#include "../Shared/TriggerProtocol.h"

#include <windows.h>
#include <wtsapi32.h>

#include <cwchar>
#include <stdlib.h>

namespace
{
    enum class ExitCode : int
    {
        Success = 0,
        ChannelOpenFailed = 10,
        WriteFailed = 11,
        PartialWrite = 12
    };

    void DebugError(const wchar_t* step, DWORD error)
    {
        wchar_t buffer[256]{};
        swprintf_s(buffer, _countof(buffer), L"PlandentRdpClientTrigger: %s fehlgeschlagen, Win32=%lu\n", step, error);
        OutputDebugStringW(buffer);
    }
}

int APIENTRY wWinMain(HINSTANCE, HINSTANCE, PWSTR, int)
{
    // WTS_CURRENT_SESSION stellt sicher, dass ausschließlich der Client der
    // RDP-Sitzung angesprochen wird, in der diese EXE ausgeführt wird.
    HANDLE channel = WTSVirtualChannelOpenEx(
        WTS_CURRENT_SESSION,
        const_cast<LPSTR>(hook::protocol::kChannelName),
        WTS_CHANNEL_OPTION_DYNAMIC | WTS_CHANNEL_OPTION_DYNAMIC_PRI_MED);

    if (channel == nullptr)
    {
        DebugError(L"WTSVirtualChannelOpenEx", GetLastError());
        return static_cast<int>(ExitCode::ChannelOpenFailed);
    }

    ULONG bytesWritten = 0;
    BOOL written = WTSVirtualChannelWrite(
        channel,
        const_cast<PCHAR>(hook::protocol::kStartMessage),
        static_cast<ULONG>(hook::protocol::kStartMessageLength),
        &bytesWritten);

    DWORD writeError = written ? ERROR_SUCCESS : GetLastError();
    WTSVirtualChannelClose(channel);

    if (!written)
    {
        DebugError(L"WTSVirtualChannelWrite", writeError);
        return static_cast<int>(ExitCode::WriteFailed);
    }

    if (bytesWritten != static_cast<ULONG>(hook::protocol::kStartMessageLength))
    {
        OutputDebugStringW(L"PlandentRdpClientTrigger: Trigger-Nachricht wurde nur teilweise geschrieben.\n");
        return static_cast<int>(ExitCode::PartialWrite);
    }

    return static_cast<int>(ExitCode::Success);
}