#include <windows.h>
#include "CMcl.h"

#define APPLICATION_WINDOW_NAME "Single Instance Application"
#define APPLICATION_CLASS_NAME  "SingleInstanceAppWindowClass"
#define APPLICATION_MUTEX_NAME  "SingleInstanceAppMutex"

LRESULT CALLBACK WindowProc( HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) {
    switch (msg) {
        case WM_DESTROY:
            PostQuitMessage(0);
            break;
        default:
            return DefWindowProc( hwnd, msg, wParam, lParam);
            break;
    }

    return 0;
}

int WINAPI WinMain( HINSTANCE hThisInst, HINSTANCE hPrevInst, LPSTR lpszArgs, int nWinMode) {
    ///////////////////////////////////////////
    // single instance synchronization stuff...
    ///////////////////////////////////////////

    CMclMutex cmSingleInstance( TRUE, APPLICATION_MUTEX_NAME);
    if (cmSingleInstance.Status() == ERROR_ALREADY_EXISTS) {
        // we are not the first running instance...

        // wait for the first instance to have finished
        // creating it's window...
        cmSingleInstance.Wait(INFINITE);

        // we can release the mutex now...
        cmSingleInstance.Release();

        // bring the window to the top...
        HWND hwnd = FindWindow( APPLICATION_CLASS_NAME, APPLICATION_WINDOW_NAME);
        if (hwnd) {
            SetForegroundWindow(hwnd);
        }
    
        return 0;
    }

    //////////////////////////////////
    // bare-bones windows app stuff...
    //////////////////////////////////

    // create a window class..
    WNDCLASS wcl;
    wcl.hInstance = hThisInst;
    wcl.lpszClassName = APPLICATION_CLASS_NAME;
    wcl.lpfnWndProc = WindowProc;
    wcl.style = 0;
    wcl.hIcon = LoadIcon( NULL, IDI_APPLICATION);
    wcl.hCursor = LoadCursor( NULL, IDC_ARROW);
    wcl.lpszMenuName = NULL;
    wcl.cbClsExtra = 0;
    wcl.cbWndExtra = 0;
    wcl.hbrBackground = GetStockObject(GRAY_BRUSH);

    // register the window class..
    if (RegisterClass(&wcl) == FALSE) {
        // fatal error, unable to register window class...
        return 0;
    }

    // create the main window...
    HWND hwnd = CreateWindow(    APPLICATION_CLASS_NAME, 
                            APPLICATION_WINDOW_NAME,
                            WS_OVERLAPPEDWINDOW,
                            CW_USEDEFAULT,
                            CW_USEDEFAULT,
                            CW_USEDEFAULT,
                            CW_USEDEFAULT,
                            HWND_DESKTOP,
                            NULL,
                            hThisInst,
                            NULL);

    // show the window...
    ShowWindow(hwnd, nWinMode);
    UpdateWindow(hwnd);

    // we are the first running instance, release the mutex...
    cmSingleInstance.Release();

    // message loop...
    MSG msg;
    while (GetMessage(&msg, NULL, 0, 0)) {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    // exit..
    return msg.wParam;
}