/*
 * 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.structure.io.binary.types;

import org.apache.commons.collections4.IteratorUtils;
import org.apache.tinkerpop.gremlin.structure.Vertex;
import org.apache.tinkerpop.gremlin.structure.io.Buffer;
import org.apache.tinkerpop.gremlin.structure.io.binary.DataType;
import org.apache.tinkerpop.gremlin.structure.io.binary.GraphBinaryReader;
import org.apache.tinkerpop.gremlin.structure.io.binary.GraphBinaryWriter;
import org.apache.tinkerpop.gremlin.structure.util.detached.DetachedVertex;
import org.apache.tinkerpop.gremlin.structure.util.detached.DetachedVertexProperty;
import org.apache.tinkerpop.gremlin.structure.util.reference.ReferenceVertex;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.List;

/**
 * @author Stephen Mallette (http://stephen.genoprime.com)
 */
public class VertexSerializer extends SimpleTypeSerializer<Vertex> {
    public VertexSerializer() {
        super(DataType.VERTEX);
    }

    @Override
    protected Vertex readValue(final Buffer buffer, final GraphBinaryReader context) throws IOException {
        final Object id = context.read(buffer);
        // Read labels as List<String> for multi-label support
        final List<String> labelList = context.readValue(buffer, List.class, false);
        final List<DetachedVertexProperty> properties = context.read(buffer);

        final DetachedVertex.Builder builder = DetachedVertex.build().setId(id);

        if (labelList != null && !labelList.isEmpty()) {
            if (labelList.size() == 1) {
                builder.setLabel(labelList.get(0));
            } else {
                builder.setLabels(new LinkedHashSet<>(labelList));
            }
        }

        if (properties != null) {
            for (final DetachedVertexProperty vp : properties) {
                builder.addProperty(vp);
            }
        }

        return builder.create();
    }

    @Override
    protected void writeValue(final Vertex value, final Buffer buffer, final GraphBinaryWriter context) throws IOException {
        context.write(value.id(), buffer);
        // Write all labels as List<String> for multi-label support.
        // Empty list is valid for zero-label elements (ZERO_OR_MORE / ZERO_OR_ONE cardinality).
        final java.util.Set<String> labels = value.labels();
        context.writeValue(labels == null ? new ArrayList<>() : new ArrayList<>(labels), buffer, false);
        if (value instanceof ReferenceVertex) {
            context.write(null, buffer);
        }
        else {
            final List<?> asList = IteratorUtils.toList(value.properties());
            context.write(asList, buffer);
        }
    }
}
