# -*- coding: utf-8 -*-

'''
Task Coach - Your friendly task manager
Copyright (C) 2004-2015 Task Coach developers <developers@taskcoach.org>
Copyright (C) 2008 Rob McMullen <rob.mcmullen@gmail.com>
Copyright (C) 2008 Thomas Sonne Olesen <tpo@sonnet.dk>

Task Coach is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

Task Coach 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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
'''

import wx
from taskcoachlib import patterns, widgets, command, render
from taskcoachlib.i18n import _
from taskcoachlib.gui import uicommand, toolbar, artprovider
from taskcoachlib.thirdparty import hypertreelist
from taskcoachlib.thirdparty.pubsub import pub
from taskcoachlib.widgets import ToolTipMixin
import mixin


class Viewer(patterns.Observer, wx.Panel):
    ''' A Viewer shows domain objects (e.g. tasks or efforts) by means of a 
        widget (e.g. a ListCtrl or a TreeListCtrl).'''
    
    __metaclass__ = patterns.NumberedInstances
    defaultTitle = 'Subclass responsibility'
    defaultBitmap = 'Subclass responsibility'
    viewerImages = artprovider.itemImages
    
    def __init__(self, parent, taskFile, settings, *args, **kwargs):
        super(Viewer, self).__init__(parent, -1)
        self.parent = parent
        self.taskFile = taskFile
        self.settings = settings
        self.__settingsSection = kwargs.pop('settingsSection')
        self.__freezeCount = 0
        # The how maniest of this viewer type are we? Used for settings
        self.__instanceNumber = kwargs.pop('instanceNumber')
        self.__use_separate_settings_section = kwargs.pop('use_separate_settings_section', 
                                                          True)
        # Selection cache:
        self.__curselection = [] 
        # Flag so that we don't notify observers while we're selecting all items
        self.__selectingAllItems = False
        # Popup menus we have to destroy before closing the viewer to prevent 
        # memory leakage:
        self._popupMenus = []
        # What are we presenting:
        self.__presentation = self.createSorter(self.createFilter(self.domainObjectsToView()))
        # The widget used to present the presentation:
        self.widget = self.createWidget()
        self.widget.SetBackgroundColour(wx.SystemSettings.GetColour(wx.SYS_COLOUR_WINDOW))
        self.toolbar = toolbar.ToolBar(self, settings, (16, 16))
        self.initLayout()
        self.registerPresentationObservers()
        self.refresh()

        pub.subscribe(self.onBeginIO, 'taskfile.aboutToRead')
        pub.subscribe(self.onBeginIO, 'taskfile.aboutToClear')
        pub.subscribe(self.onBeginIO, 'taskfile.aboutToSave')
        pub.subscribe(self.onEndIO, 'taskfile.justRead')
        pub.subscribe(self.onEndIO, 'taskfile.justCleared')
        pub.subscribe(self.onEndIO, 'taskfile.justSaved')

        if isinstance(self.widget, ToolTipMixin):
            pub.subscribe(self.onShowTooltipsChanged, 'settings.view.descriptionpopups')
            self.widget.SetToolTipsEnabled(settings.getboolean('view', 'descriptionpopups'))

        wx.CallAfter(self.__DisplayBalloon)

    def __DisplayBalloon(self):
        # AuiFloatingFrame is instantiated from framemanager, we can't derive it from BalloonTipManager
        if self.toolbar.IsShownOnScreen() and hasattr(wx.GetTopLevelParent(self), 'AddBalloonTip'):
            wx.GetTopLevelParent(self).AddBalloonTip(self.settings, 'customizabletoolbars', self.toolbar,
                title=_('Toolbars are customizable'),
                getRect=lambda: self.toolbar.GetToolRect(self.toolbar.getToolIdByCommand('EditToolBarPerspective')),
                message=_('''Click on the gear icon on the right to add buttons and rearrange them.'''))

    def onShowTooltipsChanged(self, value):
        self.widget.SetToolTipsEnabled(value)

    def onBeginIO(self, taskFile):
        self.__freezeCount += 1
        self.__presentation.freeze()

    def onEndIO(self, taskFile):
        self.__freezeCount -= 1
        self.__presentation.thaw()
        if self.__freezeCount == 0:
            self.refresh()

    def activate(self):
        pass

    def domainObjectsToView(self):
        ''' Return the domain objects that this viewer should display. For
            global viewers this will be part of the task file, 
            e.g. self.taskFile.tasks(), for local viewers this will be a list
            of objects passed to the viewer constructor. '''
        raise NotImplementedError
    
    def registerPresentationObservers(self):
        self.removeObserver(self.onPresentationChanged)
        self.registerObserver(self.onPresentationChanged, 
                              eventType=self.presentation().addItemEventType(),
                              eventSource=self.presentation())
        self.registerObserver(self.onPresentationChanged, 
                              eventType=self.presentation().removeItemEventType(),
                              eventSource=self.presentation())
        self.registerObserver(self.onNewItem, eventType='newitem')
               
    def detach(self):
        ''' Should be called by viewer.container before closing the viewer '''
        observers = [self, self.presentation()]
        observable = self.presentation()
        while True:
            try:
                observable = observable.observable()
            except AttributeError:
                break
            else:
                observers.append(observable)
        for observer in observers:
            try:
                observer.removeInstance()
            except AttributeError:
                pass  # Ignore observables that are not an observer themselves

        for popupMenu in self._popupMenus:
            try:
                popupMenu.clearMenu()
                popupMenu.Destroy()
            except wx.PyDeadObjectError:
                pass

        pub.unsubscribe(self.onBeginIO, 'taskfile.aboutToRead')
        pub.unsubscribe(self.onBeginIO, 'taskfile.aboutToClear')
        pub.unsubscribe(self.onBeginIO, 'taskfile.aboutToSave')
        pub.unsubscribe(self.onEndIO, 'taskfile.justRead')
        pub.unsubscribe(self.onEndIO, 'taskfile.justCleared')
        pub.unsubscribe(self.onEndIO, 'taskfile.justSaved')

        self.presentation().detach()
        self.toolbar.detach()

    def viewerStatusEventType(self):
        return 'viewer%s.status' % id(self)
    
    def sendViewerStatusEvent(self):
        pub.sendMessage(self.viewerStatusEventType(), viewer=self)
    
    def statusMessages(self):
        return '', ''
    
    def title(self):
        return self.settings.get(self.settingsSection(), 'title') or self.defaultTitle
    
    def setTitle(self, title):
        titleToSaveInSettings = '' if title == self.defaultTitle else title
        self.settings.set(self.settingsSection(), 'title', titleToSaveInSettings)
        self.parent.setPaneTitle(self, title)
        self.parent.manager.Update()

    def initLayout(self):
        self._sizer = wx.BoxSizer(wx.VERTICAL)  # pylint: disable=W0201
        self._sizer.Add(self.toolbar, flag=wx.EXPAND)
        self._sizer.Add(self.widget, proportion=1, flag=wx.EXPAND)
        self.SetSizerAndFit(self._sizer)
    
    def createWidget(self, *args):
        raise NotImplementedError
    
    def createImageList(self):
        size = (16, 16)
        imageList = wx.ImageList(*size)  # pylint: disable=W0142
        self.imageIndex = {}  # pylint: disable=W0201
        for index, image in enumerate(self.viewerImages):
            try:
                imageList.Add(wx.ArtProvider_GetBitmap(image, wx.ART_MENU, size))
            except:
                print image
                raise
            self.imageIndex[image] = index
        return imageList

    def getWidget(self):
        return self.widget
    
    def SetFocus(self, *args, **kwargs):
        try:
            self.widget.SetFocus(*args, **kwargs)
        except wx.PyDeadObjectError:
            pass
            
    def createSorter(self, collection):
        ''' This method can be overridden to decorate the presentation with a 
            sorter. '''
        return collection
        
    def createFilter(self, collection):
        ''' This method can be overridden to decorate the presentation with a 
            filter. '''
        return collection

    def onAttributeChanged(self, newValue, sender):  # pylint: disable=W0613
        if self:
            self.refreshItems(sender)
        
    def onAttributeChanged_Deprecated(self, event):
        self.refreshItems(*event.sources())
        
    def onNewItem(self, event):
        self.select([item for item in event.values() if item in self.presentation()]) 
        
    def onPresentationChanged(self, event):  # pylint: disable=W0613
        ''' Whenever our presentation is changed (items added, items removed) 
            the viewer refreshes itself. '''
        def itemsRemoved():
            return event.type() == self.presentation().removeItemEventType()
        
        def allItemsAreSelected():
            return set(self.__curselection).issubset(set(event.values()))
        
        self.refresh()
        if itemsRemoved() and allItemsAreSelected(): 
            self.selectNextItemsAfterRemoval(event.values())
        self.updateSelection(sendViewerStatusEvent=False)
        self.sendViewerStatusEvent()
        
    def selectNextItemsAfterRemoval(self, removedItems):
        raise NotImplementedError        
        
    def onSelect(self, event=None):  # pylint: disable=W0613
        ''' The selection of items in the widget has been changed. Notify 
            our observers. '''
        if self.IsBeingDeleted() or self.__selectingAllItems:
            # Some widgets change the selection and send selection events when 
            # deleting all items as part of the Destroy process. Ignore.
            return
        # Be sure all wx events are handled before we update our selection 
        # cache and notify our observers:
        wx.CallAfter(self.updateSelection)

    def updateSelection(self, sendViewerStatusEvent=True):
        newSelection = self.widget.curselection()
        if newSelection != self.__curselection:
            self.__curselection = newSelection
            if sendViewerStatusEvent:
                self.sendViewerStatusEvent()

    def freeze(self):
        self.widget.Freeze()

    def thaw(self):
        self.widget.Thaw()

    def refresh(self):
        if self and not self.__freezeCount:
            self.widget.RefreshAllItems(len(self.presentation()))
    
    def refreshItems(self, *items):
        if not self.__freezeCount:
            items = [item for item in items if item in self.presentation()]
            self.widget.RefreshItems(*items)  # pylint: disable=W0142
        
    def select(self, items):
        self.__curselection = items
        self.widget.select(items)
        
    def curselection(self):
        ''' Return a list of items (domain objects) currently selected in our
            widget. '''
        return self.__curselection
        
    def curselectionIsInstanceOf(self, class_):
        ''' Return whether all items in the current selection are instances of
            class_. Can be overridden in subclasses that show only one type
            of items to simply check the class. '''
        return all(isinstance(item, class_) for item in self.curselection())

    def isselected(self, item):
        ''' Returns True if the given item is selected. See
            L{EffortViewer} for an explanation of why this may be
            different than 'if item in viewer.curselection()'. '''
        return item in self.curselection()

    def select_all(self):
        ''' Select all items in the presentation. Since some of the widgets we
            use may send events for each individual item (!) we stop processing
            selection events while we select all items. '''
        self.__selectingAllItems = True
        self.widget.select_all()
        # Use CallAfter to make sure we start processing selection events 
        # after all selection events have been fired (and ignored):
        wx.CallAfter(self.endOfSelectAll)
        
    def endOfSelectAll(self):
        self.__curselection = self.presentation()
        self.__selectingAllItems = False
        # Pretend we received one selection event for the select_all() call:
        self.onSelect()

    def clear_selection(self):
        self.__curselection = []
        self.widget.clear_selection()
        
    def size(self):
        return self.widget.GetItemCount()
    
    def presentation(self):
        ''' Return the domain objects that this viewer is currently 
            displaying. '''
        return self.__presentation
        
    def setPresentation(self, presentation):
        ''' Change the presentation of the viewer. '''
        self.__presentation = presentation
    
    def widgetCreationKeywordArguments(self):
        return {}

    def isViewerContainer(self):
        return False
    
    def isShowingTasks(self): 
        return False

    def isShowingEffort(self): 
        return False
    
    def isShowingCategories(self):
        return False
    
    def isShowingNotes(self):
        return False

    def isShowingAttachments(self):
        return False

    def visibleColumns(self):
        return [widgets.Column('subject', _('Subject'))]
    
    def bitmap(self):
        ''' Return the bitmap that represents this viewer. Used for the 
            'Viewer->New viewer' menu item, for example. '''
        return self.defaultBitmap  # Class attribute of concrete viewers
    
    def settingsSection(self):
        ''' Return the settings section of this viewer. '''
        section = self.__settingsSection
        if self.__use_separate_settings_section and self.__instanceNumber > 0:
            # We're not the first viewer of our class, so we need a different
            # settings section than the default one.
            section += str(self.__instanceNumber)
            if not self.settings.has_section(section):
                # Our section does not exist yet. Create it and copy the 
                # settings from the previous section as starting point. We're 
                # copying from the previous section instead of the default
                # section so that when the user closes a viewer and then opens
                # a new one, the settings of that closed viewer are reused. 
                self.settings.add_section(section, 
                    copyFromSection=self.previousSettingsSection())
        return section
        
    def previousSettingsSection(self):
        ''' Return the settings section of the previous viewer of this 
            class. '''
        previousSectionNumber = self.__instanceNumber - 1
        while previousSectionNumber > 0:
            previousSection = self.__settingsSection + str(previousSectionNumber)
            if self.settings.has_section(previousSection):
                return previousSection
            previousSectionNumber -= 1
        return self.__settingsSection
    
    def hasModes(self):
        return False
    
    def getModeUICommands(self):
        return []
    
    def isSortable(self):
        return False

    def getSortUICommands(self):
        return []
    
    def isSearchable(self):
        return False
        
    def hasHideableColumns(self):
        return False
    
    def getColumnUICommands(self):
        return []

    def isFilterable(self):
        return False
    
    def getFilterUICommands(self):
        return []
    
    def supportsRounding(self):
        return False
    
    def getRoundingUICommands(self):
        return []
    
    def createToolBarUICommands(self):
        ''' UI commands to put on the toolbar of this viewer. '''
        table = wx.AcceleratorTable([(wx.ACCEL_CMD, ord('X'), wx.ID_CUT),
                                     (wx.ACCEL_CMD, ord('C'), wx.ID_COPY),
                                     (wx.ACCEL_CMD, ord('V'), wx.ID_PASTE),
                                     (wx.ACCEL_NORMAL, wx.WXK_RETURN, wx.ID_EDIT),
                                     (wx.ACCEL_NORMAL, wx.WXK_DELETE, wx.ID_DELETE)])
        self.SetAcceleratorTable(table)
        
        clipboardToolBarUICommands = self.createClipboardToolBarUICommands()
        creationToolBarUICommands = self.createCreationToolBarUICommands()
        editToolBarUICommands = self.createEditToolBarUICommands() 
        actionToolBarUICommands = self.createActionToolBarUICommands()
        modeToolBarUICommands = self.createModeToolBarUICommands()
        
        def separator(uiCommands, *otherUICommands):
            return (None,) if (uiCommands and any(otherUICommands)) else ()
        
        clipboardSeparator = separator(clipboardToolBarUICommands, creationToolBarUICommands,
                                       editToolBarUICommands, actionToolBarUICommands,
                                       modeToolBarUICommands)
        creationSeparator = separator(creationToolBarUICommands, editToolBarUICommands,
                                      actionToolBarUICommands, modeToolBarUICommands)
        editSeparator = separator(editToolBarUICommands, actionToolBarUICommands,
                                  modeToolBarUICommands)
        actionSeparator = separator(actionToolBarUICommands, modeToolBarUICommands)
        
        return clipboardToolBarUICommands + clipboardSeparator + \
            creationToolBarUICommands + creationSeparator + \
            editToolBarUICommands + editSeparator + \
            actionToolBarUICommands + actionSeparator + \
            modeToolBarUICommands

    def getToolBarPerspective(self):
        return self.settings.get(self.settingsSection(), 'toolbarperspective')

    def saveToolBarPerspective(self, perspective):
        self.settings.set(self.settingsSection(), 'toolbarperspective', perspective)

    def createClipboardToolBarUICommands(self):
        ''' UI commands for manipulating the clipboard (cut, copy, paste). '''
        cutCommand = uicommand.EditCut(viewer=self)
        copyCommand = uicommand.EditCopy(viewer=self)
        pasteCommand = uicommand.EditPaste()
        cutCommand.bind(self, wx.ID_CUT)
        copyCommand.bind(self, wx.ID_COPY)
        pasteCommand.bind(self, wx.ID_PASTE)
        return cutCommand, copyCommand, pasteCommand
    
    def createCreationToolBarUICommands(self):
        ''' UI commands for creating new items. '''
        return ()
    
    def createEditToolBarUICommands(self):
        ''' UI commands for editing items. '''
        editCommand = uicommand.Edit(viewer=self)
        self.deleteUICommand = uicommand.Delete(viewer=self)  # For unittests pylint: disable=W0201
        editCommand.bind(self, wx.ID_EDIT)
        self.deleteUICommand.bind(self, wx.ID_DELETE)
        return editCommand, self.deleteUICommand
    
    def createActionToolBarUICommands(self):
        ''' UI commands for actions. '''
        return ()
    
    def createModeToolBarUICommands(self):
        ''' UI commands for mode switches (e.g. list versus tree mode). '''
        return ()
    
    def newItemDialog(self, *args, **kwargs):
        bitmap = kwargs.pop('bitmap')
        newItemCommand = self.newItemCommand(*args, **kwargs)
        newItemCommand.do()
        return self.editItemDialog(newItemCommand.items, bitmap, 
                                   items_are_new=True)

    def newSubItemDialog(self, bitmap):
        newSubItemCommand = self.newSubItemCommand()
        newSubItemCommand.do()
        return self.editItemDialog(newSubItemCommand.items, bitmap, 
                                   items_are_new=True)   
    
    def editItemDialog(self, items, bitmap, columnName='', items_are_new=False):
        Editor = self.itemEditorClass()
        return Editor(wx.GetTopLevelParent(self), items, 
                      self.settings, self.presentation(), self.taskFile, 
                      bitmap=bitmap, columnName=columnName, 
                      items_are_new=items_are_new)
        
    def itemEditorClass(self):
        raise NotImplementedError
    
    def newItemCommand(self, *args, **kwargs):
        return self.newItemCommandClass()(self.presentation(), *args, **kwargs)

    def newItemCommandClass(self):
        raise NotImplementedError
    
    def newSubItemCommand(self):
        return self.newSubItemCommandClass()(self.presentation(), 
                                             self.curselection())

    def newSubItemCommandClass(self):
        raise NotImplementedError

    def deleteItemCommand(self):
        return self.deleteItemCommandClass()(self.presentation(), self.curselection())

    def deleteItemCommandClass(self):
        return command.DeleteCommand

    def cutItemCommand(self):
        return self.cutItemCommandClass()(self.presentation(), self.curselection())

    def cutItemCommandClass(self):
        return command.CutCommand

    def onEditSubject(self, item, newValue):
        command.EditSubjectCommand(items=[item], newValue=newValue).do()
        
    def onEditDescription(self, item, newValue):
        command.EditDescriptionCommand(items=[item], newValue=newValue).do()

    def getItemTooltipData(self, item):
        lines = [line.rstrip('\r') for line in item.description().split('\n')] 
        return [(None, lines)] if lines and lines != [''] else [] 


class CategorizableViewerMixin(object):
    def getItemTooltipData(self, item):
        return [('folder_blue_arrow_icon', [u', '.join(sorted([cat.subject() for cat in item.categories()]))] if item.categories() else [])] + \
            super(CategorizableViewerMixin, self).getItemTooltipData(item)


class WithAttachmentsViewerMixin(object):
    def getItemTooltipData(self, item):
        return [('paperclip_icon', sorted([unicode(attachment) for attachment in item.attachments()]))] + \
          super(WithAttachmentsViewerMixin, self).getItemTooltipData(item)


class ListViewer(Viewer):  # pylint: disable=W0223
    def isTreeViewer(self):
        return False

    def visibleItems(self):
        ''' Iterate over the items in the presentation. '''
        for item in self.presentation():
            yield item
    
    def getItemWithIndex(self, index):
        return self.presentation()[index]
            
    def getIndexOfItem(self, item):
        return self.presentation().index(item)

    def selectNextItemsAfterRemoval(self, removedItems):
        pass  # Done automatically by list controls        
        

class TreeViewer(Viewer):  # pylint: disable=W0223
    def __init__(self, *args, **kwargs):
        self.__selectionIndex = 0
        super(TreeViewer, self).__init__(*args, **kwargs)
        self.widget.Bind(wx.EVT_TREE_ITEM_EXPANDED, self.onItemExpanded)
        self.widget.Bind(wx.EVT_TREE_ITEM_COLLAPSED, self.onItemCollapsed)

    def onItemExpanded(self, event):
        self.__handleExpandedOrCollapsedItem(event, expanded=True)
        
    def onItemCollapsed(self, event):
        self.__handleExpandedOrCollapsedItem(event, expanded=False)
        
    def __handleExpandedOrCollapsedItem(self, event, expanded):
        event.Skip()
        treeItem = event.GetItem()
        # If we get an expanded or collapsed event for the root item, ignore it
        if treeItem == self.widget.GetRootItem():
            return
        item = self.widget.GetItemPyData(treeItem)
        item.expand(expanded, context=self.settingsSection())
            
    def expandAll(self):
        ''' Expand all items, recursively. '''
        # Since the widget does not send EVT_TREE_ITEM_EXPANDED when expanding
        # all items, we have to do the bookkeeping ourselves:
        for item in self.visibleItems():
            item.expand(True, context=self.settingsSection(), notify=False)
        self.refresh()

    def collapseAll(self):
        ''' Collapse all items, recursively. '''
        # Since the widget does not send EVT_TREE_ITEM_COLLAPSED when collapsing
        # all items, we have to do the bookkeeping ourselves:
        for item in self.visibleItems():
            item.expand(False, context=self.settingsSection(), notify=False)
        self.refresh()
                
    def isAnyItemExpandable(self):
        return self.widget.isAnyItemExpandable()

    def isAnyItemCollapsable(self):
        return self.widget.isAnyItemCollapsable()
        
    def isTreeViewer(self):
        return True
    
    def select(self, items):
        for item in items:
            self.__expandItemRecursively(item)
        self.refresh()
        super(TreeViewer, self).select(items)
        
    def __expandItemRecursively(self, item):
        parent = self.getItemParent(item)
        if parent:
            parent.expand(True, context=self.settingsSection(), notify=False)
            self.__expandItemRecursively(parent)

    def selectNextItemsAfterRemoval(self, removedItems):
        parents = [self.getItemParent(item) for item in removedItems]
        parents = [parent for parent in parents if parent in self.presentation()]
        parent = parents[0] if parents else None
        siblings = self.children(parent)
        newSelection = siblings[min(len(siblings) - 1, self.__selectionIndex)] if siblings else parent
        if newSelection:
            self.select([newSelection])
    
    def updateSelection(self, *args, **kwargs):        
        super(TreeViewer, self).updateSelection(*args, **kwargs)
        curselection = self.curselection()
        if curselection:
            siblings = self.children(self.getItemParent(curselection[0]))
            self.__selectionIndex = siblings.index(curselection[0]) if curselection[0] in siblings else 0
        else:
            self.__selectionIndex = 0
            
    def visibleItems(self):
        ''' Iterate over the items in the presentation. '''            
                            
        def yieldItemsAndChildren(items):
            sortedItems = [item for item in self.presentation() if item in items]
            for item in sortedItems:
                yield item
                children = self.children(item)
                if children:
                    for child in yieldItemsAndChildren(children):
                        yield child

        for item in yieldItemsAndChildren(self.getRootItems()):
            yield item
        
    def getRootItems(self):
        ''' Allow for overriding what the rootItems are. '''
        return self.presentation().rootItems()
            
    def getItemParent(self, item):
        ''' Allow for overriding what the parent of an item is. '''
        return item.parent()

    def getItemExpanded(self, item):
        return item.isExpanded(context=self.settingsSection())
    
    def children(self, parent=None):
        if parent:
            children = parent.children()
            if children:
                return [child for child in self.presentation() if child in children]
            else:
                return []
        else:
            return self.getRootItems()
        
    def getItemText(self, item):
        return item.subject()

            
class ViewerWithColumns(Viewer):  # pylint: disable=W0223
    def __init__(self, *args, **kwargs):
        self.__initDone = False
        self._columns = []
        self.__visibleColumns = []
        self.__columnUICommands = []
        super(ViewerWithColumns, self).__init__(*args, **kwargs)
        self.initColumns()
        self.__initDone = True
        self.refresh()
        
    def hasHideableColumns(self):
        return True

    def hasOrderingColumn(self):
        for column in self.__visibleColumns:
            if column.name() == 'ordering':
                return True
        return False

    def getColumnUICommands(self):
        if not self.__columnUICommands:
            self.__columnUICommands = self.createColumnUICommands()
        return self.__columnUICommands

    def createColumnUICommands(self):
        raise NotImplementedError
    
    def refresh(self, *args, **kwargs):
        if self and self.__initDone:
            super(ViewerWithColumns, self).refresh(*args, **kwargs)
                    
    def initColumns(self):
        for column in self.columns():
            self.initColumn(column)
        if self.hasOrderingColumn():
            self.widget.SetResizeColumn(1)
            self.widget.SetMainColumn(1)

    def initColumn(self, column):
        if column.name() in self.settings.getlist(self.settingsSection(), 
                                                  'columnsalwaysvisible'):
            show = True
        else:
            show = column.name() in self.settings.getlist(self.settingsSection(), 'columns')
            self.widget.showColumn(column, show=show)
        if show:
            self.__visibleColumns.append(column)
            self.__startObserving(column.eventTypes())
    
    def showColumnByName(self, columnName, show=True):
        for column in self.hideableColumns():
            if columnName == column.name():
                isVisibleColumn = self.isVisibleColumn(column)
                if (show and not isVisibleColumn) or \
                   (not show and isVisibleColumn):
                    self.showColumn(column, show)
                break

    def showColumn(self, column, show=True, refresh=True):
        if column.name() == 'ordering':
            self.widget.SetResizeColumn(1 if show else 0)
            self.widget.SetMainColumn(1 if show else 0)

        if show:
            self.__visibleColumns.append(column)
            # Make sure we keep the columns in the right order:
            self.__visibleColumns = [c for c in self.columns() if \
                                     c in self.__visibleColumns]
            self.__startObserving(column.eventTypes())
        else:
            self.__visibleColumns.remove(column)
            self.__stopObserving(column.eventTypes())
        self.widget.showColumn(column, show)
        self.settings.set(self.settingsSection(), 'columns', 
            str([column.name() for column in self.__visibleColumns]))
        if refresh:
            self.widget.RefreshAllItems(len(self.presentation()))

    def hideColumn(self, visibleColumnIndex):
        column = self.visibleColumns()[visibleColumnIndex]
        self.showColumn(column, show=False)
                
    def columns(self):
        return self._columns

    def selectableColumns(self):
        return self._columns

    def isVisibleColumnByName(self, columnName):
        return columnName in [column.name() for column in self.__visibleColumns]
        
    def isVisibleColumn(self, column):
        return column in self.__visibleColumns
    
    def visibleColumns(self):
        return self.__visibleColumns
        
    def hideableColumns(self):
        return [column for column in self._columns if column.name() not in \
                self.settings.getlist(self.settingsSection(), 
                                      'columnsalwaysvisible')]
                
    def isHideableColumn(self, visibleColumnIndex):
        column = self.visibleColumns()[visibleColumnIndex]
        unhideableColumns = self.settings.getlist(self.settingsSection(), 
                                                  'columnsalwaysvisible')
        return column.name() not in unhideableColumns

    def getColumnWidth(self, columnName):
        columnWidths = self.settings.getdict(self.settingsSection(),
                                             'columnwidths')
        defaultWidth = 28 if columnName == 'ordering' else hypertreelist._DEFAULT_COL_WIDTH  # pylint: disable=W0212
        return columnWidths.get(columnName, defaultWidth)

    def onResizeColumn(self, column, width):
        columnWidths = self.settings.getdict(self.settingsSection(), 'columnwidths')
        columnWidths[column.name()] = width
        self.settings.setdict(self.settingsSection(), 'columnwidths', columnWidths)

    def validateDrag(self, dropItem, dragItems, columnIndex):
        if columnIndex == -1 or self.visibleColumns()[columnIndex].name() != 'ordering':
            return None # Normal behavior

        # Ordering

        if not self.isTreeViewer():
            return True

        # Tree mode. Only allow drag if all selected items are siblings.
        if len(set([item.parent() for item in dragItems])) >= 2:
            wx.GetTopLevelParent(self).AddBalloonTip(self.settings, 'treemanualordering', self,
                title=_('Reordering in tree mode'),
                getRect=lambda: wx.Rect(0, 0, 28, 16),
                message=_('''When in tree mode, manual ordering is only possible when all selected items are siblings.'''))
            return False

        # If they are, only allow drag at the same level
        if dragItems[0].parent() != (None if dropItem is None else dropItem.parent()):
            wx.GetTopLevelParent(self).AddBalloonTip(self.settings, 'treechildrenmanualordering', self,
                title=_('Reordering in tree mode'),
                getRect=lambda: wx.Rect(0, 0, 28, 16),
                message=_('''When in tree mode, you can only put objects at the same level (parent).'''))
            return False

        return True

    def getItemText(self, item, column=None):
        if column is None:
            column = 1 if self.hasOrderingColumn() else 0
        column = self.visibleColumns()[column]
        return column.render(item)
    
    def getItemImages(self, item, column=0):
        column = self.visibleColumns()[column]
        return column.imageIndices(item)
    
    def hasColumnImages(self, column):
        return self.visibleColumns()[column].hasImages()
    
    def subjectImageIndices(self, item):
        normalIcon = item.icon(recursive=True)
        selectedIcon = item.selectedIcon(recursive=True) or normalIcon
        normalImageIndex = self.imageIndex[normalIcon] if normalIcon else -1
        selectedImageIndex = self.imageIndex[selectedIcon] if selectedIcon else -1
        return {wx.TreeItemIcon_Normal: normalImageIndex,
                wx.TreeItemIcon_Expanded: selectedImageIndex} 
            
    def __startObserving(self, eventTypes):
        for eventType in eventTypes:
            if eventType.startswith('pubsub'):
                pub.subscribe(self.onAttributeChanged, eventType)
            else:
                self.registerObserver(self.onAttributeChanged_Deprecated, 
                                      eventType=eventType)                    
        
    def __stopObserving(self, eventTypes):
        # Collect the event types that the currently visible columns are
        # interested in and make sure we don't stop observing those event types.
        eventTypesOfVisibleColumns = []
        for column in self.visibleColumns():
            eventTypesOfVisibleColumns.extend(column.eventTypes())
        for eventType in eventTypes:
            if eventType not in eventTypesOfVisibleColumns:
                if eventType.startswith('pubsub'):
                    pub.unsubscribe(self.onAttributeChanged, eventType)
                else:
                    self.removeObserver(self.onAttributeChanged_Deprecated, eventType=eventType)

    def renderCategories(self, item):
        return self.renderSubjectsOfRelatedItems(item, item.categories)        
    
    def renderSubjectsOfRelatedItems(self, item, getItems):
        subjects = []
        ownItems = getItems(recursive=False)
        if ownItems:
            subjects.append(self.renderSubjects(ownItems))
        isListViewer = not self.isTreeViewer()  # pylint: disable=E1101
        if isListViewer or self.isItemCollapsed(item):
            childItems = [theItem for theItem in getItems(recursive=True, upwards=isListViewer) if theItem not in ownItems]
            if childItems:
                subjects.append('(%s)' % self.renderSubjects(childItems))
        return ' '.join(subjects)
    
    @staticmethod
    def renderSubjects(items):
        subjects = [item.subject(recursive=True) for item in items]
        return ', '.join(sorted(subjects))
    
    @staticmethod
    def renderCreationDateTime(item, humanReadable=True):
        return render.dateTime(item.creationDateTime(), 
                               humanReadable=humanReadable)
        
    @staticmethod
    def renderModificationDateTime(item, humanReadable=True):
        return render.dateTime(item.modificationDateTime(),
                               humanReadable=humanReadable)
            
    def isItemCollapsed(self, item): 
        # pylint: disable=E1101
        # pylint: disable=E1101
        return not self.getItemExpanded(item) \
            if self.isTreeViewer() and item.children() else False


class SortableViewerWithColumns(mixin.SortableViewerMixin, ViewerWithColumns):  # pylint: disable=W0223
    def initColumn(self, column):
        super(SortableViewerWithColumns, self).initColumn(column)
        if self.isSortedBy(column.name()):
            self.widget.showSortColumn(column)
            self.showSortOrder()

    def setSortOrderAscending(self, *args, **kwargs):  # pylint: disable=W0221
        super(SortableViewerWithColumns, self).setSortOrderAscending(*args, **kwargs)
        self.showSortOrder()
        
    def sortBy(self, *args, **kwargs):  # pylint: disable=W0221
        super(SortableViewerWithColumns, self).sortBy(*args, **kwargs)
        self.showSortColumn()
        self.showSortOrder()

    def showSortColumn(self):
        for column in self.columns():
            if self.isSortedBy(column.name()):
                self.widget.showSortColumn(column)
                break

    def showSortOrder(self):
        self.widget.showSortOrder(self.imageIndex[self.getSortOrderImage()])
        
    def getSortOrderImage(self):
        return 'arrow_up_icon' if self.isSortOrderAscending() else 'arrow_down_icon'
