code: // Licensed to the Software Freedom Conservancy (SFC) under one
  // or more contributor license agreements.  See the NOTICE file
  // distributed with this work for additional information
  // regarding copyright ownership.  The SFC 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
  //
  //   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.openqa.selenium.grid.graphql;
  
  import com.google.common.collect.ImmutableList;
  import java.net.URI;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  import java.util.stream.Collectors;
  import org.openqa.selenium.Capabilities;
  import org.openqa.selenium.ImmutableCapabilities;
  import org.openqa.selenium.grid.data.DistributorStatus;
  import org.openqa.selenium.grid.data.NodeStatus;
  import org.openqa.selenium.grid.data.SessionRequestCapability;
  import org.openqa.selenium.grid.data.Slot;
  import org.openqa.selenium.grid.distributor.Distributor;
  import org.openqa.selenium.grid.sessionqueue.NewSessionQueue;
  import org.openqa.selenium.internal.Require;
  import org.openqa.selenium.json.Json;
  import org.openqa.selenium.remote.SessionId;
  
  public class Grid {
  
    private static final Json JSON = new Json();
    private static final SessionId RESERVED = new SessionId("reserved");
    private final URI uri;
    private final DistributorStatus distributorStatus;
    private final List<Set<Capabilities>> queueInfoList;
    private final String version;
  
    public Grid(Distributor distributor, NewSessionQueue newSessionQueue, URI uri, String version) {
      Require.nonNull("Distributor", distributor);
      this.uri = Require.nonNull("Grid's public URI", uri);
      NewSessionQueue sessionQueue = Require.nonNull("New session queue", newSessionQueue);
      this.queueInfoList =
          sessionQueue.getQueueContents().stream()
              .map(SessionRequestCapability::getDesiredCapabilities)
              .collect(Collectors.toList());
      this.distributorStatus = distributor.getStatus();
      this.version = Require.nonNull("Grid's version", version);
    }
  
    public URI getUri() {
      return uri;
    }
  
    public String getVersion() {
      return version;
    }
  
    public List<Node> getNodes() {
      ImmutableList.Builder<Node> toReturn = ImmutableList.builder();
  
      for (NodeStatus status : distributorStatus.getNodes()) {
        Map<Capabilities, Integer> stereotypes = new HashMap<>();
        Map<org.openqa.selenium.grid.data.Session, Slot> sessions = new HashMap<>();
  
        for (Slot slot : status.getSlots()) {
          org.openqa.selenium.grid.data.Session session = slot.getSession();
          if (session != null) {
            sessions.put(session, slot);
          }
  
          int count = stereotypes.getOrDefault(slot.getStereotype(), 0);
          count++;
          stereotypes.put(slot.getStereotype(), count);
        }
  
        OsInfo osInfo =
            new OsInfo(
                status.getOsInfo().get("arch"),
                status.getOsInfo().get("name"),
                status.getOsInfo().get("version"));
  
        toReturn.add(
            new Node(
                status.getNodeId(),
                status.getExternalUri(),
                status.getAvailability(),
                status.getMaxSessionCount(),
                status.getSlots().size(),
                stereotypes,
                sessions,
                status.getVersion(),
                osInfo));
      }
  
      return toReturn.build();
    }
  
    public int getNodeCount() {
      return distributorStatus.getNodes().size();
    }
  
    public int getSessionCount() {
      return distributorStatus.getNodes().stream()
          .map(NodeStatus::getSlots)
          .flatMap(Collection::stream)
          .filter(slot -> slot.getSession() != null)
          .filter(slot -> !slot.getSession().getId().equals(RESERVED))
          .mapToInt(slot -> 1)
          .sum();
    }
  
    public int getTotalSlots() {
      return distributorStatus.getNodes().stream().mapToInt(status -> status.getSlots().size()).sum();
    }
  
    public int getMaxSession() {
      return distributorStatus.getNodes().stream().mapToInt(NodeStatus::getMaxSessionCount).sum();
    }
  
    public int getSessionQueueSize() {
      return queueInfoList.size();
    }
  
    public List<String> getSessionQueueRequests() {
      // TODO: The Grid UI expects there to be a single capability per new session request, which is
      // not correct
      return queueInfoList.stream()
          .map(set -> set.isEmpty() ? new ImmutableCapabilities() : set.iterator().next())
          .map(JSON::toJson)
          .collect(Collectors.toList());
    }
  
    public List<Session> getSessions() {
      List<Session> sessions = new ArrayList<>();
      for (NodeStatus status : distributorStatus.getNodes()) {
        for (Slot slot : status.getSlots()) {
          if (slot.getSession() != null && !slot.getSession().getId().equals(RESERVED)) {
            org.openqa.selenium.grid.data.Session session = slot.getSession();
            sessions.add(
                new org.openqa.selenium.grid.graphql.Session(
                    session.getId().toString(),
                    session.getCapabilities(),
                    session.getStartTime(),
                    session.getUri(),
                    status.getNodeId().toString(),
                    status.getExternalUri(),
                    slot));
          }
        }
      }
      return sessions;
    }
  }
  