JWTService.java

package com.fredmaina.chatapp.Auth.services;


import io.jsonwebtoken.security.Keys;
import jakarta.annotation.PostConstruct;
import org.springframework.stereotype.Service;
import io.jsonwebtoken.Claims;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;

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

@Service
public class JWTService {

    @Value("${jwt.secret}")
    private String secret;

    @Value("${jwt.expiration}")
    private long expiration;

    private SecretKey key;

    @PostConstruct
    public void init() {
        this.key = new SecretKeySpec(secret.getBytes(StandardCharsets.UTF_8), "HmacSHA256");
    }



    public String generateToken(String username) {

        return Jwts.builder()
                .setSubject(username)
                .setIssuedAt(new Date())
                .setExpiration(new Date(System.currentTimeMillis() + expiration))
                .signWith(key, SignatureAlgorithm.HS256)
                .compact();
    }

    public Claims getClaimsFromToken(String token) {

        return Jwts.parserBuilder()
                .setSigningKey(key)
                .build()
                .parseClaimsJws(token)
                .getBody();

    }
    public String getClaimFromToken(String token, String claimKey) {
        Claims claims = getClaimsFromToken(token);
        return claims.get(claimKey, String.class);
    }

    public boolean isTokenValid(String token) {
        try {
            Claims claims = getClaimsFromToken(token);
            return !claims.getExpiration().before(new Date());
        } catch (Exception e) {
            return false;
        }
    }

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

}