UrlsWorker/src/main/java/eu/openaire/urls_worker/util/AssignmentHandler.java

package eu.openaire.urls_worker.util;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.Multimap;
import eu.openaire.urls_worker.UrlsWorkerApplication;
import eu.openaire.urls_worker.models.Assignment;
import eu.openaire.urls_worker.models.UrlReport;
import eu.openaire.urls_worker.payloads.requests.AssignmentRequest;
import eu.openaire.urls_worker.payloads.responces.WorkerReport;
import eu.openaire.urls_worker.plugins.PublicationsRetrieverPlugin;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.web.client.RestTemplateBuilder;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;

import java.util.*;


public class AssignmentHandler {

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

    public static boolean isAvailableForWork = true;

    public static List<UrlReport> urlReports = null;

    private static final boolean askForTest = false; // Enable this only for testing.


    public static AssignmentRequest requestAssignments()
    {
        String requestUrl = UrlsWorkerApplication.controllerBaseUrl + "urls" + (askForTest ? "/test" : "") + "?workerId=" + UrlsWorkerApplication.workerId + "&workerAssignmentsLimit=" + WorkerConstants.ASSIGNMENTS_LIMIT;
        logger.info("Going to request assignments from the controller-server: " + requestUrl);

        String json = null;
        try {
            json = new RestTemplateBuilder().build().getForObject(requestUrl, String.class);
        } catch (Exception e) {
            logger.error("Could not retrieve the assignments!\n" + e.getMessage());
            return null;
        }

        AssignmentRequest assignmentRequest = null;
        try {
            assignmentRequest = new ObjectMapper().readValue(json, AssignmentRequest.class);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }

        if ( assignmentRequest == null ) {
            String errorMessage = "Could not map the json to an \"assignmentRequest\"!";
            System.err.println(errorMessage);
            logger.error(errorMessage);
            System.exit(1);
        }

        //logger.debug(assignmentRequest.toString());   // DEBUG!

        logger.info("AssignmentRequest < " + assignmentRequest.getAssignmentCounter() + " > was received and it's ready to be processed. It contains " + assignmentRequest.getAssignments().size() + " tasks.");

        return assignmentRequest;
    }


    public static void handleAssignments()
    {
        AssignmentRequest assignmentRequest = requestAssignments();
        if ( assignmentRequest == null ) {
            logger.error("The \"assignmentRequest\" was \"null\"!");
            return;
        }

        Long assignmentRequestCounter = assignmentRequest.getAssignmentCounter();

        List<Assignment> assignments = assignmentRequest.getAssignments();
        if ( assignments == null ) {
            logger.warn("The assignments were found to be null for assignmentRequestCounter = " + assignmentRequestCounter);
            return;
        }

        // Start handling the assignments, the worker is busy.
        isAvailableForWork = false;

        // Iterate over the tasks and add each task in it's own list depending on the DATASOURCE in order to decide which plugin to use later.

        Multimap<String, Assignment> assignmentsForPlugins = HashMultimap.create();

        for ( Assignment assignment : assignments ) {
            // Add each task in its own HashSet.
            assignmentsForPlugins.put(assignment.getDatasource().getId(), assignment);
        }

        urlReports = new ArrayList<>(assignments.size()); // Define the new UrlReport-list. It is reinitialized each time.

        // TODO - Decide which tasks run with what plugin (depending on their datasource).

        // First run -in parallel- the tasks which require some specific plugin.

        // Then run the remaining tasks in the generic plugin (which handles parallelism itself).

        // For now, let's just run all tasks in the generic plugin.

        try {
            PublicationsRetrieverPlugin.processAssignments(assignmentRequestCounter, assignmentsForPlugins.values());
        } catch (Exception e) {
            logger.error(e.getMessage(), e);
        }

        isAvailableForWork = true;  // State this before posting, to catch the soonest next scheduled request.

        /*logger.debug("UrlReports:");  // DEBUG!
        for ( UrlReport urlReport : urlReports ) {
            logger.debug(urlReport.toString());
        }*/

        postWorkerReport(assignmentRequestCounter);

        // Note: Cannot call this method here retrospectively, as if it runs 100s of times, the memory may break..
        // The scheduler will handle calling it every half an hour, in case the Worker is available for work..
    }


    public static boolean postWorkerReport(Long assignmentRequestCounter)
    {
        String postUrl = UrlsWorkerApplication.controllerBaseUrl + "urls/addWorkerReport";
        logger.info("Going to post the WorkerReport to the controller-server: " + postUrl);

        try {
            ResponseEntity<String> responseEntity = new RestTemplateBuilder().build().postForEntity(postUrl, new WorkerReport(UrlsWorkerApplication.workerId, assignmentRequestCounter, urlReports), String.class);
            int responseCode = responseEntity.getStatusCode().value();
            if ( responseCode != HttpStatus.OK.value() ) {
                logger.error("Connection problem with the submission of the WorkerReport of assignment_" + assignmentRequestCounter + " to the Controller. Error-code was: " + responseCode);
                return false;
            }
        } catch (Exception e) {
            logger.error("Error when submitting the WorkerReport of assignment_" + assignmentRequestCounter + " to the Controller: ", e);
            return false;
        } finally {
            AssignmentHandler.urlReports.clear();   //  Reset the UrlReports list for the next assignments-handling.
        }

        return true;
    }

}