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.data;
  
  import java.io.Serializable;
  import java.util.Arrays;
  import java.util.List;
  import java.util.Objects;
  import org.openqa.selenium.Capabilities;
  
  /**
   * Default matching implementation for slots, loosely based on the requirements for capability
   * matching from the WebDriver spec. A match is made if the following are all true:
   *
   * <ul>
   *   <li>All non-extension capabilities from the {@code stereotype} match those in the {@link
   *       Capabilities} being considered.
   *   <li>If the {@link Capabilities} being considered contain any of:
   *       <ul>
   *         <li>browserName
   *         <li>browserVersion
   *         <li>platformName
   *       </ul>
   *       Then the {@code stereotype} must contain the same values.
   * </ul>
   *
   * <p>One thing to note is that extension capabilities are not considered when matching slots, since
   * the matching of these is implementation-specific to each driver.
   */
  public class DefaultSlotMatcher implements SlotMatcher, Serializable {
  
    /*
     List of prefixed extension capabilities we never should try to match, they should be
     matched in the Node or in the browser driver.
    */
    private static final List<String> EXTENSION_CAPABILITIES_PREFIXES =
        Arrays.asList("goog:", "moz:", "ms:", "se:");
  
    @Override
    public boolean matches(Capabilities stereotype, Capabilities capabilities) {
  
      if (capabilities.asMap().isEmpty()) {
        return false;
      }
  
      if (!initialMatch(stereotype, capabilities)) {
        return false;
      }
  
      if (!managedDownloadsEnabled(stereotype, capabilities)) {
        return false;
      }
  
      if (!platformVersionMatch(stereotype, capabilities)) {
        return false;
      }
  
      if (!extensionCapabilitiesMatch(stereotype, capabilities)) {
        return false;
      }
  
      // At the end, a simple browser, browserVersion and platformName match
      boolean browserNameMatch =
          (capabilities.getBrowserName() == null || capabilities.getBrowserName().isEmpty())
              || Objects.equals(stereotype.getBrowserName(), capabilities.getBrowserName());
      boolean browserVersionMatch =
          (capabilities.getBrowserVersion() == null || capabilities.getBrowserVersion().isEmpty())
              || Objects.equals(stereotype.getBrowserVersion(), capabilities.getBrowserVersion());
      boolean platformNameMatch =
          capabilities.getPlatformName() == null
              || Objects.equals(stereotype.getPlatformName(), capabilities.getPlatformName())
              || (stereotype.getPlatformName() != null
                  && stereotype.getPlatformName().is(capabilities.getPlatformName()));
      return browserNameMatch && browserVersionMatch && platformNameMatch;
    }
  
    private Boolean initialMatch(Capabilities stereotype, Capabilities capabilities) {
      return stereotype.getCapabilityNames().stream()
          // Matching of extension capabilities is implementation independent. Skip them
          .filter(name -> !name.contains(":"))
          // Platform matching is special, we do it later
          .filter(name -> !"platformName".equalsIgnoreCase(name))
          .map(
              name -> {
                if (capabilities.getCapability(name) instanceof String) {
                  return stereotype
                      .getCapability(name)
                      .toString()
                      .equalsIgnoreCase(capabilities.getCapability(name).toString());
                } else {
                  return capabilities.getCapability(name) == null
                      || Objects.equals(
                          stereotype.getCapability(name), capabilities.getCapability(name));
                }
              })
          .reduce(Boolean::logicalAnd)
          .orElse(true);
    }
  
    private Boolean managedDownloadsEnabled(Capabilities stereotype, Capabilities capabilities) {
      // First lets check if user wanted a Node with managed downloads enabled
      Object raw = capabilities.getCapability("se:downloadsEnabled");
      if (raw == null || !Boolean.parseBoolean(raw.toString())) {
        // User didn't ask. So lets move on to the next matching criteria
        return true;
      }
      // User wants managed downloads enabled to be done on this Node, let's check the stereotype
      raw = stereotype.getCapability("se:downloadsEnabled");
      // Try to match what the user requested
      return raw != null && Boolean.parseBoolean(raw.toString());
    }
  
    private Boolean platformVersionMatch(Capabilities stereotype, Capabilities capabilities) {
      /*
       This platform version match is not W3C compliant but users can add Appium servers as
       Nodes, so we avoid delaying the match until the Slot, which makes the whole matching
       process faster.
      */
      return capabilities.getCapabilityNames().stream()
          .filter(name -> name.contains("platformVersion"))
          .map(
              platformVersionCapName ->
                  Objects.equals(
                      stereotype.getCapability(platformVersionCapName),
                      capabilities.getCapability(platformVersionCapName)))
          .reduce(Boolean::logicalAnd)
          .orElse(true);
    }
  
    private Boolean extensionCapabilitiesMatch(Capabilities stereotype, Capabilities capabilities) {
      /*
       We match extension capabilities when they are not prefixed with any of the
       EXTENSION_CAPABILITIES_PREFIXES items. Also, we match them only when the capabilities
       of the new session request contains that specific extension capability.
      */
      return stereotype.getCapabilityNames().stream()
          .filter(name -> name.contains(":"))
          .filter(name -> capabilities.asMap().containsKey(name))
          .filter(name -> EXTENSION_CAPABILITIES_PREFIXES.stream().noneMatch(name::contains))
          .map(
              name -> {
                if (capabilities.getCapability(name) instanceof String) {
                  return stereotype
                      .getCapability(name)
                      .toString()
                      .equalsIgnoreCase(capabilities.getCapability(name).toString());
                } else {
                  return capabilities.getCapability(name) == null
                      || Objects.equals(
                          stereotype.getCapability(name), capabilities.getCapability(name));
                }
              })
          .reduce(Boolean::logicalAnd)
          .orElse(true);
    }
  }
  