// Copyright 2017 JanusGraph Authors
//
// 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 org.janusgraph.hadoop.formats.util;

import org.janusgraph.diskstorage.Entry;
import org.janusgraph.diskstorage.StaticBuffer;
import org.apache.tinkerpop.gremlin.hadoop.structure.io.VertexWritable;
import org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerVertex;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;

/**
 * @author Marko A. Rodriguez (http://markorodriguez.com)
 */
public class GiraphRecordReader extends RecordReader<NullWritable, VertexWritable> {

    private static final Logger log =
            LoggerFactory.getLogger(GiraphRecordReader.class);

    private RecordReader<StaticBuffer, Iterable<Entry>> reader;
    private GiraphInputFormat.RefCountedCloseable countedDeser;
    private JanusGraphVertexDeserializer deser;
    private VertexWritable vertex;

    public GiraphRecordReader(final GiraphInputFormat.RefCountedCloseable<JanusGraphVertexDeserializer> countedDeser,
                              final RecordReader<StaticBuffer, Iterable<Entry>> reader) {
        this.countedDeser = countedDeser;
        this.reader = reader;
        this.deser = countedDeser.acquire();
    }

    @Override
    public void initialize(final InputSplit inputSplit, final TaskAttemptContext taskAttemptContext) throws IOException, InterruptedException {
        reader.initialize(inputSplit, taskAttemptContext);
    }

    @Override
    public boolean nextKeyValue() throws IOException, InterruptedException {
        while (reader.nextKeyValue()) {
            // TODO janusgraph05 integration -- the duplicate() call may be unnecessary
            final TinkerVertex maybeNullTinkerVertex =
                    deser.readHadoopVertex(reader.getCurrentKey(), reader.getCurrentValue());
            if (null != maybeNullTinkerVertex) {
                vertex = new VertexWritable(maybeNullTinkerVertex);
                //vertexQuery.filterRelationsOf(vertex); // TODO reimplement vertexquery filtering
                return true;
            }
        }
        return false;
    }

    @Override
    public NullWritable getCurrentKey() throws IOException, InterruptedException {
        return NullWritable.get();
    }

    @Override
    public VertexWritable getCurrentValue() throws IOException, InterruptedException {
        return vertex;
    }

    @Override
    public void close() throws IOException {
        try {
            deser = null;
            countedDeser.release();
        } catch (Exception e) {
            throw new IOException(e);
        }
        reader.close();
    }

    @Override
    public float getProgress() throws IOException, InterruptedException {
        return reader.getProgress();
    }
}