#-------------------------------------------------------------------------------
#
#  Copyright (c) 2005, 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: David C. Morrill
#  Date:   09/27/2005
#
#-------------------------------------------------------------------------------

""" Editor that displays an interactive Python shell.
"""

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



from traits.api import Bool, Str, Event, Property

from ..editor import Editor

from ..basic_editor_factory import BasicEditorFactory

from ..toolkit import toolkit_object


#-------------------------------------------------------------------------------
#  'ShellEditor' class:
#-------------------------------------------------------------------------------

class _ShellEditor ( Editor ):
    """ Base class for an editor that displays an interactive Python shell.
    """

    #---------------------------------------------------------------------------
    #  Trait definitions:
    #---------------------------------------------------------------------------

    # An event fired to execute a command in the shell.
    command_to_execute = Event()

    # An event fired whenver the user executes a command in the shell:
    command_executed = Event( Bool )

    # Is the shell editor is scrollable? This value overrides the default.
    scrollable = True

    #---------------------------------------------------------------------------
    #  Finishes initializing the editor by creating the underlying toolkit
    #  widget:
    #---------------------------------------------------------------------------

    def init ( self, parent ):
        """ Finishes initializing the editor by creating the underlying toolkit
            widget.
        """
        # Moving the import here, since PythonShell is implemented in the
        # Pyface backend packages, and we want to delay loading this toolkit
        # specific class until this editor is actually used.
        from pyface.python_shell import PythonShell

        locals = None
        value  = self.value
        if self.factory.share and isinstance( value, dict ):
            locals = value
        self._shell  = shell = PythonShell( parent, locals = locals )
        self.control = shell.control
        if locals is None:
            object = self.object
            shell.bind( 'self', object )
            shell.on_trait_change( self.update_object, 'command_executed',
                                   dispatch = 'ui' )
            if not isinstance( value, dict ):
                object.on_trait_change( self.update_any, dispatch = 'ui' )
            else:
                self._base_locals = locals = {}
                for name in list(self._shell.interpreter().locals.keys()):
                    locals[ name ] = None

        # Synchronize any editor events:
        self.sync_value( self.factory.command_to_execute,
                         'command_to_execute', 'from' )
        self.sync_value( self.factory.command_executed,
                         'command_executed', 'to' )

        self.set_tooltip()

    #---------------------------------------------------------------------------
    #  Handles the user entering input data in the edit control:
    #---------------------------------------------------------------------------

    def update_object ( self, event ):
        """ Handles the user entering input data in the edit control.
        """
        locals      = self._shell.interpreter().locals
        base_locals = self._base_locals
        if base_locals is None:
            object = self.object
            for name in object.trait_names():
                if name in locals:
                    try:
                        setattr( object, name, locals[ name ] )
                    except:
                        pass
        else:
            dic = self.value
            for name in list(locals.keys()):
                if name not in base_locals:
                    try:
                        dic[ name ] = locals[ name ]
                    except:
                        pass

        self.command_executed = True

    #---------------------------------------------------------------------------
    #  Updates the editor when the object trait changes external to the editor:
    #---------------------------------------------------------------------------

    def update_editor ( self ):
        """ Updates the editor when the object trait changes externally to the
            editor.
        """
        if self.factory.share:
            value = self.value
            if isinstance( value, dict ):
                self._shell.interpreter().locals = value
        else:
            locals      = self._shell.interpreter().locals
            base_locals = self._base_locals
            if base_locals is None:
                object = self.object
                for name in object.trait_names():
                    locals[ name ] = getattr( object, name, None )
            else:
                dic = self.value
                for name, value in list(dic.items()):
                    locals[ name ] = value

    #---------------------------------------------------------------------------
    #  Updates the editor when the object trait changes external to the editor:
    #---------------------------------------------------------------------------

    def update_any ( self, object, name, old, new ):
        """ Updates the editor when the object trait changes externally to the
            editor.
        """
        locals = self._shell.interpreter().locals
        if self._base_locals is None:
            locals[ name ] = new
        else:
            self.value[ name ] = new

    #---------------------------------------------------------------------------
    #  Disposes of the contents of an editor:
    #---------------------------------------------------------------------------

    def dispose ( self ):
        """ Disposes of the contents of an editor.
        """
        self._shell.on_trait_change( self.update_object, 'command_executed',
                                     remove = True )
        if self._base_locals is None:
            self.object.on_trait_change( self.update_any, remove = True )

        super( _ShellEditor, self ).dispose()

    #---------------------------------------------------------------------------
    #  Restores any saved user preference information associated with the
    #  editor:
    #---------------------------------------------------------------------------

    def restore_prefs ( self, prefs ):
        """ Restores any saved user preference information associated with the
            editor.
        """
        control = self._shell.control
        try:
            control.history      = prefs.get( 'history', [] )
            control.historyIndex = prefs.get( 'historyIndex', -1 )
        except:
            pass

    #---------------------------------------------------------------------------
    #  Returns any user preference information associated with the editor:
    #---------------------------------------------------------------------------

    def save_prefs ( self ):
        """ Returns any user preference information associated with the editor.
        """
        control = self._shell.control
        return { 'history':      control.history,
                 'historyIndex': control.historyIndex }

    #---------------------------------------------------------------------------
    #  Handles the 'command_to_execute' trait being fired:
    #---------------------------------------------------------------------------

    def _command_to_execute_fired ( self, command ):
        """ Handles the 'command_to_execute' trait being fired.
        """
        # Show the command. A 'hidden' command should be executed directly on
        # the namespace trait!
        self._shell.execute_command(command, hidden=False)

#-------------------------------------------------------------------------------
#  Create the editor factory object:
#-------------------------------------------------------------------------------

# Editor factory for shell editors.
class ToolkitEditorFactory ( BasicEditorFactory ):

    # The editor class to be instantiated.
    klass = Property

    # Should the shell interpreter use the object value's dictionary?
    share = Bool( False )

    # Extended trait name of the object event trait which triggers a command
    # execution in the shell when fired.
    command_to_execute = Str

    # Extended trait name of the object event trait which is fired when a
    # command is executed.
    command_executed = Str

    def _get_klass(self):
        """ Returns the toolkit-specific editor class to be used in the UI.
        """
        return toolkit_object('shell_editor:_ShellEditor')

# Define the ShellEditor
ShellEditor = ToolkitEditorFactory

### EOF ##################################################################
