package eu.dnetlib.dhp.actionmanager.opencitations;

import static eu.dnetlib.dhp.actionmanager.Constants.DEFAULT_DELIMITER;
import static eu.dnetlib.dhp.actionmanager.Constants.isSparkSessionManaged;
import static eu.dnetlib.dhp.common.SparkSessionSupport.runWithSparkSession;

import java.io.IOException;
import java.io.Serializable;
import java.util.Arrays;
import java.util.Optional;

import org.apache.commons.io.IOUtils;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import org.apache.spark.SparkConf;
import org.apache.spark.api.java.function.FilterFunction;
import org.apache.spark.api.java.function.MapFunction;
import org.apache.spark.sql.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import eu.dnetlib.dhp.actionmanager.opencitations.model.COCI;
import eu.dnetlib.dhp.application.ArgumentApplicationParser;

public class ReadCOCI implements Serializable {

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

	public static void main(String[] args) throws Exception {
		String jsonConfiguration = IOUtils
			.toString(
				ReadCOCI.class
					.getResourceAsStream(
						"/eu/dnetlib/dhp/actionmanager/opencitations/input_readcoci_parameters.json"));

		final ArgumentApplicationParser parser = new ArgumentApplicationParser(jsonConfiguration);
		parser.parseArgument(args);

		final String outputPath = parser.get("outputPath");
		log.info("outputPath: {}", outputPath);

		final String hdfsNameNode = parser.get("hdfsNameNode");
		log.info("hdfsNameNode {}", hdfsNameNode);

		Boolean isSparkSessionManaged = isSparkSessionManaged(parser);
		log.info("isSparkSessionManaged: {}", isSparkSessionManaged);

		final String workingPath = parser.get("inputPath");
		log.info("workingPath {}", workingPath);

		SparkConf sconf = new SparkConf();

		Configuration conf = new Configuration();
		conf.set("fs.defaultFS", hdfsNameNode);

		FileSystem fileSystem = FileSystem.get(conf);
		final String delimiter = Optional
			.ofNullable(parser.get("delimiter"))
			.orElse(DEFAULT_DELIMITER);

		runWithSparkSession(
			sconf,
			isSparkSessionManaged,
			spark -> {
				doRead(
					spark,
					workingPath,
					fileSystem,
					outputPath,
					delimiter);
			});
	}

	private static void doRead(SparkSession spark, String workingPath, FileSystem fileSystem,
		String outputPath,
		String delimiter) throws IOException {
		RemoteIterator<LocatedFileStatus> fileStatusListIterator = fileSystem
			.listFiles(
				new Path(workingPath), true);
		while (fileStatusListIterator.hasNext()) {
			LocatedFileStatus fileStatus = fileStatusListIterator.next();
			log.info("extracting file {}", fileStatus.getPath().toString());
			Dataset<Row> cociData = spark
				.read()
				.format("csv")
				.option("sep", delimiter)
				.option("inferSchema", "true")
				.option("header", "true")
				.option("quotes", "\"")
				.load(fileStatus.getPath().toString())
				.repartition(100);

			cociData.map((MapFunction<Row, COCI>) row -> {

				COCI coci = new COCI();

				coci.setCiting(row.getString(1));
				coci.setCited(row.getString(2));

				coci.setOci(row.getString(0));

				return coci;
			}, Encoders.bean(COCI.class))
				.filter((FilterFunction<COCI>) c -> c != null)
				.write()
				.mode(SaveMode.Append)
				.option("compression", "gzip")
				.json(outputPath);
			fileSystem.rename(fileStatus.getPath(), new Path("/tmp/miriam/OC/DONE"));
		}

	}

}