UrlsController/src/main/java/eu/openaire/urls_controller/models/BulkImportReport.java

package eu.openaire.urls_controller.models;

import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.google.common.collect.LinkedHashMultimap;
import com.google.common.collect.Multimaps;
import com.google.common.collect.SetMultimap;
import com.google.gson.Gson;
import eu.openaire.urls_controller.util.GenericUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Collection;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;


@JsonInclude(JsonInclude.Include.NON_NULL)
public class BulkImportReport {

    private static final Logger logger = LoggerFactory.getLogger(BulkImportReport.class);

    private static final Gson gson = new Gson();    // This is "transient" by default. It won't be included in any json object.

    @JsonProperty
    private String provenance;

    @JsonProperty
    private String reportLocation;

    @JsonProperty
    private String reportID;

    // This will not be serialized, since Gson cannot serialize Multimaps. Instead, it will be converted to the "simpler" map below.
    transient private SetMultimap<String, String> eventsMultimap = Multimaps.synchronizedSetMultimap(LinkedHashMultimap.create());
    // We need a "LinkedHashMultimap", se that the order of the keys (timestamps) stay ascending, so the final report makes sense in chronological order.
    // We need for one key (timestamp) to have multiple values (events), in order to not lose events happening at the same time.

    @JsonProperty
    private Map<String, Collection<String>> eventsMap;

    transient private final Lock reportLock = new ReentrantLock(true);


    public BulkImportReport(String provenance, String reportLocation, String reportID) {
        this.provenance = provenance;
        this.reportLocation = reportLocation;
        this.reportID = reportID;
    }


    public void addEvent(String event) {
        eventsMultimap.put(GenericUtils.getReadableCurrentTimeAndZone(), event);    // This is synchronized.
    }

    /**
     * Synchronize it with a lock, to avoid concurrency issues when concurrent calls are made to the same bulkImport-Report object.
     * */
    public String getJsonReport()
    {
        String reportToReturn = null;
        reportLock.lock();
        try {
            //Convert the SetMultimap<String, String> to Map<String, Collection<String>>, since Gson cannot serialize Multimaps.
            eventsMap = new LinkedHashMap<>(eventsMultimap.asMap());  // Make sure we use a clone of the original data, in order to avoid any exception in the "gson.toJson()" method, when at the same time another thread modifies the "eventsMultimap".
            reportToReturn = gson.toJson(this, BulkImportReport.class);
        } catch (Exception e) {
            logger.error("Problem when producing the JSON-string with the BulkImportReport! | reportID: '" + reportID + "'", e);
        } finally {
            reportLock.unlock();
        }
        return reportToReturn;  // It may be null.
    }

    public String getProvenance() {
        return provenance;
    }

    public void setProvenance(String provenance) {
        this.provenance = provenance;
    }

    public String getReportLocation() {
        return reportLocation;
    }

    public void setReportLocation(String reportLocation) {
        this.reportLocation = reportLocation;
    }

    public String getReportID() {
        return reportID;
    }

    public void setReportID(String reportID) {
        this.reportID = reportID;
    }

    public SetMultimap<String, String> getEventsMultimap() {
        return eventsMultimap;
    }

    public void setEventsMultimap(SetMultimap<String, String> eventsMultimap) {
        this.eventsMultimap = eventsMultimap;
    }

    public Map<String, Collection<String>> getEventsMap() {
        return eventsMap;
    }

    public void setEventsMap(Map<String, Collection<String>> eventsMap) {
        this.eventsMap = eventsMap;
    }

    @Override
    public String toString() {
        return "BulkImportReport{" +
                "provenance='" + provenance + '\'' +
                ", reportLocation='" + reportLocation + '\'' +
                ", reportID='" + reportID + '\'' +
                ", eventsMultimap=" + eventsMultimap +
                ", eventsMap=" + eventsMap +
                '}';
    }

}