package eu.openaire.urls_worker.plugins;

import edu.uci.ics.crawler4j.url.URLCanonicalizer;
import eu.openaire.publications_retriever.PublicationsRetriever;
import eu.openaire.publications_retriever.exceptions.DocFileNotRetrievedException;
import eu.openaire.publications_retriever.util.file.FileUtils;
import eu.openaire.publications_retriever.util.file.S3ObjectStoreMinIO;
import eu.openaire.publications_retriever.util.http.ConnSupportUtils;
import eu.openaire.publications_retriever.util.http.HttpConnUtils;
import eu.openaire.publications_retriever.util.url.DataToBeLogged;
import eu.openaire.publications_retriever.util.url.LoaderAndChecker;
import eu.openaire.publications_retriever.util.url.UrlUtils;
import eu.openaire.urls_worker.models.Assignment;
import eu.openaire.urls_worker.models.Error;
import eu.openaire.urls_worker.models.Payload;
import eu.openaire.urls_worker.models.UrlReport;
import eu.openaire.urls_worker.util.AssignmentHandler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.nio.charset.StandardCharsets;
import java.util.*;
import java.util.concurrent.Callable;
import java.util.concurrent.Executors;


public class PublicationsRetrieverPlugin {

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

    private static final String workingDir = System.getProperty("user.dir") + File.separator;
    private static String assignmentsBasePath = workingDir + "assignments" + File.separator;
    private static String assignmentsBaseFullTextsPath = assignmentsBasePath + "fullTexts" + File.separator;

    static {
        File assignmentsDir = new File(assignmentsBaseFullTextsPath);
        if ( !assignmentsDir.exists() ) {
            if ( !assignmentsDir.mkdirs() ) {   // Create the directory.
                logger.error("Could not create the \"assignments directories\": \"" + assignmentsBaseFullTextsPath + "\". Using the \"workingDir\" instead (" + workingDir + ").");
                assignmentsBasePath = workingDir;
                assignmentsBaseFullTextsPath = assignmentsBasePath;
            }
        }

        // Specify some configurations
        LoaderAndChecker.retrieveDocuments = true;
        LoaderAndChecker.retrieveDatasets = false;
        FileUtils.shouldDownloadDocFiles = true;
        FileUtils.shouldUploadFilesToS3 = true;
        FileUtils.docFileNameType = FileUtils.DocFileNameType.idName;
        PublicationsRetriever.targetUrlType = "docUrl";

        if ( FileUtils.shouldUploadFilesToS3 )
            new S3ObjectStoreMinIO();   // Check here on how to create the credentials-file: https://github.com/LSmyrnaios/PublicationsRetriever/blob/master/README.md

        int workerThreadsCount = Runtime.getRuntime().availableProcessors() * PublicationsRetriever.threadsMultiplier;
        logger.info("Use " + workerThreadsCount + " worker-threads.");
        PublicationsRetriever.executor = Executors.newFixedThreadPool(workerThreadsCount);
    }


    public static void processAssignments(Long assignmentRequestCounter, Collection<Assignment> assignments) throws RuntimeException, FileNotFoundException
    {
        ConnSupportUtils.setKnownMimeTypes();

        FileUtils.storeDocFilesDir = assignmentsBaseFullTextsPath + "assignment_" + assignmentRequestCounter + "_fullTexts" + File.separator;  // It needs the last separator, because of how the docFiles are named and stored.

        FileUtils.setOutput(new FileOutputStream(assignmentsBasePath + "assignment_" + assignmentRequestCounter + "_generic_results.json"));

        int tasksSize = assignments.size();
        int batchCount = 0;
        int taskCount = 0;
        List<Callable<Boolean>> callableTasks = new ArrayList<>(FileUtils.jsonBatchSize);

        // Start loading and checking urls.
        for ( Assignment assignment : assignments )
        {
            callableTasks.add(() -> {
                String id = assignment.getId();
                String url = assignment.getOriginalUrl();

                if ( (url = LoaderAndChecker.handleUrlChecks(id, url)) == null ) {
                    return false;
                }    // The "url" might have changed (inside "handleUrlChecks()").

                String urlToCheck = url;
                String sourceUrl = urlToCheck;    // Hold it here for the logging-messages.
                if ( !sourceUrl.contains("#/") && (urlToCheck = URLCanonicalizer.getCanonicalURL(sourceUrl, null, StandardCharsets.UTF_8)) == null ) {
                    logger.warn("Could not canonicalize url: " + sourceUrl);
                    UrlUtils.logOutputData(id, sourceUrl, null, "unreachable", "Discarded at loading time, due to canonicalization's problems.", null, true, "true", "false", "false", "false", "false", null, null);
                    LoaderAndChecker.connProblematicUrls.incrementAndGet();
                    return false;
                }

                if ( UrlUtils.docOrDatasetUrlsWithIDs.containsKey(url) ) {    // If we got into an already-found docUrl, log it and return.
                    ConnSupportUtils.handleReCrossedDocUrl(id, url, url, url, logger, true);
                    return true;
                }

                boolean isPossibleDocOrDatasetUrl = false;    // Used for specific connection settings.
                String lowerCaseRetrievedUrl = url.toLowerCase();
                // Check if it's a possible-DocUrl, if so, this info will be used for optimal web-connection later.
                if ( (LoaderAndChecker.retrieveDocuments && LoaderAndChecker.DOC_URL_FILTER.matcher(lowerCaseRetrievedUrl).matches())
                        || (LoaderAndChecker.retrieveDatasets && LoaderAndChecker.DATASET_URL_FILTER.matcher(lowerCaseRetrievedUrl).matches()) ) {
                    //logger.debug("Possible docUrl or datasetUrl: " + url);
                    isPossibleDocOrDatasetUrl = true;
                }

                try {    // Check if it's a docUrl, if not, it gets crawled.
                    HttpConnUtils.connectAndCheckMimeType(id, sourceUrl, urlToCheck, urlToCheck, null, true, isPossibleDocOrDatasetUrl);
                } catch (Exception e) {
                    List<String> list = LoaderAndChecker.getWasValidAndCouldRetry(e);
                    String wasUrlValid = list.get(0);
                    String couldRetry = list.get(1);
                    UrlUtils.logOutputData(id, urlToCheck, null, "unreachable", "Discarded at loading time, due to connectivity problems.", null, true, "true", wasUrlValid, "false", "false", couldRetry, null, null);
                    return false;
                }
                return true;
            });

            if ( ((++taskCount) >= FileUtils.jsonBatchSize) || (taskCount >= tasksSize) )
            {
                logger.info("Batch counter: " + (++batchCount) + " | progress: " + PublicationsRetriever.df.format(((batchCount-1) * taskCount) * 100.0 / tasksSize) + "% | every batch contains " + FileUtils.jsonBatchSize + " id-url pairs.");
                LoaderAndChecker.invokeAllTasksAndWait(callableTasks);
                addUrlReportsToWorkerReport();
                callableTasks.clear(); // Reset the thread-tasks-list for the next batch.
            }
        }// end tasks-for-loop
    }


    private static final String DocFileNotRetrievedExceptionName = DocFileNotRetrievedException.class.getName();  // Keep it here for easily spot if the exception changes inside the PublicationsRetriever library.

    public static void addUrlReportsToWorkerReport()
    {
        for ( DataToBeLogged data : FileUtils.dataToBeLoggedList )
        {
            String status = null, fileLocation = null, comment = data.getComment(), mimeType = null;
            Error error = null;

            if ( data.getWasDocumentOrDatasetAccessible().equals("true") )
            {
                status = "accessible";
                if ( comment.contains(UrlUtils.alreadyDownloadedByIDMessage) ) {
                    // The file of this docUrl was already downloaded by another docUrl.
                    String previousId = comment.substring(UrlUtils.alreadyDownloadedByIDMessage.length() +1);
                    //logger.debug("previousId: " + previousId);    // DEBUG!
                    // Search that ID inside the list and if that instance gave the docUrl (there might be multiple ID instances) then get the file-location.
                    for ( DataToBeLogged data_2 : FileUtils.dataToBeLoggedList ) {
                        if ( data_2.getUrlId().equals(previousId) && data_2.getWasDocumentOrDatasetAccessible().equals("true") ) {
                            fileLocation = data_2.getComment();
                            mimeType = "application/pdf";
                            break;
                        }
                    }
                }
                else if ( comment.contains(DocFileNotRetrievedExceptionName) )
                    fileLocation = "File not retrieved";
                else {
                    fileLocation = comment;
                    mimeType = "application/pdf";
                }
                error = new Error(null, null);  // We do not want to send a "null" object, since it just adds more complicated handling in the controller..
            }
            else {
                status = "non-accessible";
                if ( data.getCouldRetry().equals("true") )
                    error = new Error(Error.ErrorType.couldRetry, comment);
                else
                    error = new Error(Error.ErrorType.noRetry, comment);
            }

            String docOrDatasetUrl = data.getDocOrDatasetUrl();
            if ( docOrDatasetUrl.equals(UrlUtils.unreachableDocOrDatasetUrlIndicator) || docOrDatasetUrl.equals(UrlUtils.duplicateUrlIndicator) )
                docOrDatasetUrl = null;

            Payload payload = new Payload(data.getUrlId(), data.getSourceUrl(), docOrDatasetUrl, new Date(), mimeType, data.getSize(), data.getHash(), fileLocation, "crawl:PublicationsRetriever");
            // TODO - If support is added for other doc-formats other than "pdf", then make sure the "mime_type" is correctly specified.

            AssignmentHandler.urlReports.add(new UrlReport(status, payload, error));
        }
        FileUtils.dataToBeLoggedList.clear();   // Empty the list, to be re-populated by the next batch / assignment.
    }


    public static boolean connectWithUrlTest(String urlToCheck) {
        try {
            return HttpConnUtils.connectAndCheckMimeType("null", urlToCheck, urlToCheck, urlToCheck, null, true, false);    // Sent the < null > in quotes to avoid an NPE in the concurrent data-structures.
        } catch (Exception e) {
            List<String> list = LoaderAndChecker.getWasValidAndCouldRetry(e);
            String wasUrlValid = list.get(0);
            String couldRetry = list.get(1);
            UrlUtils.logOutputData(null, urlToCheck, null, "unreachable", "Discarded at loading time, due to connectivity problems.", null, true, "true", wasUrlValid, "false", "false", couldRetry, null, null);
            return false;
        }
    }
}