XR_DEFINE_HANDLE(XrSpatialPersistenceContextEXT)

XrResult xrCreateSpatialPersistenceContextAsyncEXT(
    XrSession                                   session,
    const XrSpatialPersistenceContextCreateInfoEXT* createInfo,
    XrFutureEXT*                                future);

typedef struct XrSpatialPersistenceContextCreateInfoEXT {
    XrStructureType                 type;
    const void*                     next;
    XrSpatialPersistenceScopeEXT    scope;
} XrSpatialPersistenceContextCreateInfoEXT;

typedef enum XrSpatialPersistenceScopeEXT {
    XR_SPATIAL_PERSISTENCE_SCOPE_SYSTEM_MANAGED_EXT = 1,
    XR_SPATIAL_PERSISTENCE_SCOPE_LOCAL_ANCHORS_EXT = 1000781000,
    XR_SPATIAL_PERSISTENCE_SCOPE_ANCHORS_FOR_CLOUD_SHARING_ANDROIDX1 = 1000808000,
    XR_SPATIAL_PERSISTENCE_SCOPE_MAX_ENUM_EXT = 0x7FFFFFFF
} XrSpatialPersistenceScopeEXT;

XrResult xrEnumerateSpatialPersistenceScopesEXT(
    XrInstance                                  instance,
    XrSystemId                                  systemId,
    uint32_t                                    persistenceScopeCapacityInput,
    uint32_t*                                   persistenceScopeCountOutput,
    XrSpatialPersistenceScopeEXT*               persistenceScopes);

XrResult xrCreateSpatialPersistenceContextCompleteEXT(
    XrSession                                   session,
    XrFutureEXT                                 future,
    XrCreateSpatialPersistenceContextCompletionEXT* completion);

typedef struct XrCreateSpatialPersistenceContextCompletionEXT {
    XrStructureType                         type;
    void*                                   next;
    XrResult                                futureResult;
    XrSpatialPersistenceContextResultEXT    createResult;
    XrSpatialPersistenceContextEXT          persistenceContext;
} XrCreateSpatialPersistenceContextCompletionEXT;

typedef enum XrSpatialPersistenceContextResultEXT {
    XR_SPATIAL_PERSISTENCE_CONTEXT_RESULT_SUCCESS_EXT = 0,
    XR_SPATIAL_PERSISTENCE_CONTEXT_RESULT_ENTITY_NOT_TRACKING_EXT = -1000781001,
    XR_SPATIAL_PERSISTENCE_CONTEXT_RESULT_PERSIST_UUID_NOT_FOUND_EXT = -1000781002,
    XR_SPATIAL_PERSISTENCE_CONTEXT_RESULT_LOCALIZATION_FAILURE_ANDROIDX1 = -1000808000,
    XR_SPATIAL_PERSISTENCE_CONTEXT_RESULT_MAP_FEATURE_INSUFFICIENT_ANDROIDX1 = -1000808001,
    XR_SPATIAL_PERSISTENCE_CONTEXT_RESULT_NETWORK_FAILURE_ANDROIDX1 = -1000808002,
    XR_SPATIAL_PERSISTENCE_CONTEXT_RESULT_NETWORK_TIMEOUT_ANDROIDX1 = -1000808003,
    XR_SPATIAL_PERSISTENCE_CONTEXT_RESULT_MAX_ENUM_EXT = 0x7FFFFFFF
} XrSpatialPersistenceContextResultEXT;

XrResult xrDestroySpatialPersistenceContextEXT(
    XrSpatialPersistenceContextEXT              persistenceContext);

typedef struct XrSpatialPersistenceDataEXT {
    XrUuid                          persistUuid;
    XrSpatialPersistenceStateEXT    persistState;
} XrSpatialPersistenceDataEXT;

typedef enum XrSpatialPersistenceStateEXT {
    XR_SPATIAL_PERSISTENCE_STATE_LOADED_EXT = 1,
    XR_SPATIAL_PERSISTENCE_STATE_NOT_FOUND_EXT = 2,
    XR_SPATIAL_PERSISTENCE_STATE_MAX_ENUM_EXT = 0x7FFFFFFF
} XrSpatialPersistenceStateEXT;

typedef struct XrSpatialComponentPersistenceListEXT {
    XrStructureType                 type;
    void*                           next;
    uint32_t                        persistDataCount;
    XrSpatialPersistenceDataEXT*    persistData;
} XrSpatialComponentPersistenceListEXT;

typedef struct XrSpatialContextPersistenceConfigEXT {
    XrStructureType                          type;
    const void*                              next;
    uint32_t                                 persistenceContextCount;
    const XrSpatialPersistenceContextEXT*    persistenceContexts;
} XrSpatialContextPersistenceConfigEXT;

typedef struct XrSpatialDiscoveryPersistenceUuidFilterEXT {
    XrStructureType    type;
    const void*        next;
    uint32_t           persistedUuidCount;
    const XrUuid*      persistedUuids;
} XrSpatialDiscoveryPersistenceUuidFilterEXT;

// Check if the required persistence scope supported
uint32_t scopeCount;
CHK_XR(xrEnumerateSpatialPersistenceScopesEXT(instance, systemId, 0, &scopeCount, nullptr));
std::vector<XrSpatialPersistenceScopeEXT> persistenceScopes(scopeCount);
CHK_XR(xrEnumerateSpatialPersistenceScopesEXT(instance, systemId, scopeCount, &scopeCount, persistenceScopes.data()));

if (std::find(persistenceScopes.begin(), persistenceScopes.end(), XR_SPATIAL_PERSISTENCE_SCOPE_SYSTEM_MANAGED_EXT) == persistenceScopes.end()) {
  return;
}

XrSpatialPersistenceContextEXT persistenceContext{};

XrSpatialPersistenceContextCreateInfoEXT persistenceContextCreateInfo{XR_TYPE_SPATIAL_PERSISTENCE_CONTEXT_CREATE_INFO_EXT};
persistenceContextCreateInfo.scope = XR_SPATIAL_PERSISTENCE_SCOPE_SYSTEM_MANAGED_EXT;
XrFutureEXT createContextFuture;
CHK_XR(xrCreateSpatialPersistenceContextAsyncEXT(session, &persistenceContextCreateInfo, &createContextFuture));

waitUntilReady(createContextFuture);

XrCreateSpatialPersistenceContextCompletionEXT completion{XR_TYPE_CREATE_SPATIAL_PERSISTENCE_CONTEXT_COMPLETION_EXT};
CHK_XR(xrCreateSpatialPersistenceContextCompleteEXT(session, createContextFuture, &completion));
if (completion.futureResult != XR_SUCCESS || completion.createResult != XR_SPATIAL_PERSISTENCE_CONTEXT_RESULT_SUCCESS_EXT) {
  return;
}

persistenceContext = completion.persistenceContext;

// ...
// Connect persistence context to a spatial context and discover persisted entities.
// ...

CHK_XR(xrDestroySpatialPersistenceContextEXT(persistenceContext));

// Note: Anchor capability is just used as an example here. Persistence can be
// supported by other capabilities too. xrEnumerateSpatialCapabilityComponentTypesEXT() can
// be used to check if a certain capability supports persistence.
if (!isSpatialCapabilitySupported(instance, systemId, XR_SPATIAL_CAPABILITY_ANCHOR_EXT)) {
  return;
}

const bool supportsPersistenceComponent = isSpatialComponentSupported(instance, systemId, XR_SPATIAL_CAPABILITY_ANCHOR_EXT, XR_SPATIAL_COMPONENT_TYPE_PERSISTENCE_EXT);

// Create a spatial spatial context
XrSpatialContextEXT spatialContext{};
{

  std::vector<XrSpatialComponentTypeEXT> enabledComponents = {
    XR_SPATIAL_COMPONENT_TYPE_ANCHOR_EXT,
  };

  if (supportsPersistenceComponent) {
    enabledComponents.push_back(XR_SPATIAL_COMPONENT_TYPE_PERSISTENCE_EXT);
  }

  XrSpatialCapabilityConfigurationAnchorEXT anchorConfig{XR_TYPE_SPATIAL_CAPABILITY_CONFIGURATION_ANCHOR_EXT};
  anchorConfig.capability = XR_SPATIAL_CAPABILITY_ANCHOR_EXT;
  anchorConfig.enabledComponentCount = enabledComponents.size();
  anchorConfig.enabledComponents = enabledComponents.data();

  std::array<XrSpatialCapabilityConfigurationBaseHeaderEXT*, 1> capabilityConfigs = {
    reinterpret_cast<XrSpatialCapabilityConfigurationBaseHeaderEXT*>(&anchorConfig),
  };

  XrSpatialContextCreateInfoEXT spatialContextCreateInfo{XR_TYPE_SPATIAL_CONTEXT_CREATE_INFO_EXT};
  spatialContextCreateInfo.capabilityConfigCount = capabilityConfigs.size();
  spatialContextCreateInfo.capabilityConfigs = capabilityConfigs.data();

  XrSpatialContextPersistenceConfigEXT persistenceConfig{XR_TYPE_SPATIAL_CONTEXT_PERSISTENCE_CONFIG_EXT};
  persistenceConfig.persistenceContextCount = 1;
  persistenceConfig.persistenceContexts = &persistenceContext;

  if (supportsPersistenceComponent) {
    spatialContextCreateInfo.next = &persistenceConfig;
  }

  XrFutureEXT createContextFuture;
  CHK_XR(xrCreateSpatialContextAsyncEXT(session, &spatialContextCreateInfo, &createContextFuture));

  waitUntilReady(createContextFuture);

  XrCreateSpatialContextCompletionEXT completion{XR_TYPE_CREATE_SPATIAL_CONTEXT_COMPLETION_EXT};
  CHK_XR(xrCreateSpatialContextCompleteEXT(session, createContextFuture, &completion));
  if (completion.futureResult != XR_SUCCESS) {
    return;
  }

  spatialContext = completion.spatialContext;
}

// ...
// Discover persisted anchors.
// ...

CHK_XR(xrDestroySpatialContextEXT(spatialContext));

XrFutureEXT future = XR_NULL_FUTURE_EXT;

// We want to look for entities that have the following components.
std::vector<XrSpatialComponentTypeEXT> snapshotComponents = {
  XR_SPATIAL_COMPONENT_TYPE_PERSISTENCE_EXT,
};

auto discoverSpatialEntities = [&](XrSpatialContextEXT spatialContext, XrTime time) {
  XrSpatialDiscoverySnapshotCreateInfoEXT snapshotCreateInfo{XR_TYPE_SPATIAL_DISCOVERY_SNAPSHOT_CREATE_INFO_EXT};
  snapshotCreateInfo.componentTypeCount = snapshotComponents.size();
  snapshotCreateInfo.componentTypes = snapshotComponents.data();
  CHK_XR(xrCreateSpatialDiscoverySnapshotAsyncEXT(spatialContext, &snapshotCreateInfo, &future));

  waitUntilReady(future);

  XrCreateSpatialDiscoverySnapshotCompletionInfoEXT completionInfo{XR_TYPE_CREATE_SPATIAL_DISCOVERY_SNAPSHOT_COMPLETION_INFO_EXT};
  completionInfo.baseSpace = localSpace;
  completionInfo.time = time;
  completionInfo.future = future;

  XrCreateSpatialDiscoverySnapshotCompletionEXT completion{XR_TYPE_CREATE_SPATIAL_DISCOVERY_SNAPSHOT_COMPLETION_EXT};
  CHK_XR(xrCreateSpatialDiscoverySnapshotCompleteEXT(spatialContext, &completionInfo, &completion));
  if (completion.futureResult == XR_SUCCESS) {

    // Query for the semantic label component data
    XrSpatialComponentDataQueryConditionEXT queryCond{XR_TYPE_SPATIAL_COMPONENT_DATA_QUERY_CONDITION_EXT};
    queryCond.componentTypeCount = snapshotComponents.size();
    queryCond.componentTypes = snapshotComponents.data();

    XrSpatialComponentDataQueryResultEXT queryResult{XR_TYPE_SPATIAL_COMPONENT_DATA_QUERY_RESULT_EXT};
    CHK_XR(xrQuerySpatialComponentDataEXT(completion.snapshot, &queryCond, &queryResult));

    std::vector<XrSpatialEntityIdEXT> entityIds(queryResult.entityIdCountOutput);
    std::vector<XrSpatialEntityTrackingStateEXT> entityStates(queryResult.entityIdCountOutput);
    queryResult.entityIdCapacityInput = entityIds.size();
    queryResult.entityIds = entityIds.data();
    queryResult.entityStateCapacityInput = entityStates.size();
    queryResult.entityStates = entityStates.data();

    std::vector<XrSpatialPersistenceDataEXT> persistenceData(queryResult.entityIdCountOutput);
    XrSpatialComponentPersistenceListEXT persistenceDataList{XR_TYPE_SPATIAL_COMPONENT_PERSISTENCE_LIST_EXT};
    persistenceDataList.persistDataCount = persistenceData.size();
    persistenceDataList.persistData = persistenceData.data();
    queryResult.next = &persistenceDataList;

    CHK_XR(xrQuerySpatialComponentDataEXT(completion.snapshot, &queryCond, &queryResult));

    for (int32_t i = 0; i < queryResult.entityIdCountOutput; ++i) {
      // persistenceData[i].persistUuid is the UUID of the persisted entity whose entity ID is entityIds[i].
      // The persistenceData array is essentially the uuids persisted in the scope that the current
      // XrSpatialPersistenceContextEXT is configured with.
    }

    CHK_XR(xrDestroySpatialSnapshotEXT(completion.snapshot));
  }
};

while (1) {
  // ...
  // For every frame in frame loop
  // ...

  XrFrameState frameState;  // previously returned from xrWaitFrame
  const XrTime time = frameState.predictedDisplayTime;

  // Poll for the XR_TYPE_EVENT_DATA_SPATIAL_DISCOVERY_RECOMMENDED_EXT event
  XrEventDataBuffer event = {XR_TYPE_EVENT_DATA_BUFFER};
  XrResult result = xrPollEvent(instance, &event);
  if (result == XR_SUCCESS) {
      switch (event.type) {
          case XR_TYPE_EVENT_DATA_SPATIAL_DISCOVERY_RECOMMENDED_EXT: {
              const XrEventDataSpatialDiscoveryRecommendedEXT& eventdata =
                  *reinterpret_cast<XrEventDataSpatialDiscoveryRecommendedEXT*>(&event);
              // Discover spatial entities for the context that we received the "discovery
              // recommended" event for.
              discoverSpatialEntities(eventdata.spatialContext, time);
              break;
          }
      }
  }

  // ...
  // Finish frame loop
  // ...
}

XrFutureEXT future = XR_NULL_FUTURE_EXT;

// Load up the uuids that the app has stored on its own i.e. the uuids it is interested in.
std::vector<XrUuid> uuidsStoredByApp = loadPersistedUuids();

// We want to look for entities that have the following components.
std::vector<XrSpatialComponentTypeEXT> snapshotComponents = {
  XR_SPATIAL_COMPONENT_TYPE_PERSISTENCE_EXT,
};

auto discoverSpatialEntities = [&](XrSpatialContextEXT spatialContext, XrTime time) {
  XrSpatialDiscoveryPersistenceUuidFilterEXT persistenceFilter{XR_TYPE_SPATIAL_DISCOVERY_PERSISTENCE_UUID_FILTER_EXT};
  persistenceFilter.persistedUuidCount = uuidsStoredByApp.size();
  persistenceFilter.persistedUuids = uuidsStoredByApp.data();

  XrSpatialDiscoverySnapshotCreateInfoEXT snapshotCreateInfo{XR_TYPE_SPATIAL_DISCOVERY_SNAPSHOT_CREATE_INFO_EXT};
  snapshotCreateInfo.componentTypeCount = snapshotComponents.size();
  snapshotCreateInfo.componentTypes = snapshotComponents.data();
  snapshotCreateInfo.next = &persistenceFilter;

  CHK_XR(xrCreateSpatialDiscoverySnapshotAsyncEXT(spatialContext, &snapshotCreateInfo, &future));

  waitUntilReady(future);

  XrCreateSpatialDiscoverySnapshotCompletionInfoEXT completionInfo{XR_TYPE_CREATE_SPATIAL_DISCOVERY_SNAPSHOT_COMPLETION_INFO_EXT};
  completionInfo.baseSpace = localSpace;
  completionInfo.time = time;
  completionInfo.future = future;

  XrCreateSpatialDiscoverySnapshotCompletionEXT completion{XR_TYPE_CREATE_SPATIAL_DISCOVERY_SNAPSHOT_COMPLETION_EXT};
  CHK_XR(xrCreateSpatialDiscoverySnapshotCompleteEXT(spatialContext, &completionInfo, &completion));
  if (completion.futureResult == XR_SUCCESS) {

    // Query for the semantic label component data
    XrSpatialComponentDataQueryConditionEXT queryCond{XR_TYPE_SPATIAL_COMPONENT_DATA_QUERY_CONDITION_EXT};
    queryCond.componentTypeCount = snapshotComponents.size();
    queryCond.componentTypes = snapshotComponents.data();

    XrSpatialComponentDataQueryResultEXT queryResult{XR_TYPE_SPATIAL_COMPONENT_DATA_QUERY_RESULT_EXT};
    CHK_XR(xrQuerySpatialComponentDataEXT(completion.snapshot, &queryCond, &queryResult));

    std::vector<XrSpatialEntityIdEXT> entityIds(queryResult.entityIdCountOutput);
    std::vector<XrSpatialEntityTrackingStateEXT> entityStates(queryResult.entityIdCountOutput);
    queryResult.entityIdCapacityInput = entityIds.size();
    queryResult.entityIds = entityIds.data();
    queryResult.entityStateCapacityInput = entityStates.size();
    queryResult.entityStates = entityStates.data();

    std::vector<XrSpatialPersistenceDataEXT> persistenceData(queryResult.entityIdCountOutput);
    XrSpatialComponentPersistenceListEXT persistenceDataList{XR_TYPE_SPATIAL_COMPONENT_PERSISTENCE_LIST_EXT};
    persistenceDataList.persistDataCount = persistenceData.size();
    persistenceDataList.persistData = persistenceData.data();
    queryResult.next = &persistenceDataList;

    CHK_XR(xrQuerySpatialComponentDataEXT(completion.snapshot, &queryCond, &queryResult));

    for (int32_t i = 0; i < queryResult.entityIdCountOutput; ++i) {
      if (persistenceData[i].persistState == XR_SPATIAL_PERSISTENCE_STATE_LOADED_EXT) {
        // persistenceData[i].persistUuid, requested by the app, is present in the persistence scope
        // and its corresponding entity ID and state are entityIds[i] & entityStates[i] respectively.
      } else if (persistenceData[i].persistState == XR_SPATIAL_PERSISTENCE_STATE_NOT_FOUND_EXT) {
        // persistenceData[i].persistUuid, requested by the app, is NOT present in the persistence scope
        // and its corresponding entity ID (entityIds[i]) would be XR_NULL_SPATIAL_ENTITY_ID_EXT
        // and tracking state (entityStates[i]) would be XR_SPATIAL_ENTITY_TRACKING_STATE_STOPPED_EXT.
      }
    }

    CHK_XR(xrDestroySpatialSnapshotEXT(completion.snapshot));
  }
};

while (1) {
  // ...
  // For every frame in frame loop
  // ...

  XrFrameState frameState;  // previously returned from xrWaitFrame
  const XrTime time = frameState.predictedDisplayTime;

  // Poll for the XR_TYPE_EVENT_DATA_SPATIAL_DISCOVERY_RECOMMENDED_EXT event
  XrEventDataBuffer event = {XR_TYPE_EVENT_DATA_BUFFER};
  XrResult result = xrPollEvent(instance, &event);
  if (result == XR_SUCCESS) {
      switch (event.type) {
          case XR_TYPE_EVENT_DATA_SPATIAL_DISCOVERY_RECOMMENDED_EXT: {
              const XrEventDataSpatialDiscoveryRecommendedEXT& eventdata =
                  *reinterpret_cast<XrEventDataSpatialDiscoveryRecommendedEXT*>(&event);
              // Discover spatial entities for the context that we received the "discovery
              // recommended" event for.
              discoverSpatialEntities(eventdata.spatialContext, time);
              break;
          }
      }
  }

  // ...
  // Finish frame loop
  // ...
}