D-Net

package eu.dnetlib.dli.resolver;

import com.google.gson.Gson;

import com.google.gson.GsonBuilder;

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.dli.resolver.model.DLIResolvedObjectDeserializer;

import eu.dnetlib.pid.resolver.AbstractPIDResolver;

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;

public class DLIOfflineResolver extends AbstractPIDResolver {

    /**

     * The Constant log.

     */

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

    @Autowired

    private MongoClient mongoClient;

    private MongoDatabase db;

    private Gson g = new GsonBuilder().registerTypeAdapter(DLIResolvedObject.class, new DLIResolvedObjectDeserializer()).create();

    @Override

    protected boolean canResolvePid(final String pidType) {

        return isAvailableOffline();

    }

    @Override

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

        final String dliItem = retrieveDLIFromDump(pid.toLowerCase().trim(),pidType.toLowerCase().trim());

        if (dliItem!= null)

            return g.fromJson(dliItem, DLIResolvedObject.class);

        return null;

    }

    private String retrieveDLIFromDump(final String pid, final String pidType) {

        log.debug(String.format("trying to find %s of type %s", pid, pidType));

        if (db == null) {

            db = mongoClient.getDatabase("dli_resolved");

        }

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

        DBObject query = QueryBuilder.start("pid").is(pid).and("pid_type").is(pidType).get();

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

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

        if (iterator.hasNext()){

            log.debug("found pid "+pid);

            return iterator.next().get("body").toString();

        }

        return null;

    }

}