"""
Test cases for tabs.
"""

from django.conf import settings
from django.core.urlresolvers import reverse
from django.http import Http404
from mock import MagicMock, Mock, patch
from nose.plugins.attrib import attr
from opaque_keys.edx.locations import SlashSeparatedCourseKey

from courseware.courses import get_course_by_id
from courseware.tabs import (
    get_course_tab_list, CoursewareTab, CourseInfoTab, ProgressTab,
    ExternalDiscussionCourseTab, ExternalLinkCourseTab
)
from courseware.tests.helpers import get_request_for_user, LoginEnrollmentTestCase
from courseware.tests.factories import InstructorFactory, StaffFactory
from courseware.views import get_static_tab_contents, static_tab
from student.models import CourseEnrollment
from student.tests.factories import UserFactory
from util import milestones_helpers
from xmodule import tabs as xmodule_tabs
from xmodule.modulestore.tests.django_utils import (
    TEST_DATA_MIXED_TOY_MODULESTORE, TEST_DATA_MIXED_CLOSED_MODULESTORE
)
from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
from xmodule.modulestore.tests.factories import CourseFactory, ItemFactory


class TabTestCase(ModuleStoreTestCase):
    """Base class for Tab-related test cases."""
    def setUp(self):
        super(TabTestCase, self).setUp()

        self.course = CourseFactory.create(org='edX', course='toy', run='2012_Fall')
        self.fake_dict_tab = {'fake_key': 'fake_value'}
        self.reverse = lambda name, args: "name/{0}/args/{1}".format(name, ",".join(str(a) for a in args))
        self.books = None

    def create_mock_user(self, is_authenticated=True, is_staff=True, is_enrolled=True):
        """
        Creates a mock user with the specified properties.
        """
        user = UserFactory()
        user.name = 'mock_user'
        user.is_staff = is_staff
        user.is_enrolled = is_enrolled
        user.is_authenticated = lambda: is_authenticated
        return user

    def is_tab_enabled(self, tab, course, user):
        """
        Returns true if the specified tab is enabled.
        """
        return tab.is_enabled(course, user=user)

    def set_up_books(self, num_books):
        """Initializes the textbooks in the course and adds the given number of books to each textbook"""
        self.books = [MagicMock() for _ in range(num_books)]
        for book_index, book in enumerate(self.books):
            book.title = 'Book{0}'.format(book_index)
        self.course.textbooks = self.books
        self.course.pdf_textbooks = self.books
        self.course.html_textbooks = self.books

    def check_tab(
            self,
            tab_class,
            dict_tab,
            expected_link,
            expected_tab_id,
            expected_name='same',
            invalid_dict_tab=None,
    ):
        """
        Helper method to verify a tab class.

        'tab_class' is the class of the tab that is being tested
        'dict_tab' is the raw dictionary value of the tab
        'expected_link' is the expected value for the hyperlink of the tab
        'expected_tab_id' is the expected value for the unique id of the tab
        'expected_name' is the expected value for the name of the tab
        'invalid_dict_tab' is an invalid dictionary value for the tab.
            Can be 'None' if the given tab class does not have any keys to validate.
        """
        # create tab
        tab = tab_class(tab_dict=dict_tab)

        # name is as expected
        self.assertEqual(tab.name, expected_name)

        # link is as expected
        self.assertEqual(tab.link_func(self.course, self.reverse), expected_link)

        # verify active page name
        self.assertEqual(tab.tab_id, expected_tab_id)

        # validate tab
        self.assertTrue(tab.validate(dict_tab))
        if invalid_dict_tab:
            with self.assertRaises(xmodule_tabs.InvalidTabsException):
                tab.validate(invalid_dict_tab)

        # check get and set methods
        self.check_get_and_set_methods(tab)

        # check to_json and from_json methods
        self.check_tab_json_methods(tab)

        # check equality methods
        self.check_tab_equality(tab, dict_tab)

        # return tab for any additional tests
        return tab

    def check_tab_equality(self, tab, dict_tab):
        """Tests the equality methods on the given tab"""
        self.assertEquals(tab, dict_tab)  # test __eq__
        ne_dict_tab = dict_tab
        ne_dict_tab['type'] = 'fake_type'
        self.assertNotEquals(tab, ne_dict_tab)  # test __ne__: incorrect type
        self.assertNotEquals(tab, {'fake_key': 'fake_value'})  # test __ne__: missing type

    def check_tab_json_methods(self, tab):
        """Tests the json from and to methods on the given tab"""
        serialized_tab = tab.to_json()
        deserialized_tab = tab.from_json(serialized_tab)
        self.assertEquals(serialized_tab, deserialized_tab)

    def check_can_display_results(
            self,
            tab,
            expected_value=True,
            for_authenticated_users_only=False,
            for_staff_only=False,
            for_enrolled_users_only=False
    ):
        """Checks can display results for various users"""
        if for_staff_only:
            user = self.create_mock_user(is_authenticated=True, is_staff=True, is_enrolled=True)
            self.assertEquals(expected_value, self.is_tab_enabled(tab, self.course, user))
        if for_authenticated_users_only:
            user = self.create_mock_user(is_authenticated=True, is_staff=False, is_enrolled=False)
            self.assertEquals(expected_value, self.is_tab_enabled(tab, self.course, user))
        if not for_staff_only and not for_authenticated_users_only and not for_enrolled_users_only:
            user = self.create_mock_user(is_authenticated=False, is_staff=False, is_enrolled=False)
            self.assertEquals(expected_value, self.is_tab_enabled(tab, self.course, user))
        if for_enrolled_users_only:
            user = self.create_mock_user(is_authenticated=True, is_staff=False, is_enrolled=True)
            self.assertEquals(expected_value, self.is_tab_enabled(tab, self.course, user))

    def check_get_and_set_methods(self, tab):
        """Test __getitem__ and __setitem__ calls"""
        self.assertEquals(tab['type'], tab.type)
        self.assertEquals(tab['tab_id'], tab.tab_id)
        with self.assertRaises(KeyError):
            _ = tab['invalid_key']

        self.check_get_and_set_method_for_key(tab, 'name')
        self.check_get_and_set_method_for_key(tab, 'tab_id')
        with self.assertRaises(KeyError):
            tab['invalid_key'] = 'New Value'

    def check_get_and_set_method_for_key(self, tab, key):
        """Test __getitem__ and __setitem__ for the given key"""
        old_value = tab[key]
        new_value = 'New Value'
        tab[key] = new_value
        self.assertEquals(tab[key], new_value)
        tab[key] = old_value
        self.assertEquals(tab[key], old_value)


class TextbooksTestCase(TabTestCase):
    """Test cases for Textbook Tab."""

    def setUp(self):
        super(TextbooksTestCase, self).setUp()

        self.set_up_books(2)

        self.dict_tab = MagicMock()
        self.course.tabs = [
            xmodule_tabs.CourseTab.load('textbooks'),
            xmodule_tabs.CourseTab.load('pdf_textbooks'),
            xmodule_tabs.CourseTab.load('html_textbooks'),
        ]
        self.num_textbook_tabs = sum(1 for tab in self.course.tabs if tab.type in [
            'textbooks', 'pdf_textbooks', 'html_textbooks'
        ])
        self.num_textbooks = self.num_textbook_tabs * len(self.books)

    @patch.dict("django.conf.settings.FEATURES", {"ENABLE_TEXTBOOK": True})
    def test_textbooks_enabled(self):

        type_to_reverse_name = {'textbook': 'book', 'pdftextbook': 'pdf_book', 'htmltextbook': 'html_book'}

        num_textbooks_found = 0
        user = self.create_mock_user(is_authenticated=True, is_staff=False, is_enrolled=True)
        for tab in xmodule_tabs.CourseTabList.iterate_displayable(self.course, user=user):
            # verify all textbook type tabs
            if tab.type == 'single_textbook':
                book_type, book_index = tab.tab_id.split("/", 1)
                expected_link = self.reverse(
                    type_to_reverse_name[book_type],
                    args=[self.course.id.to_deprecated_string(), book_index]
                )
                self.assertEqual(tab.link_func(self.course, self.reverse), expected_link)
                self.assertTrue(tab.name.startswith('Book{0}'.format(book_index)))
                num_textbooks_found = num_textbooks_found + 1
        self.assertEquals(num_textbooks_found, self.num_textbooks)


@attr('shard_1')
class StaticTabDateTestCase(LoginEnrollmentTestCase, ModuleStoreTestCase):
    """Test cases for Static Tab Dates."""

    MODULESTORE = TEST_DATA_MIXED_TOY_MODULESTORE

    def setUp(self):
        super(StaticTabDateTestCase, self).setUp()
        self.course = CourseFactory.create()
        self.page = ItemFactory.create(
            category="static_tab", parent_location=self.course.location,
            data="OOGIE BLOOGIE", display_name="new_tab"
        )
        self.course.tabs.append(xmodule_tabs.CourseTab.load('static_tab', name='New Tab', url_slug='new_tab'))
        self.course.save()
        self.toy_course_key = SlashSeparatedCourseKey('edX', 'toy', '2012_Fall')

    def test_logged_in(self):
        self.setup_user()
        url = reverse('static_tab', args=[self.course.id.to_deprecated_string(), 'new_tab'])
        resp = self.client.get(url)
        self.assertEqual(resp.status_code, 200)
        self.assertIn("OOGIE BLOOGIE", resp.content)

    def test_anonymous_user(self):
        url = reverse('static_tab', args=[self.course.id.to_deprecated_string(), 'new_tab'])
        resp = self.client.get(url)
        self.assertEqual(resp.status_code, 200)
        self.assertIn("OOGIE BLOOGIE", resp.content)

    def test_invalid_course_key(self):
        self.setup_user()
        request = get_request_for_user(self.user)
        with self.assertRaises(Http404):
            static_tab(request, course_id='edX/toy', tab_slug='new_tab')

    def test_get_static_tab_contents(self):
        self.setup_user()
        course = get_course_by_id(self.toy_course_key)
        request = get_request_for_user(self.user)
        tab = xmodule_tabs.CourseTabList.get_tab_by_slug(course.tabs, 'resources')

        # Test render works okay
        tab_content = get_static_tab_contents(request, course, tab)
        self.assertIn(self.toy_course_key.to_deprecated_string(), tab_content)
        self.assertIn('static_tab', tab_content)

        # Test when render raises an exception
        with patch('courseware.views.get_module') as mock_module_render:
            mock_module_render.return_value = MagicMock(
                render=Mock(side_effect=Exception('Render failed!'))
            )
            static_tab = get_static_tab_contents(request, course, tab)
            self.assertIn("this module is temporarily unavailable", static_tab)


@attr('shard_1')
class StaticTabDateTestCaseXML(LoginEnrollmentTestCase, ModuleStoreTestCase):
    """
    Tests for the static tab dates of an XML course
    """

    MODULESTORE = TEST_DATA_MIXED_CLOSED_MODULESTORE

    # The following XML test course (which lives at common/test/data/2014)
    # is closed; we're testing that tabs still appear when
    # the course is already closed
    xml_course_key = SlashSeparatedCourseKey('edX', 'detached_pages', '2014')

    # this text appears in the test course's tab
    # common/test/data/2014/tabs/8e4cce2b4aaf4ba28b1220804619e41f.html
    xml_data = "static 463139"
    xml_url = "8e4cce2b4aaf4ba28b1220804619e41f"

    @patch.dict('django.conf.settings.FEATURES', {'DISABLE_START_DATES': False})
    def test_logged_in_xml(self):
        self.setup_user()
        url = reverse('static_tab', args=[self.xml_course_key.to_deprecated_string(), self.xml_url])
        resp = self.client.get(url)
        self.assertEqual(resp.status_code, 200)
        self.assertIn(self.xml_data, resp.content)

    @patch.dict('django.conf.settings.FEATURES', {'DISABLE_START_DATES': False})
    def test_anonymous_user_xml(self):
        url = reverse('static_tab', args=[self.xml_course_key.to_deprecated_string(), self.xml_url])
        resp = self.client.get(url)
        self.assertEqual(resp.status_code, 200)
        self.assertIn(self.xml_data, resp.content)


@attr('shard_1')
class EntranceExamsTabsTestCase(LoginEnrollmentTestCase, ModuleStoreTestCase):
    """
    Validate tab behavior when dealing with Entrance Exams
    """
    MODULESTORE = TEST_DATA_MIXED_CLOSED_MODULESTORE

    if settings.FEATURES.get('ENTRANCE_EXAMS', False):

        def setUp(self):
            """
            Test case scaffolding
            """
            super(EntranceExamsTabsTestCase, self).setUp()

            self.course = CourseFactory.create()
            self.instructor_tab = ItemFactory.create(
                category="instructor", parent_location=self.course.location,
                data="Instructor Tab", display_name="Instructor"
            )
            self.extra_tab_2 = ItemFactory.create(
                category="static_tab", parent_location=self.course.location,
                data="Extra Tab", display_name="Extra Tab 2"
            )
            self.extra_tab_3 = ItemFactory.create(
                category="static_tab", parent_location=self.course.location,
                data="Extra Tab", display_name="Extra Tab 3"
            )
            self.setup_user()
            self.enroll(self.course)
            self.user.is_staff = True
            self.relationship_types = milestones_helpers.get_milestone_relationship_types()
            milestones_helpers.seed_milestone_relationship_types()

        def test_get_course_tabs_list_entrance_exam_enabled(self):
            """
            Unit Test: test_get_course_tabs_list_entrance_exam_enabled
            """
            entrance_exam = ItemFactory.create(
                category="chapter",
                parent_location=self.course.location,
                data="Exam Data",
                display_name="Entrance Exam",
                is_entrance_exam=True
            )
            milestone = {
                'name': 'Test Milestone',
                'namespace': '{}.entrance_exams'.format(unicode(self.course.id)),
                'description': 'Testing Courseware Tabs'
            }
            self.user.is_staff = False
            request = get_request_for_user(self.user)
            self.course.entrance_exam_enabled = True
            self.course.entrance_exam_id = unicode(entrance_exam.location)
            milestone = milestones_helpers.add_milestone(milestone)
            milestones_helpers.add_course_milestone(
                unicode(self.course.id),
                self.relationship_types['REQUIRES'],
                milestone
            )
            milestones_helpers.add_course_content_milestone(
                unicode(self.course.id),
                unicode(entrance_exam.location),
                self.relationship_types['FULFILLS'],
                milestone
            )
            course_tab_list = get_course_tab_list(request, self.course)
            self.assertEqual(len(course_tab_list), 1)
            self.assertEqual(course_tab_list[0]['tab_id'], 'courseware')
            self.assertEqual(course_tab_list[0]['name'], 'Entrance Exam')

        def test_get_course_tabs_list_skipped_entrance_exam(self):
            """
            Tests tab list is not limited if user is allowed to skip entrance exam.
            """
            #create a user
            student = UserFactory()
            # login as instructor hit skip entrance exam api in instructor app
            instructor = InstructorFactory(course_key=self.course.id)
            self.client.logout()
            self.client.login(username=instructor.username, password='test')

            url = reverse('mark_student_can_skip_entrance_exam', kwargs={'course_id': unicode(self.course.id)})
            response = self.client.post(url, {
                'unique_student_identifier': student.email,
            })
            self.assertEqual(response.status_code, 200)

            # log in again as student
            self.client.logout()
            self.login(self.email, self.password)
            request = get_request_for_user(self.user)
            course_tab_list = get_course_tab_list(request, self.course)
            self.assertEqual(len(course_tab_list), 5)

        def test_course_tabs_list_for_staff_members(self):
            """
            Tests tab list is not limited if user is member of staff
            and has not passed entrance exam.
            """
            # Login as member of staff
            self.client.logout()
            staff_user = StaffFactory(course_key=self.course.id)
            self.client.login(username=staff_user.username, password='test')
            request = get_request_for_user(staff_user)
            course_tab_list = get_course_tab_list(request, self.course)
            self.assertEqual(len(course_tab_list), 5)


@attr('shard_1')
class TextBookCourseViewsTestCase(LoginEnrollmentTestCase, ModuleStoreTestCase):
    """
    Validate tab behavior when dealing with textbooks.
    """
    MODULESTORE = TEST_DATA_MIXED_TOY_MODULESTORE

    def setUp(self):
        super(TextBookCourseViewsTestCase, self).setUp()

        self.course = CourseFactory.create()
        self.set_up_books(2)
        self.setup_user()
        self.enroll(self.course)
        self.num_textbook_tabs = sum(1 for tab in self.course.tabs if tab.type in [
            'textbooks', 'pdf_textbooks', 'html_textbooks'
        ])
        self.num_textbooks = self.num_textbook_tabs * len(self.books)

    def set_up_books(self, num_books):
        """Initializes the textbooks in the course and adds the given number of books to each textbook"""
        self.books = [MagicMock() for _ in range(num_books)]
        for book_index, book in enumerate(self.books):
            book.title = 'Book{0}'.format(book_index)
        self.course.textbooks = self.books
        self.course.pdf_textbooks = self.books
        self.course.html_textbooks = self.books

    def test_pdf_textbook_tabs(self):
        """
        Test that all textbooks tab links generating correctly.
        """
        type_to_reverse_name = {'textbook': 'book', 'pdftextbook': 'pdf_book', 'htmltextbook': 'html_book'}
        request = get_request_for_user(self.user)
        course_tab_list = get_course_tab_list(request, self.course)
        num_of_textbooks_found = 0
        for tab in course_tab_list:
            # Verify links of all textbook type tabs.
            if tab.type == 'single_textbook':
                book_type, book_index = tab.tab_id.split("/", 1)
                expected_link = reverse(
                    type_to_reverse_name[book_type],
                    args=[self.course.id.to_deprecated_string(), book_index]
                )
                tab_link = tab.link_func(self.course, reverse)
                self.assertEqual(tab_link, expected_link)
                num_of_textbooks_found += 1
        self.assertEqual(num_of_textbooks_found, self.num_textbooks)

    @patch.dict("django.conf.settings.FEATURES", {"ENABLE_TEXTBOOK": False})
    def test_textbooks_disabled(self):
        tab = xmodule_tabs.CourseTab.load('textbooks')
        self.assertFalse(tab.is_enabled(self.course, self.user))


class TabListTestCase(TabTestCase):
    """Base class for Test cases involving tab lists."""

    def setUp(self):
        super(TabListTestCase, self).setUp()

        # invalid tabs
        self.invalid_tabs = [
            # less than 2 tabs
            [{'type': CoursewareTab.type}],
            # missing course_info
            [{'type': CoursewareTab.type}, {'type': 'discussion', 'name': 'fake_name'}],
            # incorrect order
            [{'type': CourseInfoTab.type, 'name': 'fake_name'}, {'type': CoursewareTab.type}],
            [{'type': 'unknown_type'}]
        ]

        # tab types that should appear only once
        unique_tab_types = [
            CoursewareTab.type,
            CourseInfoTab.type,
            'textbooks',
            'pdf_textbooks',
            'html_textbooks',
        ]

        for unique_tab_type in unique_tab_types:
            self.invalid_tabs.append([
                {'type': CoursewareTab.type},
                {'type': CourseInfoTab.type, 'name': 'fake_name'},
                # add the unique tab multiple times
                {'type': unique_tab_type},
                {'type': unique_tab_type},
            ])

        # valid tabs
        self.valid_tabs = [
            # any empty list is valid because a default list of tabs will be
            # generated to replace the empty list.
            [],
            # all valid tabs
            [
                {'type': CoursewareTab.type},
                {'type': CourseInfoTab.type, 'name': 'fake_name'},
                {'type': 'discussion', 'name': 'fake_name'},
                {'type': ExternalLinkCourseTab.type, 'name': 'fake_name', 'link': 'fake_link'},
                {'type': ExternalLinkCourseTab.type, 'name': 'fake_name', 'link': 'fake_link'},
                {'type': 'textbooks'},
                {'type': 'pdf_textbooks'},
                {'type': 'html_textbooks'},
                {'type': ProgressTab.type, 'name': 'fake_name'},
                {'type': xmodule_tabs.StaticTab.type, 'name': 'fake_name', 'url_slug': 'schlug'},
                {'type': 'syllabus'},
            ],
            # with external discussion
            [
                {'type': CoursewareTab.type},
                {'type': CourseInfoTab.type, 'name': 'fake_name'},
                {'type': ExternalDiscussionCourseTab.type, 'name': 'fake_name', 'link': 'fake_link'}
            ],
        ]

        self.all_valid_tab_list = xmodule_tabs.CourseTabList().from_json(self.valid_tabs[1])


@attr('shard_1')
class ValidateTabsTestCase(TabListTestCase):
    """Test cases for validating tabs."""

    def test_validate_tabs(self):
        tab_list = xmodule_tabs.CourseTabList()
        for invalid_tab_list in self.invalid_tabs:
            with self.assertRaises(xmodule_tabs.InvalidTabsException):
                tab_list.from_json(invalid_tab_list)

        for valid_tab_list in self.valid_tabs:
            from_json_result = tab_list.from_json(valid_tab_list)
            self.assertEquals(len(from_json_result), len(valid_tab_list))

    def test_invalid_tab_type(self):
        """
        Verifies that having an unrecognized tab type does not cause
        the tabs to be undisplayable.
        """
        tab_list = xmodule_tabs.CourseTabList()
        self.assertEquals(
            len(tab_list.from_json([
                {'type': CoursewareTab.type},
                {'type': CourseInfoTab.type, 'name': 'fake_name'},
                {'type': 'no_such_type'}
            ])),
            2
        )


@attr('shard_1')
class CourseTabListTestCase(TabListTestCase):
    """Testing the generator method for iterating through displayable tabs"""

    def has_tab(self, tab_list, tab_type):
        """ Searches the given lab_list for a given tab_type. """
        for tab in tab_list:
            if tab.type == tab_type:
                return True
        return False

    def test_initialize_default_without_syllabus(self):
        self.course.tabs = []
        self.course.syllabus_present = False
        xmodule_tabs.CourseTabList.initialize_default(self.course)
        self.assertFalse(self.has_tab(self.course.tabs, 'syllabus'))

    def test_initialize_default_with_syllabus(self):
        self.course.tabs = []
        self.course.syllabus_present = True
        xmodule_tabs.CourseTabList.initialize_default(self.course)
        self.assertTrue(self.has_tab(self.course.tabs, 'syllabus'))

    def test_initialize_default_with_external_link(self):
        self.course.tabs = []
        self.course.discussion_link = "other_discussion_link"
        xmodule_tabs.CourseTabList.initialize_default(self.course)
        self.assertTrue(self.has_tab(self.course.tabs, 'external_discussion'))
        self.assertFalse(self.has_tab(self.course.tabs, 'discussion'))

    def test_initialize_default_without_external_link(self):
        self.course.tabs = []
        self.course.discussion_link = ""
        xmodule_tabs.CourseTabList.initialize_default(self.course)
        self.assertFalse(self.has_tab(self.course.tabs, 'external_discussion'))
        self.assertTrue(self.has_tab(self.course.tabs, 'discussion'))

    @patch.dict("django.conf.settings.FEATURES", {
        "ENABLE_TEXTBOOK": True,
        "ENABLE_DISCUSSION_SERVICE": True,
        "ENABLE_STUDENT_NOTES": True,
        "ENABLE_EDXNOTES": True,
    })
    def test_iterate_displayable(self):
        self.course.hide_progress_tab = False

        # create 1 book per textbook type
        self.set_up_books(1)

        # initialize the course tabs to a list of all valid tabs
        self.course.tabs = self.all_valid_tab_list

        # enumerate the tabs with no user
        for i, tab in enumerate(xmodule_tabs.CourseTabList.iterate_displayable(
                self.course,
                inline_collections=False
        )):
            self.assertEquals(tab.type, self.course.tabs[i].type)

        # enumerate the tabs with a staff user
        user = UserFactory(is_staff=True)
        CourseEnrollment.enroll(user, self.course.id)
        for i, tab in enumerate(xmodule_tabs.CourseTabList.iterate_displayable(self.course, user=user)):
            if getattr(tab, 'is_collection_item', False):
                # a collection item was found as a result of a collection tab
                self.assertTrue(getattr(self.course.tabs[i], 'is_collection', False))
            else:
                # all other tabs must match the expected type
                self.assertEquals(tab.type, self.course.tabs[i].type)

        # test including non-empty collections
        self.assertIn(
            {'type': 'html_textbooks'},
            list(xmodule_tabs.CourseTabList.iterate_displayable(self.course, inline_collections=False)),
        )

        # test not including empty collections
        self.course.html_textbooks = []
        self.assertNotIn(
            {'type': 'html_textbooks'},
            list(xmodule_tabs.CourseTabList.iterate_displayable(self.course, inline_collections=False)),
        )

    def test_get_tab_by_methods(self):
        """Tests the get_tab methods in CourseTabList"""
        self.course.tabs = self.all_valid_tab_list
        for tab in self.course.tabs:

            # get tab by type
            self.assertEquals(xmodule_tabs.CourseTabList.get_tab_by_type(self.course.tabs, tab.type), tab)

            # get tab by id
            self.assertEquals(xmodule_tabs.CourseTabList.get_tab_by_id(self.course.tabs, tab.tab_id), tab)


@attr('shard_1')
class ProgressTestCase(TabTestCase):
    """Test cases for Progress Tab."""

    def check_progress_tab(self):
        """Helper function for verifying the progress tab."""
        return self.check_tab(
            tab_class=ProgressTab,
            dict_tab={'type': ProgressTab.type, 'name': 'same'},
            expected_link=self.reverse('progress', args=[self.course.id.to_deprecated_string()]),
            expected_tab_id=ProgressTab.type,
            invalid_dict_tab=None,
        )

    @patch('student.models.CourseEnrollment.is_enrolled')
    def test_progress(self, is_enrolled):
        is_enrolled.return_value = True
        self.course.hide_progress_tab = False
        tab = self.check_progress_tab()
        self.check_can_display_results(
            tab, for_staff_only=True, for_enrolled_users_only=True
        )

        self.course.hide_progress_tab = True
        self.check_progress_tab()
        self.check_can_display_results(
            tab, for_staff_only=True, for_enrolled_users_only=True, expected_value=False
        )


@attr('shard_1')
class StaticTabTestCase(TabTestCase):
    """Test cases for Static Tab."""

    def test_static_tab(self):

        url_slug = 'schmug'

        tab = self.check_tab(
            tab_class=xmodule_tabs.StaticTab,
            dict_tab={'type': xmodule_tabs.StaticTab.type, 'name': 'same', 'url_slug': url_slug},
            expected_link=self.reverse('static_tab', args=[self.course.id.to_deprecated_string(), url_slug]),
            expected_tab_id='static_tab_schmug',
            invalid_dict_tab=self.fake_dict_tab,
        )
        self.check_can_display_results(tab)
        self.check_get_and_set_method_for_key(tab, 'url_slug')


@attr('shard_1')
class DiscussionLinkTestCase(TabTestCase):
    """Test cases for discussion link tab."""

    def setUp(self):
        super(DiscussionLinkTestCase, self).setUp()

        self.tabs_with_discussion = [
            xmodule_tabs.CourseTab.load('discussion'),
        ]
        self.tabs_without_discussion = [
        ]

    @staticmethod
    def _reverse(course):
        """Custom reverse function"""
        def reverse_discussion_link(viewname, args):
            """reverse lookup for discussion link"""
            if viewname == "django_comment_client.forum.views.forum_form_discussion" and args == [unicode(course.id)]:
                return "default_discussion_link"
        return reverse_discussion_link

    def check_discussion(
            self, tab_list,
            expected_discussion_link,
            expected_can_display_value,
            discussion_link_in_course="",
            is_staff=True,
            is_enrolled=True,
    ):
        """Helper function to verify whether the discussion tab exists and can be displayed"""
        self.course.tabs = tab_list
        self.course.discussion_link = discussion_link_in_course
        discussion_tab = xmodule_tabs.CourseTabList.get_discussion(self.course)
        user = self.create_mock_user(is_authenticated=True, is_staff=is_staff, is_enrolled=is_enrolled)
        with patch('student.models.CourseEnrollment.is_enrolled') as check_is_enrolled:
            check_is_enrolled.return_value = is_enrolled
            self.assertEquals(
                (
                    discussion_tab is not None and
                    self.is_tab_enabled(discussion_tab, self.course, user) and
                    (discussion_tab.link_func(self.course, self._reverse(self.course)) == expected_discussion_link)
                ),
                expected_can_display_value
            )

    @patch.dict("django.conf.settings.FEATURES", {"ENABLE_DISCUSSION_SERVICE": False})
    def test_explicit_discussion_link(self):
        """Test that setting discussion_link overrides everything else"""
        self.check_discussion(
            tab_list=self.tabs_with_discussion,
            discussion_link_in_course="other_discussion_link",
            expected_discussion_link="other_discussion_link",
            expected_can_display_value=True,
        )

    @patch.dict("django.conf.settings.FEATURES", {"ENABLE_DISCUSSION_SERVICE": False})
    def test_discussions_disabled(self):
        """Test that other cases return None with discussions disabled"""
        for tab_list in [[], self.tabs_with_discussion, self.tabs_without_discussion]:
            self.check_discussion(
                tab_list=tab_list,
                expected_discussion_link=not None,
                expected_can_display_value=False,
            )

    @patch.dict("django.conf.settings.FEATURES", {"ENABLE_DISCUSSION_SERVICE": True})
    def test_tabs_with_discussion(self):
        """Test a course with a discussion tab configured"""
        self.check_discussion(
            tab_list=self.tabs_with_discussion,
            expected_discussion_link="default_discussion_link",
            expected_can_display_value=True,
        )

    @patch.dict("django.conf.settings.FEATURES", {"ENABLE_DISCUSSION_SERVICE": True})
    def test_tabs_without_discussion(self):
        """Test a course with tabs configured but without a discussion tab"""
        self.check_discussion(
            tab_list=self.tabs_without_discussion,
            expected_discussion_link=not None,
            expected_can_display_value=False,
        )

    @patch.dict("django.conf.settings.FEATURES", {"ENABLE_DISCUSSION_SERVICE": True})
    def test_tabs_enrolled_or_staff(self):
        for is_enrolled, is_staff in [(True, False), (False, True)]:
            self.check_discussion(
                tab_list=self.tabs_with_discussion,
                expected_discussion_link="default_discussion_link",
                expected_can_display_value=True,
                is_enrolled=is_enrolled,
                is_staff=is_staff
            )

    @patch.dict("django.conf.settings.FEATURES", {"ENABLE_DISCUSSION_SERVICE": True})
    def test_tabs_not_enrolled_or_staff(self):
        is_enrolled = is_staff = False
        self.check_discussion(
            tab_list=self.tabs_with_discussion,
            expected_discussion_link="default_discussion_link",
            expected_can_display_value=False,
            is_enrolled=is_enrolled,
            is_staff=is_staff
        )
