/*
 * =====================================================================================
 *
 *       Filename:  pubsub.cpp
 *
 *    Description:  
 *
 *        Version:  1.0
 *        Created:  2021年03月24日 18时44分13秒
 *       Revision:  none
 *       Compiler:  gcc
 *
 *         Author:  Li Chao (), 
 *   Organization:  
 *
 * =====================================================================================
 */
#include "pubsub.h"
#include <chrono>
#include "bh_util.h"
#include "defs.h"

namespace bhome_shm {

using namespace std::chrono_literals;
const int kMaxWorker = 16;
using namespace bhome_msg;

BusManager::BusManager(SharedMemory &shm):
shm_(shm),
busq_(kBHBusQueueId, shm, 1000),
run_(false)
{
}
	
BusManager::~BusManager()
{
    Stop();
}

bool BusManager::Start(const int nworker)
{
    std::lock_guard<std::mutex> guard(mutex_);
    StopNoLock();
    // start
    auto Worker = [&](){
        while (this->run_) {
            BusManager &self = *this;
            BHMsg msg;
            const int timeout_ms = 100;
            if (self.busq_.Recv(msg, timeout_ms)) {
                self.OnMsg(msg);
            }
        }
    };

    run_.store(true);
    const int n = std::min(nworker, kMaxWorker);
    for (int i = 0; i < n; ++i) {
        workers_.emplace_back(Worker);
    }
    return true;
}

bool BusManager::Stop()
{
    std::lock_guard<std::mutex> guard(mutex_);
    return StopNoLock();
}

bool BusManager::StopNoLock()
{
    if (run_.exchange(false)) {
        for (auto &w: workers_) {
            if (w.joinable()) {
                w.join();
            }
        }
        return true;
    }    
    return false;
}

void BusManager::OnMsg(const BHMsg &msg)
{
    auto OnSubChange = [&](auto &&update) {
        DataSub sub;
        if (!msg.route().empty() && sub.ParseFromString(msg.body()) && !sub.topics().empty()) {
            assert(sizeof(MQId) == msg.route(0).mq_id().size());
            MQId client;
            memcpy(&client, msg.route(0).mq_id().data(), sizeof(client));

            std::lock_guard<std::mutex> guard(mutex_);
            auto &topics = sub.topics();
            for (auto &topic : topics) {
                try {
                    update(topic, client);
                } catch(...) {
                    //TODO log error
                }
            }
        }
    };

    auto Sub1 = [this](const std::string &topic, const MQId &id) {
        records_[topic].insert(id);
    };

    auto Unsub1 = [this](const std::string &topic, const MQId &id) {
        auto pos = records_.find(topic);
        if (pos != records_.end()) {
            if (pos->second.erase(id) && pos->second.empty()) {
                records_.erase(pos);
            }
        }
    };

    auto OnPublish = [&]() {
        DataPub pub;
        MsgI pubmsg;
        if (!pub.ParseFromString(msg.body()) || !pubmsg.MakeRC(shm_, msg)) {
            return;
        }
        DEFER1(pubmsg.Release(shm_));

        std::lock_guard<std::mutex> guard(mutex_);
        auto pos = records_.find(pub.topic());
        if (pos != records_.end() && !pos->second.empty()) {
            auto &clients = pos->second;
            for (auto &cli : clients) {
                busq_.Send(cli, pubmsg, 100);
            }
        } else {
            // printf("invalid topic: %s\n", pub.topic().c_str());
        }
    };

    switch (msg.type()) {
        case kMsgTypeSubscribe: OnSubChange(Sub1); break;
        case kMsgTypeUnsubscribe: OnSubChange(Unsub1); break;
        case kMsgTypePublish : OnPublish(); break;
        default: break;
    }
}

} // namespace bhome_shm