/**
 * Copyright - See the COPYRIGHT that is included with this distribution.
 * pvAccessCPP is distributed subject to a Software License Agreement found
 * in file LICENSE that is included with this distribution.
 */

#include <pv/blockingTCP.h>
#include <pv/remote.h>
#include <pv/namedLockPattern.h>
#include <pv/logger.h>
#include <pv/codec.h>

#include <epicsThread.h>
#include <osiSock.h>

#include <sys/types.h>
#include <sstream>

using namespace epics::pvData;

namespace epics {
    namespace pvAccess {

        BlockingTCPConnector::BlockingTCPConnector(
                Context::shared_pointer const & context,
                int receiveBufferSize,
                float heartbeatInterval) :
            _context(context),
            _namedLocker(),
            _receiveBufferSize(receiveBufferSize),
            _heartbeatInterval(heartbeatInterval)
        {
        }

        BlockingTCPConnector::~BlockingTCPConnector() {
        }

        SOCKET BlockingTCPConnector::tryConnect(osiSockAddr& address, int tries) {
            
            char strBuffer[64];
            ipAddrToDottedIP(&address.ia, strBuffer, sizeof(strBuffer));

            for(int tryCount = 0; tryCount<tries; tryCount++) {

                LOG(logLevelDebug,
                        "Opening socket to PVA server %s, attempt %d.",
                        strBuffer, tryCount+1);

                SOCKET socket = epicsSocketCreate(AF_INET, SOCK_STREAM, IPPROTO_TCP);
                if (socket == INVALID_SOCKET)
                {
                    epicsSocketConvertErrnoToString(strBuffer, sizeof(strBuffer));
                    LOG(logLevelWarn, "Socket create error: %s.", strBuffer);
                    return INVALID_SOCKET;
                }
                else {
                    if(::connect(socket, &address.sa, sizeof(sockaddr))==0) {
                        return socket;
                    }
                    else {
                        epicsSocketDestroy (socket);
                        epicsSocketConvertErrnoToString(strBuffer, sizeof(strBuffer));
                        LOG(logLevelDebug, "Socket connect error: %s.", strBuffer);
                    }
                }
            }
            return INVALID_SOCKET;
        }

        Transport::shared_pointer BlockingTCPConnector::connect(TransportClient::shared_pointer const & client,
                std::auto_ptr<ResponseHandler>& responseHandler, osiSockAddr& address,
                int8 transportRevision, int16 priority) {

            SOCKET socket = INVALID_SOCKET;

            char ipAddrStr[64];
            ipAddrToDottedIP(&address.ia, ipAddrStr, sizeof(ipAddrStr));
            
            Context::shared_pointer context = _context.lock();

            // first try to check cache w/o named lock...
            Transport::shared_pointer transport = context->getTransportRegistry()->get("TCP", &address, priority);
            if(transport.get()) {
                LOG(logLevelDebug,
                    "Reusing existing connection to PVA server: %s.",
                    ipAddrStr);
                if (transport->acquire(client))
                    return transport;
            }

            bool lockAcquired = _namedLocker.acquireSynchronizationObject(&address, LOCK_TIMEOUT);
            if(lockAcquired) {
                try {
                    // ... transport created during waiting in lock
                    transport = context->getTransportRegistry()->get("TCP", &address, priority);
                    if(transport.get()) {
                        LOG(logLevelDebug,
                            "Reusing existing connection to PVA server: %s.",
                            ipAddrStr);
                        if (transport->acquire(client))
                            return transport;
                    }

                    LOG(logLevelDebug, "Connecting to PVA server: %s.", ipAddrStr);

                    socket = tryConnect(address, 3);
                    
                    // verify
                    if(socket==INVALID_SOCKET) {
                        LOG(logLevelDebug,
                                "Connection to PVA server %s failed.", ipAddrStr);
                        std::ostringstream temp;
                        temp<<"Failed to verify TCP connection to '"<<ipAddrStr<<"'.";
                        THROW_BASE_EXCEPTION(temp.str().c_str());
                    }

                    LOG(logLevelDebug, "Socket connected to PVA server: %s.", ipAddrStr);

                    // enable TCP_NODELAY (disable Nagle's algorithm)
                    int optval = 1; // true
                    int retval = ::setsockopt(socket, IPPROTO_TCP, TCP_NODELAY,
                                              (char *)&optval, sizeof(int));
                    if(retval<0) {
                        char errStr[64];
                        epicsSocketConvertErrnoToString(errStr, sizeof(errStr));
                        LOG(logLevelWarn, "Error setting TCP_NODELAY: %s.", errStr);
                    }
                    
                    // enable TCP_KEEPALIVE
                    retval = ::setsockopt(socket, SOL_SOCKET, SO_KEEPALIVE,
                                          (char *)&optval, sizeof(int));
                    if(retval<0) 
                    {
                        char errStr[64];
                        epicsSocketConvertErrnoToString(errStr, sizeof(errStr));
                        LOG(logLevelWarn, "Error setting SO_KEEPALIVE: %s.", errStr);
                    }
                    
                    // TODO tune buffer sizes?! Win32 defaults are 8k, which is OK

                    // create transport
                    // TODO introduce factory
                    // get TCP send buffer size
                    osiSocklen_t intLen = sizeof(int);
                    int _socketSendBufferSize;
                    retval = getsockopt(socket, SOL_SOCKET, SO_SNDBUF, (char *)&_socketSendBufferSize, &intLen);
                    if(retval<0) {
                        char strBuffer[64];
                        epicsSocketConvertErrnoToString(strBuffer, sizeof(strBuffer));
                        LOG(logLevelDebug, "Error getting SO_SNDBUF: %s.", strBuffer);
                    }

                    transport = detail::BlockingClientTCPTransportCodec::create(
                                            context, socket, responseHandler, _receiveBufferSize, _socketSendBufferSize,
                                            client, transportRevision, _heartbeatInterval, priority);

                    // verify
                    if(!transport->verify(5000)) {
                        LOG(
                                logLevelDebug,
                                "Connection to PVA server %s failed to be validated, closing it.",
                                ipAddrStr);

                        std::ostringstream temp;
                        temp<<"Failed to verify TCP connection to '"<<ipAddrStr<<"'.";
                        THROW_BASE_EXCEPTION(temp.str().c_str());
                    }

                    LOG(logLevelDebug, "Connected to PVA server: %s.", ipAddrStr);

                    _namedLocker.releaseSynchronizationObject(&address);
                    return transport;
                } catch(std::exception&) {
                    if(transport.get())
                        transport->close();
                    else if(socket!=INVALID_SOCKET) epicsSocketDestroy(socket);
                    _namedLocker.releaseSynchronizationObject(&address);
                    throw;
                } catch(...) {
                    if(transport.get())
                        transport->close();
                    else if(socket!=INVALID_SOCKET) epicsSocketDestroy(socket);
                    _namedLocker.releaseSynchronizationObject(&address);
                    throw;
                }
            }
            else {
                std::ostringstream temp;
                temp<<"Failed to obtain synchronization lock for '"<<ipAddrStr;
                temp<<"', possible deadlock.";
                THROW_BASE_EXCEPTION(temp.str().c_str());
            }
        }

    }
}