandardCharsets;
import java.util.Date;

@Slf4j
@Component
public class JwtTokenProvider {

    private final SecretKey secretKey;
    private final long expirationMs;

    public JwtTokenProvider(
        @Value("${app.jwt.secret}") String secret,
        @Value("${app.jwt.expiration-ms}") long expirationMs
    ) {
        this.secretKey = Keys.hmacShaKeyFor(secret.getBytes(StandardCharsets.UTF_8));
        this.expirationMs = expirationMs;
    }

    public String generateToken(Long userId, String email, boolean isAdmin) {
        Date now = new Date();
        Date expiry = new Date(now.getTime() + expirationMs);

        return Jwts.builder()
            .subject(userId.toString())
            .claim("email", email)
            .claim("isAdmin", isAdmin)
            .issuedAt(now)
            .expiration(expiry)
            .signWith(secretKey)
            .compact();
    }

    public Long getUserIdFromToken(String token) {
        Claims claims = parseToken(token);
        return Long.parseLong(claims.getSubject());
    }

    public boolean validateToken(String token) {
        try {
            parseToken(token);
            return true;
        } catch (JwtException | IllegalArgumentException e) {
            log.debug("JWT 토큰 검증 실패: {}", e.getMessage());
            return false;
        }
    }

    private Claims parseToken(String token) {
        return Jwts.parser()
            .verifyWith(secretKey)
            .build()
            .parseSignedClaims(token)
            .getPayload();
    }
}