#include <set>
#include <vector>
#include <string>
#include <exception>

#if !defined(_WIN32)
#include <signal.h>
#define USE_SIGNAL
#endif

#include <epicsExit.h>
#include <epicsEvent.h>

//! [Headers]
#include <pv/configuration.h>
#include <pv/pvAccess.h>
#include <pv/clientFactory.h>
#include <pv/caProvider.h>
//! [Headers]

namespace pvd = epics::pvData;
namespace pva = epics::pvAccess;

namespace {

epicsEvent done;

#ifdef USE_SIGNAL
void alldone(int num)
{
    (void)num;
    done.signal();
}
#endif

void onthewayout(void* arg) {
    (void)arg;
    std::cout<<"Done\n";
}

struct ChanReq : public pva::ChannelRequester
{
    virtual ~ChanReq() {}

    virtual std::string getRequesterName() { return "ChanReq"; }

    virtual void channelCreated(const epics::pvData::Status& status,
                                pva::Channel::shared_pointer const & channel)
    {
        // called once, recursively during ChannelProvider::createChannel()
        if(!status.isSuccess()) {
            std::cout<<"Oops Connect: "<<status<<"\n";
        } else {
            std::cout<<"Connect: "<<channel->getChannelName()<<"\n";
        }
    }

    virtual void channelStateChange(pva::Channel::shared_pointer const & channel,
                                    pva::Channel::ConnectionState connectionState)
    {
        // Called for each connect/disconnect event, and on shutdown (destroy)
        switch(connectionState) {
        case pva::Channel::NEVER_CONNECTED:
        case pva::Channel::CONNECTED:
        case pva::Channel::DISCONNECTED:
        case pva::Channel::DESTROYED:
            std::cout<<"CHANNEL "<<channel->getChannelName()<<" "<<pva::Channel::ConnectionStateNames[connectionState]<<"\n";
            break;

        default:
            break;
        }
    }
};

struct GetReq : public pva::ChannelGetRequester
{
    virtual ~GetReq() {}

    virtual std::string getRequesterName() { return "GetReq"; }

    virtual void channelGetConnect(
        const epics::pvData::Status& status,
        pva::ChannelGet::shared_pointer const & channelGet,
        pvd::Structure::const_shared_pointer const & structure)
    {
        // Called each time get operation becomes "ready" (channel connected)
        if(status.isSuccess()) {
            std::cout<<"Get execute "<<channelGet->getChannel()->getChannelName()<<"\n";
            // can now execute the get operation
            channelGet->get();
        } else {
            std::cout<<"Oops GetConnect: "<<channelGet->getChannel()->getChannelName()<<" "<<status<<"\n";
        }
    }

    virtual void channelDisconnect(bool destroy) {
        // Called each time operation becomes no "ready" (channel disconnected)
        // same as channelStateChange() for DISCONNECTED and DESTROYED
        std::cout<<"Get disconnected\n";
    }

    virtual void getDone(
        const epics::pvData::Status& status,
        pva::ChannelGet::shared_pointer const & channelGet,
        pvd::PVStructure::shared_pointer const & pvStructure,
        pvd::BitSet::shared_pointer const & bitSet)
    {
        // when execution completes
        if(status.isSuccess()) {
            pvd::PVFieldPtr valfld(pvStructure->getSubField("value"));
            if(!valfld)
                valfld = pvStructure;
            std::cout<<channelGet->getChannel()->getChannelName()<<" : "<<*valfld<<"\n";
        } else {
            std::cout<<"Oops Get: "<<status<<"\n";
        }
    }
};

} // namespace

int main(int argc, char *argv[]) {
    try {
        std::string providerName("pva");
        typedef std::vector<std::string> pvs_t;
        pvs_t pvs;

        for(int i=1; i<argc; i++) {
            if(argv[i][0]=='-') {
                if(strcmp(argv[i], "-P")==0 || strcmp(argv[i], "--provider")==0) {
                    if(i<argc-1) {
                        providerName = argv[i+1];
                    } else {
                        std::cerr << "--provider requires value\n";
                        return 1;
                    }
                } else {
                    std::cerr<<"Unknown argument: "<<argv[i]<<"\n";
                }

            } else {
                pvs.push_back(argv[i]);
            }

        }

        epicsAtExit(&onthewayout, 0);

#ifdef USE_SIGNAL
        signal(SIGINT, alldone);
        signal(SIGTERM, alldone);
        signal(SIGQUIT, alldone);
#endif

        // build "pvRequest" which asks for all fields
        pvd::PVStructure::shared_pointer pvReq(pvd::createRequest("field()"));

        // explicitly select configuration from process environment
        pva::Configuration::shared_pointer conf(pva::ConfigurationBuilder()
                                                .push_env()
                                                .build());

        // add "pva" provider to registry
        pva::ClientFactory::start();
        // add "ca" provider to registry
        pva::ca::CAClientFactory::start();

        std::cout<<"Use provider: "<<providerName<<"\n";
        pva::ChannelProvider::shared_pointer provider(pva::getChannelProviderRegistry()->createProvider(providerName, conf));
        if(!provider)
            throw std::logic_error("pva provider not registered");

        // need to store references to keep get (and channel) from being closed
        typedef std::set<pva::ChannelGet::shared_pointer> gets_t;
        gets_t gets;

        // as we have no channel or operation specific data,
        // use the same requesters for all PVs
        pva::ChannelRequester::shared_pointer chanreq(new ChanReq);
        pva::ChannelGetRequester::shared_pointer getreq(new GetReq);

        for(pvs_t::const_iterator it=pvs.begin(); it!=pvs.end(); ++it) {
            const std::string& pv = *it;

            pva::Channel::shared_pointer chan(provider->createChannel(pv, chanreq));
            // if !chan then channelCreated() called with error status
            if(!chan) continue;

            // no need to wait for connection

            pva::ChannelGet::shared_pointer op(chan->createChannelGet(getreq, pvReq));
            // if !op then channelGetConnect() called with error status
            if(!op) continue;

            gets.insert(op);
            // drop our explicit Channel reference, ChannelGet holds an additional reference
        }

        done.wait();

        return 0;
    } catch(std::exception& e){
        std::cerr<<"Error: "<<e.what()<<"\n";
        return 1;
    }
}