package de.thedevstack.conversationsplus.services.filetransfer;

import java.util.HashMap;
import java.util.Map;
import java.util.SortedSet;
import java.util.TreeSet;

import de.thedevstack.android.logcat.Logging;
import de.thedevstack.conversationsplus.Config;
import de.thedevstack.conversationsplus.entities.Message;
import de.thedevstack.conversationsplus.services.FileTransferService;
import de.thedevstack.conversationsplus.services.filetransfer.http.upload.HttpFileTransferEntity;
import de.thedevstack.conversationsplus.utils.MessageUtil;

/**
 *
 */
public class FileTransferManager implements FileTransferStatusListener {
    private SortedSet<WeightedTransferService> transferServices;
    private static final FileTransferManager INSTANCE = new FileTransferManager();
    private final HashMap<String, WeightedTransferService> activeTransfers = new HashMap<>();

    private FileTransferManager() {
        this.transferServices = new TreeSet<>();
    }

    public static FileTransferManager getInstance() {
        return INSTANCE;
    }

    public static void init(FileTransferService... fileTransferServices) {
        if (null != fileTransferServices && fileTransferServices.length > 0) {
            for (FileTransferService fts : fileTransferServices) {
                addFileTransferService(fts);
            }
        }
    }

    public static void init(HashMap<Integer, FileTransferService> fileTransferServices) {
        for (Map.Entry<Integer, FileTransferService> entry : fileTransferServices.entrySet()) {
            addFileTransferService(entry.getKey(), entry.getValue());
        }
    }

    public static void addFileTransferService(int weight, FileTransferService fts) {
        fts.addFileTransferStatusListener(INSTANCE);
        INSTANCE.transferServices.add(new WeightedTransferService(weight, fts));
    }

    public static void addFileTransferService(FileTransferService fts) {
        int weight = 1;
        if (!INSTANCE.transferServices.isEmpty()) {
            weight = INSTANCE.transferServices.last().weight + 1;
        }
        addFileTransferService(weight, fts);
    }

    /**
     * Transfers a file for the corresponding message.
     *
     * @param message the message containing the file to transfer
     * @return <code>true</code> if the file transfer was successful, <code>false</code> otherwise
     */
    public boolean transferFile(Message message) {
        return this.transferFile(message, false);
    }

    /**
     * Transfers a file for the corresponding message.
     *
     * @param message the message containing the file to transfer
     * @param delay   whether the message is delayed or not
     * @return <code>true</code> if the file transfer was successful, <code>false</code> otherwise
     */
    public boolean transferFile(Message message, boolean delay) {
        Logging.d(Config.LOGTAG, "send file message");
        boolean transferSuccessfullyStarted = false;
        for (WeightedTransferService wts : this.transferServices) {
            try {
                if (wts.fileTransferService.accept(message)) {
                    transferSuccessfullyStarted = this.startFileTransfer(message, delay, wts);
                    if (transferSuccessfullyStarted) {
                        break;
                    }
                }
            } catch (Exception e) {
                //TODO Do real exception handling!!!!!
            }
        }
        return transferSuccessfullyStarted;
    }

    /**
     * Checks whether a message can be sent using this service or not.
     *
     * @param message the message to be checked
     * @return <code>true</code> if the message can be processed, <code>false</code> otherwise
     */
    public boolean accept(Message message) {
        return message.needsUploading();
    }

    @Override
    public void onFailure(FileTransferEntity entity, FileTransferFailureReason failureReason) {
        WeightedTransferService wts = this.activeTransfers.get(entity.getMessage().getUuid());
        if (null == wts) {
            return;
        }
        boolean delayed = (entity instanceof HttpFileTransferEntity) && ((HttpFileTransferEntity) entity).isDelayed();
        if (failureReason.isRecoverable()) {
            wts.fileTransferService.transferFile(entity.getMessage(), delayed);
        } else {
            boolean retransferStarted = false;
            this.activeTransfers.remove(entity.getMessage().getUuid());
            for (WeightedTransferService newWts : this.transferServices.tailSet(wts)) {
                if (newWts == wts) { // Same Reference
                    continue;
                }
                if (newWts.fileTransferService.accept(entity.getMessage())) {
                    retransferStarted = startFileTransfer(entity.getMessage(), delayed, newWts);
                    if (retransferStarted) {
                        break;
                    }
                }
            }
            if (!retransferStarted) {
                MessageUtil.markMessage(entity.getMessage(), Message.STATUS_SEND_FAILED);
            }
        }
    }

    @Override
    public void onCancel(FileTransferEntity entity) {
        this.activeTransfers.remove(entity.getMessage().getUuid());
        MessageUtil.markMessage(entity.getMessage(), Message.STATUS_SEND_FAILED); // TODO New Status CANCELED!
    }

    @Override
    public void onSuccess(FileTransferEntity entity) {
        this.activeTransfers.remove(entity.getMessage().getUuid());
    }

    private boolean startFileTransfer(Message message, boolean delayed, WeightedTransferService wts) {
        boolean transferSuccessfullyStarted = wts.fileTransferService.transferFile(message, delayed);
        if (transferSuccessfullyStarted) {
            this.activeTransfers.put(message.getUuid(), wts);
        }
        return transferSuccessfullyStarted;
    }

    static class WeightedTransferService implements Comparable<WeightedTransferService> {
        int weight;
        FileTransferService fileTransferService;

        WeightedTransferService(int weight, FileTransferService service) {
            this.weight = weight;
            this.fileTransferService = service;
        }

        /**
         * Compares this object to the specified object to determine their relative
         * order.
         *
         * @param another the object to compare to this instance.
         * @return a negative integer if this instance is less than {@code another};
         * a positive integer if this instance is greater than
         * {@code another}; 0 if this instance has the same order as
         * {@code another}.
         * @throws ClassCastException if {@code another} cannot be converted into something
         *                            comparable to {@code this} instance.
         */
        @Override
        public int compareTo(WeightedTransferService another) {
            return this.weight - another.weight;
        }
    }
}