import com.sun.jna.Native ;
import com.sun.jna.win32.StdCallLibrary ;

/**
 * Interface for kernel32 using JNA. 
 * Minimum supported client: Windows 2000 Professional [desktop apps only] 
 * Minimum supported server: Windows 2000 Server [desktop apps only] 
 * Header: Winbase.h (include Windows.h) 
 * @author Microsoft
 */
public interface Kernel32 extends StdCallLibrary {

    /**
     * Instance of Kernel32 mapped with Native library kernel32.
     */
    Kernel32 INSTANCE = (Kernel32) Native.loadLibrary("kernel32", Kernel32.class);

    /**
     * Retrieves the number of milliseconds that have elapsed since the system was started. 
     * @see http://msdn2.microsoft.com/en-us/library/ms724408.aspx 
     * @return number of milliseconds that have elapsed since the system was started.
     */
    int GetTickCount();
}

import com.sun.jna.Native ;
import com.sun.jna.platform.win32.WinDef.HWND ;
import com.sun.jna.platform.win32.WinDef.LPARAM ;
import com.sun.jna.platform.win32.WinDef.LRESULT ;
import com.sun.jna.platform.win32.WinDef.WPARAM ;
import com.sun.jna.platform.win32.WinUser.LASTINPUTINFO ;
import com.sun.jna.ptr.PointerByReference ;
import com.sun.jna.win32.StdCallLibrary ;

/**
 * Interface for user32 using JNA. 
 * Minimum supported client: Windows 2000 Professional [desktop apps only] 
 * Minimum supported server: Windows 2000 Server [desktop apps only] 
 * Header: Winbase.h (include Windows.h)
 *
 *
 * * @author Microsoft
 */
public interface User32 extends StdCallLibrary {

    /**
     * Instance of Kernel32 mapped with Native library user32.
     */
    User32 INSTANCE = (User32) Native.loadLibrary("user32", User32.class);


    // Constants definition ---------------------------------------------------
    /*       
     * From WM_SYSCOMMAND message.      
     * @see http://msdn.microsoft.com/en-us/library/windows/desktop/ms646360(v=vs.85).aspx      
     */ 

    /**
     * Sets the state of the display. 
     * This command supports devices that have power-saving features, 
     * such as a battery-powered personal computer. 
     * The lParam parameter can have the following values: 
     * -1 (the display is powering on) 
     * 1 (the display is going to low power)
     * 2 (the display is being shut off)
     */
    int SC_MONITORPOWER = 0xF170;
    /**
     * the display is powering on value of SC_MONITORPOWER.
     */
    int SC_MONITOR_ON = -1;
    /**
     * the display is being shut off value of SC_MONITORPOWER.
     */
    int SC_MONITOR_OFF = 2;
    /**
     * Executes the screen saver application specified in the [boot] section
     * of the System.ini file.
     */
    int SC_SCREENSAVE = 0xF140;
    /**
     * Determines whether a screen saver is currently running on the window
     * station of the calling process.
     */
    int SPI_GETSCREENSAVERRUNNING = 0x0072;

    // Methods definition ------------------------------------------------------          
    /**
     * Retrieves the time of the last input event. 
     * @see http://msdn.microsoft.com/en-us/library/windows/desktop/ms646302(v=vs.85).aspx
     * @param result [out]: a LASTINPUTINFO structure that receives the time of the last input event. 
     * @return If the function succeeds, the return value is nonzero else the return value is zero.
     */
    boolean GetLastInputInfo(LASTINPUTINFO result);

    /**
     * Retrieves a handle to the foreground window (the window with which the user is currently working). The system assigns a slightly higher priority to the thread that creates the foreground window than it does to other threads. 
     * @see http://msdn.microsoft.com/en-us/library/windows/desktop/ms633505(v=vs.85).aspx
     * @return handle to the foreground window. The foreground window can be NULL in certain circumstances, such as when a window is losing activation.
     */
    HWND GetForegroundWindow();

    /**
     * Sends the specified message to a window or windows (ANSI version).
     * @see http://msdn.microsoft.com/en-us/library/windows/desktop/ms644950(v=vs.85).aspx
     * @param paramHWND [in] A handle to the window whose window procedure will receive the message. If this parameter is HWND_BROADCAST ((HWND)0xffff), the message is sent to all top-level windows in the system, including disabled or invisible unowned windows, overlapped windows, and pop-up windows; but the message is not sent to child windows. 
     * Message sending is subject to UIPI. The thread of a process can send messages only to message queues of threads in processes of lesser or equal integrity level. 
     * @param paramInt [in] The message to be sent. 
     * @param paramWPARAM [in] Additional message-specific information. 
     * @param paramLPARAM [in] Additional message-specific information. 
     * @return LRESULT - The return value specifies the result of the message processing; it depends on the message sent.
     */
    LRESULT SendMessageA(HWND paramHWND, int paramInt, WPARAM paramWPARAM, LPARAM paramLPARAM);

    /**
     * Retrieves or sets the value of one of the system-wide parameters.
     * This function can also update the user profile while setting a parameter. 
     * @see http://msdn.microsoft.com/en-us/library/windows/desktop/ms724947(v=vs.85).aspx
     * @param uiAction UINT - The system-wide parameter to be retrieved or set 
     * @param uiParam UINT - A parameter whose usage and format depends on the system parameter being queried or set 
     * @param pvParam PVOID - A parameter whose usage and format depends on the system parameter being queried or set 
     * @param fWInIni UINT - If a system parameter is being set, specifies whether the user profile is to be updated, and if so, whether the WM_SETTINGCHANGE message is to be broadcast to all top-level windows to notify them of the change
     * @return If the function succeeds, the return value is a nonzero value, else the return value is zero
     */
    boolean SystemParametersInfoA(int uiAction, int uiParam, PointerByReference pvParam, int fWInIni);
}

import com.sun.jna.platform.win32.WinDef ;
    import com.sun.jna.platform.win32.WinUser ;
    import com.sun.jna.platform.win32.WinUser.LASTINPUTINFO ;
    import com.sun.jna.ptr.PointerByReference ;

    /**
     * Get the amount of milliseconds that have elapsed since the last input event (mouse or keyboard) 
     * @return idle time in milliseconds
     */
    public static int getIdleTimeMillisWin32() {
        LASTINPUTINFO lastInputInfo = new LASTINPUTINFO();
        User32.INSTANCE.GetLastInputInfo(lastInputInfo);
        return Kernel32.INSTANCE.GetTickCount() - lastInputInfo.dwTime;
    }

    /**
     * @return true if the screensaver is displayed
     */
    public static boolean isScreenSaverDisplayed() {
        PointerByReference pointer = new PointerByReference();
        User32.INSTANCE.SystemParametersInfoA(User32.SPI_GETSCREENSAVERRUNNING, 0, pointer, 0);
        // pointer points to a BOOL variable that receives TRUE if a screen saver is currently running, or FALSE otherwise 
        return pointer.getPointer().getByte(0) == 1; 
    }

    /**
     * Force scrensaver to go away.
     */
    public static void forceScreenSaverExit() {
        User32.INSTANCE.SendMessageA(User32.INSTANCE.GetForegroundWindow(), WinUser.WM_CLOSE, new WinDef.WPARAM(0), new WinDef.LPARAM(0));
    }

    /**
     * Force scrensaver display.
     */
    public static void forceScreenSaverDisplay() {
        final WinDef.HWND lHwnd = User32.INSTANCE.GetForegroundWindow();
        User32.INSTANCE.SendMessageA(lHwnd, WinUser.WM_SYSCOMMAND, new WinDef.WPARAM(User32.SC_SCREENSAVE), new WinDef.LPARAM(0));
    }