package de.hftstuttgart.utils;

import de.hftstuttgart.models.ModocotResult;
import de.hftstuttgart.models.ModocotResultSummary;
import de.hftstuttgart.unifiedticketing.core.Filter;
import de.hftstuttgart.unifiedticketing.core.Ticket;
import de.hftstuttgart.unifiedticketing.core.TicketBuilder;
import de.hftstuttgart.unifiedticketing.core.TicketSystem;
import de.hftstuttgart.unifiedticketing.exceptions.UnifiedticketingException;
import org.apache.log4j.LogManager;
import org.apache.log4j.Logger;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

public class UnifiedTicketingUtil {

    private final static Logger LOG = LogManager.getLogger(UnifiedTicketingUtil.class);

    private final static String MODOCOT_LABEL = "MoDoCoT created";
    private final static String MODOCOT_TITLE = " | " + MODOCOT_LABEL;

    public static String createTicketDescriptionFromResult(TicketSystem ts, ModocotResult result, boolean compilationError) {
        StringBuilder sb = new StringBuilder();

        // heading
        if (compilationError) {
            sb.append(String.format("# %s is not compilable", result.name));
        } else {
            sb.append(String.format("# Unittest for %s fails", result.name));
        }

        sb.append("\n\n");

        // meta data table
        sb.append("|||\n");
        sb.append("|:-|:-|\n");

        if (compilationError) {
            sb.append(String.format("|File|`%s`|\n", result.name));
        } else {
            sb.append(String.format("|Test|`%s`|\n", result.name));
        }
        sb.append(String.format("|Reason|`%s`|\n", result.failureReason));

        if (compilationError) {
            sb.append(String.format("|Line|`%s`|\n", result.lineNumber));
            sb.append(String.format("|Column|`%s`|\n", result.columnNumber));
            sb.append(String.format("|Position|`%s`|\n", result.position));
        } else {
            sb.append(String.format("|Type|`%s`|\n", result.failureType));
        }

        sb.append("\n\n");

        // stacktrace
        sb.append("<details>\n\n");
        sb.append("<summary>show stacktrace</summary>\n\n");
        sb.append("```");
        sb.append(result.stacktrace);
        sb.append("\n```");
        sb.append("\n\n</details>\n");

        return sb.toString();
    }

    public static String createTicketTitleFromResult(TicketSystem ts, ModocotResult result, boolean compilationError) {
        StringBuilder sb = new StringBuilder();
        String separator = " | ";

        if (compilationError) sb.append("compilation fails");
        else sb.append("test method fails");
        sb.append(separator);

        sb.append(result.name);

        if (!compilationError) {
            sb.append(separator);
            sb.append(result.failureReason);
        }

        // if label-support is not present, place global identifier into title
        if (!ts.hasLabelSupport()) sb.append(MODOCOT_TITLE);

        sb.append(separator);
        sb.append(getHashForFailure(result));

        return sb.toString();
    }

    public static Ticket createTicketFromResult(TicketSystem ts, ModocotResult result, boolean compilationError) {
        TicketBuilder tb = ts.createTicket()
            .title(createTicketTitleFromResult(ts, result, compilationError))
            .description(createTicketDescriptionFromResult(ts, result, compilationError));

        if (ts.hasLabelSupport()) tb.labels(Collections.singleton(MODOCOT_LABEL));

        return tb.create();
    }

    public static Set<Ticket> fetchExistingModocotTickets(TicketSystem ts) {
        Set<Ticket> ret = new HashSet<>();
        Filter f = ts.find();

        // depending on label support, identify MoDoCoT tickets by label or title containing string
        if (ts.hasLabelSupport()) {
            LOG.debug(String.format(
                "ticketsystem has label support, using label %s to find modocot tickets", MODOCOT_LABEL));
            f.withLabel(MODOCOT_LABEL);
        }
        else {
            LOG.debug(String.format(
                "ticketsystem without labels, searching for ticket titles containing %s", MODOCOT_TITLE));
            f.withTitleContain(MODOCOT_TITLE);
        }

        LOG.debug("prepare pagination cycling");
        // set first page and page size for pagination
        int page = 1;
        int pageSize = 10;
        f.setPageSize(pageSize);
        LOG.debug(String.format("using pagination with %s elements per page", pageSize));
        // declare list for received tickets
        List<Ticket> received;
        // go into do-while to evaluate after receiving if another round is needed
        do {
            LOG.debug(String.format("calling page %s", page));
            f.setPage(page++);
            received = f.get();
            ret.addAll(received);
        } while (f.getLastReceivedItemCount() >= pageSize);

        return ret;
    }

    public static String getHashForFailure(ModocotResult result) {
        MessageDigest digest;

        try {
            digest = MessageDigest.getInstance("SHA-512");
        } catch (NoSuchAlgorithmException e) {
            throw new UnifiedticketingException(e);
        }

        byte[] data = digest.digest(result.name.getBytes(StandardCharsets.UTF_8));
        StringBuilder hexString = new StringBuilder(2 * data.length);
        for (byte character: data)
        {
            String hex = Integer.toHexString(0xff & character);
            if (hex.length() == 1)
            {
                hexString.append('0');
            }
            hexString.append(hex);
        }

        return hexString.substring(hexString.length() - 9, hexString.length() - 1);
    }

    public static void processResult(TicketSystem ts, Set<Ticket> tickets, ModocotResult result, boolean compilationError) {
        LOG.debug(String.format("retrieving hash for %s", result.name));
        String hash = getHashForFailure(result);

        // check if corresponding ticket exists yet, otherwise create new one
        Ticket ticket = tickets.stream()
            .filter(t -> t.getTitle().endsWith(hash))
            .findFirst()
            .orElse(null);

        if (ticket != null) {
            // if yet existing, remove from found list
            LOG.debug("found ticket with matching hash, removing from collection");
            tickets.remove(ticket);
            LOG.debug("updating ticket with new result");
            updateTicketFromResult(ts, ticket, result, compilationError);
        } else {
            LOG.debug("no ticket found, creating new one");
            createTicketFromResult(ts, result, compilationError);
        }
    }

    /**
     * search file for unified-ticketing URI's and report to every set ticket system,
     * not waiting for it to finish and catching an eventually interrupted thread.
     *
     * @param meta student uploaded file
     * @param resultSummary summary from the testrunner container
     */
    public static void reportResults(InputStream meta, ModocotResultSummary resultSummary) {
        try {
            reportResults(meta, resultSummary, false);
        } catch (InterruptedException e) {
            LOG.error(String.format("Unified-Ticketing got interrupted with: %s", e.getMessage()));
        }
    }

    /**
     * report all failures and compilation errors to all configured ticket systems.
     * You can optionally wait for the ticket creation to finish, which is done in a separate thread.
     *
     * @param meta student uploaded file
     * @param resultSummary summary from the testrunner container
     * @param wait if we should block until the ticket creation has finished
     * @throws InterruptedException
     */
    public static void reportResults(InputStream meta, ModocotResultSummary resultSummary, boolean wait) throws InterruptedException {

        LOG.debug("preparing thread for ticket result submitting");
        Thread unifiedTicketingUtil = new Thread(() -> {
            // read student transmitted file
            try (BufferedReader br = new BufferedReader(new InputStreamReader(meta))) {
                String line = null;
                while ((line = br.readLine()) != null) {
                    TicketSystem ts = null;

                    // try each line as URI for a unified-ticketing instantiation
                    try {
                        ts = TicketSystem.fromUri(line);
                        LOG.info(String.format("ticket system for reporting found: %s", ts.baseUrl));
                    } catch (UnifiedticketingException e) {
                        // ignore if line didn't match a unified-ticketing URI
                    }

                    // if a ticketsystem got instantiated, start the submission.
                    // If errors occur, log it this time.
                    try {
                        if (ts != null) reportToTicketsystem(ts, resultSummary);
                    } catch (UnifiedticketingException e) {
                        LOG.warn(String.format(
                            "reporting fails to ticketsystem %s failed with: ",
                            ts.baseUrl,
                            e.getMessage()));
                    }
                }
            } catch (IOException e) {
                LOG.error(String.format("couldn't read config to find lines for ticket reporting: %s", e.getMessage()));
            }
        });

        LOG.debug("starting ticket submitting thread");
        unifiedTicketingUtil.start();

        if (wait) {
            LOG.debug("wait for ticket submission completion");
            unifiedTicketingUtil.join();
        } else {
            LOG.debug("tickets will be submitted in background");
        }
    }

    public static void reportToTicketsystem(TicketSystem ts, ModocotResultSummary resultSummary) {
        // tickets existing yet
        LOG.debug("fetching existing tickets");
        Set<Ticket> tickets = fetchExistingModocotTickets(ts);

        // for each fail or compile error
        LOG.debug("start failed tests reporting");
        resultSummary.failures.forEach(f -> processResult(ts, tickets, f, false));
        LOG.debug("start compilation errors reporting");
        resultSummary.compilationErrors.forEach(c -> processResult(ts, tickets, c, true));

        LOG.debug("closing all remaining tickets, no longer appeared");
        tickets.forEach(ticket -> ticket.close().save());
    }

    public static Ticket updateTicketFromResult(TicketSystem ts, Ticket ticket, ModocotResult result, boolean compilationError) {
        ticket
            .open()
            .setTitle(createTicketTitleFromResult(ts, result, compilationError))
            .setDescription(createTicketDescriptionFromResult(ts, result, compilationError));
        if (ts.hasLabelSupport()) ticket.addLabel(MODOCOT_LABEL);

        return ticket.save();
    }
}