/*
    * #%L
    * wcm.io
    * %%
    * Copyright (C) 2014 wcm.io
    * %%
    * 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.
   * #L%
   */
  package io.wcm.caravan.io.http.impl;
  
  import java.util.Map;
  
  import org.apache.commons.configuration.Configuration;
  import org.apache.commons.lang3.StringUtils;
  import org.apache.felix.scr.annotations.Activate;
  import org.apache.felix.scr.annotations.Component;
  import org.apache.felix.scr.annotations.ConfigurationPolicy;
  import org.apache.felix.scr.annotations.Deactivate;
  import org.apache.felix.scr.annotations.Property;
  import org.apache.sling.commons.osgi.PropertiesUtil;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Configures thread pool options for the transport layer.
   * The configuration is mapped to archaius configuration internally.
   */
  @Component(immediate = true, metatype = true,
  label = "wcm.io Caravan Resilient Http Thread Pool Configuration",
  description = " Configures thread pool options for the transport layer.",
  configurationFactory = true, policy = ConfigurationPolicy.REQUIRE)
  @Property(name = "webconsole.configurationFactory.nameHint", value = "{threadPoolName}: {hystrixThreadpoolCoresize}")
  public class CaravanHttpThreadPoolConfig {
  
    private static final Logger log = LoggerFactory.getLogger(CaravanHttpThreadPoolConfig.class);
  
    /**
     * Thread Pool Name
     */
    @Property(label = "Thread Pool Name", description = "Internal thread pool name.")
    public static final String THREAD_POOL_NAME_PROPERTY = "threadPoolName";
  
    /**
     * Threadpool size
     */
    @Property(label = "Threadpool size",
        description = "Hystrix: Maximum number of HystrixCommands that can execute concurrently.")
    public static final String HYSTRIX_THREADPOOL_CORESIZE_PROPERTY = "hystrixThreadpoolCoresize";
    static final int HYSTRIX_THREADPOOL_CORESIZE_DEFAULT = 10;
  
    /**
     * Max. Threadpool Queue Size
     */
    @Property(label = "Max. Threadpool Queue Size",
        description = "Hystrix: Maximum queue size at which rejections will occur. Note: This property only applies at initialization time.")
    public static final String HYSTRIX_THREADPOOL_MAXQUEUESIZE_PROPERTY = "hystrixThreadpoolMaxqueuesize";
    static final int HYSTRIX_THREADPOOL_MAXQUEUESIZE_DEFAULT = 4096;
  
    /**
     * Dynamic Threadpool Queue Size
     */
    @Property(label = "Dynamic Threadpool Queue Size",
        description = "Hystrix: Artificial maximum queue size at which rejections will occur even if hystrixThreadpoolDefaultMaxqueuesize has not been reached.")
    public static final String HYSTRIX_THREADPOOL_QUEUESIZEREJECTIONTHRESHOLD_PROPERTY = "hystrixThreadpoolQueuesizerejectionthreshold";
    static final int HYSTRIX_THREADPOOL_QUEUESIZEREJECTIONTHRESHOLD_DEFAULT = 4096;
  
    private static final String HYSTRIX_THREADPOOL_PREFIX = "hystrix.threadpool.";
    private static final String HYSTRIX_PARAM_THREADPOOL_CORESIZE = ".coreSize";
    private static final String HYSTRIX_PARAM_THREADPOOL_MAXQUEUESIZE = ".maxQueueSize";
    private static final String HYSTRIX_PARAM_THREADPOOL_QUEUESIZEREJECTIONTHRESHOLD = ".queueSizeRejectionThreshold";
  
    @Activate
    protected void activate(Map<String, Object> config) {
      String threadPoolName = getThreadPoolName(config);
      if (validateConfig(threadPoolName, config)) {
        setArchiausProperties(threadPoolName, config);
      }
    }
  
    @Deactivate
    protected void deactivate(Map<String, Object> config) {
      // clear configuration by writing empty properties
      String threadPoolName = getThreadPoolName(config);
      clearArchiausProperties(threadPoolName);
    }
  
    private String getThreadPoolName(Map<String, Object> config) {
      return PropertiesUtil.toString(config.get(THREAD_POOL_NAME_PROPERTY), null);
   }
 
   /**
    * Validates configuration
    * @param threadPoolName Thread pool name
    * @param config OSGi config
    */
   private boolean validateConfig(String threadPoolName, Map<String, Object> config) {
     if (StringUtils.isBlank(threadPoolName)) {
       log.warn("Invalid http thread pool configuration without thread pool name, ignoring.", threadPoolName);
       return false;
     }
     return true;
   }
 
   /**
    * Writes OSGi configuration to archaius configuration.
    * @param threadPoolName Thread pool name
    * @param config OSGi config
    */
   private void setArchiausProperties(String threadPoolName, Map<String, Object> config) {
     Configuration archaiusConfig = ArchaiusConfig.getConfiguration();
     // thread pool size
     archaiusConfig.setProperty(HYSTRIX_THREADPOOL_PREFIX + threadPoolName + HYSTRIX_PARAM_THREADPOOL_CORESIZE,
         PropertiesUtil.toInteger(config.get(HYSTRIX_THREADPOOL_CORESIZE_PROPERTY), HYSTRIX_THREADPOOL_CORESIZE_DEFAULT));
     // maximum thread queue size
     archaiusConfig.setProperty(HYSTRIX_THREADPOOL_PREFIX + threadPoolName + HYSTRIX_PARAM_THREADPOOL_MAXQUEUESIZE,
         PropertiesUtil.toInteger(config.get(HYSTRIX_THREADPOOL_MAXQUEUESIZE_PROPERTY), HYSTRIX_THREADPOOL_MAXQUEUESIZE_DEFAULT));
     // dynamic thread queue size
     archaiusConfig.setProperty(HYSTRIX_THREADPOOL_PREFIX + threadPoolName + HYSTRIX_PARAM_THREADPOOL_QUEUESIZEREJECTIONTHRESHOLD,
         PropertiesUtil.toInteger(config.get(HYSTRIX_THREADPOOL_QUEUESIZEREJECTIONTHRESHOLD_PROPERTY), HYSTRIX_THREADPOOL_QUEUESIZEREJECTIONTHRESHOLD_DEFAULT));
   }
 
   /**
    * Removes OSGi configuration from archaius configuration.
    * @param threadPoolName Thread pool name
    */
   private void clearArchiausProperties(String threadPoolName) {
     Configuration archaiusConfig = ArchaiusConfig.getConfiguration();
     archaiusConfig.clearProperty(HYSTRIX_THREADPOOL_PREFIX + threadPoolName + HYSTRIX_PARAM_THREADPOOL_CORESIZE);
     archaiusConfig.clearProperty(HYSTRIX_THREADPOOL_PREFIX + threadPoolName + HYSTRIX_PARAM_THREADPOOL_MAXQUEUESIZE);
     archaiusConfig.clearProperty(HYSTRIX_THREADPOOL_PREFIX + threadPoolName + HYSTRIX_PARAM_THREADPOOL_QUEUESIZEREJECTIONTHRESHOLD);
   }
 
 }