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/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch 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.elasticsearch.hadoop.cascading;

import java.util.List;

import org.apache.hadoop.io.Writable;
import org.elasticsearch.hadoop.cfg.Settings;
import org.elasticsearch.hadoop.mr.WritableValueWriter;
import org.elasticsearch.hadoop.serialization.Generator;
import org.elasticsearch.hadoop.serialization.builder.FilteringValueWriter;
import org.elasticsearch.hadoop.serialization.builder.JdkValueWriter;

import cascading.scheme.SinkCall;
import cascading.tuple.Tuple;

/**
 * Basic delegate around {@link JdkValueWriter} that handles the unwraping of {@link SinkCall}
 */
public class CascadingValueWriter extends FilteringValueWriter> {

    final static int SINK_CTX_SIZE = 1;
    final static int SINK_CTX_ALIASES = 0;

    private final JdkValueWriter jdkWriter;
    private final WritableValueWriter writableWriter;

    public CascadingValueWriter() {
        this(false);
    }

    public CascadingValueWriter(boolean writeUnknownTypes) {
        jdkWriter = new JdkValueWriter(writeUnknownTypes);
        writableWriter = new WritableValueWriter(writeUnknownTypes);
    }

    @SuppressWarnings("unchecked")
    @Override
    public Result write(SinkCall sinkCall, Generator generator) {
        Tuple tuple = CascadingUtils.coerceToString(sinkCall);
        // consider names (in case of aliases these are already applied)
        List names = (List) sinkCall.getContext()[SINK_CTX_ALIASES];

        generator.writeBeginObject();
        for (int i = 0; i < tuple.size(); i++) {
            String name = (i < names.size() ? names.get(i) : "tuple" + i);
            // filter out fields
            if (shouldKeep(generator.getParentPath(), name)) {
                generator.writeFieldName(name);
                Object object = tuple.getObject(i);
                Result result = jdkWriter.write(object, generator);
                if (!result.isSuccesful()) {
                    if (object instanceof Writable) {
                        return writableWriter.write((Writable) object, generator);
                    }
                    return Result.FAILED(object);
                }
            }
        }
        generator.writeEndObject();
        return Result.SUCCESFUL();
    }

    @Override
    public void setSettings(Settings settings) {
        super.setSettings(settings);
        jdkWriter.setSettings(settings);
        writableWriter.setSettings(settings);
    }
}