package com.izouma.dingdong.security;

import io.jsonwebtoken.ExpiredJwtException;
import io.jsonwebtoken.SignatureException;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.web.authentication.WebAuthenticationDetailsSource;
import org.springframework.stereotype.Component;
import org.springframework.web.filter.OncePerRequestFilter;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@Component
@Slf4j
public class JwtAuthorizationTokenFilter extends OncePerRequestFilter {

    private final UserDetailsService userDetailsService;
    private final JwtTokenUtil       jwtTokenUtil;
    private final String             tokenHeader;

    public JwtAuthorizationTokenFilter(@Qualifier("jwtUserDetailsService") UserDetailsService userDetailsService, JwtTokenUtil jwtTokenUtil, @Value("${jwt.header}") String tokenHeader) {
        this.userDetailsService = userDetailsService;
        this.jwtTokenUtil = jwtTokenUtil;
        this.tokenHeader = tokenHeader;
    }

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain chain) throws ServletException, IOException {
        log.debug("processing authentication for '{}'", request.getRequestURL());

        final String requestHeader = request.getHeader(this.tokenHeader);

        String username = null;
        String authToken = null;
        if (requestHeader != null && requestHeader.startsWith("Bearer ")) {
            authToken = requestHeader.substring(7);
            try {
                username = jwtTokenUtil.getUsernameFromToken(authToken);
            } catch (IllegalArgumentException e) {
                log.error("an error occurred during getting username from token", e);
            } catch (ExpiredJwtException e) {
                log.warn("the token is expired and not valid anymore", e);
            } catch (SignatureException e) {
                log.error(e.getMessage());
            }
        } else {
            log.warn("couldn't find bearer string, will ignore the header");
        }

        log.debug("checking authentication for user '{}'", username);
        if (username != null && SecurityContextHolder.getContext().getAuthentication() == null) {
            log.debug("security context was null, so authorizing user");

            // It is not compelling necessary to load the use details from the database. You could also store the information
            // in the token and read it from it. It's up to you ;)            
            UserDetails userDetails;
            try {
                userDetails = userDetailsService.loadUserByUsername(username);
            } catch (Exception e) {
                //response.sendError(HttpServletResponse.SC_UNAUTHORIZED, e.getMessage());
                chain.doFilter(request, response);
                return;
            }


            // For simple validation it is completely sufficient to just check the token integrity. You don't have to call
            // the database compellingly. Again it's up to you ;)
            if (jwtTokenUtil.validateToken(authToken, userDetails)) {
                UsernamePasswordAuthenticationToken authentication = new UsernamePasswordAuthenticationToken(userDetails, null, userDetails.getAuthorities());
                authentication.setDetails(new WebAuthenticationDetailsSource().buildDetails(request));
                log.info("authorized user '{}', setting security context", username);
                SecurityContextHolder.getContext().setAuthentication(authentication);
            }
        }

        chain.doFilter(request, response);
    }
}
