ValidationModelRetrieverImpl.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.sling.validation.impl;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.SortedMap;

import javax.annotation.CheckForNull;
import javax.annotation.Nonnull;

import org.apache.commons.collections4.trie.PatriciaTrie;
import org.apache.commons.lang3.StringUtils;
import org.apache.sling.api.resource.LoginException;
import org.apache.sling.api.resource.ResourceResolver;
import org.apache.sling.api.resource.ResourceResolverFactory;
import org.apache.sling.validation.impl.model.MergedValidationModel;
import org.apache.sling.validation.model.ValidationModel;
import org.apache.sling.validation.model.spi.ValidationModelProvider;
import org.apache.sling.validation.model.spi.ValidationModelRetriever;
import org.osgi.framework.ServiceReference;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.annotations.FieldOption;
import org.osgi.service.component.annotations.Reference;
import org.osgi.service.component.annotations.ReferenceCardinality;
import org.osgi.service.component.annotations.ReferencePolicy;
import org.osgi.service.component.annotations.ReferencePolicyOption;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/** Retrieves the most appropriate model (the one with the longest matching applicablePath) from any of the
 * {@link ValidationModelProvider}s. */
@Component
public class ValidationModelRetrieverImpl implements ValidationModelRetriever {

    /** 
     * List of validation providers, Declarative Services 1.3 takes care that the list is ordered according to {@link ServiceReference#compareTo(Object)}.
     * Highest ranked service is the last one in the list.
     * 
     * @see "OSGi R6 Comp, 112.3.8.1"
     */
    @Reference(policy = ReferencePolicy.DYNAMIC, cardinality = ReferenceCardinality.MULTIPLE, policyOption = ReferencePolicyOption.GREEDY, fieldOption = FieldOption.REPLACE)
    protected volatile List<ValidationModelProvider> modelProviders;

    @Reference
    ResourceResolverFactory resourceResolverFactory;

    private static final Logger LOG = LoggerFactory.getLogger(ValidationModelRetrieverImpl.class);

    /*
     * (non-Javadoc)
     * 
     * @see org.apache.sling.validation.impl.ValidationModelRetriever#getModels(java.lang.String, java.lang.String)
     */
    @CheckForNull
    public ValidationModel getValidationModel(@Nonnull String resourceType, String resourcePath, boolean considerResourceSuperTypeModels) {
        // first get model for exactly the requested resource type
        ValidationModel baseModel = getModel(resourceType, resourcePath);
        String currentResourceType = resourceType;
        if (considerResourceSuperTypeModels) {
            Collection<ValidationModel> modelsToMerge = new ArrayList<ValidationModel>();
            ResourceResolver resourceResolver = null;
            try {
                resourceResolver = resourceResolverFactory.getServiceResourceResolver(null);
                while ((currentResourceType = resourceResolver.getParentResourceType(currentResourceType)) != null) {
                    LOG.debug("Retrieving validation models for resource super type {}...", currentResourceType);
                    ValidationModel modelToMerge = getModel(currentResourceType, resourcePath);
                    if (modelToMerge != null) {
                        if (baseModel == null) {
                            baseModel = modelToMerge;
                        } else {
                            modelsToMerge.add(modelToMerge);
                        }
                    }
                }
                if (!modelsToMerge.isEmpty()) {
                    return new MergedValidationModel(baseModel, modelsToMerge.toArray(new ValidationModel[modelsToMerge
                            .size()]));
                }
            } catch (LoginException e) {
                throw new IllegalStateException("Could not get service resource resolver", e);
            } finally {
                if (resourceResolver != null) {
                    resourceResolver.close();
                }
            }
        }
        return baseModel;
    }

    private @CheckForNull ValidationModel getModel(@Nonnull String resourceType, String resourcePath) {
        PatriciaTrie<ValidationModel> modelsForResourceType = fillTrieForResourceType(resourceType);
        ValidationModel model = null;
        // for empty/null resource paths, always return the entry stored for ""
        if (StringUtils.isEmpty(resourcePath)) {
            model = modelsForResourceType.get("");
        } else {
            // get longest prefix entry, which still matches
            SortedMap<String, ValidationModel> modelMap = modelsForResourceType.subMap("", resourcePath + "/");
            if (!modelMap.isEmpty()) {
                model =  modelMap.get(modelMap.lastKey());
            }
        }
        if (model == null && !modelsForResourceType.isEmpty()) {
            LOG.warn("Although at least one model for resource type '{}' is available, none of them are allowed to be applied to path {}", resourceType,
                    resourcePath);
        }
        return model;
    }

    private @Nonnull PatriciaTrie<ValidationModel> fillTrieForResourceType(@Nonnull String resourceType) {
        // create a new (empty) trie
        PatriciaTrie<ValidationModel> modelsForResourceType = new PatriciaTrie<ValidationModel>();

        // fill trie with data from model providers (all models for the given resource type, independent of resource path)
        // lowest ranked model provider inserts first (i.e. higher ranked should overwrite)
        for (ValidationModelProvider modelProvider : modelProviders) {
            LOG.debug("Retrieving validation models with resource type {} from provider {}...", resourceType, modelProvider.getClass().getName());
            List<ValidationModel> models = modelProvider.getValidationModels(resourceType);
            for (ValidationModel model : models) {
                for (String applicablePath : model.getApplicablePaths()) {
                    LOG.debug("Found validation model for resource type {} for applicable path {}", resourceType, applicablePath);
                    modelsForResourceType.put(applicablePath, model);
                }
            }
            if (models.isEmpty()) {
                LOG.debug("Found no validation model with resource type {} from provider {}", resourceType, modelProvider.getClass().getName());
            }
        }
        return modelsForResourceType;
    }

}