package io.moquette.spi.impl;

import io.moquette.parser.proto.messages.AbstractMessage;
import io.moquette.parser.proto.messages.PublishMessage;
import io.moquette.server.ConnectionDescriptor;
import io.moquette.spi.ClientSession;
import io.moquette.spi.IMessagesStore;
import io.moquette.spi.ISessionsStore;
import io.moquette.spi.MessageGUID;
import io.moquette.spi.impl.subscriptions.Subscription;
import io.netty.channel.Channel;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.nio.ByteBuffer;
import java.util.List;
import java.util.concurrent.ConcurrentMap;

import static io.moquette.spi.impl.ProtocolProcessor.lowerQosToTheSubscriptionDesired;

class Qos1Publisher {

    private static final Logger LOG = LoggerFactory.getLogger(Qos1Publisher.class);
    private final ConcurrentMap<String, ConnectionDescriptor> connectionDescriptors;
    private final ISessionsStore m_sessionsStore;
    private final IMessagesStore m_messagesStore;

    public Qos1Publisher(ConcurrentMap<String, ConnectionDescriptor> connectionDescriptors, ISessionsStore sessionsStore,
                         IMessagesStore messagesStore) {
        this.connectionDescriptors = connectionDescriptors;
        this.m_sessionsStore = sessionsStore;
        m_messagesStore = messagesStore;
    }

    void publish2Subscribers_qos1(IMessagesStore.StoredMessage pubMsg, List<Subscription> topicMatchingSubscriptions) {
        final String topic = pubMsg.getTopic();
        final AbstractMessage.QOSType publishingQos = pubMsg.getQos();
        final ByteBuffer origMessage = pubMsg.getMessage();

        //if QoS 1 or 2 store the message
        MessageGUID guid = m_messagesStore.storePublishForFuture(pubMsg);

        LOG.trace("Found {} matching subscriptions to <{}>", topicMatchingSubscriptions.size(), topic);
        for (final Subscription sub : topicMatchingSubscriptions) {
            AbstractMessage.QOSType qos = lowerQosToTheSubscriptionDesired(sub, publishingQos);
            ClientSession targetSession = m_sessionsStore.sessionForClient(sub.getClientId());

            boolean targetIsActive = this.connectionDescriptors.containsKey(sub.getClientId());

            LOG.debug("Broker republishing to client <{}> topic <{}> qos <{}>, active {}",
                    sub.getClientId(), sub.getTopicFilter(), qos, targetIsActive);
            ByteBuffer message = origMessage.duplicate();
            if (qos == AbstractMessage.QOSType.MOST_ONE && targetIsActive) {
                //QoS 0
                publishQos1(targetSession, topic, qos, message, false, null);
            } else {
                //QoS 1 or 2
                //if the target subscription is not clean session and is not connected => store it
                if (!targetSession.isCleanSession() && !targetIsActive) {
                    //store the message in targetSession queue to deliver
                    targetSession.enqueueToDeliver(guid);
                } else {
                    //publish
                    if (targetIsActive) {
                        int messageId = targetSession.nextPacketId();
                        targetSession.inFlightAckWaiting(guid, messageId);
                        publishQos1(targetSession, topic, qos, message, false, messageId);
                    }
                }
            }
        }
    }

    private void publishQos1(ClientSession clientsession, String topic, AbstractMessage.QOSType qos,
                             ByteBuffer message, boolean retained, Integer messageID) {
        String clientId = clientsession.clientID;
        LOG.debug("directSend invoked clientId <{}> on topic <{}> QoS {} retained {} messageID {}",
                clientId, topic, qos, retained, messageID);
        PublishMessage pubMessage = new PublishMessage();
        pubMessage.setRetainFlag(retained);
        pubMessage.setTopicName(topic);
        pubMessage.setQos(qos);
        pubMessage.setPayload(message);

        LOG.info("send publish message to <{}> on topic <{}>", clientId, topic);
        if (LOG.isDebugEnabled()) {
            LOG.debug("content <{}>", DebugUtils.payload2Str(message));
        }
        //set the PacketIdentifier only for QoS > 0
        if (pubMessage.getQos() != AbstractMessage.QOSType.MOST_ONE) {
            pubMessage.setMessageID(messageID);
        } else {
            if (messageID != null) {
                throw new RuntimeException("Internal bad error, trying to forwardPublish a QoS 0 message " +
                        "with PacketIdentifier: " + messageID);
            }
        }

        if (connectionDescriptors == null) {
            throw new RuntimeException("Internal bad error, found connectionDescriptors to null while it should be " +
                    "initialized, somewhere it's overwritten!!");
        }
        if (connectionDescriptors.get(clientId) == null) {
            //TODO while we were publishing to the target client, that client disconnected,
            // could happen is not an error HANDLE IT
            throw new RuntimeException(String.format("Can't find a ConnectionDescriptor for client <%s> in cache <%s>",
                    clientId, connectionDescriptors));
        }
        Channel channel = connectionDescriptors.get(clientId).channel;
        LOG.trace("Session for clientId {}", clientId);
        if (channel.isWritable()) {
            LOG.debug("channel is writable");
            //if channel is writable don't enqueue
            channel.writeAndFlush(pubMessage);
        } else {
            //enqueue to the client session
            LOG.debug("enqueue to client session");
            clientsession.enqueue(pubMessage);
        }
    }
}