/*
 * Copyright (C) 2008-2020, Juick
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.juick.service.security;

import com.juick.model.User;
import com.juick.SignatureManager;
import com.juick.service.UserService;
import com.juick.service.security.entities.JuickUser;
import org.apache.commons.lang3.StringUtils;
import org.springframework.security.authentication.AnonymousAuthenticationToken;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.Authentication;
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.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));
            if (StringUtils.isNotEmpty(headers.get("signature"))) {
                User user = signatureManager.verifySignature(request.getMethod(), request.getRequestURI(), headers);
                String userUri = user.getUri().toString();
                if (!user.isAnonymous() || userUri.length() > 0) {
                    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,
                                new JuickUser(user), JuickUser.ANONYMOUS_AUTHORITY);
                        SecurityContextHolder.getContext().setAuthentication(authentication);
                    }
                }
            }
        }

        filterChain.doFilter(request, response);
    }

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

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