/*==LICENSE==*

CyanWorlds.com Engine - MMOG client, server and tools
Copyright (C) 2011 Cyan Worlds, Inc.

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.

Additional permissions under GNU GPL version 3 section 7

If you modify this Program, or any covered work, by linking or
combining it with any of RAD Game Tools Bink SDK, Autodesk 3ds Max SDK,
NVIDIA PhysX SDK, Microsoft DirectX SDK, OpenSSL library, Independent
JPEG Group JPEG library, Microsoft Windows Media SDK, or Apple QuickTime SDK
(or a modified version of those libraries),
containing parts covered by the terms of the Bink SDK EULA, 3ds Max EULA,
PhysX SDK EULA, DirectX SDK EULA, OpenSSL and SSLeay licenses, IJG
JPEG Library README, Windows Media SDK EULA, or QuickTime SDK EULA, the
licensors of this Program grant you additional
permission to convey the resulting work. Corresponding Source for a
non-source form of such a combination shall include the source code for
the parts of OpenSSL and IJG JPEG Library used as well as that of the covered
work.

You can contact Cyan Worlds, Inc. by email legal@cyan.com
 or by snail mail at:
      Cyan Worlds, Inc.
      14617 N Newport Hwy
      Mead, WA   99021

*==LICENSE==*/
/*****************************************************************************
*
*   $/Plasma20/Sources/Plasma/NucleusLib/pnAsyncCoreExe/Private/Win32/pnAceW32Dns.cpp
*   
***/

#include "../../Pch.h"
#pragma hdrstop


/*****************************************************************************
*
*   Private
*
***/

enum {
    WM_LOOKUP_EXIT = WM_APP,
    WM_LOOKUP_FOUND_HOST
};

const unsigned kMaxLookupName = 128;

struct Lookup {
    LINK(Lookup)        link;
    AsyncCancelId       cancelId;
    HANDLE              cancelHandle;
    FAsyncLookupProc    lookupProc;
    unsigned            port;
    void *              param;
    wchar               name[kMaxLookupName];
    char                buffer[MAXGETHOSTSTRUCT];
};

static CCritSect                s_critsect;
static LISTDECL(Lookup, link)   s_lookupList;
static HANDLE                   s_lookupThread;
static HWND                     s_lookupWindow;
static unsigned                 s_nextLookupCancelId = 1;


/*****************************************************************************
*
*   Internal functions
*
***/

//===========================================================================
static void LookupProcess (Lookup * lookup, unsigned error) {
    unsigned count      = 0;
    NetAddress * addrs  = nil;
    for (ONCE) {
        if (error)
            break;

        const HOSTENT & host = * (HOSTENT *) lookup->buffer;
        if (host.h_addrtype != AF_INET)
            break;
        if (host.h_length != sizeof(in_addr))
            break;
        if (!host.h_addr_list)
            break;

        in_addr const * const * const inAddr = (in_addr **) host.h_addr_list;

        // count the number of addresses
        while (inAddr[count])
            ++count;

        // allocate a buffer large enough to hold all the addresses
        addrs = (NetAddress *) _alloca(sizeof(*addrs) * count);
        MemZero(addrs, sizeof(*addrs) * count);

        // fill in address data
        const word port = htons((word) lookup->port);
        for (unsigned i = 0; i < count; ++i) {
            sockaddr_in * inetaddr = (sockaddr_in *) &addrs[i];
            inetaddr->sin_family    = AF_INET;
            inetaddr->sin_addr      = *inAddr[i];
            inetaddr->sin_port      = port;
        }

        if (host.h_name && host.h_name[0])
            StrToUnicode(lookup->name, host.h_name, arrsize(lookup->name));
    }

    if (lookup->lookupProc)
        lookup->lookupProc(lookup->param, lookup->name, count, addrs);

    // we can delete the operation outside an IoConn critical
    // section because it isn't linked into an ioConn opList
    // and because connection attempts are not waitable
    ASSERT(!lookup->link.IsLinked());
    DEL(lookup);
    PerfSubCounter(kAsyncPerfNameLookupAttemptsCurr, 1);
}

//===========================================================================
static void LookupFindAndProcess (HANDLE cancelHandle, unsigned error) {
    // find the operation for this cancel handle
    Lookup * lookup;
    s_critsect.Enter();
    for (lookup = s_lookupList.Head(); lookup; lookup = s_lookupList.Next(lookup)) {
        if (lookup->cancelHandle == cancelHandle) {
            lookup->cancelHandle = nil;
            s_lookupList.Unlink(lookup);
            break;
        }
    }
    s_critsect.Leave();
    if (lookup)
        LookupProcess(lookup, error);
}

//===========================================================================
static unsigned THREADCALL LookupThreadProc (AsyncThread * thread) {
    static const char WINDOW_CLASS[] = "AsyncLookupWnd";
    WNDCLASS wc;
    ZERO(wc);
    wc.lpfnWndProc      = DefWindowProc;
    wc.hInstance        = GetModuleHandle(0);
    wc.lpszClassName    = WINDOW_CLASS;
    RegisterClass(&wc);

    s_lookupWindow = CreateWindow(
        WINDOW_CLASS,
        WINDOW_CLASS,
        WS_OVERLAPPED,
        CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, 
        (HWND)0,
        (HMENU) 0,
        wc.hInstance,
        0
    );
    if (!s_lookupWindow)
        ErrorFatal(__LINE__, __FILE__, "CreateWindow %#x", GetLastError());

    HANDLE lookupStartEvent = (HANDLE) thread->argument;
    SetEvent(lookupStartEvent);

    MSG msg;
    while (GetMessage(&msg, s_lookupWindow, 0, 0)) {
        if (msg.message == WM_LOOKUP_FOUND_HOST)
            LookupFindAndProcess((HANDLE) msg.wParam, HIWORD(msg.lParam));
        else if (msg.message == WM_LOOKUP_EXIT)
            break;
        else {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
    }

    // fail all pending name lookups
    for (;;) {
        s_critsect.Enter();
        Lookup * lookup = s_lookupList.Head();
        if (lookup) {
            WSACancelAsyncRequest(lookup->cancelHandle);
            lookup->cancelHandle = nil;
            s_lookupList.Unlink(lookup);
        }
        s_critsect.Leave();
        if (!lookup)
            break;

        LookupProcess(lookup, (unsigned) -1);
    }

    // cleanup
    DestroyWindow(s_lookupWindow);
    s_lookupWindow = nil;

    return 0;
}

//===========================================================================
static void StartLookupThread () {
    if (s_lookupThread)
        return;

    // create a shutdown event
    HANDLE lookupStartEvent = CreateEvent(
        (LPSECURITY_ATTRIBUTES) 0,
        true,           // manual reset
        false,          // initial state off
        (LPCTSTR) 0     // name
    );
    if (!lookupStartEvent)
        ErrorFatal(__LINE__, __FILE__, "CreateEvent %#x", GetLastError());

    // create a thread to perform lookups
    s_lookupThread = (HANDLE) AsyncThreadCreate(
        LookupThreadProc,
        lookupStartEvent,
        L"AsyncLookupThread"
    );

    WaitForSingleObject(lookupStartEvent, INFINITE);
    CloseHandle(lookupStartEvent);
    ASSERT(s_lookupWindow);
}


/*****************************************************************************
*
*   Module functions
*
***/

//===========================================================================
void DnsDestroy (unsigned exitThreadWaitMs) {
    if (s_lookupThread) {
        PostMessage(s_lookupWindow, WM_LOOKUP_EXIT, 0, 0);
        WaitForSingleObject(s_lookupThread, exitThreadWaitMs);
        CloseHandle(s_lookupThread);
        s_lookupThread = nil;
        ASSERT(!s_lookupWindow);
    }
}


/*****************************************************************************
*
*   Public functions
*
***/

//===========================================================================
void AsyncAddressLookupName (
    AsyncCancelId *     cancelId,   // out
    FAsyncLookupProc    lookupProc,
    const wchar         name[], 
    unsigned            port, 
    void *              param
) {
    ASSERT(lookupProc);
    ASSERT(name);

    PerfAddCounter(kAsyncPerfNameLookupAttemptsCurr, 1);
    PerfAddCounter(kAsyncPerfNameLookupAttemptsTotal, 1);

    // Get name/port
    char ansiName[kMaxLookupName];
    StrToAnsi(ansiName, name, arrsize(ansiName));
    if (char * portStr = StrChr(ansiName, ':')) {
        if (unsigned newPort = StrToUnsigned(portStr + 1, nil, 10))
            port = newPort;
        *portStr = 0;
    }

    // Initialize lookup
    Lookup * lookup         = NEW(Lookup);
    lookup->lookupProc      = lookupProc;
    lookup->port            = port;
    lookup->param           = param;
    StrCopy(lookup->name, name, arrsize(lookup->name));

    s_critsect.Enter();
    {
        // Start the lookup thread if it wasn't started already
        StartLookupThread();
        s_lookupList.Link(lookup);

        // get cancel id; we can avoid checking for zero by always using an odd number
        ASSERT(s_nextLookupCancelId & 1);
        s_nextLookupCancelId += 2;
        *cancelId = lookup->cancelId = (AsyncCancelId) s_nextLookupCancelId;

        // Perform async lookup
        lookup->cancelHandle = WSAAsyncGetHostByName(
            s_lookupWindow, 
            WM_LOOKUP_FOUND_HOST,
            ansiName,
            &lookup->buffer[0],
            sizeof(lookup->buffer)
        );
        if (!lookup->cancelHandle) {
            PostMessage(s_lookupWindow, WM_LOOKUP_FOUND_HOST, nil, (unsigned) -1);
        }
    }
    s_critsect.Leave();
}

//===========================================================================
void AsyncAddressLookupAddr (
    AsyncCancelId *     cancelId,   // out
    FAsyncLookupProc    lookupProc,
    const NetAddress &  address,
    void *              param
) {
    ASSERT(lookupProc);

    PerfAddCounter(kAsyncPerfNameLookupAttemptsCurr, 1);
    PerfAddCounter(kAsyncPerfNameLookupAttemptsTotal, 1);

    // Initialize lookup
    Lookup * lookup         = NEW(Lookup);
    lookup->lookupProc      = lookupProc;
    lookup->port            = 1;
    lookup->param           = param;
    NetAddressToString(
        address,
        lookup->name,
        arrsize(lookup->name),
        kNetAddressFormatNodeNumber
    );
        
    s_critsect.Enter();
    {
        // Start the lookup thread if it wasn't started already
        StartLookupThread();
        s_lookupList.Link(lookup);

        // get cancel id; we can avoid checking for zero by always using an odd number
        ASSERT(s_nextLookupCancelId & 1);
        s_nextLookupCancelId += 2;
        *cancelId = lookup->cancelId = (AsyncCancelId) s_nextLookupCancelId;

        // Perform async lookup
        u_long addr = ((const sockaddr_in *) &address)->sin_addr.S_un.S_addr;
        lookup->cancelHandle = WSAAsyncGetHostByAddr(
            s_lookupWindow, 
            WM_LOOKUP_FOUND_HOST,
            (const char *) &addr,
            sizeof(addr),
            AF_INET,
            &lookup->buffer[0],
            sizeof(lookup->buffer)
        );
        if (!lookup->cancelHandle) {
            PostMessage(s_lookupWindow, WM_LOOKUP_FOUND_HOST, nil, (unsigned) -1);
        }
    }
    s_critsect.Leave();
}

//===========================================================================
void AsyncAddressLookupCancel (
    FAsyncLookupProc    lookupProc,
    AsyncCancelId       cancelId        // nil = cancel all with specified lookupProc
) {
    s_critsect.Enter();
    for (Lookup * lookup = s_lookupList.Head(); lookup; lookup = s_lookupList.Next(lookup)) {
        if (lookup->lookupProc && (lookup->lookupProc != lookupProc))
            continue;
        if (cancelId && (lookup->cancelId != cancelId))
            continue;
        if (!lookup->cancelHandle)
            continue;

        // cancel this request
        WSACancelAsyncRequest(lookup->cancelHandle);
        lookup->cancelHandle = nil;

        // initiate user callback
        PostMessage(s_lookupWindow, WM_LOOKUP_FOUND_HOST, nil, (unsigned) -1);
    }
    s_critsect.Leave();
}