#-------------------------------------------------------------------------------
#
#  Copyright(c) 2009, Enthought, Inc.
#  All rights reserved.
#
#  This software is provided without warranty under the terms of the BSD
#  license included in enthought/LICENSE.txt and may be redistributed only
#  under the conditions described in the aforementioned license.  The license
#  is also available online at http://www.enthought.com/licenses/BSD.txt
#
#  Thanks for using Enthought open source!
#
#  Author: Evan Patterson
#  Date:   08/21/2009
#
#-------------------------------------------------------------------------------

""" Defines a text editor which displays a text field and maintains a history
    of previously entered values.
"""

#-------------------------------------------------------------------------------
#  Imports:
#-------------------------------------------------------------------------------

from pyface.qt import QtCore, QtGui

from editor import Editor

#-------------------------------------------------------------------------------
#  '_HistoryEditor' class:
#-------------------------------------------------------------------------------

class _HistoryEditor(Editor):
    """ Simple style text editor, which displays a text field and maintains a
        history of previously entered values, the maximum number of which is
        specified by the 'entries' trait of the HistoryEditor factory.
    """

    #---------------------------------------------------------------------------
    #  'Editor' interface:
    #---------------------------------------------------------------------------

    def init(self, parent):
        """ Finishes initializing the editor by creating the underlying toolkit
            widget.
        """
        self.control = control = QtGui.QComboBox()
        control.setEditable(True)
        control.setInsertPolicy(QtGui.QComboBox.InsertAtTop)

        if self.factory.entries > 0:
            signal = QtCore.SIGNAL('rowsInserted(const QModelIndex&, int, int)')
            QtCore.QObject.connect(control.model(), signal, self._truncate)

        if self.factory.auto_set:
            signal = QtCore.SIGNAL('editTextChanged(QString)')
        else:
            signal = QtCore.SIGNAL('activated(QString)')
        QtCore.QObject.connect(control, signal, self.update_object)

        self.set_tooltip()

    def update_object(self, text):
        """ Handles the user entering input data in the edit control.
        """
        if not self._no_update:
            self.value = unicode(text)

    def update_editor(self):
        """ Updates the editor when the object trait changes externally to the
            editor.
        """
        self._no_update = True
        self.control.setEditText(self.str_value)
        self._no_update = False

    #-- UI preference save/restore interface -----------------------------------

    def restore_prefs(self, prefs):
        """ Restores any saved user preference information associated with the
            editor.
        """
        history = prefs.get('history')
        if history:
            self._no_update = True
            self.control.addItems(history[:self.factory.entries])

            # Adding items sets the edit text, so we reset it afterwards:
            self.control.setEditText(self.str_value)

            self._no_update = False

    def save_prefs(self):
        """ Returns any user preference information associated with the editor.
        """
        history = [ str(self.control.itemText(index))
                    for index in xrange(self.control.count()) ]

        # If the view closed successfully, update the history with the current
        # editor value, as long it is different from the current object value:
        if self.ui.result:
            current = str(self.control.currentText())
            if current != self.str_value:
                history.insert(0, current)

        return { 'history': history }

    #---------------------------------------------------------------------------
    #  '_HistoryEditor' private interface:
    #---------------------------------------------------------------------------

    def _truncate(self, parent, start, end):
        """ Handle items being added to the combo box. If there are too many,
            remove items at the end.
        """
        diff = self.control.count() - self.factory.entries
        if diff > 0:
            for i in xrange(diff):
                self.control.removeItem(self.factory.entries)
