/*************************GO-LICENSE-START*********************************
 * Copyright 2014 ThoughtWorks, Inc.
 *
 * 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.
 *************************GO-LICENSE-END***********************************/

package com.thoughtworks.go.server.security;

import java.io.IOException;
import java.util.regex.Pattern;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.thoughtworks.go.server.service.SecurityService;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.security.AuthenticationException;
import org.springframework.security.context.SecurityContextHolder;
import org.springframework.security.ui.AbstractProcessingFilter;
import org.springframework.security.ui.AuthenticationEntryPoint;
import org.springframework.security.ui.ExceptionTranslationFilter;
import org.springframework.security.ui.savedrequest.SavedRequest;

public class GoExceptionTranslationFilter extends ExceptionTranslationFilter {
    private String urlPatternsThatShouldNotBeRedirectedToAfterLogin;
    private AuthenticationEntryPoint basicAuthenticationEntryPoint;
    public static final String REQUEST__FORMAT = "format";
    private SecurityService securityService;

    protected void sendStartAuthentication(ServletRequest request, ServletResponse response, FilterChain chain,
                                           AuthenticationException reason) throws ServletException, IOException {
        HttpServletRequest httpRequest = (HttpServletRequest) request;
        HttpServletResponse httpResponse = (HttpServletResponse) response;

        //TODO: This is a hack for bug #3175, we should revisit this code in V2.0
        if (isJson(httpRequest) || isJsonFormat(httpRequest)) {
            httpResponse.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
            return;
        }

        final Log logger = LogFactory.getLog(GoExceptionTranslationFilter.class);
        SavedRequest savedRequest = new SavedRequest(httpRequest, getPortResolver());

        if (logger.isDebugEnabled()) {
            logger.debug("Authentication entry point being called; SavedRequest added to Session: " + savedRequest);
        }

        if (isCreateSessionAllowed() && shouldRedirect(savedRequest.getRequestUrl())) {
            // Store the HTTP request itself. Used by AbstractProcessingFilter
            // for redirection after successful authentication (SEC-29)
            httpRequest.getSession().setAttribute(AbstractProcessingFilter.SPRING_SECURITY_SAVED_REQUEST_KEY,
                    savedRequest);
        }

        // SEC-112: Clear the SecurityContextHolder's Authentication, as the
        // existing Authentication is no longer considered valid
        SecurityContextHolder.getContext().setAuthentication(null);

        determineAuthenticationPoint(httpRequest).commence(httpRequest, response, reason);
    }

    private AuthenticationEntryPoint determineAuthenticationPoint(HttpServletRequest httpRequest) {
        AuthenticationEntryPoint point = getAuthenticationEntryPoint();
        if (isJsonp(httpRequest)) {
            return basicAuthenticationEntryPoint;
        }
        return point;
    }

    private boolean isJsonFormat(HttpServletRequest httpRequest) {
        String format = httpRequest.getParameter(REQUEST__FORMAT);
        return format != null && format.equalsIgnoreCase("json");
    }

    private boolean isJson(HttpServletRequest httpRequest) {
        return httpRequest.getRequestURI().endsWith(".json") && StringUtils.isBlank(httpRequest.getParameter("callback"));
    }

    private boolean isJsonp(HttpServletRequest httpRequest) {
        return httpRequest.getRequestURI().endsWith(".json") &&
                !StringUtils.isBlank(httpRequest.getParameter("callback"));
    }


    boolean shouldRedirect(String url) {
        Pattern regexPattern = Pattern.compile(urlPatternsThatShouldNotBeRedirectedToAfterLogin);
        return !regexPattern.matcher(url).find();
    }

    public String getUrlPatternsThatShouldNotBeRedirectedToAfterLogin() {
        return urlPatternsThatShouldNotBeRedirectedToAfterLogin;
    }

    public void setUrlPatternsThatShouldNotBeRedirectedToAfterLogin(String value) {
        urlPatternsThatShouldNotBeRedirectedToAfterLogin = value;
    }

    public void setBasicAuthenticationEntryPoint(AuthenticationEntryPoint basicAuthenticationEntryPoint) {
        this.basicAuthenticationEntryPoint = basicAuthenticationEntryPoint;
    }

    public void setSecurityService(SecurityService service) {
        this.securityService = service;
    }
}