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package org.glassfish.jersey.message.filtering;

import java.util.Collections;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentMap;

import org.glassfish.jersey.internal.util.collection.DataStructures;
import org.glassfish.jersey.message.filtering.spi.EntityGraph;
import org.glassfish.jersey.message.filtering.spi.EntityGraphProvider;
import org.glassfish.jersey.message.filtering.spi.ObjectGraph;

/**
 * Provides {@link EntityGraph entity graph} and {@link ObjectGraph object graph} instances.
 *
 * @author Michal Gajdos (michal.gajdos at oracle.com)
 */
final class EntityGraphProviderImpl implements EntityGraphProvider {

    private final ConcurrentMap<Class<?>, EntityGraph> writerClassToGraph = DataStructures.createConcurrentMap();
    private final ConcurrentMap<Class<?>, EntityGraph> readerClassToGraph = DataStructures.createConcurrentMap();

    @Override
    public EntityGraph getOrCreateEntityGraph(final Class<?> entityClass, final boolean forWriter) {
        final ConcurrentMap<Class<?>, EntityGraph> classToGraph = forWriter ? writerClassToGraph : readerClassToGraph;

        if (!classToGraph.containsKey(entityClass)) {
            classToGraph.putIfAbsent(entityClass, new EntityGraphImpl(entityClass));
        }
        return classToGraph.get(entityClass);
    }

    @Override
    public EntityGraph getOrCreateEmptyEntityGraph(final Class<?> entityClass, final boolean forWriter) {
        final ConcurrentMap<Class<?>, EntityGraph> classToGraph = forWriter ? writerClassToGraph : readerClassToGraph;

        if (!classToGraph.containsKey(entityClass)
                || !(classToGraph.get(entityClass) instanceof EmptyEntityGraphImpl)) {
            classToGraph.put(entityClass, new EmptyEntityGraphImpl(entityClass));
        }
        return classToGraph.get(entityClass);
    }

    /**
     * Return an unmodifiable map of entity graphs for reader/writer.
     *
     * @param forWriter flag determining whether the returned map should be for writer/reader.
     * @return an unmodifiable map of entity graphs.
     */
    public Map<Class<?>, EntityGraph> asMap(final boolean forWriter) {
        return Collections.unmodifiableMap(forWriter ? writerClassToGraph : readerClassToGraph);
    }

    @Override
    public boolean containsEntityGraph(final Class<?> entityClass, final boolean forWriter) {
        return forWriter ? writerClassToGraph.containsKey(entityClass) : readerClassToGraph.containsKey(entityClass);
    }

    @Override
    public ObjectGraph createObjectGraph(final Class<?> entityClass, final Set<String> filteringScopes,
                                         final boolean forWriter) {
        final Map<Class<?>, EntityGraph> classToGraph = forWriter ? writerClassToGraph : readerClassToGraph;
        final EntityGraph entityGraph = classToGraph.get(entityClass);

        return entityGraph == null
                ? new EmptyObjectGraph(entityClass)
                : new ObjectGraphImpl(classToGraph, entityGraph, filteringScopes);
    }
}
