/**
 * 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.hcatalog.utils;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import java.util.Map.Entry;

import org.apache.hcatalog.common.HCatException;
import org.apache.hcatalog.data.transfer.DataTransferFactory;
import org.apache.hcatalog.data.transfer.HCatWriter;
import org.apache.hcatalog.data.transfer.WriteEntity;
import org.apache.hcatalog.data.transfer.WriterContext;

public class DataWriterMaster {

    public static void main(String[] args) throws FileNotFoundException, IOException, ClassNotFoundException {

        // This config contains all the configuration that master node wants to provide
        // to the HCatalog.
        Properties externalConfigs = new Properties();
        externalConfigs.load(new FileReader(args[0]));
        Map<String, String> config = new HashMap<String, String>();

        for (Entry<Object, Object> kv : externalConfigs.entrySet()) {
            System.err.println("k: " + kv.getKey() + "\t v: " + kv.getValue());
            config.put((String) kv.getKey(), (String) kv.getValue());
        }

        if (args.length == 3 && "commit".equalsIgnoreCase(args[2])) {
            // Then, master commits if everything goes well.
            ObjectInputStream ois = new ObjectInputStream(new FileInputStream(new File(args[1])));
            WriterContext cntxt = (WriterContext) ois.readObject();
            commit(config, true, cntxt);
            System.exit(0);
        }
        // This piece of code runs in master node and gets necessary context.
        WriterContext cntxt = runsInMaster(config);


        // Master node will serialize writercontext and will make it available at slaves.
        File f = new File(args[1]);
        f.delete();
        ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(f));
        oos.writeObject(cntxt);
        oos.flush();
        oos.close();
    }

    private static WriterContext runsInMaster(Map<String, String> config) throws HCatException {

        WriteEntity.Builder builder = new WriteEntity.Builder();
        WriteEntity entity = builder.withTable(config.get("table")).build();
        HCatWriter writer = DataTransferFactory.getHCatWriter(entity, config);
        WriterContext info = writer.prepareWrite();
        return info;
    }

    private static void commit(Map<String, String> config, boolean status, WriterContext cntxt) throws HCatException {

        WriteEntity.Builder builder = new WriteEntity.Builder();
        WriteEntity entity = builder.withTable(config.get("table")).build();
        HCatWriter writer = DataTransferFactory.getHCatWriter(entity, config);
        if (status) {
            writer.commit(cntxt);
        } else {
            writer.abort(cntxt);
        }
    }
}