/*
 * 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.tinkerpop.gremlin.process.traversal.step.map;

import org.apache.tinkerpop.gremlin.process.traversal.Traversal;
import org.apache.tinkerpop.gremlin.process.traversal.Traverser;
import org.apache.tinkerpop.gremlin.process.traversal.step.Configuring;
import org.apache.tinkerpop.gremlin.process.traversal.step.util.Parameters;
import org.apache.tinkerpop.gremlin.process.traversal.traverser.TraverserRequirement;
import org.apache.tinkerpop.gremlin.structure.Element;
import org.apache.tinkerpop.gremlin.structure.PropertyType;
import org.apache.tinkerpop.gremlin.structure.util.StringFactory;

import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.Objects;
import java.util.Set;
import java.util.stream.Collectors;

/**
 * @author Marko A. Rodriguez (http://markorodriguez.com)
 */
public class PropertiesStep<E> extends FlatMapStep<Element, E> implements AutoCloseable, Configuring {

    protected Parameters parameters = new Parameters();
    protected final String[] propertyKeys;
    protected final PropertyType returnType;

    public PropertiesStep(final Traversal.Admin traversal, final PropertyType propertyType, final String... propertyKeys) {
        super(traversal);
        this.returnType = propertyType;
        this.propertyKeys = propertyKeys;
    }

    @Override
    public Parameters getParameters() {
        return this.parameters;
    }

    @Override
    public void configure(final Object... keyValues) {
        this.parameters.set(null, keyValues);
    }

    @Override
    protected Iterator<E> flatMap(final Traverser.Admin<Element> traverser) {
        return this.returnType.equals(PropertyType.VALUE) ?
                traverser.get().values(this.propertyKeys) :
                (Iterator) traverser.get().properties(this.propertyKeys);
    }

    public PropertyType getReturnType() {
        return this.returnType;
    }

    public String[] getPropertyKeys() {
        return this.propertyKeys;
    }

    @Override
    public String toString() {
        return StringFactory.stepString(this, Arrays.asList(this.propertyKeys), this.returnType.name().toLowerCase());
    }

    @Override
    public int hashCode() {
        int result = Objects.hash(super.hashCode(), returnType);
        // property keys' order does not matter because properties("x", "y"), and properties("y", "x") should be
        // considered identical.
        if (propertyKeys != null) {
            final List<String> sortedPropertyKeys = Arrays.stream(propertyKeys)
                    .sorted(Comparator.nullsLast(Comparator.naturalOrder())).collect(Collectors.toList());
            for (final String propertyKey : sortedPropertyKeys) {
                result = 31 * result + Objects.hashCode(propertyKey);
            }
        }
        return result;
    }

    @Override
    public Set<TraverserRequirement> getRequirements() {
        return Collections.singleton(TraverserRequirement.OBJECT);
    }

    @Override
    public void close() throws Exception {
        closeIterator();
    }
}
