package eu.dnetlib.dhp.oa.graph.hive;

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

import java.util.Optional;

import org.apache.commons.io.IOUtils;
import org.apache.spark.SparkConf;
import org.apache.spark.api.java.JavaSparkContext;
import org.apache.spark.sql.Encoders;
import org.apache.spark.sql.SaveMode;
import org.apache.spark.sql.SparkSession;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.fasterxml.jackson.databind.ObjectMapper;

import eu.dnetlib.dhp.application.ArgumentApplicationParser;
import eu.dnetlib.dhp.schema.common.ModelSupport;

public class GraphHiveImporterJob {

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

	private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();

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

		final ArgumentApplicationParser parser = new ArgumentApplicationParser(
			IOUtils
				.toString(
					GraphHiveImporterJob.class
						.getResourceAsStream(
							"/eu/dnetlib/dhp/oa/graph/input_graph_hive_parameters.json")));
		parser.parseArgument(args);

		Boolean isSparkSessionManaged = Optional
			.ofNullable(parser.get("isSparkSessionManaged"))
			.map(Boolean::valueOf)
			.orElse(Boolean.TRUE);
		log.info("isSparkSessionManaged: {}", isSparkSessionManaged);

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

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

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

		SparkConf conf = new SparkConf();
		conf.set("hive.metastore.uris", hiveMetastoreUris);

		runWithSparkHiveSession(
			conf, isSparkSessionManaged, spark -> loadGraphAsHiveDB(spark, inputPath, hiveDbName));
	}

	// protected for testing
	private static void loadGraphAsHiveDB(SparkSession spark, String inputPath, String hiveDbName) {

		spark.sql(String.format("DROP DATABASE IF EXISTS %s CASCADE", hiveDbName));
		spark.sql(String.format("CREATE DATABASE IF NOT EXISTS %s", hiveDbName));

		final JavaSparkContext sc = JavaSparkContext.fromSparkContext(spark.sparkContext());
		// Read the input file and convert it into RDD of serializable object
		ModelSupport.oafTypes
			.forEach(
				(name, clazz) -> spark
					.createDataset(
						sc
							.textFile(inputPath + "/" + name)
							.map(s -> OBJECT_MAPPER.readValue(s, clazz))
							.rdd(),
						Encoders.bean(clazz))
					.write()
					.mode(SaveMode.Overwrite)
					.saveAsTable(hiveDbName + "." + name));
	}
}