content: package com.alibou.book.security;
  
  import io.jsonwebtoken.Claims;
  import io.jsonwebtoken.Jwts;
  import io.jsonwebtoken.io.Decoders;
  import io.jsonwebtoken.security.Keys;
  import org.springframework.beans.factory.annotation.Value;
  import org.springframework.security.core.GrantedAuthority;
  import org.springframework.security.core.userdetails.UserDetails;
  import org.springframework.stereotype.Service;
  
  import java.security.Key;
  import java.util.Date;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.function.Function;
  
  // @Service
  public class JwtService {
      /*@Value("${application.security.jwt.secret-key}")
      private String secretKey;
      @Value("${application.security.jwt.expiration}")
      private long jwtExpiration;
  
      public String extractUsername(String token) {
          return extractClaim(token, Claims::getSubject);
      }
  
      public <T> T extractClaim(String token, Function<Claims, T> claimsResolver) {
          final Claims claims = extractAllClaims(token);
          return claimsResolver.apply(claims);
      }
  
      public String generateToken(UserDetails userDetails) {
          return generateToken(new HashMap<>(), userDetails);
      }
  
      public String generateToken(
              Map<String, Object> extraClaims,
              UserDetails userDetails
      ) {
          return buildToken(extraClaims, userDetails, jwtExpiration);
      }
  
      private String buildToken(
              Map<String, Object> extraClaims,
              UserDetails userDetails,
              long expiration
      ) {
          var authorities = userDetails.getAuthorities()
                  .stream().
                  map(GrantedAuthority::getAuthority)
                  .toList();
          return Jwts
                  .builder()
                  .setClaims(extraClaims)
                  .setSubject(userDetails.getUsername())
                  .setIssuedAt(new Date(System.currentTimeMillis()))
                  .setExpiration(new Date(System.currentTimeMillis() + expiration))
                  .claim("authorities", authorities)
                  .signWith(getSignInKey())
                  .compact();
      }
  
      public boolean isTokenValid(String token, UserDetails userDetails) {
          final String username = extractUsername(token);
          return (username.equals(userDetails.getUsername())) && !isTokenExpired(token);
      }
  
      private boolean isTokenExpired(String token) {
          return extractExpiration(token).before(new Date());
      }
  
      private Date extractExpiration(String token) {
          return extractClaim(token, Claims::getExpiration);
      }
  
      private Claims extractAllClaims(String token) {
          return Jwts
                  .parserBuilder()
                  .setSigningKey(getSignInKey())
                  .build()
                  .parseClaimsJws(token)
                  .getBody();
      }
  
      private Key getSignInKey() {
          byte[] keyBytes = Decoders.BASE64.decode(secretKey);
          return Keys.hmacShaKeyFor(keyBytes);
      }*/
  }
  