/**
 * 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.cas.services.web;

import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.regex.Pattern;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.jasig.cas.authentication.principal.Service;
import org.jasig.cas.services.RegisteredService;
import org.jasig.cas.services.ServicesManager;
import org.jasig.cas.web.support.ArgumentExtractor;
import org.jasig.cas.web.support.WebUtils;
import org.springframework.util.StringUtils;
import org.springframework.web.servlet.theme.AbstractThemeResolver;

/**
 * ThemeResolver to determine the theme for CAS based on the service provided and the current
 * browser user agent. The theme resolver will extract the service parameter from the Request object
 * and attempt to match the URL provided to a Service Id. If the service is found, the theme
 * associated with it will be used. If not, these is associated with the service or the service was
 * not found, a default theme will be used.
 *
 * <p>Once this service theme name is resolved, this implementation will look in its overrides map
 * to determine if an alternate theme name is configured for the current user agent. This class is
 * designed to allow us to define alternate themes for mobile devices on a per-service basis.
 *
 */
public class ConfigurableUserAgentOverrideThemeResolver extends AbstractThemeResolver {

    /** The ServiceRegistry to look up the service. */
    private ServicesManager servicesManager;

    private List<ArgumentExtractor> argumentExtractors;

    private Map<String, Map<Pattern, String>> overrides;

    /*
     * (non-Javadoc)
     * @see org.springframework.web.servlet.ThemeResolver#resolveThemeName(javax.servlet.http.HttpServletRequest)
     */
    public String resolveThemeName(HttpServletRequest request) {

        // get the theme name indicated by the service
        String themeName = resolveServiceThemeName(request);

        /*
         * If the overrides map contains overrides for this theme name, iterate
         * through the mapped user agent regexes for this theme name.  If we
         * find a matching regex, set the theme name to the one mapped to that
         * regex.
         */

        if (overrides.containsKey(themeName)) {

            // retrieve the user agent string from the request
            String userAgent = request.getHeader("User-Agent");

            for (Entry<Pattern, String> entry : overrides.get(themeName).entrySet()) {
                if (entry.getKey().matcher(userAgent).matches()) {
                    return entry.getValue();
                }
            }
        }

        // if no override was found for the current theme and user agent,
        // return the default theme for this service
        return themeName;
    }

    /*
     * (non-Javadoc)
     * @see org.springframework.web.servlet.ThemeResolver#setThemeName(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, java.lang.String)
     */
    public void setThemeName(
            HttpServletRequest request, HttpServletResponse response, String themeName) {
        // nothing to do here
    }

    /**
     * Resolve the theme for the service. This method's logic is taken from ServiceThemeResolver.
     *
     * @param request
     * @return configured theme for this service
     */
    protected String resolveServiceThemeName(HttpServletRequest request) {
        if (this.servicesManager == null) {
            return getDefaultThemeName();
        }

        final Service service = WebUtils.getService(this.argumentExtractors, request);

        final RegisteredService rService = this.servicesManager.findServiceBy(service);

        return service != null && rService != null && StringUtils.hasText(rService.getTheme())
                ? rService.getTheme()
                : getDefaultThemeName();
    }

    public void setServicesManager(final ServicesManager servicesManager) {
        this.servicesManager = servicesManager;
    }

    public void setArgumentExtractors(final List<ArgumentExtractor> argumentExtractors) {
        this.argumentExtractors = argumentExtractors;
    }

    /**
     * Set the map of theme name overrides. This map is of the format { service theme name -> { user
     * agent regular expression -> override theme name } }
     *
     * @param overrides
     */
    public void setOverrides(Map<String, Map<String, String>> overrides) {
        // initialize the overrides variable to an empty map
        this.overrides = new HashMap<String, Map<Pattern, String>>();

        // convert the provided map's regular expressions to Pattern objects
        for (Entry<String, Map<String, String>> themeMapping : overrides.entrySet()) {
            Map<Pattern, String> mappings = new LinkedHashMap<Pattern, String>();
            for (Entry<String, String> browserMapping : themeMapping.getValue().entrySet()) {
                Pattern p = Pattern.compile(browserMapping.getKey());
                mappings.put(p, browserMapping.getValue());
            }
            this.overrides.put(themeMapping.getKey(), mappings);
        }
    }
}