/**
 * Copyright (C) 2003-2008 eXo Platform SAS.
 *
 * 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see<http://www.gnu.org/licenses/>.
 */

package org.etk.core.rest.impl.method;

import java.util.HashMap;
import java.util.Map;

import javax.ws.rs.core.Context;
import javax.ws.rs.core.HttpHeaders;
import javax.ws.rs.core.Request;
import javax.ws.rs.core.SecurityContext;
import javax.ws.rs.core.UriInfo;
import javax.ws.rs.ext.Providers;

import org.etk.core.rest.impl.ApplicationContext;
import org.etk.core.rest.impl.EnvironmentContext;


public class ContextParameterResolver extends ParameterResolver<Context> {

  /**
   * Known essences that can be passed to method via parameters that has
   * @Context annotation.
   */
  private enum CONTEXT_PARAMS {
    /**
     * @see HttpHeaders
     */
    HTTP_HEADERS,
    /**
     * @see SecurityContext
     */
    SECURITY_CONTEXT,
    /**
     * @see Request
     */
    REQUEST,
    /**
     * @see UriInfo
     */
    URI_INFO,
    /**
     * @see Providers
     */
    PROVIDERS
  }

  /**
   * Mapping from class name to member of {@link CONTEXT_PARAMS}.
   */
  private static final Map<String, CONTEXT_PARAMS> CONTEXT_PARAMETERS_MAP = new HashMap<String, CONTEXT_PARAMS>(4);

  static {
    CONTEXT_PARAMETERS_MAP.put(HttpHeaders.class.getName(), CONTEXT_PARAMS.HTTP_HEADERS);
    CONTEXT_PARAMETERS_MAP.put(SecurityContext.class.getName(), CONTEXT_PARAMS.SECURITY_CONTEXT);
    CONTEXT_PARAMETERS_MAP.put(Request.class.getName(), CONTEXT_PARAMS.REQUEST);
    CONTEXT_PARAMETERS_MAP.put(UriInfo.class.getName(), CONTEXT_PARAMS.URI_INFO);
    CONTEXT_PARAMETERS_MAP.put(Providers.class.getName(), CONTEXT_PARAMS.PROVIDERS);
  }

  /**
   * @param contextParam {@link Context}
   */
  ContextParameterResolver(Context contextParam) {
    // @Context annotation has not value.
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public Object resolve(org.etk.core.rest.Parameter parameter, ApplicationContext context) throws Exception {
    String className = parameter.getParameterClass().getName();
    CONTEXT_PARAMS cp = CONTEXT_PARAMETERS_MAP.get(className);
    if (cp != null) {
      switch (cp) {
      case HTTP_HEADERS:
        return context.getHttpHeaders();
      case SECURITY_CONTEXT:
        return context.getSecurityContext();
      case REQUEST:
        return context.getRequest();
      case URI_INFO:
        return context.getUriInfo();
      case PROVIDERS:
        return context.getProviders();
      }
    }
    // For servlet container environment context contains HttpServletRequest,
    // HttpServletResponse, ServletConfig, ServletContext
    return EnvironmentContext.getCurrent().get(parameter.getParameterClass());
  }

}