/**
 * Licensed to Apereo under one or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information regarding copyright ownership. Apereo
 * licenses this file to you 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 the
 * following location:
 *
 * <p>http://www.apache.org/licenses/LICENSE-2.0
 *
 * <p>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 org.apereo.portal.utils.web;

import java.io.IOException;
import java.util.HashSet;
import java.util.Set;
import java.util.regex.Pattern;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import org.apereo.portal.rest.RemoteCookieCheckController;

public class RemoteCookieCheckFilter implements Filter {
    public static final String COOKIE_NAME = "JSESSIONID";
    public static final String REFERER_ATTRIBUTE = "COOKIE_CHECK_REFERER";

    // Set of User-Agent header values that will not be forced through the cookie check.
    private Set<Pattern> regexIgnoredUserAgents = new HashSet<>();

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {}

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        if (!"POST".equals(httpServletRequest.getMethod())) {
            boolean cookieFound = false;
            Cookie[] cookies = httpServletRequest.getCookies();

            if (cookies != null) {
                for (Cookie cookie : cookies) {
                    if (cookie.getName().equalsIgnoreCase(COOKIE_NAME)) {
                        cookieFound = true;
                        break;
                    }
                }
            }

            String userAgent = ((HttpServletRequest) request).getHeader("User-Agent");
            if (!cookieFound && !userAgentInIgnoreList(userAgent)) {
                final HttpSession session = httpServletRequest.getSession(true);

                String requestURI = httpServletRequest.getRequestURI();
                final String queryString = httpServletRequest.getQueryString();
                if (queryString != null) {
                    requestURI += "?" + queryString;
                }

                session.setAttribute(REFERER_ATTRIBUTE, requestURI);
                String url =
                        httpServletRequest.getContextPath()
                                + "/api"
                                + RemoteCookieCheckController.COOKIE_CHECK_REQUEST_MAPPING;
                ((HttpServletResponse) response).sendRedirect(url);
                return;
            }
        }

        chain.doFilter(request, response);
    }

    private boolean userAgentInIgnoreList(String userAgent) {
        for (Pattern ignorePattern : regexIgnoredUserAgents) {
            if (ignorePattern.matcher(userAgent).matches()) {
                return true;
            }
        }
        return false;
    }

    @Override
    public void destroy() {}

    public void setRegexIgnoredUserAgents(Set<String> regexIgnoredUserAgents) {
        HashSet<Pattern> ignorePatterns = new HashSet<>();
        for (String regex : regexIgnoredUserAgents) {
            ignorePatterns.add(Pattern.compile(regex));
        }
        this.regexIgnoredUserAgents = ignorePatterns;
    }
}