package com.juick.service.security;

import com.juick.User;
import com.juick.server.SignatureManager;
import com.juick.service.UserService;
import org.apache.commons.io.IOUtils;
import org.springframework.security.authentication.AnonymousAuthenticationToken;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.web.filter.OncePerRequestFilter;

import javax.annotation.Nonnull;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.Collections;
import java.util.Map;
import java.util.stream.Collectors;

public class HTTPSignatureAuthenticationFilter extends OncePerRequestFilter {

    private final SignatureManager signatureManager;
    private final UserService userService;


    public HTTPSignatureAuthenticationFilter(
            final SignatureManager signatureManager,
            final UserService userService) {
        this.signatureManager = signatureManager;
        this.userService = userService;
    }
    @Override
    protected void doFilterInternal(@Nonnull HttpServletRequest request, @Nonnull HttpServletResponse response, @Nonnull FilterChain filterChain) throws IOException, ServletException {
        if (authenticationIsRequired()) {
            Map<String, String> headers = Collections.list(request.getHeaderNames())
                    .stream()
                    .collect(Collectors.toMap(String::toLowerCase, request::getHeader));
            try {
                User user = signatureManager.verifySignature(request.getMethod(), request.getRequestURI(), headers);
                if (!user.isAnonymous()) {
                    String userUri = user.getUri().toString();
                    if (userUri.length() == 0) {
                        User userWithPassword = userService.getUserByName(user.getName());
                        userWithPassword.setAuthHash(userService.getHashByUID(userWithPassword.getUid()));
                        Authentication authentication = new UsernamePasswordAuthenticationToken(userWithPassword.getName(), userWithPassword.getCredentials());
                        SecurityContextHolder.getContext().setAuthentication(authentication);
                    } else {
                        Authentication authentication = new AnonymousAuthenticationToken(userUri, user, Collections.singletonList(new SimpleGrantedAuthority("ROLE_ANONYMOUS")));
                        SecurityContextHolder.getContext().setAuthentication(authentication);
                    }
                }
            } catch (IOException e) {
                logger.warn(String.format("Signature %s is not verified, context: %s", headers.get("Signature"),
                        IOUtils.toString(request.getInputStream(), StandardCharsets.UTF_8)), e);
            }
        }

        filterChain.doFilter(request, response);
    }

    private boolean authenticationIsRequired() {
        Authentication existingAuth = SecurityContextHolder.getContext().getAuthentication();

        return existingAuth == null ||
                !existingAuth.isAuthenticated() ||
                existingAuth instanceof AnonymousAuthenticationToken;
    }
}