Add ClientLibrariesLookupService

Adds a new service `ClientLibrariesLookupService`.
This service provides a means by which to resolve ClientLibraries
by resource type.

The service will internally cache `resourceType` -> `ClientLibrary`
mappings such that future lookups for the same `resourceType` will
not require costly lookup or service-user sessions.

This service listens to the event topic: `com/adobe/granite/ui/librarymanager/INVALIDATED`.
When an event matching this topic occurs, then the cache items are cleared.

----
refs issue adobe#2446

bundles/core/src/main/java/com/adobe/cq/wcm/core/components/internal/services/clientLibraries/ClientLibraryLookupServiceImpl.java

@@ -0,0 +1,201 @@
+/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ ~ Copyright 2023 Adobe
+ ~
+ ~ Licensed 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 com.adobe.cq.wcm.core.components.internal.services.clientLibraries;
+
+import com.adobe.cq.wcm.core.components.internal.Utils;
+import com.adobe.cq.wcm.core.components.services.clientLibraries.ClientLibraryLookupService;
+import com.adobe.granite.ui.clientlibs.ClientLibrary;
+import com.adobe.granite.ui.clientlibs.HtmlLibraryManager;
+import org.apache.sling.api.resource.LoginException;
+import org.apache.sling.api.resource.Resource;
+import org.apache.sling.api.resource.ResourceResolver;
+import org.apache.sling.api.resource.ResourceResolverFactory;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.osgi.service.component.annotations.Activate;
+import org.osgi.service.component.annotations.Component;
+import org.osgi.service.component.annotations.Reference;
+import org.osgi.service.event.Event;
+import org.osgi.service.event.EventConstants;
+import org.osgi.service.event.EventHandler;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.LinkedHashMap;
+import java.util.LinkedHashSet;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+/**
+ * Implementation of {@link ClientLibraryLookupService}.
+ */
+@Component(service = {ClientLibraryLookupService.class, EventHandler.class},
+    immediate = true,
+    property = {
+        EventConstants.EVENT_TOPIC + "=com/adobe/granite/ui/librarymanager/INVALIDATED"
+    }
+)
+public final class ClientLibraryLookupServiceImpl implements ClientLibraryLookupService, EventHandler {
+
+    /**
+     * Default logger.
+     */
+    private static final Logger LOG = LoggerFactory.getLogger(ClientLibraryLookupServiceImpl.class);
+
+    /**
+     * Name of the sub-service used to authenticate as in order to be able to read details about components and
+     * client libraries.
+     */
+    private static final String COMPONENTS_SERVICE = "components-service";
+
+    /**
+     * Placeholder set used to indicate a cache miss.
+     */
+    private static final LinkedHashSet<ClientLibrary> CACHE_MISS_SET = new LinkedHashSet<>();
+
+    /**
+     * Resource resolver factory service.
+     */
+    private final ResourceResolverFactory resolverFactory;
+
+    /**
+     * Html Library Manager service.
+     */
+    private final HtmlLibraryManager libraryManager;
+
+    /**
+     * Cache used to store previous resource type -> client library mappings.
+     */
+    private final ConcurrentHashMap<String, Set<ClientLibrary>> cache = new ConcurrentHashMap<>();
+
+    /**
+     * Activate the service.
+     *
+     * @param resourceResolverFactory The resource resolver factory service.
+     * @param htmlLibraryManager      The Html Library Manager service.
+     */
+    @Activate
+    public ClientLibraryLookupServiceImpl(@NotNull @Reference final ResourceResolverFactory resourceResolverFactory,
+                                          @NotNull @Reference final HtmlLibraryManager htmlLibraryManager) {
+        this.resolverFactory = resourceResolverFactory;
+        this.libraryManager = htmlLibraryManager;
+    }
+
+    @Override
+    @NotNull
+    public Set<ClientLibrary> getAllClientLibraries(@NotNull final Set<String> resourceTypes, boolean inherited, @NotNull final ResourceResolver resourceResolver) {
+        Set<String> allResourceTypes = getAllResourceTypes(resourceTypes, inherited, resourceResolver);
+        LinkedHashMap<String, Set<ClientLibrary>> results = new LinkedHashMap<>();
+        boolean hasMisses = false;
+
+        // loop through each resource type getting the client libraries from cache or
+        // adding a placeholder if not in cache already.
+        for (String resourceType : allResourceTypes) {
+            Set<ClientLibrary> libraries = this.cache.get(resourceType);
+            if (libraries == null) {
+                LOG.debug("Cache miss {}", resourceType);
+                results.put(resourceType, CACHE_MISS_SET);
+                hasMisses = true;
+            } else {
+                LOG.debug("Cache hit {}", resourceType);
+                results.put(resourceType, libraries);
+            }
+        }
+
+        // handle all cache misses. Cache misses are handled as a block so that there is only
+        // one call to expensive methods (such as session logins, or getting every library).
+        if (hasMisses) {
+            Map<String, ClientLibrary> allLibraries = this.libraryManager.getLibraries();
+            try (ResourceResolver serviceResourceResolver = resolverFactory.getServiceResourceResolver(Collections.singletonMap(ResourceResolverFactory.SUBSERVICE, COMPONENTS_SERVICE))) {
+                LOG.debug("Service resource resolver login");
+                // resolve all the cache misses
+                LinkedHashMap<String, Set<ClientLibrary>> resolvedLibraries = results.entrySet().stream()
+                    .filter(entry -> entry.getValue() == CACHE_MISS_SET)
+                    .map(Map.Entry::getKey)
+                    .collect(Collectors.toMap(
+                        Function.identity(),
+                        resourceType -> Optional.ofNullable(serviceResourceResolver.getResource(resourceType))
+                            .map(resource -> getClientLibraries(resource, allLibraries))
+                            .orElseGet(LinkedHashSet::new),
+                        (a, b) -> a,
+                        LinkedHashMap::new
+                    ));
+
+                // add all newly resolved libraries to the cache
+                this.cache.putAll(resolvedLibraries);
+
+                // add all newly resolved libraries to the results
+                results.putAll(resolvedLibraries);
+            } catch (LoginException e) {
+                LOG.error("Cannot login as a service user", e);
+            }
+        }
+
+        // merge and return all the results
+        return results.values().stream()
+            .flatMap(Collection::stream)
+            .collect(Collectors.toCollection(LinkedHashSet::new));
+    }
+
+    /**
+     * Gets a list of client libraries, starting from the given resource
+     * and diving into its descendants.
+     *
+     * @param resource     - the given resource, which will be checked to see if it's a client library
+     * @param allLibraries - Map of all client libraries.
+     * @return Set of client libraries for the given resource.
+     */
+    @NotNull
+    private static LinkedHashSet<ClientLibrary> getClientLibraries(@Nullable final Resource resource, @NotNull final Map<String, ClientLibrary> allLibraries) {
+        return Optional.ofNullable(resource)
+            .map(Resource::getPath)
+            .map(path -> allLibraries.entrySet().stream()
+                .filter(entry -> entry.getKey().equals(path) || entry.getKey().startsWith(path + "/"))
+                .map(Map.Entry::getValue)
+                .collect(Collectors.toCollection(LinkedHashSet::new)))
+            .orElseGet(LinkedHashSet::new);
+    }
+
+    /**
+     * Gets all resource types.
+     *
+     * @param resourceTypes    Set of initial resource types.
+     * @param inherited        Flag indicating if super resource types should be included.
+     * @param resourceResolver A resource resolver - does not have to be a special resource resolver.
+     * @return Set of all resource types under which to search for client libraries.
+     */
+    @NotNull
+    private Set<String> getAllResourceTypes(@NotNull final Set<String> resourceTypes, boolean inherited, @NotNull final ResourceResolver resourceResolver) {
+        Set<String> allResourceTypes = new LinkedHashSet<>(resourceTypes);
+        if (inherited) {
+            for (String resourceType : resourceTypes) {
+                allResourceTypes.addAll(Utils.getSuperTypes(resourceType, resourceResolver));
+            }
+        }
+        return allResourceTypes;
+    }
+
+    @Override
+    public void handleEvent(@NotNull final Event event) {
+        this.cache.clear();
+    }
+}

bundles/core/src/main/java/com/adobe/cq/wcm/core/components/services/clientLibraries/ClientLibraryLookupService.java

@@ -0,0 +1,40 @@
+/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ ~ Copyright 2023 Adobe
+ ~
+ ~ Licensed 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 com.adobe.cq.wcm.core.components.services.clientLibraries;
+
+import com.adobe.granite.ui.clientlibs.ClientLibrary;
+import org.apache.sling.api.resource.ResourceResolver;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Set;
+
+/**
+ * Service for looking up client libraries belonging to resource types.
+ *
+ * @since com.adobe.cq.wcm.core.components.services.clientLibraries 1.0.0
+ */
+public interface ClientLibraryLookupService {
+
+    /**
+     * Gets all the client libraries for a given set of resource types.
+     *
+     * @param inherited Flag indicating if super resource types should be included.
+     * @param resourceResolver A resource resolver - does not have to be a special resource resolver.
+     * @return Set of all client libraries.
+     */
+    @NotNull
+    Set<ClientLibrary> getAllClientLibraries(@NotNull Set<String> resourceTypes, boolean inherited, @NotNull ResourceResolver resourceResolver);
+}

bundles/core/src/main/java/com/adobe/cq/wcm/core/components/services/clientLibraries/package-info.java

@@ -0,0 +1,19 @@
+/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ ~ Copyright 2023 Adobe
+ ~
+ ~ Licensed 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.
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
+@Version("1.0.0")
+package com.adobe.cq.wcm.core.components.services.clientLibraries;
+
+import org.osgi.annotation.versioning.Version;