<%#
 Copyright 2013-2018 the original author or authors from the JHipster project.

 This file is part of the JHipster project, see http://www.jhipster.tech/
 for more information.

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
-%>
package <%=packageName%>.security;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.security.core.Authentication;
import org.springframework.security.web.DefaultRedirectStrategy;
import org.springframework.security.web.RedirectStrategy;
import org.springframework.security.web.WebAttributes;
import org.springframework.security.web.authentication.AuthenticationSuccessHandler;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

import static <%=packageName%>.config.OAuth2Configuration.SAVED_LOGIN_ORIGIN_URI;

/**
 * AuthenticationSuccessHandler that looks for a saved login origin and redirects to it if it exists.
 */
public class OAuth2AuthenticationSuccessHandler implements AuthenticationSuccessHandler {

    private final Logger log = LoggerFactory.getLogger(OAuth2AuthenticationSuccessHandler.class);

    private RedirectStrategy redirectStrategy = new DefaultRedirectStrategy();

    @Override
    public void onAuthenticationSuccess(HttpServletRequest request, HttpServletResponse response,
                                        Authentication authentication)
        throws IOException {

        handle(request, response);
        clearAuthenticationAttributes(request);
    }

    private void handle(HttpServletRequest request, HttpServletResponse response)
        throws IOException {

        String targetUrl = determineTargetUrl(request);

        if (response.isCommitted()) {
            log.error("Response has already been committed. Unable to redirect to " + targetUrl);
            return;
        }

        redirectStrategy.sendRedirect(request, response, targetUrl);
    }

    private String determineTargetUrl(HttpServletRequest request) {
        Object savedReferrer = request.getSession().getAttribute(SAVED_LOGIN_ORIGIN_URI);
        if (savedReferrer != null) {
            String savedLoginOrigin = request.getSession().getAttribute(SAVED_LOGIN_ORIGIN_URI).toString();
            log.debug("Redirecting to saved login origin URI: {}", savedLoginOrigin);
            request.getSession().removeAttribute(SAVED_LOGIN_ORIGIN_URI);
            return savedLoginOrigin;
        } else {
            return "/";
        }
    }

    private void clearAuthenticationAttributes(HttpServletRequest request) {
        HttpSession session = request.getSession(false);
        if (session == null) {
            return;
        }
        session.removeAttribute(WebAttributes.AUTHENTICATION_EXCEPTION);
    }
}