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   1 /**
   2  * Copyright (c) 2010-2024 Contributors to the openHAB project
   3  *
   4  * See the NOTICE file(s) distributed with this work for additional
   5  * information.
   6  *
   7  * This program and the accompanying materials are made available under the
   8  * terms of the Eclipse Public License 2.0 which is available at
   9  * http://www.eclipse.org/legal/epl-2.0
  10  *
  11  * SPDX-License-Identifier: EPL-2.0
  12  */
  13 package org.openhab.io.homekit.internal.accessories;
  14
  15 import static org.openhab.io.homekit.internal.HomekitAccessoryType.*;
  16 import static org.openhab.io.homekit.internal.HomekitCharacteristicType.*;
  17
  18 import java.lang.reflect.InvocationTargetException;
  19 import java.util.AbstractMap.SimpleEntry;
  20 import java.util.ArrayList;
  21 import java.util.Arrays;
  22 import java.util.Collections;
  23 import java.util.HashMap;
  24 import java.util.HashSet;
  25 import java.util.List;
  26 import java.util.Map;
  27 import java.util.Map.Entry;
  28 import java.util.Objects;
  29 import java.util.Optional;
  30 import java.util.Set;
  31 import java.util.TreeMap;
  32 import java.util.stream.Collectors;
  33 import java.util.stream.Stream;
  34
  35 import org.eclipse.jdt.annotation.NonNullByDefault;
  36 import org.eclipse.jdt.annotation.Nullable;
  37 import org.openhab.core.items.GenericItem;
  38 import org.openhab.core.items.GroupItem;
  39 import org.openhab.core.items.Item;
  40 import org.openhab.core.items.ItemRegistry;
  41 import org.openhab.core.items.Metadata;
  42 import org.openhab.core.items.MetadataKey;
  43 import org.openhab.core.items.MetadataRegistry;
  44 import org.openhab.io.homekit.internal.HomekitAccessoryType;
  45 import org.openhab.io.homekit.internal.HomekitAccessoryUpdater;
  46 import org.openhab.io.homekit.internal.HomekitCharacteristicType;
  47 import org.openhab.io.homekit.internal.HomekitException;
  48 import org.openhab.io.homekit.internal.HomekitOHItemProxy;
  49 import org.openhab.io.homekit.internal.HomekitSettings;
  50 import org.openhab.io.homekit.internal.HomekitTaggedItem;
  51 import org.slf4j.Logger;
  52 import org.slf4j.LoggerFactory;
  53
  54 import io.github.hapjava.characteristics.Characteristic;
  55
  56 /**
  57  * Creates a HomekitAccessory for a given HomekitTaggedItem.
  58  *
  59  * @author Andy Lintner - Initial contribution
  60  * @author Eugen Freiter - refactoring for optional characteristics
  61  */
  62 @NonNullByDefault
  63 public class HomekitAccessoryFactory {
  64     private static final Logger LOGGER = LoggerFactory.getLogger(HomekitAccessoryFactory.class);
  65     public static final String METADATA_KEY = "homekit"; // prefix for HomeKit meta information in items.xml
  66
  67     /** List of mandatory attributes for each accessory type. **/
  68     private static final Map<HomekitAccessoryType, HomekitCharacteristicType[]> MANDATORY_CHARACTERISTICS = new HashMap<>() {
  69         {
  70             put(ACCESSORY_GROUP, new HomekitCharacteristicType[] {});
  71
  72             put(AIR_QUALITY_SENSOR, new HomekitCharacteristicType[] { AIR_QUALITY });
  73             put(BASIC_FAN, new HomekitCharacteristicType[] { ON_STATE });
  74             put(BATTERY, new HomekitCharacteristicType[] { BATTERY_LEVEL, BATTERY_LOW_STATUS });
  75             put(CARBON_DIOXIDE_SENSOR, new HomekitCharacteristicType[] { CARBON_DIOXIDE_DETECTED_STATE });
  76             put(CARBON_MONOXIDE_SENSOR, new HomekitCharacteristicType[] { CARBON_MONOXIDE_DETECTED_STATE });
  77             put(CONTACT_SENSOR, new HomekitCharacteristicType[] { CONTACT_SENSOR_STATE });
  78             put(DOOR, new HomekitCharacteristicType[] { CURRENT_POSITION, TARGET_POSITION, POSITION_STATE });
  79             put(FAN, new HomekitCharacteristicType[] { ACTIVE_STATUS });
  80             put(FAUCET, new HomekitCharacteristicType[] { ACTIVE_STATUS });
  81             put(FILTER_MAINTENANCE, new HomekitCharacteristicType[] { FILTER_CHANGE_INDICATION });
  82             put(GARAGE_DOOR_OPENER,
  83                     new HomekitCharacteristicType[] { CURRENT_DOOR_STATE, TARGET_DOOR_STATE, OBSTRUCTION_STATUS });
  84             put(HEATER_COOLER, new HomekitCharacteristicType[] { ACTIVE_STATUS, CURRENT_HEATER_COOLER_STATE,
  85                     TARGET_HEATER_COOLER_STATE, CURRENT_TEMPERATURE });
  86             put(HUMIDITY_SENSOR, new HomekitCharacteristicType[] { RELATIVE_HUMIDITY });
  87             put(INPUT_SOURCE, new HomekitCharacteristicType[] {});
  88             put(IRRIGATION_SYSTEM, new HomekitCharacteristicType[] { ACTIVE, INUSE_STATUS, PROGRAM_MODE });
  89             put(LEAK_SENSOR, new HomekitCharacteristicType[] { LEAK_DETECTED_STATE });
  90             put(LIGHT_SENSOR, new HomekitCharacteristicType[] { LIGHT_LEVEL });
  91             put(LIGHTBULB, new HomekitCharacteristicType[] { ON_STATE });
  92             put(LOCK, new HomekitCharacteristicType[] { LOCK_CURRENT_STATE, LOCK_TARGET_STATE });
  93             put(MICROPHONE, new HomekitCharacteristicType[] { MUTE });
  94             put(MOTION_SENSOR, new HomekitCharacteristicType[] { MOTION_DETECTED_STATE });
  95             put(OCCUPANCY_SENSOR, new HomekitCharacteristicType[] { OCCUPANCY_DETECTED_STATE });
  96             put(OUTLET, new HomekitCharacteristicType[] { ON_STATE, INUSE_STATUS });
  97             put(SECURITY_SYSTEM,
  98                     new HomekitCharacteristicType[] { SECURITY_SYSTEM_CURRENT_STATE, SECURITY_SYSTEM_TARGET_STATE });
  99             put(SMART_SPEAKER, new HomekitCharacteristicType[] { CURRENT_MEDIA_STATE, TARGET_MEDIA_STATE });
 100             put(SMOKE_SENSOR, new HomekitCharacteristicType[] { SMOKE_DETECTED_STATE });
 101             put(SLAT, new HomekitCharacteristicType[] { CURRENT_SLAT_STATE });
 102             put(SPEAKER, new HomekitCharacteristicType[] { MUTE });
 103             put(SWITCH, new HomekitCharacteristicType[] { ON_STATE });
 104             put(TELEVISION, new HomekitCharacteristicType[] { ACTIVE });
 105             put(TELEVISION_SPEAKER, new HomekitCharacteristicType[] { MUTE });
 106             put(TEMPERATURE_SENSOR, new HomekitCharacteristicType[] { CURRENT_TEMPERATURE });
 107             put(THERMOSTAT, new HomekitCharacteristicType[] { CURRENT_HEATING_COOLING_STATE,
 108                     TARGET_HEATING_COOLING_STATE, CURRENT_TEMPERATURE });
 109             put(VALVE, new HomekitCharacteristicType[] { ACTIVE_STATUS, INUSE_STATUS });
 110             put(WINDOW, new HomekitCharacteristicType[] { CURRENT_POSITION, TARGET_POSITION, POSITION_STATE });
 111             put(WINDOW_COVERING, new HomekitCharacteristicType[] { TARGET_POSITION, CURRENT_POSITION, POSITION_STATE });
 112         }
 113     };
 114
 115     /** List of service implementation for each accessory type. **/
 116     private static final Map<HomekitAccessoryType, Class<? extends AbstractHomekitAccessoryImpl>> SERVICE_IMPL_MAP = new HashMap<>() {
 117         {
 118             put(ACCESSORY_GROUP, HomekitAccessoryGroupImpl.class);
 119
 120             put(AIR_QUALITY_SENSOR, HomekitAirQualitySensorImpl.class);
 121             put(BASIC_FAN, HomekitBasicFanImpl.class);
 122             put(BATTERY, HomekitBatteryImpl.class);
 123             put(CARBON_DIOXIDE_SENSOR, HomekitCarbonDioxideSensorImpl.class);
 124             put(CARBON_MONOXIDE_SENSOR, HomekitCarbonMonoxideSensorImpl.class);
 125             put(CONTACT_SENSOR, HomekitContactSensorImpl.class);
 126             put(DOOR, HomekitDoorImpl.class);
 127             put(FAN, HomekitFanImpl.class);
 128             put(FAUCET, HomekitFaucetImpl.class);
 129             put(FILTER_MAINTENANCE, HomekitFilterMaintenanceImpl.class);
 130             put(GARAGE_DOOR_OPENER, HomekitGarageDoorOpenerImpl.class);
 131             put(HEATER_COOLER, HomekitHeaterCoolerImpl.class);
 132             put(HUMIDITY_SENSOR, HomekitHumiditySensorImpl.class);
 133             put(INPUT_SOURCE, HomekitInputSourceImpl.class);
 134             put(IRRIGATION_SYSTEM, HomekitIrrigationSystemImpl.class);
 135             put(LEAK_SENSOR, HomekitLeakSensorImpl.class);
 136             put(LIGHT_SENSOR, HomekitLightSensorImpl.class);
 137             put(LIGHTBULB, HomekitLightbulbImpl.class);
 138             put(LOCK, HomekitLockImpl.class);
 139             put(MICROPHONE, HomekitMicrophoneImpl.class);
 140             put(MOTION_SENSOR, HomekitMotionSensorImpl.class);
 141             put(OCCUPANCY_SENSOR, HomekitOccupancySensorImpl.class);
 142             put(OUTLET, HomekitOutletImpl.class);
 143             put(SECURITY_SYSTEM, HomekitSecuritySystemImpl.class);
 144             put(SLAT, HomekitSlatImpl.class);
 145             put(SMART_SPEAKER, HomekitSmartSpeakerImpl.class);
 146             put(SMOKE_SENSOR, HomekitSmokeSensorImpl.class);
 147             put(SPEAKER, HomekitSpeakerImpl.class);
 148             put(SWITCH, HomekitSwitchImpl.class);
 149             put(TELEVISION, HomekitTelevisionImpl.class);
 150             put(TELEVISION_SPEAKER, HomekitTelevisionSpeakerImpl.class);
 151             put(TEMPERATURE_SENSOR, HomekitTemperatureSensorImpl.class);
 152             put(THERMOSTAT, HomekitThermostatImpl.class);
 153             put(VALVE, HomekitValveImpl.class);
 154             put(WINDOW, HomekitWindowImpl.class);
 155             put(WINDOW_COVERING, HomekitWindowCoveringImpl.class);
 156         }
 157     };
 158
 159     private static List<HomekitCharacteristicType> getRequiredCharacteristics(HomekitTaggedItem taggedItem) {
 160         final List<HomekitCharacteristicType> characteristics = new ArrayList<>();
 161         if (MANDATORY_CHARACTERISTICS.containsKey(taggedItem.getAccessoryType())) {
 162             characteristics.addAll(Arrays.asList(MANDATORY_CHARACTERISTICS.get(taggedItem.getAccessoryType())));
 163         }
 164         if (taggedItem.getAccessoryType() == BATTERY) {
 165             final boolean isChargeable = taggedItem.getConfigurationAsBoolean(HomekitBatteryImpl.BATTERY_TYPE, false);
 166             if (isChargeable) {
 167                 characteristics.add(BATTERY_CHARGING_STATE);
 168             }
 169         }
 170         return characteristics;
 171     }
 172
 173     /**
 174      * creates HomeKit accessory for an openhab item.
 175      *
 176      * @param taggedItem openhab item tagged as HomeKit item
 177      * @param metadataRegistry openhab metadata registry required to get item meta information
 178      * @param updater OH HomeKit update class that ensure the status sync between OH item and corresponding HomeKit
 179      *            characteristic.
 180      * @param settings OH settings
 181      * @return HomeKit accessory
 182      * @throws HomekitException exception in case HomeKit accessory could not be created, e.g. due missing mandatory
 183      *             characteristic
 184      */
 185     public static AbstractHomekitAccessoryImpl create(HomekitTaggedItem taggedItem, MetadataRegistry metadataRegistry,
 186             HomekitAccessoryUpdater updater, HomekitSettings settings) throws HomekitException {
 187         Set<HomekitTaggedItem> ancestorServices = new HashSet<>();
 188         return create(taggedItem, metadataRegistry, updater, settings, ancestorServices);
 189     }
 190
 191     @SuppressWarnings("null")
 192     private static AbstractHomekitAccessoryImpl create(HomekitTaggedItem taggedItem, MetadataRegistry metadataRegistry,
 193             HomekitAccessoryUpdater updater, HomekitSettings settings, Set<HomekitTaggedItem> ancestorServices)
 194             throws HomekitException {
 195         final HomekitAccessoryType accessoryType = taggedItem.getAccessoryType();
 196         LOGGER.trace("Constructing {} of accessory type {}", taggedItem.getName(), accessoryType.getTag());
 197         final List<HomekitTaggedItem> characteristics = new ArrayList<>();
 198         final List<Characteristic> rawCharacteristics = new ArrayList<>();
 199
 200         getMandatoryCharacteristicsFromItem(taggedItem, metadataRegistry, characteristics, rawCharacteristics);
 201         final List<HomekitCharacteristicType> mandatoryCharacteristics = getRequiredCharacteristics(taggedItem);
 202         if (characteristics.size() + rawCharacteristics.size() < mandatoryCharacteristics.size()) {
 203             LOGGER.warn("Accessory of type {} must have following characteristics {}. Found only {}, {}",
 204                     accessoryType.getTag(), mandatoryCharacteristics, characteristics, rawCharacteristics);
 205             throw new HomekitException("Missing mandatory characteristics");
 206         }
 207         AbstractHomekitAccessoryImpl accessoryImpl;
 208         try {
 209             final @Nullable Class<? extends AbstractHomekitAccessoryImpl> accessoryImplClass = SERVICE_IMPL_MAP
 210                     .get(accessoryType);
 211             if (accessoryImplClass != null) {
 212                 if (ancestorServices.contains(taggedItem)) {
 213                     LOGGER.warn("Item {} has already been created. Perhaps you have circular Homekit accessory groups?",
 214                             taggedItem.getName());
 215                     throw new HomekitException("Circular accessory references");
 216                 }
 217                 accessoryImpl = accessoryImplClass
 218                         .getConstructor(HomekitTaggedItem.class, List.class, List.class, HomekitAccessoryUpdater.class,
 219                                 HomekitSettings.class)
 220                         .newInstance(taggedItem, characteristics, rawCharacteristics, updater, settings);
 221                 addOptionalCharacteristics(taggedItem, accessoryImpl, metadataRegistry);
 222                 addOptionalMetadataCharacteristics(taggedItem, accessoryImpl);
 223                 accessoryImpl.setIsLinkedService(!ancestorServices.isEmpty());
 224                 accessoryImpl.init();
 225                 ancestorServices.add(taggedItem);
 226                 addLinkedServices(taggedItem, accessoryImpl, metadataRegistry, updater, settings, ancestorServices);
 227                 return accessoryImpl;
 228             } else {
 229                 LOGGER.warn("Unsupported HomeKit type: {}", accessoryType.getTag());
 230                 throw new HomekitException("Unsupported HomeKit type: " + accessoryType);
 231             }
 232         } catch (NoSuchMethodException | IllegalAccessException | InstantiationException
 233                 | InvocationTargetException e) {
 234             LOGGER.warn("Cannot instantiate accessory implementation for accessory {}", accessoryType.getTag(), e);
 235             throw new HomekitException("Cannot instantiate accessory implementation for accessory " + accessoryType);
 236         }
 237     }
 238
 239     /**
 240      * return HomeKit accessory types for an OH item based on meta data
 241      *
 242      * @param item OH item
 243      * @param metadataRegistry meta data registry
 244      * @return list of HomeKit accessory types and characteristics.
 245      */
 246     public static List<Entry<HomekitAccessoryType, HomekitCharacteristicType>> getAccessoryTypes(Item item,
 247             MetadataRegistry metadataRegistry) {
 248         final List<Entry<HomekitAccessoryType, HomekitCharacteristicType>> accessories = new ArrayList<>();
 249         final @Nullable Metadata metadata = metadataRegistry.get(new MetadataKey(METADATA_KEY, item.getUID()));
 250         if (metadata != null) {
 251             String[] tags = metadata.getValue().split(",");
 252             for (String tag : tags) {
 253                 final String[] meta = tag.split("\\.");
 254                 Optional<HomekitAccessoryType> accessoryType = HomekitAccessoryType.valueOfTag(meta[0].trim());
 255                 if (accessoryType.isPresent()) { // it accessory, check for characteristic
 256                     HomekitAccessoryType type = accessoryType.get();
 257                     if (meta.length > 1) {
 258                         // it has characteristic as well
 259                         accessories.add(new SimpleEntry<>(type, Objects
 260                                 .requireNonNull(HomekitCharacteristicType.valueOfTag(meta[1].trim()).orElse(EMPTY))));
 261                     } else {// it has no characteristic
 262                         accessories.add(new SimpleEntry<>(type, EMPTY));
 263                     }
 264                 } else { // it is no accessory, so, maybe it is a characteristic
 265                     HomekitCharacteristicType.valueOfTag(meta[0].trim())
 266                             .ifPresent(c -> accessories.add(new SimpleEntry<>(DUMMY, c)));
 267                 }
 268             }
 269         }
 270         return accessories;
 271     }
 272
 273     public static @Nullable Map<String, Object> getItemConfiguration(Item item, MetadataRegistry metadataRegistry) {
 274         final @Nullable Metadata metadata = metadataRegistry.get(new MetadataKey(METADATA_KEY, item.getUID()));
 275         return metadata != null ? metadata.getConfiguration() : null;
 276     }
 277
 278     /**
 279      * return list of HomeKit relevant groups linked to an accessory
 280      *
 281      * @param item OH item
 282      * @param itemRegistry item registry
 283      * @param metadataRegistry metadata registry
 284      * @return list of relevant group items
 285      */
 286     public static List<GroupItem> getAccessoryGroups(Item item, ItemRegistry itemRegistry,
 287             MetadataRegistry metadataRegistry) {
 288         return item.getGroupNames().stream().flatMap(name -> {
 289             final @Nullable Item itemFromRegistry = itemRegistry.get(name);
 290             if (itemFromRegistry instanceof GroupItem groupItem) {
 291                 return Stream.of(groupItem);
 292             } else {
 293                 return Stream.empty();
 294             }
 295         }).filter(groupItem -> !getAccessoryTypes(groupItem, metadataRegistry).isEmpty()).collect(Collectors.toList());
 296     }
 297
 298     /**
 299      * collect all mandatory characteristics for a given tagged item, e.g. collect all mandatory HomeKit items from a
 300      * GroupItem
 301      *
 302      * @param taggedItem HomeKit tagged item
 303      * @param metadataRegistry meta data registry
 304      * @return list of mandatory
 305      */
 306     private static void getMandatoryCharacteristicsFromItem(HomekitTaggedItem taggedItem,
 307             MetadataRegistry metadataRegistry, List<HomekitTaggedItem> characteristics,
 308             List<Characteristic> rawCharacteristics) {
 309         if (taggedItem.isGroup()) {
 310             for (Item item : ((GroupItem) taggedItem.getItem()).getMembers()) {
 311                 addMandatoryCharacteristics(taggedItem, characteristics, rawCharacteristics, item, metadataRegistry);
 312             }
 313         } else {
 314             addMandatoryCharacteristics(taggedItem, characteristics, rawCharacteristics, taggedItem.getItem(),
 315                     metadataRegistry);
 316         }
 317         LOGGER.trace("Mandatory characteristics: {}, {}", characteristics, rawCharacteristics);
 318     }
 319
 320     /**
 321      * add mandatory HomeKit items for a given main item to a list of characteristics.
 322      * Main item is use only to determine, which characteristics are mandatory.
 323      * The characteristics are added to item.
 324      * e.g. mainItem could be a group tagged as "thermostat" and item could be item linked to the group and marked as
 325      * TargetTemperature
 326      *
 327      * @param mainItem main item
 328      * @param characteristics list of characteristics
 329      * @param item current item
 330      * @param metadataRegistry meta date registry
 331      */
 332     private static void addMandatoryCharacteristics(HomekitTaggedItem mainItem, List<HomekitTaggedItem> characteristics,
 333             List<Characteristic> rawCharacteristics, Item item, MetadataRegistry metadataRegistry) {
 334         // get list of mandatory characteristics
 335         List<HomekitCharacteristicType> mandatoryCharacteristics = getRequiredCharacteristics(mainItem);
 336         if (mandatoryCharacteristics.isEmpty()) {
 337             // no mandatory characteristics linked to accessory type of mainItem. we are done
 338             return;
 339         }
 340         // check whether we are adding characteristic to the main item, and if yes, use existing item proxy.
 341         // if we are adding not to the main item (typical for groups), create new proxy item.
 342         final HomekitOHItemProxy itemProxy = mainItem.getItem().equals(item) ? mainItem.getProxyItem()
 343                 : new HomekitOHItemProxy(item);
 344         // an item can have several tags, e.g. "ActiveStatus, InUse". we iterate here over all his tags
 345         for (Entry<HomekitAccessoryType, HomekitCharacteristicType> accessory : getAccessoryTypes(item,
 346                 metadataRegistry)) {
 347             // if the item has only accessory tag, e.g. TemperatureSensor,
 348             // then we will link all mandatory characteristic to this item,
 349             // e.g. we will link CurrentTemperature in case of TemperatureSensor.
 350             // Note that accessories that are members of other accessories do _not_
 351             // count - we're already constructing another root accessory.
 352             if (isRootAccessory(accessory) && mainItem.getItem().equals(item)) {
 353                 mandatoryCharacteristics.forEach(c -> characteristics.add(new HomekitTaggedItem(itemProxy,
 354                         accessory.getKey(), c, mainItem.isGroup() ? (GroupItem) mainItem.getItem() : null,
 355                         HomekitAccessoryFactory.getItemConfiguration(item, metadataRegistry))));
 356             } else {
 357                 // item has characteristic tag on it, so, adding it as that characteristic.
 358
 359                 final HomekitCharacteristicType characteristic = accessory.getValue();
 360
 361                 // check whether it is a mandatory characteristic. optional will be added later by another method.
 362                 if (belongsToType(mainItem.getAccessoryType(), accessory)
 363                         && isMandatoryCharacteristic(mainItem, characteristic)) {
 364                     characteristics.add(new HomekitTaggedItem(itemProxy, accessory.getKey(), characteristic,
 365                             mainItem.isGroup() ? (GroupItem) mainItem.getItem() : null,
 366                             HomekitAccessoryFactory.getItemConfiguration(item, metadataRegistry)));
 367                 }
 368             }
 369         }
 370         mandatoryCharacteristics.forEach(c -> {
 371             // Check every metadata key looking for a characteristics we can create
 372             var config = mainItem.getConfiguration();
 373             if (config == null) {
 374                 return;
 375             }
 376             for (var entry : config.entrySet().stream().sorted((lhs, rhs) -> lhs.getKey().compareTo(rhs.getKey()))
 377                     .collect(Collectors.toList())) {
 378                 var type = HomekitCharacteristicType.valueOfTag(entry.getKey());
 379                 if (type.isPresent() && isMandatoryCharacteristic(mainItem, type.get())) {
 380                     var characteristic = HomekitMetadataCharacteristicFactory.createCharacteristic(type.get(),
 381                             entry.getValue());
 382
 383                     characteristic.ifPresent(rc -> rawCharacteristics.add(rc));
 384                 }
 385             }
 386         });
 387     }
 388
 389     /**
 390      * add optional characteristics for given accessory.
 391      *
 392      * @param taggedItem main item
 393      * @param accessory accessory
 394      * @param metadataRegistry metadata registry
 395      */
 396     private static void addOptionalCharacteristics(HomekitTaggedItem taggedItem, AbstractHomekitAccessoryImpl accessory,
 397             MetadataRegistry metadataRegistry) {
 398         Map<HomekitCharacteristicType, GenericItem> characteristics = getOptionalCharacteristics(
 399                 accessory.getRootAccessory(), metadataRegistry);
 400         HashMap<String, HomekitOHItemProxy> proxyItems = new HashMap<>();
 401         proxyItems.put(taggedItem.getItem().getUID(), taggedItem.getProxyItem());
 402         // an accessory can have multiple optional characteristics. iterate over them.
 403         characteristics.forEach((type, item) -> {
 404             try {
 405                 // check whether a proxyItem already exists, if not create one.
 406                 final HomekitOHItemProxy proxyItem = Objects
 407                         .requireNonNull(proxyItems.computeIfAbsent(item.getUID(), k -> new HomekitOHItemProxy(item)));
 408                 final HomekitTaggedItem optionalItem = new HomekitTaggedItem(proxyItem,
 409                         accessory.getRootAccessory().getAccessoryType(), type,
 410                         accessory.getRootAccessory().getRootDeviceGroupItem(),
 411                         getItemConfiguration(item, metadataRegistry));
 412                 final Characteristic characteristic = HomekitCharacteristicFactory.createCharacteristic(optionalItem,
 413                         accessory.getUpdater());
 414                 accessory.addCharacteristic(optionalItem, characteristic);
 415             } catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException | HomekitException e) {
 416                 LOGGER.warn("Unsupported optional HomeKit characteristic: type {}, characteristic type {}",
 417                         accessory.getPrimaryService(), type.getTag());
 418             }
 419         });
 420     }
 421
 422     /**
 423      * add optional characteristics for given accessory from metadata
 424      *
 425      * @param taggedItem main item
 426      * @param accessory accessory
 427      */
 428     private static void addOptionalMetadataCharacteristics(HomekitTaggedItem taggedItem,
 429             AbstractHomekitAccessoryImpl accessory)
 430             throws NoSuchMethodException, IllegalAccessException, InvocationTargetException, HomekitException {
 431         // Check every metadata key looking for a characteristics we can create
 432         var config = taggedItem.getConfiguration();
 433         if (config == null) {
 434             return;
 435         }
 436         for (var entry : config.entrySet().stream().sorted((lhs, rhs) -> lhs.getKey().compareTo(rhs.getKey()))
 437                 .collect(Collectors.toList())) {
 438             var characteristic = HomekitMetadataCharacteristicFactory.createCharacteristic(entry.getKey(),
 439                     entry.getValue());
 440             if (characteristic.isPresent()) {
 441                 accessory.addCharacteristic(characteristic.get());
 442             }
 443         }
 444     }
 445
 446     /**
 447      * creates HomeKit services for an openhab item that are members of this group item.
 448      *
 449      * @param taggedItem openhab item tagged as HomeKit item
 450      * @param AbstractHomekitAccessoryImpl the accessory to add services to
 451      * @param metadataRegistry openhab metadata registry required to get item meta information
 452      * @param updater OH HomeKit update class that ensure the status sync between OH item and corresponding HomeKit
 453      *            characteristic.
 454      * @param settings OH settings
 455      * @param ancestorServices set of all accessories/services under the same root accessory, for
 456      *            for preventing circular references
 457      * @throws HomekitException exception in case HomeKit accessory could not be created, e.g. due missing mandatory
 458      *             characteristic
 459      */
 460     private static void addLinkedServices(HomekitTaggedItem taggedItem, AbstractHomekitAccessoryImpl accessory,
 461             MetadataRegistry metadataRegistry, HomekitAccessoryUpdater updater, HomekitSettings settings,
 462             Set<HomekitTaggedItem> ancestorServices) throws HomekitException {
 463         final var item = taggedItem.getItem();
 464         if (!(item instanceof GroupItem)) {
 465             return;
 466         }
 467
 468         for (var groupMember : ((GroupItem) item).getMembers().stream()
 469                 .sorted((lhs, rhs) -> lhs.getName().compareTo(rhs.getName())).collect(Collectors.toList())) {
 470             final var characteristicTypes = getAccessoryTypes(groupMember, metadataRegistry);
 471             var accessoryTypes = characteristicTypes.stream().filter(HomekitAccessoryFactory::isRootAccessory)
 472                     .collect(Collectors.toList());
 473
 474             LOGGER.trace("accessory types for {} are {}", groupMember.getName(), accessoryTypes);
 475             if (accessoryTypes.isEmpty()) {
 476                 continue;
 477             }
 478
 479             if (accessoryTypes.size() > 1) {
 480                 LOGGER.warn("Item {} is a HomeKit sub-accessory, but multiple accessory types are not allowed.",
 481                         groupMember.getName());
 482                 continue;
 483             }
 484
 485             final @Nullable Map<String, Object> itemConfiguration = getItemConfiguration(groupMember, metadataRegistry);
 486
 487             final var accessoryType = accessoryTypes.iterator().next().getKey();
 488             LOGGER.trace("Item {} is a HomeKit sub-accessory of type {}.", groupMember.getName(), accessoryType);
 489             final var itemProxy = new HomekitOHItemProxy(groupMember);
 490             final var subTaggedItem = new HomekitTaggedItem(itemProxy, accessoryType, itemConfiguration);
 491             final var subAccessory = create(subTaggedItem, metadataRegistry, updater, settings, ancestorServices);
 492             subAccessory.promoteNameCharacteristic();
 493
 494             if (subAccessory.isLinkable(accessory)) {
 495                 accessory.getPrimaryService().addLinkedService(subAccessory.getPrimaryService());
 496             } else {
 497                 accessory.getServices().add(subAccessory.getPrimaryService());
 498             }
 499         }
 500     }
 501
 502     /**
 503      * collect optional HomeKit characteristics for a OH item.
 504      *
 505      * @param taggedItem main OH item
 506      * @param metadataRegistry OH metadata registry
 507      * @return a map with characteristics and corresponding OH items
 508      */
 509     private static Map<HomekitCharacteristicType, GenericItem> getOptionalCharacteristics(HomekitTaggedItem taggedItem,
 510             MetadataRegistry metadataRegistry) {
 511         Map<HomekitCharacteristicType, GenericItem> characteristicItems = new TreeMap<>();
 512         if (taggedItem.isGroup()) {
 513             GroupItem groupItem = (GroupItem) taggedItem.getItem();
 514             groupItem.getMembers().forEach(item -> getAccessoryTypes(item, metadataRegistry).stream()
 515                     .filter(c -> !isRootAccessory(c)).filter(c -> belongsToType(taggedItem.getAccessoryType(), c))
 516                     .filter(c -> !isMandatoryCharacteristic(taggedItem, c.getValue()))
 517                     .forEach(characteristic -> characteristicItems.put(characteristic.getValue(), (GenericItem) item)));
 518         } else {
 519             getAccessoryTypes(taggedItem.getItem(), metadataRegistry).stream().filter(c -> !isRootAccessory(c))
 520                     .filter(c -> !isMandatoryCharacteristic(taggedItem, c.getValue()))
 521                     .forEach(characteristic -> characteristicItems.put(characteristic.getValue(),
 522                             (GenericItem) taggedItem.getItem()));
 523         }
 524         LOGGER.trace("Optional characteristics for item {}: {}", taggedItem.getName(), characteristicItems.values());
 525         return Collections.unmodifiableMap(characteristicItems);
 526     }
 527
 528     /**
 529      * return true is characteristic is a mandatory characteristic for the accessory.
 530      *
 531      * @param item item
 532      * @param characteristic characteristic
 533      * @return true if characteristic is mandatory, false if not mandatory
 534      */
 535     private static boolean isMandatoryCharacteristic(HomekitTaggedItem item, HomekitCharacteristicType characteristic) {
 536         return MANDATORY_CHARACTERISTICS.containsKey(item.getAccessoryType())
 537                 && getRequiredCharacteristics(item).contains(characteristic);
 538     }
 539
 540     /**
 541      * check whether accessory is root accessory, i.e. without characteristic tag.
 542      *
 543      * @param accessory accessory
 544      * @return true if accessory has not characteristic.
 545      */
 546     private static boolean isRootAccessory(Entry<HomekitAccessoryType, HomekitCharacteristicType> accessory) {
 547         return ((accessory.getValue() == null) || (accessory.getValue() == EMPTY));
 548     }
 549
 550     /**
 551      * check whether characteristic belongs to the specific accessory type.
 552      * characteristic with no accessory type mentioned in metadata are considered as candidates for all types.
 553      *
 554      * @param accessoryType accessory type
 555      * @param characteristic characteristic
 556      * @return true if characteristic belongs to the accessory type.
 557      */
 558     private static boolean belongsToType(HomekitAccessoryType accessoryType,
 559             Entry<HomekitAccessoryType, HomekitCharacteristicType> characteristic) {
 560         return ((characteristic.getKey() == accessoryType) || (characteristic.getKey() == DUMMY));
 561     }
 562 }