/* 
    * 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 org.esigate.url;
  
  import org.apache.http.cookie.Cookie;
  import org.apache.http.impl.cookie.BasicClientCookie;
  import org.esigate.api.BaseUrlRetrieveStrategy;
  import org.esigate.http.IncomingRequest;
  
  public class StickySessionBaseUrlRetrieveStrategy implements BaseUrlRetrieveStrategy {
      public static final String ESI_SESSION_COOKIE_NAME = "_esigate_session_cookie";
      private final String[] urls;
  
      public StickySessionBaseUrlRetrieveStrategy(String[] urls) {
          super();
          this.urls = urls;
      }
  
      private int generateIndex() {
          return (int) (Math.random() * this.urls.length);
      }
  
      @Override
      public String getBaseURL(IncomingRequest originalRequest) {
          Cookie sessionCookie = getEsiSessionCookie(originalRequest.getCookies());
          int index = 0;
          boolean toGenerate = true;
  
          if (null != sessionCookie) {
              toGenerate = false;
              String indexStr = sessionCookie.getValue();
  
              if (null != indexStr) {
                  try {
                      index = Integer.parseInt(indexStr);
                  } catch (Exception e) {
                      index = -1;
                  }
                  if (index < 0 || index >= this.urls.length) {
                      toGenerate = true;
                  }
              } else {
                  toGenerate = true;
              }
          }
          if (toGenerate) {
              index = generateIndex();
              Cookie cookie = new BasicClientCookie(ESI_SESSION_COOKIE_NAME, Integer.toString(index));
              originalRequest.addNewCookie(cookie);
          }
  
          return this.urls[index];
      }
  
      private Cookie getEsiSessionCookie(Cookie[] cookies) {
          Cookie ret = null;
          if (null != cookies && cookies.length > 0) {
              for (Cookie cookie : cookies) {
                  if (ESI_SESSION_COOKIE_NAME.equals(cookie.getName())) {
                      ret = cookie;
                      break;
                  }
              }
          }
          return ret;
      }
  
  }