"""
Tests for custom Teams Serializers.
"""


import six
from django.core.paginator import Paginator
from django.test.client import RequestFactory

from common.djangoapps.student.tests.factories import CourseEnrollmentFactory, UserFactory
from lms.djangoapps.teams.serializers import BulkTeamCountTopicSerializer, MembershipSerializer, TopicSerializer
from lms.djangoapps.teams.tests.factories import CourseTeamFactory, CourseTeamMembershipFactory
from openedx.core.lib.teams_config import TeamsConfig
from xmodule.modulestore.tests.django_utils import SharedModuleStoreTestCase
from xmodule.modulestore.tests.factories import CourseFactory


class SerializerTestCase(SharedModuleStoreTestCase):
    """
    Base test class to set up a course with topics
    """
    def setUp(self):
        """
        Set up a course with a teams configuration.
        """
        super().setUp()
        self.course = CourseFactory.create(
            teams_configuration=TeamsConfig({
                "max_team_size": 10,
                "topics": [{'name': 'Tøpic', 'description': 'The bést topic!', 'id': '0'}]
            }),
        )


class MembershipSerializerTestCase(SerializerTestCase):
    """
    Tests for the membership serializer.
    """

    def setUp(self):
        super().setUp()
        self.team = CourseTeamFactory.create(
            course_id=self.course.id,
            topic_id=self.course.teamsets[0].teamset_id,
        )
        self.user = UserFactory.create()
        CourseEnrollmentFactory.create(user=self.user, course_id=self.course.id)
        self.team_membership = CourseTeamMembershipFactory.create(team=self.team, user=self.user)

    def test_membership_serializer_expand_user_and_team(self):
        """Verify that the serializer only expands the user and team one level."""
        data = MembershipSerializer(self.team_membership, context={
            'expand': ['team', 'user'],
            'request': RequestFactory().get('/api/team/v0/team_membership')
        }).data
        username = self.user.username
        assert data['user'] == {'url': ('http://testserver/api/user/v1/accounts/' + username),
                                'username': username,
                                'profile_image': {'image_url_full': 'http://testserver/static/default_500.png',
                                                  'image_url_large': 'http://testserver/static/default_120.png',
                                                  'image_url_medium': 'http://testserver/static/default_50.png',
                                                  'image_url_small': 'http://testserver/static/default_30.png',
                                                  'has_image': False}, 'account_privacy': 'private'}
        assert 'membership' not in data['team']


class TopicSerializerTestCase(SerializerTestCase):
    """
    Tests for the `TopicSerializer`, which should serialize team count data for
    a single topic.
    """

    def test_topic_with_no_team_count(self):
        """
        Verifies that the `TopicSerializer` correctly displays a topic with a
        team count of 0, and that it takes a known number of SQL queries.
        """
        with self.assertNumQueries(2):
            serializer = TopicSerializer(
                self.course.teamsets[0].cleaned_data,
                context={'course_id': self.course.id},
            )
            assert serializer.data == {'name': 'Tøpic', 'description': 'The bést topic!', 'id': '0',
                                       'team_count': 0, 'type': 'open', 'max_team_size': None}

    def test_topic_with_team_count(self):
        """
        Verifies that the `TopicSerializer` correctly displays a topic with a
        positive team count, and that it takes a known number of SQL queries.
        """
        CourseTeamFactory.create(
            course_id=self.course.id, topic_id=self.course.teamsets[0].teamset_id
        )
        with self.assertNumQueries(2):
            serializer = TopicSerializer(
                self.course.teamsets[0].cleaned_data,
                context={'course_id': self.course.id},
            )
            assert serializer.data == {'name': 'Tøpic', 'description': 'The bést topic!', 'id': '0',
                                       'team_count': 1, 'type': 'open', 'max_team_size': None}

    def test_scoped_within_course(self):
        """Verify that team count is scoped within a course."""
        duplicate_topic = self.course.teamsets[0].cleaned_data
        second_course = CourseFactory.create(
            teams_configuration=TeamsConfig({
                "max_team_size": 10,
                "topics": [duplicate_topic]
            }),
        )
        CourseTeamFactory.create(course_id=self.course.id, topic_id=duplicate_topic['id'])
        CourseTeamFactory.create(course_id=second_course.id, topic_id=duplicate_topic['id'])
        with self.assertNumQueries(2):
            serializer = TopicSerializer(
                self.course.teamsets[0].cleaned_data,
                context={'course_id': self.course.id},
            )
            assert serializer.data == {'name': 'Tøpic', 'description': 'The bést topic!', 'id': '0',
                                       'team_count': 1, 'type': 'open', 'max_team_size': None}


class BaseTopicSerializerTestCase(SerializerTestCase):
    """
    Base class for testing the two paginated topic serializers.
    """

    __test__ = False
    PAGE_SIZE = 5
    # Extending test classes should specify their serializer class.
    serializer = None

    def _merge_dicts(self, first, second):
        """Convenience method to merge two dicts in a single expression"""
        result = first.copy()
        result.update(second)
        return result

    def setup_topics(self, num_topics=5, teams_per_topic=0):
        """
        Helper method to set up topics on the course.  Returns a list of
        created topics.
        """
        topics = [
            {
                'name': f'Tøpic {i}',
                'description': f'The bést topic! {i}',
                'id': str(i),
                'type': 'open',
                'max_team_size': i + 10
            }
            for i in six.moves.range(num_topics)
        ]
        for topic in topics:
            for _ in six.moves.range(teams_per_topic):
                CourseTeamFactory.create(course_id=self.course.id, topic_id=topic['id'])
        self.course.teams_configuration = TeamsConfig({
            'max_team_size': self.course.teams_configuration.default_max_team_size,
            'topics': topics,
        })
        return topics

    def assert_serializer_output(self, topics, num_teams_per_topic, num_queries):
        """
        Verify that the serializer produced the expected topics.
        """
        with self.assertNumQueries(num_queries):
            page = Paginator(
                self.course.teams_configuration.cleaned_data['teamsets'],
                self.PAGE_SIZE,
            ).page(1)
            # pylint: disable=not-callable
            serializer = self.serializer(instance=page, context={'course_id': self.course.id})
            assert serializer.data['results'] ==\
                   [self._merge_dicts(topic, {'team_count': num_teams_per_topic}) for topic in topics]

    def test_no_topics(self):
        """
        Verify that we return no results and make no SQL queries for a page
        with no topics.
        """
        self.course.teams_configuration = TeamsConfig({'topics': []})
        self.assert_serializer_output([], num_teams_per_topic=0, num_queries=0)


class BulkTeamCountTopicSerializerTestCase(BaseTopicSerializerTestCase):
    """
    Tests for the `BulkTeamCountTopicSerializer`, which should serialize team_count
    data for many topics with constant time SQL queries.
    """
    __test__ = True
    serializer = BulkTeamCountTopicSerializer

    NUM_TOPICS = 6

    def setUp(self):
        super().setUp()
        self.user = UserFactory.create()
        CourseEnrollmentFactory.create(user=self.user, course_id=self.course.id)

    def test_topics_with_no_team_counts(self):
        """
        Verify that we serialize topics with no team count, making only one SQL
        query.
        """
        topics = self.setup_topics(teams_per_topic=0)
        self.assert_serializer_output(topics, num_teams_per_topic=0, num_queries=2)

    def test_topics_with_team_counts(self):
        """
        Verify that we serialize topics with a positive team count, making only
        one SQL query.
        """
        teams_per_topic = 10
        topics = self.setup_topics(teams_per_topic=teams_per_topic)
        self.assert_serializer_output(topics, num_teams_per_topic=teams_per_topic, num_queries=2)

    def test_subset_of_topics(self):
        """
        Verify that we serialize a subset of the course's topics, making only
        one SQL query.
        """
        teams_per_topic = 10
        topics = self.setup_topics(num_topics=self.NUM_TOPICS, teams_per_topic=teams_per_topic)
        self.assert_serializer_output(topics, num_teams_per_topic=teams_per_topic, num_queries=2)

    def test_scoped_within_course(self):
        """Verify that team counts are scoped within a course."""
        teams_per_topic = 10
        first_course_topics = self.setup_topics(num_topics=self.NUM_TOPICS, teams_per_topic=teams_per_topic)
        duplicate_topic = first_course_topics[0]
        second_course = CourseFactory.create(
            teams_configuration=TeamsConfig({
                "max_team_size": 10,
                "topics": [duplicate_topic]
            }),
        )
        CourseTeamFactory.create(course_id=second_course.id, topic_id=duplicate_topic['id'])
        self.assert_serializer_output(first_course_topics, num_teams_per_topic=teams_per_topic, num_queries=2)

    def _merge_dicts(self, first, second):
        """Convenience method to merge two dicts in a single expression"""
        result = first.copy()
        result.update(second)
        return result

    def assert_serializer_output(self, topics, num_teams_per_topic, num_queries):
        """
        Verify that the serializer produced the expected topics.
        """
        # Set a request user
        request = RequestFactory().get('/api/team/v0/topics')
        request.user = self.user

        with self.assertNumQueries(num_queries):
            serializer = self.serializer(
                topics,
                context={
                    'course_id': self.course.id,
                    'request': request
                },
                many=True
            )
            assert serializer.data ==\
                   [self._merge_dicts(topic, {'team_count': num_teams_per_topic}) for topic in topics]

    def test_no_topics(self):
        """
        Verify that we return no results and make no SQL queries for a page
        with no topics.
        """
        self.course.teams_configuration = TeamsConfig({'topics': []})
        self.assert_serializer_output([], num_teams_per_topic=0, num_queries=1)