package com.denniseckerskorn.security;

import io.jsonwebtoken.*;
import io.jsonwebtoken.security.Keys;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import java.security.Key;
import java.util.Date;

/**
 * Utility class for generating and validating JWT tokens.
 */
@Component
public class JwtUtil {

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

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

    /**
     * Generates a signing key using the secret key.
     *
     * @return the signing key
     */
    private Key getSigningKey() {
        return Keys.hmacShaKeyFor(secretKey.getBytes());
    }

    /**
     * Generates a JWT token for the given username.
     *
     * @param username the username to include in the token
     * @return the generated JWT token
     */
    public String generateToken(String username, String authority) {
        Date now = new Date();
        Date expiryDate = new Date(now.getTime() + expirationTime);

        return Jwts.builder()
                .setSubject(username)
                .claim("role", authority)
                .setIssuedAt(now)
                .setExpiration(expiryDate)
                .signWith(getSigningKey(), SignatureAlgorithm.HS256)
                .compact();
    }

    /**
     * Extracts the username from the given JWT token.
     *
     * @param token the JWT token
     * @return the username extracted from the token
     */
    public String extractUsername(String token) {
        return Jwts.parserBuilder()
                .setSigningKey(getSigningKey())
                .build()
                .parseClaimsJws(token)
                .getBody()
                .getSubject();
    }

    /**
     * Validates the given JWT token.
     *
     * @param token the JWT token to validate
     * @return true if the token is valid, false otherwise
     */
    public boolean validateToken(String token) {
        try {
            extractUsername(token);
            return true;
        } catch (JwtException e) {
            return false;
        }
    }

    /**
     * Checks if the given JWT token is expired.
     *
     * @param token the JWT token to check
     * @return true if the token is expired, false otherwise
     */
    public Claims getAllClaimsFromToken(String token) throws ExpiredJwtException {
        return Jwts.parserBuilder()
                .setSigningKey(getSigningKey())
                .build()
                .parseClaimsJws(token)
                .getBody();
    }

}