package eu.dnetlib.dhp.blacklist;

import static eu.dnetlib.dhp.common.SparkSessionSupport.runWithSparkSession;

import java.util.Objects;
import java.util.Optional;

import org.apache.commons.io.IOUtils;
import org.apache.spark.SparkConf;
import org.apache.spark.api.java.function.MapFunction;
import org.apache.spark.sql.*;
import org.apache.spark.sql.Dataset;
import org.apache.spark.sql.Encoders;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.fasterxml.jackson.databind.ObjectMapper;

import eu.dnetlib.dhp.application.ArgumentApplicationParser;
import eu.dnetlib.dhp.common.HdfsSupport;
import eu.dnetlib.dhp.schema.oaf.Relation;
import scala.Tuple2;

public class SparkRemoveBlacklistedRelationJob {
	private static final Logger log = LoggerFactory.getLogger(SparkRemoveBlacklistedRelationJob.class);
	private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();

	public static void main(String[] args) throws Exception {

		String jsonConfiguration = IOUtils
			.toString(
				SparkRemoveBlacklistedRelationJob.class
					.getResourceAsStream(
						"/eu/dnetlib/dhp/blacklist/sparkblacklist_parameters.json"));

		final ArgumentApplicationParser parser = new ArgumentApplicationParser(jsonConfiguration);

		parser.parseArgument(args);

		Boolean isSparkSessionManaged = Optional
			.ofNullable(parser.get("isSparkSessionManaged"))
			.map(Boolean::valueOf)
			.orElse(Boolean.TRUE);

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

		String inputPath = parser.get("sourcePath");
		log.info("inputPath: {}", inputPath);

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

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

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

		SparkConf conf = new SparkConf();

		runWithSparkSession(
			conf,
			isSparkSessionManaged,
			spark -> {
				removeOutputDir(spark, outputPath);
				removeBlacklistedRelations(
					spark,
					blacklistPath,
					inputPath,
					outputPath,
					mergesPath);
			});
	}

	private static void removeBlacklistedRelations(SparkSession spark, String blacklistPath, String inputPath,
		String outputPath, String mergesPath) {
		Dataset<Relation> blackListed = readRelations(spark, blacklistPath + "/blacklist");
		Dataset<Relation> inputRelation = readRelations(spark, inputPath);
		Dataset<Relation> mergesRelation = readRelations(spark, mergesPath);

		Dataset<Relation> dedupSource = blackListed
			.joinWith(
				mergesRelation, blackListed.col("source").equalTo(mergesRelation.col("target")),
				"left_outer")
			.map((MapFunction<Tuple2<Relation, Relation>, Relation>) c -> {
				Optional
					.ofNullable(c._2())
					.ifPresent(mr -> c._1().setSource(mr.getSource()));
				return c._1();
			}, Encoders.bean(Relation.class));

		Dataset<Relation> dedupBL = dedupSource
			.joinWith(
				mergesRelation, dedupSource.col("target").equalTo(mergesRelation.col("target")),
				"left_outer")
			.map((MapFunction<Tuple2<Relation, Relation>, Relation>) c -> {
				Optional
					.ofNullable(c._2())
					.ifPresent(mr -> c._1().setTarget(mr.getSource()));
				return c._1();
			}, Encoders.bean(Relation.class));

		inputRelation
			.joinWith(
				dedupBL, (inputRelation
					.col("source")
					.equalTo(dedupBL.col("source"))
					.and(
						inputRelation
							.col("target")
							.equalTo(dedupBL.col("target")))),
				"left_outer")
			.map((MapFunction<Tuple2<Relation, Relation>, Relation>) c -> {
				Relation ir = c._1();
				Optional<Relation> obl = Optional.ofNullable(c._2());
				if (obl.isPresent() && ir.equals(obl.get())) {
					return null;
				}
				return ir;
			}, Encoders.bean(Relation.class))
			.filter(Objects::nonNull)
			.write()
			.mode(SaveMode.Overwrite)
			.option("compression", "gzip")
			.json(outputPath);
	}

	public static org.apache.spark.sql.Dataset<Relation> readRelations(
		SparkSession spark, String inputPath) {
		return spark
			.read()
			.textFile(inputPath)
			.map(
				(MapFunction<String, Relation>) value -> OBJECT_MAPPER.readValue(value, Relation.class),
				Encoders.bean(Relation.class));
	}

	private static void removeOutputDir(SparkSession spark, String path) {
		HdfsSupport.remove(path, spark.sparkContext().hadoopConfiguration());
	}

}