require 'win/library'

module Win

  # Contains constants, functions and wrappers related to Windows manipulation
  #
  module Window
    include Win::Library

    #General constants:

    # Windows Message Get Text
    WM_GETTEXT = 0x000D
    # Windows Message Sys Command
    WM_SYSCOMMAND = 0x0112
    # Sys Command Close
    SC_CLOSE = 0xF060

    # 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


    # 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:
    #   visible?( win_handle ), 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

    # 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
    # TODO: should be private
    def self.return_string( encode = nil )  #:nodoc:
      lambda do |api, *args|
        namespace.enforce_count( args, api.prototype, -2)
        args += [string = buffer, string.length]
        num_chars = api.call(*args)
        return nil if num_chars == 0
        string = string.force_encoding('utf-16LE').encode(encode) if encode
        string.rstrip
      end
    end                 

    ##
    # 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

    # Hides the window and activates another window
    def hide_window(win_handle)
      show_window(win_handle, SW_HIDE)
    end

    return_thread_process = lambda do |api, *args|
      namespace.enforce_count( args, api.prototype, -1)
      thread = api.call(args.first, process = [1].pack('L'))
      nonzero_array(thread, *process.unpack('L'))
    end

    ##
    # 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', 'LP', 'L', &return_thread_process

    return_rect = lambda do |api, *args|
      namespace.enforce_count( args, api.prototype, -1)
      rectangle = [0, 0, 0, 0].pack('L*')
      res = api.call args.first, rectangle
      res == 0 ? [nil, nil, nil, nil] : rectangle.unpack('L*')
    end

    ##
    # 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', &return_rect

#    # Procedure that calls api function expecting a callback. If runtime block is given
#    # it is converted into callback, otherwise procedure returns an array of all handles
#    # pushed into callback by api enumeration
#    # TODO: should be private
#    #
#    def self.return_enum  #:nodoc:
#      lambda do |api, *args, &block|
#        namespace.enforce_count( args, api.prototype, -1)
#        handles = []
#        cb = if block
#          callback('LP', 'I', &block)
#        else
#          callback('LP', 'I') do |handle, message|
#            handles << handle
#            true
#          end
#        end
#        args[api.prototype.find_index('K'), 0] = cb # Insert callback into appropriate place of args Array
#        api.call *args
#        handles
#      end
#    end
#
#    ##
#    # 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).
#    #   message [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:
#    #   status = enum_windows( message ) {|win_handle, message| callback procedure }
#    #
#    function'EnumWindows', 'KP', 'L', boolean: true, &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 two args: parent handle and message.
#    # New Parameters:
#    #   parent (L) - Handle to the parent window whose child windows are to be enumerated.
#    #   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 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:
#    #   enum_windows( parent_handle, message ) {|win_handle, message| callback procedure }
#    #
#    function 'EnumChildWindows', 'LKP', 'L', &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'

    def foreground?(win_handle)
      win_handle == foreground_window
    end

    ##
    # 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'

    function 'keybd_event', 'IILL', 'V'
    function 'PostMessage', 'LLLL', 'L'
    function 'SendMessage', 'LLLP', 'L'
    function 'GetDlgItem', 'LL', 'L'


    # Convenience wrapper methods:

    # emulates combinations of keys pressed (Ctrl+Alt+P+M, etc)
    def keystroke(*keys)
      return if keys.empty?
      keybd_event keys.first, 0, KEYEVENTF_KEYDOWN, 0
      sleep WG_KEY_DELAY
      keystroke *keys[1..-1]
      sleep WG_KEY_DELAY
      keybd_event keys.first, 0, KEYEVENTF_KEYUP, 0
    end

    # types text message into window holding the focus
    def type_in(message)
      message.scan(/./m) do |char|
        keystroke(*char.to_vkeys)
      end
    end

    # finds top-level dialog window by title and yields it to given block
    def dialog(title, seconds=3)
      d = begin
        win = Window.top_level(title, seconds)
        yield(win) ? win : nil
      rescue TimeoutError
      end
      d.wait_for_close if d
      return d
    end

    # Thin wrapper around window handle
    class Window
      include Win::Window
      extend Win::Window

      attr_reader :handle

      # find top level window by title, return wrapped Window object
      def self.top_level(title, seconds=3)
        @handle = timeout(seconds) do
          sleep WG_SLEEP_DELAY while (h = find_window nil, title) == nil; h
        end
        Window.new @handle
      end

      def initialize(handle)
        @handle = handle
      end

      # find child window (control) by title, window class, or control ID:
      def child(id)
        result = case id
          when String
          by_title = find_window_ex @handle, 0, nil, id.gsub('_' , '&' )
          by_class = find_window_ex @handle, 0, id, nil
          by_title ? by_title : by_class
          when Fixnum
          get_dlg_item @handle, id
          when nil
          find_window_ex @handle, 0, nil, nil
        else
          nil
        end
        raise "Control '#{id}' not found" unless result
        Window.new result
      end

      def children
        enum_child_windows(@handle,'Msg').map{|child_handle| Window.new child_handle}
      end

      # emulate click of the control identified by id
      def click(id)
        h = child(id).handle
        rectangle = [0, 0, 0, 0].pack 'LLLL'
        get_window_rect h, rectangle
        left, top, right, bottom = rectangle.unpack 'LLLL'
        center = [(left + right) / 2, (top + bottom) / 2]
        set_cursor_pos *center
        mouse_event MOUSEEVENTF_LEFTDOWN, 0, 0, 0, 0
        mouse_event MOUSEEVENTF_LEFTUP, 0, 0, 0, 0
      end

      def close
        post_message @handle, WM_SYSCOMMAND, SC_CLOSE, 0
      end

      def wait_for_close
        timeout(WG_CLOSE_TIMEOUT) do
          sleep WG_SLEEP_DELAY while window_visible?(@handle)
        end
      end

      def text
        buffer = "\x0" * 2048
        length = send_message @handle, WM_GETTEXT, buffer.length, buffer
        length == 0 ? '' : buffer[0..length - 1]
      end
    end
    
  end
end