{-# LANGUAGE CPP #-}
-- -*-haskell-*-
--  GIMP Toolkit (GTK) Widget UIManager
--
--  Author : Duncan Coutts
--
--  Created: 6 April 2005
--
--  Copyright (C) 2005 Duncan Coutts
--
--  This library is free software; you can redistribute it and/or
--  modify it under the terms of the GNU Lesser General Public
--  License as published by the Free Software Foundation; either
--  version 2.1 of the License, or (at your option) any later version.
--
--  This library is distributed in the hope that it will be useful,
--  but WITHOUT ANY WARRANTY; without even the implied warranty of
--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
--  Lesser General Public License for more details.
--
-- TODO
--   check if uiManagerGetToplevels returns widgets derived from some common
--   class, eg ToolItem (though it looks like it can return MenuBars too)
--
-- |
-- Maintainer  : gtk2hs-users@lists.sourceforge.net
-- Stability   : provisional
-- Portability : portable (depends on GHC)
--
-- Constructing menus and toolbars from an XML description
--
-- * Module available since Gtk+ version 2.4
--
module Graphics.UI.Gtk.ActionMenuToolbar.UIManager (
-- * Detail
-- 
-- | A 'UIManager' constructs a user interface (menus and toolbars) from one
-- or more UI definitions, which reference actions from one or more action
-- groups.

-- ** UI Definitions
-- 
-- | #XML-UI# The UI definitions are specified in an XML format which can be roughly
-- described by the following DTD.
--
-- > <!ELEMENT ui          (menubar|toolbar|popup|accelerator)* >
-- > <!ELEMENT menubar     (menuitem|separator|placeholder|menu)* >
-- > <!ELEMENT menu        (menuitem|separator|placeholder|menu)* >
-- > <!ELEMENT popup       (menuitem|separator|placeholder|menu)* >
-- > <!ELEMENT toolbar     (toolitem|separator|placeholder)* >
-- > <!ELEMENT placeholder (menuitem|toolitem|separator|placeholder|menu)* >
-- > <!ELEMENT menuitem     EMPTY >
-- > <!ELEMENT toolitem     EMPTY >
-- > <!ELEMENT separator    EMPTY >
-- > <!ELEMENT accelerator  EMPTY >
-- > <!ATTLIST menubar      name                  #IMPLIED 
-- >                        action                #IMPLIED >
-- > <!ATTLIST toolbar      name                  #IMPLIED 
-- >                        action                #IMPLIED >
-- > <!ATTLIST popup        name                  #IMPLIED 
-- >                        action                #IMPLIED >
-- > <!ATTLIST placeholder  name                  #IMPLIED
-- >                        action                #IMPLIED
-- >                        expand   (true|false) #IMPLIED >
-- > <!ATTLIST separator    name                  #IMPLIED
-- >                        action                #IMPLIED >
-- > <!ATTLIST menu         name                  #IMPLIED
-- >                        action                #REQUIRED
-- >                        position (top|bot)    #IMPLIED >
-- > <!ATTLIST menuitem     name                  #IMPLIED
-- >                        action                #REQUIRED
-- >                        position (top|bot)    #IMPLIED >
-- > <!ATTLIST toolitem     name                  #IMPLIED
-- >                        action                #REQUIRED
-- >                        position (top|bot)    #IMPLIED >
-- > <!ATTLIST accelerator  name                  #IMPLIED
-- >                        action                #REQUIRED >
--
-- There are some additional restrictions beyond those specified in the DTD,
-- e.g. every toolitem must have a toolbar in its anchestry and every menuitem
-- must have a menubar or popup in its anchestry. Since a GMarkup
-- parser is used to parse the UI description, it must not
-- only be valid XML, but valid GMarkup.
--
-- If a name is not specified, it defaults to the action. If an action is
-- not specified either, the element name is used. The name and action
-- attributes must not contain \'\/\' characters after parsing (since that
-- would mess up path lookup) and must be usable as XML attributes when
-- enclosed in doublequotes, thus they must not \'\"\' characters or references
-- to the &quot; entity.

-- ** A UI definition
-- |
--
-- > <ui>
-- >   <menubar>
-- >     <menu name="FileMenu" action="FileMenuAction">
-- >       <menuitem name="New" action="New2Action" />
-- >       <placeholder name="FileMenuAdditions" />
-- >     </menu>
-- >     <menu name="JustifyMenu" action="JustifyMenuAction">
-- >       <menuitem name="Left" action="justify-left"/>
-- >       <menuitem name="Centre" action="justify-center"/>
-- >       <menuitem name="Right" action="justify-right"/>
-- >       <menuitem name="Fill" action="justify-fill"/>
-- >     </menu>
-- >   </menubar>
-- >   <toolbar action="toolbar1">
-- >     <placeholder name="JustifyToolItems">
-- >       <separator/>
-- >       <toolitem name="Left" action="justify-left"/>
-- >       <toolitem name="Centre" action="justify-center"/>
-- >       <toolitem name="Right" action="justify-right"/>
-- >       <toolitem name="Fill" action="justify-fill"/>
-- >       <separator/>
-- >     </placeholder>
-- >   </toolbar>
-- > </ui>

-- The constructed widget hierarchy is very similar to the element tree of
-- the XML, with the exception that placeholders are merged into their parents.
-- The correspondence of XML elements to widgets should be almost obvious:
--
-- [menubar] a 'MenuBar'
--
-- [toolbar] a 'Toolbar'
--
-- [popup] a toplevel 'Menu'
--
-- [menu] a 'Menu' attached to a menuitem
--
-- [menuitem] a 'MenuItem' subclass, the exact type depends on the action
--
-- [toolitem] a 'ToolItem' subclass, the exact type depends on the action.
-- Note that toolitem elements may contain a menu element, but only if their
-- associated action specifies a 'MenuToolButton' as proxy.
--
-- [separator] a 'SeparatorMenuItem' or 'SeparatorToolItem'
--
-- [accelerator] a keyboard accelerator
--
-- The \"position\" attribute determines where a constructed widget is
-- positioned wrt. to its siblings in the partially constructed tree. If it is
-- \"top\", the widget is prepended, otherwise it is appended.

-- ** UI Merging
-- 
-- | The most remarkable feature of 'UIManager' is that it can overlay a set
-- of menuitems and toolitems over another one, and demerge them later.
--
-- Merging is done based on the names of the XML elements. Each element is
-- identified by a path which consists of the names of its anchestors,
-- separated by slashes. For example, the menuitem named \"Left\" in the
-- example above has the path @\/ui\/menubar\/JustifyMenu\/Left@ and the
-- toolitem with the same name has path
-- @\/ui\/toolbar1\/JustifyToolItems\/Left@.

-- ** Accelerators
-- 
-- | Every action has an accelerator path. Accelerators are installed together
-- with menuitem proxies, but they can also be explicitly added with
-- \<accelerator> elements in the UI definition. This makes it possible to have
-- accelerators for actions even if they have no visible proxies.

-- ** Smart Separators
-- 
-- | The separators created by 'UIManager' are \"smart\", i.e. they do not
-- show up in the UI unless they end up between two visible menu or tool items.
-- Separators which are located at the very beginning or end of the menu or
-- toolbar containing them, or multiple separators next to each other, are
-- hidden. This is a useful feature, since the merging of UI elements from
-- multiple sources can make it hard or impossible to determine in advance
-- whether a separator will end up in such an unfortunate position.
--
-- For separators in toolbars, you can set @expand=\"true\"@ to turn them
-- from a small, visible separator to an expanding, invisible one. Toolitems
-- following an expanding separator are effectively right-aligned.

-- ** Empty Menus
-- 
-- | Submenus pose similar problems to separators inconnection with merging.
-- It is impossible to know in advance whether they will end up empty after
-- merging. 'UIManager' offers two ways to treat empty submenus:
--
-- * make them disappear by hiding the menu item they\'re attached to
--
-- * add an insensitive \"Empty\" item
--
-- The behaviour is chosen based on the \"hide_if_empty\" property of the
-- action to which the submenu is associated.
-- 

-- * Class Hierarchy
-- |
-- @
-- |  'GObject'
-- |   +----UIManager
-- @

#if GTK_CHECK_VERSION(2,4,0)
-- * Types
  UIManager,
  UIManagerClass,
  castToUIManager, gTypeUIManager,
  toUIManager,
  UIManagerItemType(..),
  MergeId,

-- * Constructors
  uiManagerNew,

-- * Methods
  uiManagerSetAddTearoffs,
  uiManagerGetAddTearoffs,
  uiManagerInsertActionGroup,
  uiManagerRemoveActionGroup,
  uiManagerGetActionGroups,
  uiManagerGetAccelGroup,
  uiManagerGetWidget,
  uiManagerGetToplevels,
  uiManagerGetAction,
  uiManagerAddUiFromString,
  uiManagerAddUiFromFile,
  uiManagerNewMergeId,
  uiManagerAddUi,
  uiManagerRemoveUi,
  uiManagerGetUi,
  uiManagerEnsureUpdate,

-- * Attributes
  uiManagerAddTearoffs,
  uiManagerUi,

-- * Signals
  addWidget,
  actionsChanged,

-- * Deprecated
#ifndef DISABLE_DEPRECATED
  onAddWidget,
  afterAddWidget,
  onActionsChanged,
  afterActionsChanged,
  onConnectProxy,
  afterConnectProxy,
  onDisconnectProxy,
  afterDisconnectProxy,
  onPreActivate,
  afterPreActivate,
  onPostActivate,
  afterPostActivate,
#endif
#endif
  ) where

import Control.Monad	(liftM)

import System.Glib.FFI
import System.Glib.Flags		(Flags, fromFlags)
import System.Glib.UTFString
import System.Glib.GList
import System.Glib.GError
import System.Glib.Attributes
import System.Glib.Properties
import System.Glib.GObject		(constructNewGObject, makeNewGObject)
import Graphics.UI.Gtk.Abstract.Object	(makeNewObject)
{#import Graphics.UI.Gtk.Types#}
{#import Graphics.UI.Gtk.Signals#}

{# context lib="gtk" prefix="gtk" #}

#if GTK_CHECK_VERSION(2,4,0)
-- | These enumeration values are used by 'uiManagerAddUi' to determine what UI
-- element to create.
--
{# enum UIManagerItemType {underscoreToCase} deriving (Bounded) #}
instance Flags UIManagerItemType

newtype MergeId = MergeId { fromMergeId :: {# type guint #}}

--------------------
-- Constructors

-- | Creates a new ui manager object.
--
uiManagerNew :: IO UIManager
uiManagerNew =
  constructNewGObject mkUIManager $
  {# call gtk_ui_manager_new #}

--------------------
-- Methods

-- | Returns an unused merge id, suitable for use with 'uiManagerAddUi'.
--
uiManagerNewMergeId :: UIManager -> IO MergeId
uiManagerNewMergeId self =
  liftM MergeId $
  {# call gtk_ui_manager_new_merge_id #}
    self

-- | Sets the \"add_tearoffs\" property, which controls whether menus
-- generated by this 'UIManager' will have tearoff menu items.
--
-- Note that this only affects regular menus. Generated popup menus never
-- have tearoff menu items.
--
uiManagerSetAddTearoffs :: UIManager
 -> Bool      -- ^ @addTearoffs@ - whether tearoff menu items are added
 -> IO ()
uiManagerSetAddTearoffs self addTearoffs =
  {# call gtk_ui_manager_set_add_tearoffs #}
    self
    (fromBool addTearoffs)

-- | Returns whether menus generated by this 'UIManager' will have tearoff
-- menu items.
--
uiManagerGetAddTearoffs :: UIManager
 -> IO Bool   -- ^ returns whether tearoff menu items are added
uiManagerGetAddTearoffs self =
  liftM toBool $
  {# call gtk_ui_manager_get_add_tearoffs #}
    self

-- | Inserts an action group into the list of action groups associated with
-- @self@. Actions in earlier groups hide actions with the same name in later
-- groups.
--
uiManagerInsertActionGroup :: UIManager
 -> ActionGroup -- ^ @actionGroup@ - the action group to be inserted
 -> Int         -- ^ @pos@ - the position at which the group will be inserted.
 -> IO ()
uiManagerInsertActionGroup self actionGroup pos =
  {# call gtk_ui_manager_insert_action_group #}
    self
    actionGroup
    (fromIntegral pos)

-- | Removes an action group from the list of action groups associated with
-- @self@.
--
uiManagerRemoveActionGroup :: UIManager
 -> ActionGroup -- ^ @actionGroup@ - the action group to be removed
 -> IO ()
uiManagerRemoveActionGroup self actionGroup =
  {# call gtk_ui_manager_remove_action_group #}
    self
    actionGroup

-- | Returns the list of action groups associated with the UI manager.
--
uiManagerGetActionGroups :: UIManager -> IO [ActionGroup]
uiManagerGetActionGroups self =
  {# call gtk_ui_manager_get_action_groups #}
    self
  >>= readGList
  >>= mapM (\elemPtr -> makeNewGObject mkActionGroup (return elemPtr))

-- | Returns the 'AccelGroup' associated with @self@.
--
uiManagerGetAccelGroup :: UIManager
 -> IO AccelGroup -- ^ returns the 'AccelGroup'.
uiManagerGetAccelGroup self =
  makeNewGObject mkAccelGroup $
  {# call gtk_ui_manager_get_accel_group #}
    self

-- | Looks up a widget by following a path. The path consists of the names
-- specified in the XML description of the UI. separated by \'\/\'. Elements
-- which don't have a name or action attribute in the XML (e.g. \<popup>) can
-- be addressed by their XML element name (e.g. \"popup\"). The root element
-- (\"\/ui\") can be omitted in the path.
--
-- Note that the widget found by following a path that ends in a \<menu>
-- element is the menuitem to which the menu is attached, not the menu itself.
--
uiManagerGetWidget :: UIManager
 -> String            -- ^ @path@ - a path
 -> IO (Maybe Widget) -- ^ returns the widget found by following the path, or
                      -- @Nothing@ if no widget was found.
uiManagerGetWidget self path =
  maybeNull (makeNewObject mkWidget) $
  withUTFString path $ \pathPtr ->
  {# call gtk_ui_manager_get_widget #}
    self
    pathPtr

-- | Obtains a list of all toplevel widgets of the requested types.
--
uiManagerGetToplevels :: UIManager
 -> [UIManagerItemType]     -- ^ @types@ - specifies the types of toplevel
                            -- widgets to include. Allowed types are
                            -- 'UiManagerMenubar', 'UiManagerToolbar' and
                            -- 'UiManagerPopup'.
 -> IO [Widget]             -- ^ returns a list of all toplevel
                            -- widgets of the requested types.
uiManagerGetToplevels self types =
  {# call gtk_ui_manager_get_toplevels #}
    self
    ((fromIntegral . fromFlags) types)
  >>= fromGSList
  >>= mapM (\elemPtr -> makeNewObject mkWidget (return elemPtr))

-- | Looks up an action by following a path. See 'uiManagerGetWidget' for more
-- information about paths.
--
uiManagerGetAction :: UIManager
 -> String            -- ^ @path@ - a path
 -> IO (Maybe Action) -- ^ returns the action whose proxy widget is found by
                      -- following the path, or @Nothing@ if no widget was
                      -- found.
uiManagerGetAction self path =
  maybeNull (makeNewGObject mkAction) $
  withUTFString path $ \pathPtr ->
  {# call gtk_ui_manager_get_action #}
    self
    pathPtr

-- | Parses a string containing a UI definition and merges it with the current
-- contents of @self@. An enclosing \<ui> element is added if it is missing.
--
-- If a parse error occurres, an exception is thrown.
--
uiManagerAddUiFromString :: UIManager
 -> String    -- ^ @buffer@ - the string to parse
 -> IO MergeId -- ^ returns The merge id for the merged UI. The merge id can be
               -- used to unmerge the UI with 'uiManagerRemoveUi'.
uiManagerAddUiFromString self buffer =
  liftM MergeId $
  propagateGError $ \errorPtr ->
  withUTFStringLen buffer $ \(bufferPtr, length) ->
  {# call gtk_ui_manager_add_ui_from_string #}
    self
    bufferPtr
    (fromIntegral length)
    errorPtr

-- | Parses a file containing a UI definition and merges it with the current
-- contents of @self@.
--
-- If a parse or IO error occurres, an exception is thrown.
--
uiManagerAddUiFromFile :: UIManager
 -> String    -- ^ @filename@ - the name of the file to parse
 -> IO MergeId -- ^ returns The merge id for the merged UI. The merge id can be
              -- used to unmerge the UI with 'uiManagerRemoveUi'.
uiManagerAddUiFromFile self filename =
  liftM MergeId $
  propagateGError $ \errorPtr ->
  withUTFString filename $ \filenamePtr ->
#if defined (WIN32) && GTK_CHECK_VERSION(2,6,0)
  {# call gtk_ui_manager_add_ui_from_file_utf8 #}
#else
  {# call gtk_ui_manager_add_ui_from_file #}
#endif
    self
    filenamePtr
    errorPtr

-- | Adds a UI element to the current contents of @self@.
--
-- If @type@ is 'UiManagerAuto', Gtk+ inserts a menuitem, toolitem or
-- separator if such an element can be inserted at the place determined by
-- @path@. Otherwise @type@ must indicate an element that can be inserted at
-- the place determined by @path@.
--
-- If @path@ points to a menuitem or toolitem, the new element will be
-- inserted before or after this item, depending on @top@.
--
uiManagerAddUi :: UIManager
 -> MergeId             -- ^ @mergeId@ - the merge id for the merged UI, see
                        -- 'uiManagerNewMergeId'
 -> String              -- ^ @path@ - a path
 -> String              -- ^ @name@ - the name for the added UI element
 -> Maybe String        -- ^ @action@ - the name of the action to be proxied,
                        -- or @Nothing@ to add a separator
 -> [UIManagerItemType] -- ^ @type@ - the type of UI element to add.
 -> Bool                -- ^ @top@ - if @True@, the UI element is added before
                        -- its siblings, otherwise it is added after its
                        -- siblings.
 -> IO ()
uiManagerAddUi self mergeId path name action type_ top =
  maybeWith withUTFString action $ \actionPtr ->
  withUTFString name $ \namePtr ->
  withUTFString path $ \pathPtr ->
  {# call gtk_ui_manager_add_ui #}
    self
    (fromMergeId mergeId)
    pathPtr
    namePtr
    actionPtr
    ((fromIntegral . fromFlags) type_)
    (fromBool top)

-- | Unmerges the part of the UI manager's content identified by @mergeId@.
--
uiManagerRemoveUi :: UIManager
 -> MergeId   -- ^ @mergeId@ - a merge id as returned by
              -- 'uiManagerAddUiFromString'
 -> IO ()
uiManagerRemoveUi self mergeId =
  {# call gtk_ui_manager_remove_ui #}
    self
    (fromMergeId mergeId)

-- | Creates a UI definition of the merged UI.
--
uiManagerGetUi :: UIManager
 -> IO String -- ^ returns string containing an XML representation of the
              -- merged UI.
uiManagerGetUi self =
  {# call gtk_ui_manager_get_ui #}
    self
  >>= readUTFString

-- | Makes sure that all pending updates to the UI have been completed.
--
-- This may occasionally be necessary, since 'UIManager' updates the UI in
-- an idle function. A typical example where this function is useful is to
-- enforce that the menubar and toolbar have been added to the main window
-- before showing it:
-- 
-- > do
-- >   containerAdd window vbox
-- >   onAddWidget merge (addWidget vbox)
-- >   uiManagerAddUiFromFile merge "my-menus"
-- >   uiManagerAddUiFromFile merge "my-toolbars"
-- >   uiManagerEnsureUpdate merge
-- >   widgetShow window
--
uiManagerEnsureUpdate :: UIManager -> IO ()
uiManagerEnsureUpdate self =
  {# call gtk_ui_manager_ensure_update #}
    self

--------------------
-- Attributes

-- | The \"add-tearoffs\" property controls whether generated menus have
-- tearoff menu items.
--
-- Note that this only affects regular menus. Generated popup menus never
-- have tearoff menu items.
--
-- Default value: @False@
--
uiManagerAddTearoffs :: Attr UIManager Bool
uiManagerAddTearoffs = newAttr
  uiManagerGetAddTearoffs
  uiManagerSetAddTearoffs

-- | An XML string describing the merged UI.
--
-- Default value: @\"\<ui\>\\n\<\/ui\>\\n\"@
--
uiManagerUi :: ReadAttr UIManager String
uiManagerUi = readAttrFromStringProperty "ui"

--------------------
-- Signals

-- %hash c:58ec d:2a79
-- | The add_widget signal is emitted for each generated menubar and toolbar.
-- It is not emitted for generated popup menus, which can be obtained by
-- 'uiManagerGetWidget'.
--
addWidget :: UIManagerClass self => Signal self (Widget -> IO ())
addWidget = Signal (connect_OBJECT__NONE "add_widget")

-- %hash c:2480 d:366c
-- | The \"actions-changed\" signal is emitted whenever the set of actions
-- changes.
--
actionsChanged :: UIManagerClass self => Signal self (IO ())
actionsChanged = Signal (connect_NONE__NONE "actions_changed")

--------------------
-- Deprecated Signals

#ifndef DISABLE_DEPRECATED
-- | The add_widget signal is emitted for each generated menubar and toolbar.
-- It is not emitted for generated popup menus, which can be obtained by
-- 'uiManagerGetWidget'.
--
onAddWidget, afterAddWidget :: UIManagerClass self => self
 -> (Widget -> IO ())
 -> IO (ConnectId self)
onAddWidget = connect_OBJECT__NONE "add_widget" False
afterAddWidget = connect_OBJECT__NONE "add_widget" True

-- | The \"actions-changed\" signal is emitted whenever the set of actions
-- changes.
--
onActionsChanged, afterActionsChanged :: UIManagerClass self => self
 -> IO ()
 -> IO (ConnectId self)
onActionsChanged = connect_NONE__NONE "actions_changed" False
afterActionsChanged = connect_NONE__NONE "actions_changed" True

-- | The connect_proxy signal is emitted after connecting a proxy to an action
-- in the group.
--
-- This is intended for simple customizations for which a custom action
-- class would be too clumsy, e.g. showing tooltips for menuitems in the
-- statusbar.
--
onConnectProxy, afterConnectProxy :: UIManagerClass self => self
 -> (Action -> Widget -> IO ())
 -> IO (ConnectId self)
onConnectProxy = connect_OBJECT_OBJECT__NONE "connect_proxy" False
afterConnectProxy = connect_OBJECT_OBJECT__NONE "connect_proxy" True

-- | The disconnect_proxy signal is emitted after disconnecting a proxy from
-- an action in the group.
--
onDisconnectProxy, afterDisconnectProxy :: UIManagerClass self => self
 -> (Action -> Widget -> IO ())
 -> IO (ConnectId self)
onDisconnectProxy = connect_OBJECT_OBJECT__NONE "disconnect_proxy" False
afterDisconnectProxy = connect_OBJECT_OBJECT__NONE "disconnect_proxy" True

-- | The pre_activate signal is emitted just before the @action@ is activated.
--
-- This is intended for applications to get notification just before any
-- action is activated.
--
onPreActivate, afterPreActivate :: UIManagerClass self => self
 -> (Action -> IO ())
 -> IO (ConnectId self)
onPreActivate = connect_OBJECT__NONE "pre_activate" False
afterPreActivate = connect_OBJECT__NONE "pre_activate" True

-- | The post_activate signal is emitted just after the @action@ is activated.
--
-- This is intended for applications to get notification just after any
-- action is activated.
--
onPostActivate, afterPostActivate :: UIManagerClass self => self
 -> (Action -> IO ())
 -> IO (ConnectId self)
onPostActivate = connect_OBJECT__NONE "post_activate" False
afterPostActivate = connect_OBJECT__NONE "post_activate" True
#endif
#endif