/*
    * Licensed to The Apereo Foundation under one or more contributor license
    * agreements. See the NOTICE file distributed with this work for additional
    * information regarding copyright ownership.
    *
    *
    * The Apereo Foundation licenses this file to you under the Educational
    * Community 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://opensource.org/licenses/ecl2.txt
   *
   * 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.opencastproject.adminui.endpoint;
  
  import static org.opencastproject.index.service.util.JSONUtils.safeString;
  import static org.opencastproject.util.doc.rest.RestParameter.Type.STRING;
  
  import org.opencastproject.index.service.resources.list.query.ServicesListQuery;
  import org.opencastproject.index.service.util.RestUtils;
  import org.opencastproject.serviceregistry.api.HostRegistration;
  import org.opencastproject.serviceregistry.api.ServiceRegistry;
  import org.opencastproject.serviceregistry.api.ServiceState;
  import org.opencastproject.serviceregistry.api.ServiceStatistics;
  import org.opencastproject.util.SmartIterator;
  import org.opencastproject.util.doc.rest.RestParameter;
  import org.opencastproject.util.doc.rest.RestQuery;
  import org.opencastproject.util.doc.rest.RestResponse;
  import org.opencastproject.util.doc.rest.RestService;
  import org.opencastproject.util.requests.SortCriterion;
  import org.opencastproject.util.requests.SortCriterion.Order;
  
  import com.google.gson.JsonObject;
  
  import org.apache.commons.lang3.StringUtils;
  import org.json.simple.JSONAware;
  import org.json.simple.JSONObject;
  import org.osgi.service.component.annotations.Activate;
  import org.osgi.service.component.annotations.Component;
  import org.osgi.service.component.annotations.Reference;
  import org.osgi.service.jaxrs.whiteboard.propertytypes.JaxrsResource;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Optional;
  import java.util.concurrent.TimeUnit;
  
  import javax.servlet.http.HttpServletResponse;
  import javax.ws.rs.GET;
  import javax.ws.rs.Path;
  import javax.ws.rs.Produces;
  import javax.ws.rs.QueryParam;
  import javax.ws.rs.core.MediaType;
  import javax.ws.rs.core.Response;
  
  @Path("/admin-ng/services")
  @RestService(name = "ServicesProxyService", title = "UI Services",
    abstractText = "This service provides the services data for the UI.",
    notes = { "These Endpoints deliver informations about the services required for the UI.",
              "<strong>Important:</strong> "
                + "<em>This service is for exclusive use by the module admin-ui. Its API might change "
                + "anytime without prior notice. Any dependencies other than the admin UI will be strictly ignored. "
                + "DO NOT use this for integration of third-party applications.<em>"})
  @Component(
    immediate = true,
    service = ServicesEndpoint.class,
    property = {
      "service.description=Admin UI - Services facade Endpoint",
      "opencast.service.type=org.opencastproject.adminui.endpoint.ServicesEndpoint",
      "opencast.service.path=/admin-ng/services"
    }
  )
  @JaxrsResource
  public class ServicesEndpoint {
    private static final Logger logger = LoggerFactory.getLogger(ServicesEndpoint.class);
    private ServiceRegistry serviceRegistry;
  
    private static final String SERVICE_STATUS_TRANSLATION_PREFIX = "SYSTEMS.SERVICES.STATUS.";
  
  
    @GET
    @Path("services.json")
    @Produces(MediaType.APPLICATION_JSON)
    @RestQuery(description = "Returns the list of services", name = "services", restParameters = {
            @RestParameter(name = "limit", description = "The maximum number of items to return per page", isRequired = false, type = RestParameter.Type.INTEGER),
           @RestParameter(name = "offset", description = "The offset", isRequired = false, type = RestParameter.Type.INTEGER),
           @RestParameter(name = "filter", description = "Filter results by name, host, actions, status or free text query", isRequired = false, type = STRING),
           @RestParameter(name = "sort", description = "The sort order.  May include any "
                   + "of the following: host, name, running, queued, completed,  meanRunTime, meanQueueTime, "
                   + "status. The sort suffix must be :asc for ascending sort order and :desc for descending.", isRequired = false, type = STRING)
   }, responses = { @RestResponse(description = "Returns the list of services from Opencast", responseCode = HttpServletResponse.SC_OK) }, returnDescription = "The list of services")
   public Response getServices(@QueryParam("limit") final int limit, @QueryParam("offset") final int offset,
           @QueryParam("filter") String filter, @QueryParam("sort") String sort) throws Exception {
 
     Optional<String> sortOpt = Optional.ofNullable(StringUtils.trimToNull(sort));
     ServicesListQuery query = new ServicesListQuery();
     EndpointUtil.addRequestFiltersToQuery(filter, query);
 
     String fName = null;
     if (query.getName().isPresent())
       fName = StringUtils.trimToNull(query.getName().get());
     String fHostname = null;
     if (query.getHostname().isPresent())
       fHostname = StringUtils.trimToNull(query.getHostname().get());
     String fNodeName = null;
     if (query.getNodeName().isPresent())
       fNodeName = StringUtils.trimToNull(query.getNodeName().get());
     String fStatus = null;
     if (query.getStatus().isPresent())
       fStatus = StringUtils.trimToNull(query.getStatus().get());
     String fFreeText = null;
     if (query.getFreeText().isPresent())
       fFreeText = StringUtils.trimToNull(query.getFreeText().get());
 
     List<HostRegistration> servers = serviceRegistry.getHostRegistrations();
     List<Service> services = new ArrayList<Service>();
     for (ServiceStatistics stats : serviceRegistry.getServiceStatistics()) {
       Service service = new Service(stats, findServerByHost(stats.getServiceRegistration().getHost(), servers));
       if (fName != null && !StringUtils.equalsIgnoreCase(service.getName(), fName))
         continue;
 
       if (fHostname != null && !StringUtils.equalsIgnoreCase(service.getHost(), fHostname))
         continue;
 
       if (fNodeName != null && !StringUtils.equalsIgnoreCase(service.getNodeName(), fNodeName))
         continue;
 
       if (fStatus != null && !StringUtils.equalsIgnoreCase(service.getStatus().toString(), fStatus))
         continue;
 
       if (query.getActions().isPresent()) {
         ServiceState serviceState = service.getStatus();
 
         if (query.getActions().get()) {
           if (ServiceState.NORMAL == serviceState)
             continue;
         } else {
           if (ServiceState.NORMAL != serviceState)
             continue;
         }
       }
 
       if (fFreeText != null && !StringUtils.containsIgnoreCase(service.getName(), fFreeText)
                 && !StringUtils.containsIgnoreCase(service.getHost(), fFreeText)
                 && !StringUtils.containsIgnoreCase(service.getNodeName(), fFreeText)
                 && !StringUtils.containsIgnoreCase(service.getStatus().toString(), fFreeText))
         continue;
 
       services.add(service);
     }
     int total = services.size();
 
     if (sortOpt.isPresent()) {
       ArrayList<SortCriterion> sortCriteria = RestUtils.parseSortQueryParameter(sortOpt.get());
       if (!sortCriteria.isEmpty()) {
         try {
           SortCriterion sortCriterion = sortCriteria.iterator().next();
           Collections.sort(services, new ServiceStatisticsComparator(
                   sortCriterion.getFieldName(),
                   sortCriterion.getOrder() == Order.Ascending));
         } catch (Exception ex) {
           logger.warn("Failed to sort services collection.", ex);
         }
       }
     }
 
     List<JsonObject> jsonList = new ArrayList<>();
     List<Service> limitedServices = new SmartIterator<Service>(limit, offset).applyLimitAndOffset(services);
 
     for (Service s : limitedServices) {
       jsonList.add(s.toJSON());
     }
 
     return RestUtils.okJsonList(jsonList, offset, limit, total);
   }
 
   /**
    * Service UI model. Wrapper class for a {@code ServiceStatistics} class.
    */
   class Service implements JSONAware {
     /** Completed model field name. */
     public static final String COMPLETED_NAME = "completed";
     /** Host model field name. */
     public static final String HOST_NAME = "hostname";
     /** Node name model field name. */
     public static final String NODE_NAME = "nodeName";
     /** MeanQueueTime model field name. */
     public static final String MEAN_QUEUE_TIME_NAME = "meanQueueTime";
     /** MeanRunTime model field name. */
     public static final String MEAN_RUN_TIME_NAME = "meanRunTime";
     /** (Service-) Name model field name. */
     public static final String NAME_NAME = "name";
     /** Queued model field name. */
     public static final String QUEUED_NAME = "queued";
     /** Running model field name. */
     public static final String RUNNING_NAME = "running";
     /** Status model field name. */
     public static final String STATUS_NAME = "status";
     /** Online model field name. */
     public static final String ONLINE_NAME = "online";
     /** Maintenance model field name. */
     public static final String MAINTENANCE_NAME = "maintenance";
 
     /** Wrapped {@code ServiceStatistics} instance. */
     private final ServiceStatistics serviceStatistics;
 
     private final Optional<HostRegistration> server;
 
     /** Constructor, set {@code ServiceStatistics} instance to a final private property. */
     Service(ServiceStatistics serviceStatistics, Optional<HostRegistration> server) {
       this.serviceStatistics = serviceStatistics;
       this.server = server;
     }
 
     /**
      * Returns completed jobs count.
      * @return completed jobs count
      */
     public int getCompletedJobs() {
       return serviceStatistics.getFinishedJobs();
     }
 
     /**
      * Returns service host name.
      * @return service host name
      */
     public String getHost() {
       return serviceStatistics.getServiceRegistration().getHost();
     }
 
     /**
      * Returns service host name.
      * @return service host name
      */
     public String getNodeName() {
       return server.isPresent() ? server.get().getNodeName() : "";
     }
 
     /**
      * Returns service mean queue time in seconds.
      * @return service mean queue time in seconds
      */
     public long getMeanQueueTime() {
       return TimeUnit.MILLISECONDS.toSeconds(serviceStatistics.getMeanQueueTime());
     }
 
     /**
      * Returns service mean run time in seconds.
      * @return service mean run time in seconds
      */
     public long getMeanRunTime() {
       return TimeUnit.MILLISECONDS.toSeconds(serviceStatistics.getMeanRunTime());
     }
 
     /**
      * Returns service name.
      * @return service name
      */
     public String getName() {
       return serviceStatistics.getServiceRegistration().getServiceType();
     }
 
     /**
      * Returns queued jobs count.
      * @return queued jobs count
      */
     public int getQueuedJobs() {
       return serviceStatistics.getQueuedJobs();
     }
 
     /**
      * Returns running jobs count.
      * @return running jobs count
      */
     public int getRunningJobs() {
       return serviceStatistics.getRunningJobs();
     }
 
     /**
      * Returns service status.
      * @return service status
      */
     public ServiceState getStatus() {
       return serviceStatistics.getServiceRegistration().getServiceState();
     }
 
     /**
      * Returns whether the service is online.
      * @return online status
      */
     public boolean getIsOnline() {
       return serviceStatistics.getServiceRegistration().isOnline();
     }
 
     /**
      * Returns whether the service is in maintenance.
      * @return maintenance status
      */
     public boolean getisMaintenance() {
       return serviceStatistics.getServiceRegistration().isInMaintenanceMode();
     }
 
     /**
      * Returns a map of all service fields.
      * @return a map of all service fields
      */
     public Map<String, String> toMap() {
       Map<String, String> serviceMap = new HashMap<String, String>();
       serviceMap.put(COMPLETED_NAME, Integer.toString(getCompletedJobs()));
       serviceMap.put(HOST_NAME, getHost());
       serviceMap.put(NODE_NAME, getNodeName());
       serviceMap.put(MEAN_QUEUE_TIME_NAME, Long.toString(getMeanQueueTime()));
       serviceMap.put(MEAN_RUN_TIME_NAME, Long.toString(getMeanRunTime()));
       serviceMap.put(NAME_NAME, getName());
       serviceMap.put(QUEUED_NAME, Integer.toString(getQueuedJobs()));
       serviceMap.put(RUNNING_NAME, Integer.toString(getRunningJobs()));
       serviceMap.put(STATUS_NAME, getStatus().name());
       serviceMap.put(ONLINE_NAME, Boolean.toString(getIsOnline()));
       serviceMap.put(MAINTENANCE_NAME, Boolean.toString(getisMaintenance()));
       return serviceMap;
     }
 
     /**
      * Returns a json representation of a service as {@code String}.
      * @return a json representation of a service as {@code String}
      */
     @Override
     public String toJSONString() {
       return JSONObject.toJSONString(toMap());
     }
 
     /**
      * Returns a json representation of a service as {@code JValue}.
      * @return a json representation of a service as {@code JValue}
      */
     public JsonObject toJSON() {
       JsonObject json = new JsonObject();
       json.addProperty(COMPLETED_NAME, getCompletedJobs());
       json.addProperty(HOST_NAME, safeString(getHost()));
       json.addProperty(NODE_NAME, safeString(getNodeName()));
       json.addProperty(MEAN_QUEUE_TIME_NAME, getMeanQueueTime());
       json.addProperty(MEAN_RUN_TIME_NAME, getMeanRunTime());
       json.addProperty(NAME_NAME, safeString(getName()));
       json.addProperty(QUEUED_NAME, getQueuedJobs());
       json.addProperty(RUNNING_NAME, getRunningJobs());
       json.addProperty(STATUS_NAME, SERVICE_STATUS_TRANSLATION_PREFIX + getStatus().name());
       json.addProperty(ONLINE_NAME, getIsOnline());
       json.addProperty(MAINTENANCE_NAME, getisMaintenance());
       return json;
     }
   }
 
   /**
    * {@code Service} comparator. Can compare service instances based on the given sort criterion and sort order.
    */
   class ServiceStatisticsComparator implements Comparator<Service> {
 
     /** Sort criterion. */
     private final String sortBy;
     /** Sort order (true if ascending, false otherwise). */
     private final boolean ascending;
 
     /** Constructor. */
     ServiceStatisticsComparator(String sortBy, boolean ascending) {
       if (StringUtils.equalsIgnoreCase(Service.COMPLETED_NAME, sortBy)) {
         this.sortBy = Service.COMPLETED_NAME;
       } else if (StringUtils.equalsIgnoreCase(Service.HOST_NAME, sortBy)) {
         this.sortBy = Service.HOST_NAME;
       } else if (StringUtils.equalsIgnoreCase(Service.NODE_NAME, sortBy)) {
         this.sortBy = Service.NODE_NAME;
       } else if (StringUtils.equalsIgnoreCase(Service.MEAN_QUEUE_TIME_NAME, sortBy)) {
         this.sortBy = Service.MEAN_QUEUE_TIME_NAME;
       } else if (StringUtils.equalsIgnoreCase(Service.MEAN_RUN_TIME_NAME, sortBy)) {
         this.sortBy = Service.MEAN_RUN_TIME_NAME;
       } else if (StringUtils.equalsIgnoreCase(Service.NAME_NAME, sortBy)) {
         this.sortBy = Service.NAME_NAME;
       } else if (StringUtils.equalsIgnoreCase(Service.QUEUED_NAME, sortBy)) {
         this.sortBy = Service.QUEUED_NAME;
       } else if (StringUtils.equalsIgnoreCase(Service.RUNNING_NAME, sortBy)) {
         this.sortBy = Service.RUNNING_NAME;
       } else if (StringUtils.equalsIgnoreCase(Service.STATUS_NAME, sortBy)) {
         this.sortBy = Service.STATUS_NAME;
       } else {
         throw new IllegalArgumentException(String.format("Can't sort services by %s.", sortBy));
       }
       this.ascending = ascending;
     }
 
     /**
      * Compare two service instances.
      * @param s1 first {@code Service} instance to compare
      * @param s2 second {@code Service} instance to compare
      * @return
      */
     @Override
     public int compare(Service s1, Service s2) {
       int result = 0;
       switch (sortBy) {
         case Service.COMPLETED_NAME:
           result = s1.getCompletedJobs() - s2.getCompletedJobs();
           break;
         case Service.HOST_NAME:
           result = s1.getHost().compareToIgnoreCase(s2.getHost());
           break;
         case Service.NODE_NAME:
           result = s1.getNodeName().compareToIgnoreCase(s2.getNodeName());
           break;
         case Service.MEAN_QUEUE_TIME_NAME:
           result = (int) (s1.getMeanQueueTime() - s2.getMeanQueueTime());
           break;
         case Service.MEAN_RUN_TIME_NAME:
           result = (int) (s1.getMeanRunTime() - s2.getMeanRunTime());
           break;
         case Service.QUEUED_NAME:
           result = s1.getQueuedJobs() - s2.getQueuedJobs();
           break;
         case Service.RUNNING_NAME:
           result = s1.getRunningJobs() - s2.getRunningJobs();
           break;
         case Service.STATUS_NAME:
           result = s1.getStatus().compareTo(s2.getStatus());
           break;
         case Service.NAME_NAME: // default sorting criterium
         default:
           result = s1.getName().compareToIgnoreCase(s2.getName());
       }
       return ascending ? result : 0 - result;
     }
   }
 
   /** OSGI activate method. */
   @Activate
   public void activate() {
     logger.info("ServicesEndpoint is activated!");
   }
 
   /**
    * @param serviceRegistry
    *          the serviceRegistry to set
    */
   @Reference
   public void setServiceRegistry(ServiceRegistry serviceRegistry) {
     this.serviceRegistry = serviceRegistry;
   }
 
   /**
    * @param hostname of server to find in list
    * @param servers, list of known servers
    */
   private Optional<HostRegistration> findServerByHost(String hostname, List<HostRegistration> servers) {
     return servers.stream().filter(o -> o.getBaseUrl().equals(hostname)).findFirst();
   }
 }