#include <WS2tcpip.h>
#include <windows.h>
#include <mswsock.h>
#include <process.h>
#include <stdio.h>
#include <exception>


using std::exception;


#pragma comment(lib, "ws2_32")
#pragma comment(lib, "mswsock")


enum EIoType
{
    eIoType_Send,
    eIoType_Recv
};


struct SIoContext
{
    SIoContext() : sock(INVALID_SOCKET), eIoType(eIoType_Send)
    {
        memset(&OverLapped, 0, sizeof OverLapped);
        wsBuff.buf = buff;
        wsBuff.len = sizeof buff;
    }

    OVERLAPPED OverLapped;
    SOCKET sock;
    WSABUF wsBuff;
    char buff[65536];
    EIoType eIoType;
};


void InitNetEnvironment()
{
    WSAData wsaData;
    if (0 == WSAStartup(MAKEWORD(2, 2), &wsaData)
        && wsaData.wVersion == 0x202)
    {
        return;
    }

    throw("網絡初始化失敗");
}


unsigned int __stdcall ThdDeal(void* pVoid);


int main()
{
    InitNetEnvironment();

    SOCKET sockSrv = socket(AF_INET, SOCK_STREAM, 0);
    if (INVALID_SOCKET == sockSrv)
    {
        throw(exception("監聽套接字初始化失敗"));
    }

    sockaddr_in sockAddr = {};
    sockAddr.sin_family = AF_INET;
    sockAddr.sin_port = htons(8000);
    if (1 != inet_pton(AF_INET, "192.168.0.51",
        &sockAddr.sin_addr.s_addr))
    {
        throw(exception("監聽套接字地址初始化失敗"));

    }

    if (SOCKET_ERROR == bind(sockSrv,
        reinterpret_cast<sockaddr*>(&sockAddr), sizeof sockaddr))
    {
        throw(exception("監聽套接字bind失敗"));

    }

    if (SOCKET_ERROR == listen(sockSrv, 100))
    {
        throw(exception("監聽套接字listen失敗"));

    }

    HANDLE hIoCmp = 
        CreateIoCompletionPort(INVALID_HANDLE_VALUE, nullptr, 0, 1);
    if (NULL == hIoCmp)
    {
        throw(exception("創建IO完成端口失敗"));
    }

    for (int i = 0; i < 4; ++i)
    {
        CloseHandle(reinterpret_cast<HANDLE>
            (_beginthreadex(nullptr, 0, ThdDeal, hIoCmp, 0, nullptr)));
    }

    while (true)
    {
        SIoContext* pIoContext = new SIoContext();

        pIoContext->sock = accept(sockSrv, nullptr, nullptr);
        if (INVALID_SOCKET == pIoContext->sock)
        {
            throw(exception("創建套接字失敗"));
        }

        CreateIoCompletionPort(reinterpret_cast<HANDLE>(pIoContext->sock),
            hIoCmp, reinterpret_cast<ULONG_PTR>(pIoContext), 0);

        DWORD nFlag = 0;
        pIoContext->eIoType = eIoType_Recv;
        WSARecv(pIoContext->sock, &pIoContext->wsBuff, 1, nullptr, &nFlag,
            &pIoContext->OverLapped, NULL);
    }

    return 0;
}


unsigned int __stdcall ThdDeal(void* pVoid)
{
    HANDLE hIoCmp = static_cast<HANDLE>(pVoid);

    DWORD nSize = 0;
    ULONG_PTR nCmpKey = 0;
    LPOVERLAPPED pOverLapped = nullptr;

    while (true)
    {
        if (GetQueuedCompletionStatus(hIoCmp, &nSize, &nCmpKey,
            &pOverLapped, INFINITE))
        {
            SIoContext* pIoContext =
                reinterpret_cast<SIoContext*>(nCmpKey);

            if (eIoType_Recv == pIoContext->eIoType)
            {
                pIoContext->eIoType = eIoType_Send;
                pIoContext->wsBuff.len = static_cast<unsigned long>
                    (pIoContext->OverLapped.InternalHigh);

                if (pIoContext->wsBuff.len)
                {
                    WSASend(pIoContext->sock, &pIoContext->wsBuff, 1,
                        nullptr, 0, &pIoContext->OverLapped, nullptr);
                }
                else
                {
                    closesocket(pIoContext->sock);
                    delete pIoContext;
                }
            }
            else
            {
                printf("Same Data Send to Client, Continue To Recv\n");

                DWORD nFlag = 0;
                pIoContext->eIoType = eIoType_Recv;
                pIoContext->wsBuff.len = sizeof pIoContext->buff;
                WSARecv(pIoContext->sock, &pIoContext->wsBuff, 1, nullptr,
                    &nFlag, &pIoContext->OverLapped, NULL);
            }
        }
    }

    return 0;
}