D-Net

package eu.dnetlib.dli.resolver;

import java.net.URLEncoder;

import com.mongodb.DBObject;

import com.mongodb.MongoClient;

import com.mongodb.QueryBuilder;

import com.mongodb.client.FindIterable;

import com.mongodb.client.MongoCollection;

import com.mongodb.client.MongoCursor;

import com.mongodb.client.MongoDatabase;

import eu.dnetlib.dli.resolver.model.DLIResolvedObject;

import eu.dnetlib.pid.resolver.AbstractPIDResolver;

import groovy.transform.Synchronized;

import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

import org.bson.Document;

import org.bson.conversions.Bson;

import org.springframework.beans.factory.annotation.Autowired;

// TODO: Auto-generated Javadoc

/**

 * The Class CrossrefDOIResolver.

 */

public class CrossrefResolver extends AbstractPIDResolver {

	/**

	 * The Constant log.

	 */

	private static final Log log = LogFactory.getLog(CrossrefResolver.class);

	/**

	 * The Constant baseUrlCrossref.

	 */

	private final static String baseUrlCrossref = "http://api.crossref.org/works/";

	/**

	 * The parser.

	 */

	@Autowired

	private CrossRefParserJSON parser;

	@Autowired

	private MongoClient mongoClient;

	private MongoDatabase db;

	@Override

	protected boolean canResolvePid(final String pidType) {

		return (pidType != null) && ("doi".equals(pidType.toLowerCase().trim()) || "handle".equals(pidType.toLowerCase().trim()));

	}

	@Override

	@Synchronized

    protected DLIResolvedObject resolve(final String pid, final String pidType) {

        String response;

		try {

//			response = requestURL(baseUrlCrossref + URLEncoder.encode(pid, "UTF-8"));

			response = retrieveCrossRefFromDump(pid);

		} catch (Exception e) {

			log.debug("unable to get response");

			return null;

		}

		try {

			log.debug("Obtained " + response);

			if (response == null) return null;

			if (response.contains("Resource not found")) return null;

            DLIResolvedObject record = parser.parseRecord(response);

            if (record.getPid() == null) return null;

			return record;

		} catch (Throwable e) {

			log.error("Error on resolve pid  " + pid, e);

		}

		return null;

	}

	private String retrieveCrossRefFromDump(final String pid) {

		if (db == null) {

			db = mongoClient.getDatabase("crossRef");

		}

		final MongoCollection<Document> crossRef = db.getCollection("dump");

		DBObject query = QueryBuilder.start("_id").is(pid).get();

		FindIterable<Document> documents = crossRef.find((Bson) query).limit(1);

		MongoCursor<Document> iterator = documents.iterator();

		if (iterator.hasNext()){

			return iterator.next().toJson();

		}

		return null;

	}

}