package eu.openaire.urls_worker.plugins;

import edu.uci.ics.crawler4j.url.URLCanonicalizer;
import eu.openaire.publications_retriever.PublicationsRetriever;
import eu.openaire.publications_retriever.util.file.FileUtils;
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.UrlsWorkerApplication;
import eu.openaire.urls_worker.components.ScheduledTasks;
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.services.FileStorageService;
import eu.openaire.urls_worker.util.AssignmentsHandler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.nio.charset.StandardCharsets;
import java.sql.Timestamp;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.Executors;


public class PublicationsRetrieverPlugin {

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

    public static String assignmentsBasePath;


    public PublicationsRetrieverPlugin() {
        // Specify some configurations
        LoaderAndChecker.retrieveDocuments = true;
        LoaderAndChecker.retrieveDatasets = false;
        ConnSupportUtils.setKnownMimeTypes();
        FileUtils.shouldDownloadDocFiles = true;
        FileUtils.docFileNameType = FileUtils.DocFileNameType.idName;
        PublicationsRetriever.targetUrlType = "docUrl";
        FileUtils.jsonBatchSize = UrlsWorkerApplication.maxAssignmentsLimitPerBatch;

        assignmentsBasePath = FileStorageService.assignmentsLocation.toString();
        if ( !assignmentsBasePath.endsWith(File.separator) )
            assignmentsBasePath += File.separator;

        ConnSupportUtils.shouldBlockMost5XXDomains = false;
        LoaderAndChecker.setCouldRetryRegex();

        PublicationsRetriever.threadsMultiplier = 4;
        int workerThreadsCount = Runtime.getRuntime().availableProcessors() * PublicationsRetriever.threadsMultiplier;
        logger.info("Use " + workerThreadsCount + " worker-threads.");
        PublicationsRetriever.executor = Executors.newFixedThreadPool(workerThreadsCount);
    }

    private static final List<Callable<Boolean>> callableTasks = new ArrayList<>(FileUtils.jsonBatchSize);

    public static void processAssignments(Long assignmentRequestCounter, Collection<Assignment> assignments) throws RuntimeException
    {
        FileUtils.storeDocFilesDir = assignmentsBasePath + "assignments_" + assignmentRequestCounter  + "_fullTexts" + File.separator;  // It needs the last separator, because of how the docFiles are named and stored.

        File curAssignmentsDirs = new File(FileUtils.storeDocFilesDir);
        try {
            if ( !curAssignmentsDirs.exists() ) {
                if ( !curAssignmentsDirs.mkdirs() ) {   // Create the directories.
                    String workingDir = System.getProperty("user.dir") + File.separator;
                    logger.error("Could not create the \"assignments_fullTexts directories\": \"" + FileUtils.storeDocFilesDir + "\". Using the \"workingDir\" instead (" + workingDir + ").");
                    FileUtils.storeDocFilesDir = assignmentsBasePath = workingDir;
                }
            }
        } catch (Exception e) {
            String errorMsg = "Failed to create the full-texts directory for assignments_" + assignmentRequestCounter;
            logger.error(errorMsg, e);
            throw new RuntimeException(errorMsg + ": " + e.getMessage());
        }

        // 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, 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;
            });
        }

        int numFailedTasks = LoaderAndChecker.invokeAllTasksAndWait(callableTasks);
        if ( numFailedTasks == -1 ) {   // The unknown exception is logged inside the above method.
            System.err.println("Invoking and/or executing the callableTasks failed with the exception written in the log files!");
            UrlsWorkerApplication.gentleAppShutdown();
        }

        if ( numFailedTasks > 0 )
            logger.warn(numFailedTasks + " tasks failed, from assignments_" + assignmentRequestCounter);

        addUrlReportsToWorkerReport();
        callableTasks.clear(); // Reset the thread-tasks-list for the next batch.

        UrlUtils.docOrDatasetUrlsWithIDs.clear();   // This HashTable is useful only for a single assignments-batch.
        // In the next batch, the previously stored files might have been already uploaded by the Controller and deleted by the worker. Also, they will be stored in a different directory anyway.
    }


    public static void addUrlReportsToWorkerReport()
    {
        Timestamp timestamp = new Timestamp(System.currentTimeMillis()); // Store it here, in order to have the same for all current records.

        for ( DataToBeLogged data : FileUtils.dataToBeLoggedList )
        {
            UrlReport.StatusType status = null;
            String fileLocation = null, comment = data.getComment(), mimeType = null, hash = data.getHash();
            Long size = data.getSize();
            Error error = null;

            if ( "true".equals(data.getWasDocumentOrDatasetAccessible()) )  // The reversed order defends against a potential NPE.
            {
                status = UrlReport.StatusType.accessible;
                if ( comment.startsWith(UrlUtils.alreadyDownloadedFromIDMessage, 0) ) {
                    // The file of this docUrl was already downloaded by another docUrl.
                    int indexOfAlreadyDownloadedFromSourceUrlMessage = comment.indexOf(UrlUtils.alreadyDownloadedFromSourceUrlContinuedMessage);
                    int indexOfAlreadyDownloadedFromSourceUrl = indexOfAlreadyDownloadedFromSourceUrlMessage + UrlUtils.alreadyDownloadedFromSourceUrlContinuedMessage.length();
                    String initialId = comment.substring(UrlUtils.alreadyDownloadedFromIDMessage.length(), indexOfAlreadyDownloadedFromSourceUrlMessage);   // The fileName starts right after the "message".
                    String initialSourceUrl = comment.substring(indexOfAlreadyDownloadedFromSourceUrl);
                    //logger.debug("initialId: " + initialId + " | sourceUrl: " + initialSourceUrl);    // DEBUG!
                    // Search that ID and sourceUrl inside the list, if that instance is the first-found one, then get the file-data (there might be duplicate ID-sourceUrl instances, but only one of them has the file-data).
                    for ( DataToBeLogged data_2 : FileUtils.dataToBeLoggedList ) {
                        if ( data_2.getUrlId().equals(initialId) && (data_2.getSourceUrl().equals(initialSourceUrl))
                                && ! data_2.getComment().startsWith(UrlUtils.alreadyDownloadedFromIDMessage) ) {
                            fileLocation = data_2.getComment();
                            size = data_2.getSize();
                            hash = data_2.getHash();
                            mimeType = "application/pdf";   // TODO - If support is added for other doc-formats other than "pdf", then make sure the "mime_type" is correctly specified.
                            break;
                        }
                    }
                    // In case the "alreadyDownloaded" full-text is not found, we have an error.
                    error = new Error(Error.ErrorType.couldRetry, comment + " | That ID-sourceUrl was not found inside the WorkerReport!"); // We can still try to download it from the found docUrl, in the future.
                }
                else if ( ! comment.equals(HttpConnUtils.docFileNotRetrievedMessage) ) {  // If it was downloaded without an error.
                    fileLocation = comment; // This is the full-file-path.
                    mimeType = "application/pdf";
                } else  // Else the file was not retrieved, so all file-related data are kept "null".
                    error = new Error(Error.ErrorType.couldRetry, comment); // We can still try to download it from the found docUrl, in the future.

                if ( error == null )    // If the file was retrieved, in any time.
                    error = new Error(Error.ErrorType.couldRetry, null);  // We do not want to send a "null" Error-object, since it just adds more complicated handling in the controller..
            }
            else {
                status = UrlReport.StatusType.non_accessible;
                if ( "true".equals(data.getCouldRetry()) )
                    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;

            // Convert "null" strings to actual < null >
            if ( (hash != null) && (hash.equals("null")) )
                hash = null;

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

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


    public static boolean connectWithUrlTest(String urlToCheck) {
        String testID = "testID";
        try {
            return HttpConnUtils.connectAndCheckMimeType(testID, 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(testID, urlToCheck, null, "unreachable", "Discarded at loading time, due to connectivity problems.", null, true, "true", wasUrlValid, "false", "false", couldRetry, null, null);
            return false;
        }
    }
}