# (C) Copyright 2005-2022 Enthought, Inc., Austin, TX
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD
# license included in 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!

import unittest

from traits.api import Delegate, HasTraits, Instance, Str

# global because event handlers are being called with wrong value for self
baz_s_handler_self = None
baz_sd_handler_self = None
baz_u_handler_self = None
baz_t_handler_self = None
foo_s_handler_self = None
foo_t_handler_self = None


class Foo(HasTraits):
    s = Str("foo")
    t = Str("foo.t")
    u = Str("foo.u")

    def _s_changed(self, name, old, new):
        global foo_s_handler_self
        foo_s_handler_self = self

    def _t_changed(self, name, old, new):
        global foo_t_handler_self
        foo_t_handler_self = self


class Bar(HasTraits):
    foo = Instance(Foo, ())
    s = Delegate("foo")


class BazModify(HasTraits):
    foo = Instance(Foo, ())
    sd = Delegate("foo", prefix="s", modify=True)
    t = Delegate("foo", modify=True)
    u = Delegate("foo", listenable=False, modify=True)

    def _s_changed(self, name, old, new):
        # should never be called
        global baz_s_handler_self
        baz_s_handler_self = self

    def _sd_changed(self, name, old, new):
        global baz_sd_handler_self
        baz_sd_handler_self = self

    def _t_changed(self, name, old, new):
        global baz_t_handler_self
        baz_t_handler_self = self

    def _u_changed(self, name, old, new):
        global baz_u_handler_self
        baz_u_handler_self = self


class BazNoModify(HasTraits):
    foo = Instance(Foo, ())
    sd = Delegate("foo", prefix="s")
    t = Delegate("foo")
    u = Delegate("foo", listenable=False)

    def _s_changed(self, name, old, new):
        global baz_s_handler_self
        baz_s_handler_self = self

    def _sd_changed(self, name, old, new):
        global baz_sd_handler_self
        baz_sd_handler_self = self

    def _t_changed(self, name, old, new):
        global baz_t_handler_self
        baz_t_handler_self = self

    def _u_changed(self, name, old, new):
        global baz_u_handler_self
        baz_u_handler_self = self


class DelegateTestCase(unittest.TestCase):
    """ Test cases for delegated traits. """

    def setUp(self):
        """ Reset all of the globals.
        """
        global baz_s_handler_self, baz_sd_handler_self, baz_u_handler_self
        global baz_t_handler_self, foo_s_handler_self, foo_t_handler_self
        baz_s_handler_self = None
        baz_sd_handler_self = None
        baz_u_handler_self = None
        baz_t_handler_self = None
        foo_s_handler_self = None
        foo_t_handler_self = None

    def test_reset(self):
        """ Test that a delegated trait may be reset.

        Deleting the attribute should reset the trait back to its initial
        delegation behavior.
        """

        f = Foo()
        b = Bar(foo=f)

        # Check initial delegation.
        self.assertEqual(f.s, b.s)

        # Check that an override works.
        b.s = "bar"
        self.assertNotEqual(f.s, b.s)

        # Check that we can reset back to delegation.  This is what we are
        # really testing for.
        del b.s
        self.assertEqual(f.s, b.s)

    # Below are 8 tests to check the calling of change notification handlers.
    # There are 8 cases for the 2x2x2 matrix with axes:
    # Delegate with prefix or not
    # Delegate with modify write through or not
    # Handler in the delegator and delegatee
    def test_modify_prefix_handler_on_delegator(self):
        f = Foo()
        b = BazModify(foo=f)

        self.assertEqual(f.s, b.sd)

        b.sd = "changed"
        self.assertEqual(f.s, b.sd)

        # Don't expect _s_changed to be called because from Baz's perspective
        # the trait is named 'sd'
        self.assertEqual(baz_s_handler_self, None)

        # Do expect '_sd_changed' to be called with b as self
        self.assertEqual(baz_sd_handler_self, b)

    def test_modify_prefix_handler_on_delegatee(self):
        f = Foo()
        b = BazModify(foo=f)

        self.assertEqual(f.s, b.sd)

        b.sd = "changed"
        self.assertEqual(f.s, b.sd)

        # Foo expects its '_s_changed' handler to be called with f as self
        self.assertEqual(foo_s_handler_self, f)

    def test_no_modify_prefix_handler_on_delegator(self):
        f = Foo()
        b = BazNoModify(foo=f)

        self.assertEqual(f.s, b.sd)

        b.sd = "changed"
        self.assertNotEqual(f.s, b.sd)

        # Don't expect _s_changed to be called because from Baz's perspective
        # the trait is named 'sd'
        self.assertEqual(baz_s_handler_self, None)

        # Do expect '_sd_changed' to be called with b as self
        self.assertEqual(baz_sd_handler_self, b)

    def test_no_modify_prefix_handler_on_delegatee_not_called(self):
        f = Foo()
        b = BazNoModify(foo=f)

        self.assertEqual(f.s, b.sd)

        b.sd = "changed"
        self.assertNotEqual(f.s, b.sd)

        # Foo expects its '_s_changed' handler to be called with f as self
        self.assertEqual(foo_s_handler_self, None)

    def test_modify_handler_on_delegator(self):
        f = Foo()
        b = BazModify(foo=f)

        self.assertEqual(f.t, b.t)

        b.t = "changed"
        self.assertEqual(f.t, b.t)

        # Do expect '_t_changed' to be called with b as self
        self.assertEqual(baz_t_handler_self, b)

    def test_modify_handler_on_delegatee(self):
        f = Foo()
        b = BazModify(foo=f)

        self.assertEqual(f.t, b.t)

        b.t = "changed"
        self.assertEqual(f.t, b.t)

        # Foo t did change so '_t_changed' handler should be called
        self.assertEqual(foo_t_handler_self, f)

    def test_no_modify_handler_on_delegator(self):
        f = Foo()
        b = BazNoModify(foo=f)

        self.assertEqual(f.t, b.t)

        b.t = "changed"
        self.assertNotEqual(f.t, b.t)

        # Do expect '_t_changed' to be called with b as self
        self.assertEqual(baz_t_handler_self, b)

    def test_no_modify_handler_on_delegatee_not_called(self):
        f = Foo()
        b = BazNoModify(foo=f)

        self.assertEqual(f.t, b.t)

        b.t = "changed"
        self.assertNotEqual(f.t, b.t)

        # Foo t did not change so '_t_changed' handler should not be called
        self.assertEqual(foo_t_handler_self, None)

    # Below are 4 tests for notification when the delegated trait is changed
    # directly rather than through the delegator.
    def test_no_modify_handler_on_delegatee_direct_change(self):
        f = Foo()
        b = BazNoModify(foo=f)

        self.assertEqual(f.t, b.t)

        f.t = "changed"
        self.assertEqual(f.t, b.t)

        # Foo t did change so '_t_changed' handler should be called
        self.assertEqual(foo_t_handler_self, f)

    def test_no_modify_handler_on_delegator_direct_change(self):
        f = Foo()
        b = BazNoModify(foo=f)

        self.assertEqual(f.t, b.t)

        f.t = "changed"
        self.assertEqual(f.t, b.t)

        # Do expect '_t_changed' to be called with b as self
        self.assertEqual(baz_t_handler_self, b)

    def test_modify_handler_on_delegatee_direct_change(self):
        f = Foo()
        b = BazModify(foo=f)

        self.assertEqual(f.t, b.t)

        f.t = "changed"
        self.assertEqual(f.t, b.t)

        # Foo t did change so '_t_changed' handler should be called
        self.assertEqual(foo_t_handler_self, f)

    def test_modify_handler_on_delegator_direct_change(self):
        f = Foo()
        b = BazModify(foo=f)

        self.assertEqual(f.t, b.t)

        f.t = "changed"
        self.assertEqual(f.t, b.t)

        # Do expect '_t_changed' to be called with b as self
        self.assertEqual(baz_t_handler_self, b)

    # Below are tests which check that we can turn off listenableness.
    def test_modify_handler_not_listenable(self):
        f = Foo()
        b = BazModify(foo=f)

        self.assertEqual(f.u, b.u)

        f.u = "changed"
        self.assertEqual(f.u, b.u)

        # Do not expect '_u_changed' to be called.
        self.assertEqual(baz_u_handler_self, None)

    def test_no_modify_handler_not_listenable(self):
        f = Foo()
        b = BazNoModify(foo=f)

        self.assertEqual(f.u, b.u)

        f.u = "changed"
        self.assertEqual(f.u, b.u)

        # Do not expect '_u_changed' to be called.
        self.assertEqual(baz_u_handler_self, None)