require 'win/library'

module Win
  module Gui
    # Contains constants and Win32API functions related to window manipulation
    #
    module Window
      include Win::Library

      # ShowWindow constants:

      # Hides the window and activates another window.
      SW_HIDE           = 0
      # Same as SW_SHOWNORMAL
      SW_NORMAL         = 1
      # Activates and displays a window. If the window is minimized or maximized, the system restores it to its
      # original size and position. An application should specify this flag when displaying the window for the first time.
      SW_SHOWNORMAL     = 1
      # Activates the window and displays it as a minimized window.
      SW_SHOWMINIMIZED  = 2
      # Activates the window and displays it as a maximized window.
      SW_SHOWMAXIMIZED  = 3
      # Activates the window and displays it as a maximized window.
      SW_MAXIMIZE       = 3
      # Displays a window in its most recent size and position. Similar to SW_SHOWNORMAL, but the window is not activated.
      SW_SHOWNOACTIVATE = 4
      # Activates the window and displays it in its current size and position.
      SW_SHOW           = 5
      # Minimizes the specified window, activates the next top-level window in the Z order.
      SW_MINIMIZE       = 6
      # Displays the window as a minimized window. Similar to SW_SHOWMINIMIZED, except the window is not activated.
      SW_SHOWMINNOACTIVE= 7
      # Displays the window in its current size and position. Similar to SW_SHOW, except the window is not activated.
      SW_SHOWNA         = 8
      # Activates and displays the window. If the window is minimized or maximized, the system restores it to its original
      # size and position. An application should specify this flag when restoring a minimized window.
      SW_RESTORE        = 9
      # Sets the show state based on the SW_ value specified in the STARTUPINFO structure  passed to the CreateProcess
      # function by the program that started the application.
      SW_SHOWDEFAULT    = 10
      # Windows 2000/XP: Minimizes a window, even if the thread that owns the window is not responding. Only use this
      # flag when minimizing windows from a different thread.
      SW_FORCEMINIMIZE  = 11

      class << self
        # Def_block that calls API function expecting EnumWindowsProc callback (EnumWindows, EnumChildWindows, ...).
        # Default callback pushes all passed handles into Array that is returned if Enum function call was successful.
        # If runtime block is given it is called after the end of default callback (handle Array is still being
        # collected and returned by the method). If Enum... function call fails, method returns nil, otherwise
        # an Array of all window handles passed into callback.
        #
        def return_enum #:nodoc:
          lambda do |api, *args, &block|
            args.push 0 if args.size == api.prototype.size - 2 # If value is missing, it defaults to 0
            handles = []

            # Insert callback proc into appropriate place of args Array
            args[api.prototype.find_index(:enum_callback), 0] =
                    proc do |handle, message|
                      handles << handle
                      block ? block[handle, message] : true
                    end
            handles if api.call *args
          end
        end

        # Helper method that creates def_block returning (possibly encoded) string as a result of
        # api function call or nil if zero characters was returned by api call
        #
        def return_string( encode = nil )  #:nodoc:
          lambda do |api, *args|
            namespace.enforce_count( args, api.prototype, -2)
            buffer = FFI::MemoryPointer.new :char, 1024
            args += [buffer, buffer.size]
            num_chars = api.call(*args)
            return nil if num_chars == 0
            if encode
              string = buffer.get_bytes(0, num_chars*2)
              string = string.force_encoding('utf-16LE').encode(encode)
            else
              string = buffer.get_bytes(0, num_chars)
            end
            string.rstrip
          end
        end

        private :return_enum, :return_string
      end

      # Windows GUI API definitions:

      ##
      # Tests whether the specified window handle identifies an existing window.
      #   A thread should not use IsWindow for a window that it did not create because the window
      #   could be destroyed after this function was called. Further, because window handles are
      #   recycled the handle could even point to a different window.
      #
      # :call-seq:
      # window?( win_handle )
      #
      function 'IsWindow', 'L', 'L'

      ##
      # Tests if the specified window, its parent window, its parent's parent window, and so forth,
      # have the WS_VISIBLE style. Because the return value specifies whether the window has the
      # WS_VISIBLE style, it may be true even if the window is totally obscured by other windows.
      #
      # :call-seq:
      #   [window_]visible?( win_handle )
      #
      function 'IsWindowVisible', 'L', 'L', aliases: :visible?

      ##
      # Tests whether the specified window is maximized.
      #
      # :call-seq:
      #   zoomed?( win_handle ), maximized?( win_handle )
      #
      function 'IsZoomed', 'L', 'L', aliases: :maximized?

      ##
      # Tests whether the specified window is maximized.
      #
      # :call-seq:
      #   iconic?( win_handle ), minimized?( win_handle )
      #
      function 'IsIconic', 'L', 'L', aliases: :minimized?

      ##
      # Tests whether a window is a child (or descendant) window of a specified parent window.
      # A child window is the direct descendant of a specified parent window if that parent window
      # is in the chain of parent windows; the chain of parent windows leads from the original overlapped
      # or pop-up window to the child window.
      #
      # :call-seq:
      #   child?( win_handle )
      #
      function 'IsChild', 'LL', 'L'

      ##
      # Returns a handle to the top-level window whose class and window name match the specified strings.
      # This function does not search child windows. This function does not perform a case-sensitive search.
      #
      # Parameters:
      #   class_name (P) - String that specifies (window) class name OR class atom created by a previous
      #     call to the RegisterClass(Ex) function. The atom must be in the low-order word of class_name;
      #     the high-order word must be zero. The class name can be any name registered with RegisterClass(Ex),
      #     or any of the predefined control-class names. If this parameter is nil, it finds any window whose
      #     title matches the win_title parameter.
      #   win_name (P) - String that specifies the window name (title). If nil, all names match.
      # Return Value (L): found window handle or NIL if nothing found
      #
      # :call-seq:
      #   win_handle = find_window( class_name, win_name )
      #
      function 'FindWindow', 'PP', 'L', zeronil: true

      ##
      # Unicode version of find_window (strings must be encoded as utf-16LE AND terminate with "\x00\x00")
      #
      # :call-seq:
      #   win_handle = find_window_w( class_name, win_name )
      #
      function 'FindWindowW', 'PP', 'L', zeronil: true

      ##
      # Retrieves a handle to a CHILD window whose class name and window name match the specified strings.
      #   The function searches child windows, beginning with the one following the specified child window.
      #   This function does NOT perform a case-sensitive search.
      #
      # Parameters:
      #   parent (L) - Handle to the parent window whose child windows are to be searched.
      #     If nil, the function uses the desktop window as the parent window.
      #     The function searches among windows that are child windows of the desktop.
      #   after_child (L) - Handle to a child window. Search begins with the NEXT child window in the Z order.
      #     The child window must be a direct child window of parent, not just a descendant window.
      #     If after_child is nil, the search begins with the first child window of parent.
      #   win_class (P), win_title (P) - Strings that specify window class and name(title). If nil, anything matches.
      # Returns (L): found child window handle or NIL if nothing found
      #
      # :call-seq:
      #   win_handle = find_window_ex( win_handle, after_child, class_name, win_name )
      #
      function 'FindWindowEx', 'LLPP', 'L', zeronil: true

      ##
      # Returns the text of the specified window's title bar (if it has one).
      #   If the specified window is a control, the text of the control is copied. However, GetWindowText
      #   cannot retrieve the text of a control in another application.
      #
      # Original Parameters:
      #   win_handle (L) - Handle to the window and, indirectly, the class to which the window belongs.
      #   text (P) - Long Pointer to the buffer that is to receive the text string.
      #   max_count (I) - Specifies the length, in TCHAR, of the buffer pointed to by the text parameter.
      #   The class name string is truncated if it is longer than the buffer and is always null-terminated.
      # Original Return Value (L): Length, in characters, of the copied string, not including the terminating null
      #   character, indicates success. Zero indicates that the window has no title bar or text, if the title bar
      #   is empty, or if the window or control handle is invalid. For extended error information, call GetLastError.
      #
      # Enhanced API requires only win_handle and returns rstripped text
      #
      # Enhanced Parameters:
      #   win_handle (L) - Handle to the window and, indirectly, the class to which the window belongs.
      # Returns: Window title bar text or nil
      #   If the window has no title bar or text, if the title bar is empty, or if the window or control handle
      #   is invalid, the return value is NIL. To get extended error information, call GetLastError.
      #
      # Remarks: This function CANNOT retrieve the text of an edit control in ANOTHER app.
      #   If the target window is owned by the current process, GetWindowText causes a WM_GETTEXT message to
      #   be sent to the specified window or control. If the target window is owned by another process and has
      #   a caption, GetWindowText retrieves the window caption text. If the window does not have a caption,
      #   the return value is a null string. This allows to call GetWindowText without becoming unresponsive
      #   if the target window owner process is not responding. However, if the unresponsive target window
      #   belongs to the calling app, GetWindowText will cause the calling app to become unresponsive.
      #   To retrieve the text of a control in another process, send a WM_GETTEXT message directly instead
      #   of calling GetWindowText.
      #
      #:call-seq:
      #   text = [get_]window_text( win_handle )
      #
      function 'GetWindowText', 'LPI', 'L', &return_string

      ##
      # Unicode version of get_window_text (returns rstripped utf-8 string)
      # API improved to require only win_handle and return rstripped string
      #
      #:call-seq:
      #   text = [get_]window_text_w( win_handle )
      #
      function 'GetWindowTextW', 'LPI', 'L', &return_string('utf-8')

      ##
      # Retrieves the name of the class to which the specified window belongs.
      #
      # Original Parameters:
      #   win_handle (L) - Handle to the window and, indirectly, the class to which the window belongs.
      #   class_name (P) - Long Pointer to the buffer that is to receive the class name string.
      #   max_count (I) - Specifies the length, in TCHAR, of the buffer pointed to by the class_name parameter.
      #   The class name string is truncated if it is longer than the buffer and is always null-terminated.
      # Original Return Value (L): Length, in characters, of the copied string, not including the terminating null
      #   character, indicates success. Zero indicates that the window has no title bar or text, if the title bar
      #   is empty, or if the window or control handle is invalid. For extended error information, call GetLastError.
      #
      # API improved to require only win_handle and return rstripped string
      #
      # Enhanced Parameters:
      #   win_handle (L) - Handle to the window and, indirectly, the class to which the window belongs.
      # Returns: Name of the class or NIL if function fails. For extended error information, call GetLastError.
      #
      #:call-seq:
      #   text = [get_]class_name( win_handle )
      #
      function 'GetClassName', 'LPI', 'I', &return_string

      ##
      # Unicode version of get_class_name (returns rstripped utf-8 string)
      # API improved to require only win_handle and return rstripped string
      #
      #:call-seq:
      #   text = [get_]class_name_w( win_handle )
      #
      function 'GetClassNameW', 'LPI', 'I', &return_string('utf-8')

      ##
      # Shows and hides windows.
      #
      # Parameters:
      #   win_handle (L) - Handle to the window.
      #   cmd (I) - Specifies how the window is to be shown. This parameter is ignored the first time an
      #     application calls ShowWindow, if the program that launched the application provides a STARTUPINFO
      #     structure. Otherwise, the first time ShowWindow is called, the value should be the value obtained
      #     by the WinMain function in its nCmdShow parameter. In subsequent calls, cmd may be:
      # SW_HIDE, SW_MAXIMIZE, SW_MINIMIZE, SW_SHOW, SW_SHOWMAXIMIZED, SW_SHOWMINIMIZED, SW_SHOWMINNOACTIVE,
      # SW_SHOWNA, SW_SHOWNOACTIVATE, SW_SHOWNORMAL, SW_RESTORE, SW_SHOWDEFAULT, SW_FORCEMINIMIZE
      #
      # Original Return Value: - Nonzero if the window was PREVIOUSLY visible, otherwise zero
      # Enhanced Returns: - True if the window was PREVIOUSLY visible, otherwise false
      #
      #:call-seq:
      #   was_visible = show_window( win_handle, cmd )
      #
      function 'ShowWindow', 'LI', 'I', boolean: true

      ##
      # Retrieves the identifier of the thread that created the specified window
      #   and, optionally, the identifier of the process that created the window.
      #
      # Original Parameters:
      #   handle (L) - Handle to the window.
      #   process (P) - A POINTER to a (Long) variable that receives the process identifier.
      # Original Return (L): Identifier of the thread that created the window.
      #
      # API improved to accept window handle as a single arg and return a pair of [thread, process] ids
      #
      # New Parameters:
      #   handle (L) - Handle to the window.
      # Returns: Pair of identifiers of the thread and process_id that created the window.
      #
      #:call-seq:
      #   thread, process_id = [get_]window_tread_process_id( win_handle )
      #
      function 'GetWindowThreadProcessId', [:long, :pointer], :long,
               &->(api, *args) {
               namespace.enforce_count( args, api.prototype, -1)
               process = FFI::MemoryPointer.new(:long)
               process.write_long(1)
               thread = api.call(args.first, process)
               thread == 0 ? [nil, nil] : [thread, process.read_long()] }
      # weird lambda literal instead of normal block is needed because current version of RDoc
      # goes crazy if block is attached to meta-definition

      ##
      # Retrieves the dimensions of the specified window bounding rectangle.
      #   Dimensions are given relative to the upper-left corner of the screen.
      #
      # Original Parameters:
      #   win_handle (L) - Handle to the window.
      #   rect (P) - Long pointer to a RECT structure that receives the screen coordinates of the upper-left and
      #     lower-right corners of the window.
      # Original Return Value: Nonzero indicates success. Zero indicates failure. For error info, call GetLastError.
      #
      # API improved to accept only window handle and return 4-member dimensions array (left, top, right, bottom)
      #
      # New Parameters:
      #   win_handle (L) - Handle to the window
      # New Return: Array(left, top, right, bottom) - rectangle dimensions
      #
      # Remarks: As a convention for the RECT structure, the bottom-right coordinates of the returned rectangle
      #   are exclusive. In other words, the pixel at (right, bottom) lies immediately outside the rectangle.
      #
      #:call-seq:
      #   rect = [get_]window_rect( win_handle )
      #
      function 'GetWindowRect', 'LP', 'I',
               &->(api, *args) {
               namespace.enforce_count( args, api.prototype, -1)
               rect = FFI::MemoryPointer.new(:long, 4)
               rect.write_array_of_long([0, 0, 0, 0])
               res = api.call args.first, rect
               res == 0 ? [nil, nil, nil, nil] : rect.read_array_of_long(4) }
      # weird lambda literal instead of normal block is needed because current version of RDoc
      # goes crazy if block is attached to meta-definition

      # This is an application-defined callback function that receives top-level window handles as a result of a call
      # to the EnumWindows, EnumChildWindows or EnumDesktopWindows function.
      #
      # Syntax: BOOL CALLBACK EnumWindowsProc( HWND hwnd, LPARAM lParam );
      #
      # Parameters:
      #   hwnd (L) - [out] Handle to a top-level window.
      #   lParam (L) - [in] Specifies the application-defined value given in EnumWindows or EnumDesktopWindows.
      # Return Values:
      #   TRUE continues enumeration. FALSE stops enumeration.
      #
      # Remarks: An application must register this callback function by passing its address to EnumWindows,
      # EnumChildWindows or EnumDesktopWindows.
      callback :enum_callback, 'LL', :bool

      ##
      # The EnumWindows function enumerates all top-level windows on the screen by passing the handle to
      #   each window, in turn, to an application-defined callback function. EnumWindows continues until
      #   the last top-level window is enumerated or the callback function returns FALSE.
      #
      # Original Parameters:
      #   callback [K] - Pointer to an application-defined callback function (see EnumWindowsProc).
      #   value [P] - Specifies an application-defined value(message) to be passed to the callback function.
      # Original Return: Nonzero if the function succeeds, zero if the function fails. GetLastError for error info.
      #   If callback returns zero, the return value is also zero. In this case, the callback function should
      #   call SetLastError to obtain a meaningful error code to be returned to the caller of EnumWindows.
      #
      # API improved to accept blocks (instead of callback objects) and message as a single arg
      #
      # New Parameters:
      #   message [P] - Specifies an application-defined value(message) to be passed to the callback function.
      #   block given to method invocation serves as an application-defined callback function (see EnumWindowsProc).
      # Returns: True if the function succeeds, false if the function fails. GetLastError for error info.
      #   If callback returns zero, the return value is also zero. In this case, the callback function should
      #   call SetLastError to obtain a meaningful error code to be returned to the caller of EnumWindows.
      #
      # Remarks: The EnumWindows function does not enumerate child windows, with the exception of a few top-level
      #   windows owned by the system that have the WS_CHILD style. This function is more reliable than calling
      #   the GetWindow function in a loop. An application that calls GetWindow to perform this task risks being
      #   caught in an infinite loop or referencing a handle to a window that has been destroyed.
      #
      # :call-seq:
      #   handles = enum_windows( [value=0] ) {|handle, value| your callback procedure }
      #
      function'EnumWindows', [:enum_callback, :long], :bool, &return_enum

      ##
      #EnumDesktopWindows Function
      #
      #Enumerates all top-level windows associated with the specified desktop. It passes the handle to each window, in turn, to an application-defined callback function.
      #
      #
      #Syntax
      #BOOL WINAPI EnumDesktopWindows(
      #  __in_opt  HDESK hDesktop,
      #  __in      WNDENUMPROC lpfn,
      #  __in      LPARAM lParam
      #);
      #
      #Parameters
      #hDesktop
      #A handle to the desktop whose top-level windows are to be enumerated. This handle is returned by the CreateDesktop, GetThreadDesktop, OpenDesktop, or OpenInputDesktop function, and must have the DESKTOP_ENUMERATE access right. For more information, see Desktop Security and Access Rights.
      #
      #If this parameter is NULL, the current desktop is used.
      #
      #lpfn
      #A pointer to an application-defined EnumWindowsProc callback function.
      #
      #lParam
      #An application-defined value to be passed to the callback function.
      #
      #Return Value
      #If the function fails or is unable to perform the enumeration, the return value is zero.
      #
      #To get extended error information, call GetLastError.
      #
      #You must ensure that the callback function sets SetLastError if it fails.
      #
      #Windows Server 2003 and Windows XP/2000:  If there are no windows on the desktop, GetLastError returns ERROR_INVALID_HANDLE.
      #Remarks
      #The EnumDesktopWindows function repeatedly invokes the lpfn callback function until the last top-level window is enumerated or the callback function returns FALSE.
      #
      #Requirements
      #Client Requires Windows Vista, Windows XP, or Windows 2000 Professional.
      #
      # :call-seq:
      #   handles = enum_desktop_windows( desktop_handle, [value=0] ) {|handle, value| your callback procedure }
      #
      function'EnumDesktopWindows', [:ulong, :enum_callback, :long], :bool, &return_enum

      ##
      # Enumerates child windows to a given window.
      #
      # Original Parameters:
      #   parent (L) - Handle to the parent window whose child windows are to be enumerated.
      #   callback [K] - Pointer to an application-defined callback function (see EnumWindowsProc).
      #   message [P] - Specifies an application-defined value(message) to be passed to the callback function.
      # Original Return: Not used (?!)
      #   If callback returns zero, the return value is also zero. In this case, the callback function should
      #   call SetLastError to obtain a meaningful error code to be returned to the caller of EnumWindows.
      #   If it is nil, this function is equivalent to EnumWindows. Windows 95/98/Me: parent cannot be NULL.
      #
      # API improved to accept blocks (instead of callback objects) and parent handle (value is optional, default 0)
      # New Parameters:
      #   parent (L) - Handle to the parent window whose child windows are to be enumerated.
      #   value (P) - Specifies an application-defined value(message) to be passed to the callback function.
      #   block given to method invocation serves as an application-defined callback function (see EnumChildProc).
      #
      # Remarks:
      #   If a child window has created child windows of its own, EnumChildWindows enumerates those windows as well.
      #   A child window that is moved or repositioned in the Z order during the enumeration process will be properly enumerated.
      #   The function does not enumerate a child window that is destroyed before being enumerated or that is created during the enumeration process.
      #
      #:call-seq:
      #   handles = enum_child_windows( parent_handle, [value=0] ) {|handle, value| your callback procedure }
      #
      function 'EnumChildWindows', [:ulong, :enum_callback, :long], :bool, &return_enum

      ##
      # GetForegroundWindow function returns 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.
      #
      # Syntax:  HWND GetForegroundWindow(VOID);
      #
      # Return Value: The return value is a handle to the foreground window. The foreground window can be NULL in
      # certain circumstances, such as when a window is losing activation.
      #
      #:call-seq:
      #   win_handle = [get_]foreground_window()
      #
      function 'GetForegroundWindow', [], 'L'

      ##
      # The GetActiveWindow function retrieves the window handle to the active window attached to
      # the calling thread's message queue.
      #
      # Syntax:  HWND GetActiveWindow(VOID);
      #
      # Return Value: The return value is the handle to the active window attached to the calling
      # thread's message queue. Otherwise, the return value is NULL.
      #
      #  Remarks: To get the handle to the foreground window, you can use GetForegroundWindow.
      #  To get the window handle to the active window in the message queue for another thread, use GetGUIThreadInfo.
      #
      #:call-seq:
      #   win_handle = [get_]active_window()
      #
      function 'GetActiveWindow', [], 'L'

    end
  end
end