#------------------------------------------------------------------------------
#
#  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:   06/21/2002
#
#------------------------------------------------------------------------------

""" Defines the standard exceptions raised by the Traits package.
"""

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

from __future__ import absolute_import

import exceptions

from types import InstanceType

from .trait_base import class_of


#-------------------------------------------------------------------------------
#  Utilities
#-------------------------------------------------------------------------------

def repr_type(obj):
    """ Return a string representation of a value and its type for readable
    error messages.
    """
    the_type = type(obj)
    if the_type is InstanceType:
        # Old-style class.
        the_type = obj.__class__
    msg = '%r %r' % (obj, the_type)
    return msg

#-------------------------------------------------------------------------------
#  'TraitError' class:
#-------------------------------------------------------------------------------

class TraitError ( exceptions.Exception ):

    def __init__ ( self, args = None, name = None, info = None, value = None ):
        if name is None:
           # If the given args is not a tuple then assume that the user intended
           # it to be the single item in a one-element tuple.
           if not isinstance(args, tuple):
               args = args,
           self.args = args
        else:
           # Save the information, in case the 'args' object is not the correct
           # one, and we need to regenerate the message later:
           self.name   = name
           self.info   = info
           self.value  = value
           self.desc   = None
           self.prefix = 'The'
           self.set_desc( None, args )

    def set_desc ( self, desc, object = None ):
        if hasattr( self, 'desc' ):
           if desc is not None:
              self.desc = desc
           if object is not None:
              self.object = object
           self.set_args()

    def set_prefix ( self, prefix ):
        if hasattr( self, 'prefix' ):
           self.prefix = prefix
           self.set_args()

    def set_args ( self ):
        if self.desc is None:
           extra = ''
        else:
           extra = ' specifies %s and' % self.desc
        obj = getattr( self, 'object', None )

        # Note: self.args must be a tuple so be sure to leave the trailing
        # commas.
        the_type = type(self.value)
        if the_type is InstanceType:
            the_type = self.value.__class__
        if obj is not None:
            self.args = ("%s '%s' trait of %s instance%s must be %s, "
                         "but a value of %s was specified." % (
                         self.prefix, self.name, class_of(obj), extra,
                         self.info, repr_type(self.value))),
        else:
            self.args = ("%s '%s' trait%s must be %s, but a value of %r %r was "
                         "specified." % (self.prefix, self.name, extra,
                                         self.info, repr_type(self.value))),

#-------------------------------------------------------------------------------
#  'TraitNotificationError' class:
#-------------------------------------------------------------------------------

class TraitNotificationError ( exceptions.Exception ):

    pass

#-------------------------------------------------------------------------------
#  'DelegationError' class:
#-------------------------------------------------------------------------------

class DelegationError ( TraitError ):

    def __init__ ( self, args ):
        # .args must be a tuple.
        self.args = args,

#-------------------------------------------------------------------------------
#  Export the defined exceptions to the C-base traits module:
#-------------------------------------------------------------------------------

from . import ctraits
ctraits._exceptions( TraitError, DelegationError )
