package eu.dnetlib.dhp.oa.dedup;

import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.collect.Lists;
import eu.dnetlib.dhp.schema.common.EntityType;
import eu.dnetlib.dhp.schema.common.ModelSupport;
import eu.dnetlib.dhp.schema.oaf.*;
import eu.dnetlib.pace.config.DedupConfig;
import org.apache.spark.api.java.JavaPairRDD;
import org.apache.spark.api.java.function.FilterFunction;
import org.apache.spark.api.java.function.MapFunction;
import org.apache.spark.api.java.function.MapGroupsFunction;
import org.apache.spark.api.java.function.PairFunction;
import org.apache.spark.sql.Dataset;
import org.apache.spark.sql.Encoders;
import org.apache.spark.sql.SparkSession;

import scala.Tuple2;

import java.util.Collection;
import java.util.Iterator;

public class DedupRecordFactory {

    protected static final ObjectMapper OBJECT_MAPPER = new com.fasterxml.jackson.databind.ObjectMapper()
            .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);

    public static <T extends OafEntity> Dataset<T> createDedupRecord(
            final SparkSession spark, final String mergeRelsInputPath, final String entitiesInputPath, final Class<T> clazz, final DedupConfig dedupConf) {

        long ts = System.currentTimeMillis();

        //<id, json_entity>
        Dataset<Tuple2<String, T>> entities = spark.read()
                .textFile(entitiesInputPath)
                .map((MapFunction<String, Tuple2<String, T>>) it -> {
                    T entity = OBJECT_MAPPER.readValue(it, clazz);
                    return new Tuple2<>(entity.getId(), entity);
                }, Encoders.tuple(Encoders.STRING(), Encoders.kryo(clazz)));


        //<source, target>: source is the dedup_id, target is the id of the mergedIn
        Dataset<Tuple2<String, String>> mergeRels = spark
                .read()
                .load(mergeRelsInputPath)
                .as(Encoders.bean(Relation.class))
                .where("relClass == 'merges'")
                .map((MapFunction<Relation, Tuple2<String, String>>)
                        r -> new Tuple2<>(r.getSource(), r.getTarget()), Encoders.tuple(Encoders.STRING(), Encoders.STRING()));

        //<dedup_id, json_entity_merged>
        return mergeRels.joinWith(entities, mergeRels.col("_1").equalTo(entities.col("_1")), "left_outer")
                .filter((FilterFunction<Tuple2<Tuple2<String, String>, Tuple2<String, T>>>) value -> value._2() != null)
                .map((MapFunction<Tuple2<Tuple2<String, String>, Tuple2<String, T>>, T>)
                        value -> value._2()._2(), Encoders.kryo(clazz))
                .groupByKey((MapFunction<T, String>) value -> value.getId(), Encoders.STRING())
                .mapGroups((MapGroupsFunction<String, T, T>)
                        (key, values) -> entityMerger(key, values, ts, clazz), Encoders.bean(clazz));
    }

    private static <T extends OafEntity> T entityMerger(String id, Iterator<T> entities, final long ts, Class<T> clazz) {
        try {
            T entity = clazz.newInstance();
            entity.setId(id);
            if (entity.getDataInfo() == null) {
                entity.setDataInfo(new DataInfo());
            }
            entity.getDataInfo().setTrust("0.9");
            entity.setLastupdatetimestamp(ts);

            final Collection<String> dates = Lists.newArrayList();
            entities.forEachRemaining(e -> {
                entity.mergeFrom(e);
                if (ModelSupport.isSubClass(e, Result.class)) {
                    Result r1 = (Result) e;
                    Result er = (Result) entity;
                    er.setAuthor(DedupUtility.mergeAuthor(er.getAuthor(), r1.getAuthor()));

                    if (er.getDateofacceptance() != null) {
                        dates.add(r1.getDateofacceptance().getValue());
                    }
                }
            });

            if (ModelSupport.isSubClass(entity, Result.class)) {
                ((Result) entity).setDateofacceptance(DatePicker.pick(dates));
            }
            return entity;
        } catch (IllegalAccessException | InstantiationException e) {
            throw new RuntimeException(e);
        }
    }

}