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