package com.krylov.refound.security;

import io.jsonwebtoken.Claims;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.security.Keys;
import java.nio.charset.StandardCharsets;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.function.Function;
import javax.crypto.SecretKey;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;

@Service
public class JwtService {

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

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

  public String generateToken(String login) {
    Map<String, Object> claims = new HashMap<>();
    return generateToken(claims, login);
  }

  public String generateToken(Map<String, Object> extraClaims, String login) {
    return Jwts.builder()
        .claims(extraClaims)
        .subject(login)
        .issuedAt(new Date(System.currentTimeMillis()))
        .expiration(new Date(System.currentTimeMillis() + expiration))
        .signWith(getSigningKey())
        .compact();
  }

  public String extractLogin(String token) {
    return extractClaim(token, Claims::getSubject);
  }

  public boolean isTokenValid(String token) {
    try {
      String login = extractLogin(token);
      return login != null && !isTokenExpired(token);
    } catch (Exception e) {
      return false;
    }
  }

  private boolean isTokenExpired(String token) {
    return extractExpiration(token).before(new Date());
  }

  private Date extractExpiration(String token) {
    return extractClaim(token, Claims::getExpiration);
  }

  private <T> T extractClaim(String token, Function<Claims, T> claimsResolver) {
    final Claims claims = extractAllClaims(token);
    return claimsResolver.apply(claims);
  }

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

  private SecretKey getSigningKey() {
    byte[] keyBytes = secret.getBytes(StandardCharsets.UTF_8);
    return Keys.hmacShaKeyFor(keyBytes);
  }
}