// ClipboardTest.cpp
//

#ifndef UNICODE
#define UNICODE
#endif 

#include <windows.h>
#include <iostream>

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam);

int main()
{
    std::cout << "Process ID = " << GetCurrentProcessId() << std::endl;

    WNDCLASS wc = {};
    wc.lpfnWndProc = WindowProc;
    wc.hInstance = GetModuleHandle(NULL);
    wc.lpszClassName = TEXT("ClipboardTestClass");
    if (!RegisterClass(&wc)) {
        std::cerr << "Could not register window class." << std::endl;
        return 1;
    }

    HWND hwnd = CreateWindowEx(0, TEXT("ClipboardTestClass"), TEXT("Clipboard Test Window"), WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, NULL, NULL, GetModuleHandle(NULL), NULL);
    if (hwnd == NULL) {
        std::cerr << "Could not create window." << std::endl;
        return 1;
    }
    ShowWindow(hwnd, SW_HIDE);

    MSG msg = {};
    while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return 0;
}

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    switch (uMsg)
    {
        case WM_CREATE:
            std::cout << "hwnd = " << hwnd << std::endl;
            if (!AddClipboardFormatListener(hwnd)) {
                std::cerr << "Could not AddClipboardFormatListener." << std::endl;
                return -1;
            }
            std::cout << "Listening to clipboard..." << std::endl;
            return 0;
        case WM_DESTROY:
            RemoveClipboardFormatListener(hwnd);
            return 0;
        case WM_CLIPBOARDUPDATE:
        {
            std::cout << "Clipboard update detected." << std::endl;

            while (!OpenClipboard(hwnd)) {
                DWORD lastError = GetLastError();
                std::cout << "Could not OpenClipboard, error " << lastError << " GetOpenClipboardWindow = " << GetOpenClipboardWindow() << " Will retry." << std::endl;
                Sleep(100); // Not production code: retry forever.
            }

            std::cout << "GetClipboardSequenceNumber = " << GetClipboardSequenceNumber() << std::endl;

            UINT format = 0;
            while (format = EnumClipboardFormats(format)) {
                std::cout << "Clipboard format = " << format << std::endl;
            }
            DWORD lastErrorEnum = GetLastError();
            if (lastErrorEnum != ERROR_SUCCESS) {
                std::cout << "Could not EnumClipboardFormats, error " << lastErrorEnum << std::endl;
            }
            std::cout << "Done listing formats." << std::endl;

            // This holds the clipboard open and is more than long enough to provoke the problem in LibreOffice.
            // Actually, the problem often happens for me even when this sleep is omitted.
            Sleep(500);

            CloseClipboard();
            return 0;
        }
    }
    return DefWindowProc(hwnd, uMsg, wParam, lParam);
}