package eu.dnetlib.data.mdstore.modular.mongodb;

import java.util.List;
import java.util.Map;
import javax.annotation.Nullable;

import com.google.common.base.Predicate;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.mongodb.BasicDBObject;
import com.mongodb.DBObject;
import com.mongodb.WriteConcern;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.model.*;
import eu.dnetlib.data.mdstore.MDStoreServiceException;
import eu.dnetlib.data.mdstore.modular.MDFormatDescription;
import eu.dnetlib.data.mdstore.modular.RecordParser;
import eu.dnetlib.data.mdstore.modular.mongodb.utils.IndexFieldRecordParser;
import eu.dnetlib.data.mdstore.modular.mongodb.utils.IndexFieldRecordParserException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import static eu.dnetlib.data.mdstore.modular.MDStoreConstants.*;

public class MongoBulkWritesManager {

	private static final Log log = LogFactory.getLog(MongoBulkWritesManager.class);
	private final boolean discardRecords;
	private final boolean indexRecords;
	private final IndexFieldRecordParser indexFieldRecordParser = new IndexFieldRecordParser();
	private final List<MDFormatDescription> mdref;
	private RecordParser recordParser;
	private MongoCollection<DBObject> validCollection;
	private List<WriteModel<DBObject>> validBulkOperationList;
	private BulkWriteOptions writeOptions;
	private MongoCollection<DBObject> discardedCollection;
	private List<WriteModel<DBObject>> discardedBulkOperationList;
	private int bulkSize;

	public MongoBulkWritesManager(final MongoCollection<DBObject> collection,
			final MongoCollection<DBObject> discardedCollection,
			final List<MDFormatDescription> mdref,
			final int bulkSize,
			final RecordParser parser,
			final boolean discardRecords) {
		this.validCollection = collection.withWriteConcern(WriteConcern.ACKNOWLEDGED);
		this.validBulkOperationList = Lists.newArrayList();

		this.discardedCollection = discardedCollection.withWriteConcern(WriteConcern.ACKNOWLEDGED);
		this.discardedBulkOperationList = Lists.newArrayList();

		this.bulkSize = bulkSize;
		this.recordParser = parser;
		this.discardRecords = discardRecords;
		this.mdref = mdref;

		this.indexRecords = (this.mdref != null &&  !this.mdref.isEmpty());
		this.writeOptions = new BulkWriteOptions().ordered(false);
	}

	public void insert(final String record) throws MDStoreServiceException {
		Map<String, String> recordProperties = null;
		try {
			recordProperties = recordParser.parseRecord(record);

		} catch (Throwable e) {
			if (discardRecords) {
				log.debug("unhandled exception: " + e.getMessage());
				discardRecord(record);
			}
		}
		Map<String, List<String>> indexRecordField = null;
		try {
			if (indexRecords) {
				indexRecordField = indexFieldRecordParser.parseRecord(record, mdref);
			}
		} catch (IndexFieldRecordParserException e) {
			// could not index record fields
			throw new MDStoreServiceException("Are you using the correct type of store / index definition for the records in " + validCollection.getNamespace() + " ?", e);
		}

		log.debug("found props: " + recordProperties);
		if (recordProperties.containsKey(ID)) {
			final DBObject obj = buildDBObject(record, recordProperties, indexRecordField);
			if (log.isDebugEnabled()) {
				log.debug("Saving object" + obj);
			}
			validBulkOperationList.add(new ReplaceOneModel(new BasicDBObject(ID, obj.get(ID)), obj, new UpdateOptions().upsert(true)));
			if (((validBulkOperationList.size() % bulkSize) == 0) && !validBulkOperationList.isEmpty()) {
				validCollection.bulkWrite(validBulkOperationList, writeOptions);
				validBulkOperationList.clear();
			}
		} else {
			if (discardRecords) {
				log.debug("parsed record seems invalid");
				discardRecord(record);
			}
		}
	}

	private void discardRecord(final String record) {
		discardedBulkOperationList.add(new InsertOneModel(new BasicDBObject(BODY, record)));

		if (((discardedBulkOperationList.size() % bulkSize) == 0) && !discardedBulkOperationList.isEmpty()) {
			discardedCollection.bulkWrite(discardedBulkOperationList, writeOptions);
			discardedBulkOperationList.clear();
		}
	}

	public void flushBulks() {
		//setting to journaled write concern to be sure that when the write returns everything has been flushed to disk (https://docs.mongodb.org/manual/faq/developers/#when-does-mongodb-write-updates-to-disk)
		//the explicit fsync command can't be run anymore: 'Command failed with error 13: 'fsync may only be run against the admin database.'
		if (!validBulkOperationList.isEmpty()) {
			validCollection = getCollectionWithWriteConcern(validCollection, WriteConcern.JOURNALED);
			validCollection.bulkWrite(validBulkOperationList, writeOptions);
		}
		if (!discardedBulkOperationList.isEmpty()) {
			discardedCollection = getCollectionWithWriteConcern(discardedCollection, WriteConcern.JOURNALED);
			discardedCollection.bulkWrite(discardedBulkOperationList, writeOptions);
		}
		//setting write concern back to ACKNOWLEDGE to avoid the execution of future writes all in Journaled mode
		validCollection = getCollectionWithWriteConcern(validCollection, WriteConcern.ACKNOWLEDGED);
		discardedCollection = getCollectionWithWriteConcern(discardedCollection, WriteConcern.ACKNOWLEDGED);
	}

	protected DBObject buildDBObject(final String record, final Map<String, String> recordProperties, final Map<String, List<String>> indexFieldProperties) {
		final DBObject obj = new BasicDBObject();
		obj.put(ID, recordProperties.get(ID));
		obj.put(ORIGINALID, recordProperties.get(ORIGINALID));
		obj.put(BODY, record);
		obj.put(TIMESTAMP, Long.valueOf(recordProperties.get(TIMESTAMP)));
		if (indexFieldProperties != null)
			obj.putAll(Maps.filterKeys(indexFieldProperties, new Predicate<String>() {
				//ensure we do not override the mandatory fields above with some unexpected value
				@Override
				public boolean apply(@Nullable final String s) {
					return !s.equalsIgnoreCase(ID) && !s.equalsIgnoreCase(ORIGINALID) && !s.equalsIgnoreCase(BODY) && !s.equalsIgnoreCase(TIMESTAMP);
				}
			}));
		return obj;
	}

	private MongoCollection<DBObject> getCollectionWithWriteConcern(MongoCollection<DBObject> collection, WriteConcern writeConcern) {
		return collection.withWriteConcern(writeConcern);
	}

}