"""
Test the behavior of the GradesTransformer
"""

import datetime
import pytz
import random

import ddt
from copy import deepcopy

from student.tests.factories import UserFactory
from xmodule.modulestore import ModuleStoreEnum
from xmodule.modulestore.django import modulestore
from xmodule.modulestore.tests.django_utils import SharedModuleStoreTestCase
from xmodule.modulestore.tests.factories import check_mongo_calls

from lms.djangoapps.course_blocks.api import get_course_blocks
from lms.djangoapps.course_blocks.transformers.tests.helpers import CourseStructureTestCase
from openedx.core.djangoapps.content.block_structure.api import clear_course_from_cache
from ..transformer import GradesTransformer


@ddt.ddt
class GradesTransformerTestCase(CourseStructureTestCase):
    """
    Verify behavior of the GradesTransformer
    """

    TRANSFORMER_CLASS_TO_TEST = GradesTransformer

    ENABLED_SIGNALS = ['course_published']

    problem_metadata = {
        u'graded': True,
        u'weight': 1,
        u'due': datetime.datetime(2099, 3, 15, 12, 30, 0, tzinfo=pytz.utc),
    }

    def setUp(self):
        super(GradesTransformerTestCase, self).setUp()
        password = u'test'
        self.student = UserFactory.create(is_staff=False, username=u'test_student', password=password)
        self.client.login(username=self.student.username, password=password)

    def _update_course_grading_policy(self, course, grading_policy):
        """
        Helper to update a course's grading policy in the modulestore.
        """
        course.set_grading_policy(grading_policy)
        modulestore().update_item(course, self.user.id)

    def _validate_grading_policy_hash(self, course_location, grading_policy_hash):
        """
        Helper to retrieve the course at the given course_location and
        assert that its hashed grading policy (from the grades transformer)
        is as expected.
        """
        block_structure = get_course_blocks(self.student, course_location, self.transformers)
        self.assert_collected_transformer_block_fields(
            block_structure,
            course_location,
            self.TRANSFORMER_CLASS_TO_TEST,
            grading_policy_hash=grading_policy_hash,
        )

    def assert_collected_xblock_fields(self, block_structure, usage_key, **expectations):
        """
        Given a block structure, a block usage key, and a list of keyword
        arguments representing XBlock fields, verify that the block structure
        has the specified values for each XBlock field.
        """
        self.assertGreater(len(expectations), 0)
        for field in expectations:
            # Append our custom message to the default assertEqual error message
            self.longMessage = True  # pylint: disable=invalid-name
            self.assertEqual(
                expectations[field],
                block_structure.get_xblock_field(usage_key, field),
                msg=u'in field {},'.format(repr(field)),
            )
        self.assertIsNotNone(
            block_structure.get_xblock_field(usage_key, u'subtree_edited_on'),
        )

    def assert_collected_transformer_block_fields(self, block_structure, usage_key, transformer_class, **expectations):
        """
        Given a block structure, a block usage key, a transformer, and a list
        of keyword arguments representing transformer block fields, verify that
        the block structure has the specified values for each transformer block
        field.
        """
        self.assertGreater(len(expectations), 0)
        # Append our custom message to the default assertEqual error message
        self.longMessage = True  # pylint: disable=invalid-name
        for field in expectations:
            self.assertEqual(
                expectations[field],
                block_structure.get_transformer_block_field(usage_key, transformer_class, field),
                msg=u'in {} and field {}'.format(transformer_class, repr(field)),
            )

    def build_course_with_problems(self, data='<problem></problem>', metadata=None):
        """
        Create a test course with the requested problem `data` and `metadata` values.

        Appropriate defaults are provided when either argument is omitted.
        """
        metadata = metadata or self.problem_metadata

        # Special structure-related keys start with '#'.  The rest get passed as
        # kwargs to Factory.create.  See docstring at
        # `CourseStructureTestCase.build_course` for details.
        return self.build_course([
            {
                u'org': u'GradesTestOrg',
                u'course': u'GB101',
                u'run': u'cannonball',
                u'metadata': {u'format': u'homework'},
                u'#type': u'course',
                u'#ref': u'course',
                u'#children': [
                    {
                        u'metadata': metadata,
                        u'#type': u'problem',
                        u'#ref': u'problem',
                        u'data': data,
                    }
                ]
            }
        ])

    def build_complicated_hypothetical_course(self):
        """
        Create a test course with a very odd structure as a stress-test for various methods.

        Current design is to test containing_subsection logic in collect_unioned_set_field.
        I can't reasonably draw this in ascii art (due to intentional complexities), so here's an overview:
            We have 1 course, containing 1 chapter, containing 2 subsections.

            From here, it starts to get hairy. Call our subsections A and B.
            Subsection A contains 3 verticals (call them 1, 2, and 3), and another subsection (C)
            Subsection B contains vertical 3 and subsection C
            Subsection C contains 1 problem (b)
            Vertical 1 contains 1 vertical (11)
            Vertical 2 contains no children
            Vertical 3 contains no children
            Vertical 11 contains 1 problem (aa) and vertical 2
            Problem b contains no children
        """
        return self.build_course([
            {
                u'org': u'GradesTestOrg',
                u'course': u'GB101',
                u'run': u'cannonball',
                u'metadata': {u'format': u'homework'},
                u'#type': u'course',
                u'#ref': u'course',
                u'#children': [
                    {
                        u'#type': u'chapter',
                        u'#ref': u'chapter',
                        u'#children': [
                            {
                                u'#type': u'sequential',
                                u'#ref': 'sub_A',
                                u'#children': [
                                    {
                                        u'#type': u'vertical',
                                        u'#ref': 'vert_1',
                                        u'#children': [
                                            {
                                                u'#type': u'vertical',
                                                u'#ref': u'vert_A11',
                                                u'#children': [{u'#type': u'problem', u'#ref': u'prob_A1aa'}]
                                            },
                                        ]
                                    },
                                    {u'#type': u'vertical', u'#ref': 'vert_2', '#parents': [u'vert_A11']},
                                ]
                            },
                            {
                                u'#type': u'sequential',
                                u'#ref': u'sub_B',
                                u'#children': [
                                    {u'#type': u'vertical', u'#ref': 'vert_3', '#parents': ['sub_A']},
                                    {
                                        u'#type': u'sequential',
                                        u'#ref': 'sub_C',
                                        '#parents': ['sub_A'],
                                        u'#children': [{u'#type': u'problem', u'#ref': u'prob_BCb'}]
                                    },
                                ]
                            },
                        ]
                    }
                ]
            }
        ])

    def test_collect_containing_subsection(self):
        expected_subsections = {
            'course': set(),
            'chapter': set(),
            'sub_A': {'sub_A'},
            'sub_B': {'sub_B'},
            'sub_C': {'sub_A', 'sub_B', 'sub_C'},
            'vert_1': {'sub_A'},
            'vert_2': {'sub_A'},
            'vert_3': {'sub_A', 'sub_B'},
            'vert_A11': {'sub_A'},
            'prob_A1aa': {'sub_A'},
            'prob_BCb': {'sub_A', 'sub_B', 'sub_C'},
        }
        blocks = self.build_complicated_hypothetical_course()
        block_structure = get_course_blocks(self.student, blocks[u'course'].location, self.transformers)
        for block_ref, expected_subsections in expected_subsections.iteritems():
            actual_subsections = block_structure.get_transformer_block_field(
                blocks[block_ref].location,
                self.TRANSFORMER_CLASS_TO_TEST,
                'subsections',
            )
            self.assertEqual(actual_subsections, {blocks[sub].location for sub in expected_subsections})

    def test_unscored_block_collection(self):
        blocks = self.build_course_with_problems()
        block_structure = get_course_blocks(self.student, blocks[u'course'].location, self.transformers)
        self.assert_collected_xblock_fields(
            block_structure,
            blocks[u'course'].location,
            weight=None,
            graded=False,
            has_score=False,
            due=None,
            format=u'homework',
        )
        self.assert_collected_transformer_block_fields(
            block_structure,
            blocks[u'course'].location,
            self.TRANSFORMER_CLASS_TO_TEST,
            max_score=None,
            explicit_graded=None,
        )

    def test_grades_collected_basic(self):

        blocks = self.build_course_with_problems()
        block_structure = get_course_blocks(self.student, blocks[u'course'].location, self.transformers)

        self.assert_collected_xblock_fields(
            block_structure,
            blocks[u'problem'].location,
            weight=self.problem_metadata[u'weight'],
            graded=self.problem_metadata[u'graded'],
            has_score=True,
            due=self.problem_metadata[u'due'],
            format=None,
        )
        self.assert_collected_transformer_block_fields(
            block_structure,
            blocks[u'problem'].location,
            self.TRANSFORMER_CLASS_TO_TEST,
            max_score=0,
            explicit_graded=True,
        )

    @ddt.data(True, False, None)
    def test_graded_at_problem(self, graded):
        problem_metadata = {
            u'has_score': True,
        }
        if graded is not None:
            problem_metadata[u'graded'] = graded
        blocks = self.build_course_with_problems(metadata=problem_metadata)
        block_structure = get_course_blocks(self.student, blocks[u'course'].location, self.transformers)
        self.assert_collected_transformer_block_fields(
            block_structure,
            blocks[u'problem'].location,
            self.TRANSFORMER_CLASS_TO_TEST,
            explicit_graded=graded,
        )

    def test_collecting_staff_only_problem(self):
        # Demonstrate that the problem data can by collected by the SystemUser
        # even if the block has access restrictions placed on it.
        problem_metadata = {
            u'graded': True,
            u'weight': 1,
            u'due': datetime.datetime(2016, 10, 16, 0, 4, 0, tzinfo=pytz.utc),
            u'visible_to_staff_only': True,
        }

        blocks = self.build_course_with_problems(metadata=problem_metadata)
        block_structure = get_course_blocks(self.student, blocks[u'course'].location, self.transformers)

        self.assert_collected_xblock_fields(
            block_structure,
            blocks[u'problem'].location,
            weight=problem_metadata[u'weight'],
            graded=problem_metadata[u'graded'],
            has_score=True,
            due=problem_metadata[u'due'],
            format=None,
        )

    def test_max_score_collection(self):
        problem_data = u'''
            <problem>
                <numericalresponse answer="2">
                    <textline label="1+1" trailing_text="%" />
                </numericalresponse>
            </problem>
        '''

        blocks = self.build_course_with_problems(data=problem_data)
        block_structure = get_course_blocks(self.student, blocks[u'course'].location, self.transformers)

        self.assert_collected_transformer_block_fields(
            block_structure,
            blocks[u'problem'].location,
            self.TRANSFORMER_CLASS_TO_TEST,
            max_score=1,
        )

    def test_max_score_for_multiresponse_problem(self):
        problem_data = u'''
            <problem>
                <numericalresponse answer="27">
                    <textline label="3^3" />
                </numericalresponse>
                <numericalresponse answer="13.5">
                    <textline label="and then half of that?" />
                </numericalresponse>
            </problem>
        '''

        blocks = self.build_course_with_problems(problem_data)
        block_structure = get_course_blocks(self.student, blocks[u'course'].location, self.transformers)

        self.assert_collected_transformer_block_fields(
            block_structure,
            blocks[u'problem'].location,
            self.TRANSFORMER_CLASS_TO_TEST,
            max_score=2,
        )

    def test_course_version_not_collected_in_old_mongo(self):
        blocks = self.build_course_with_problems()
        block_structure = get_course_blocks(self.student, blocks[u'course'].location, self.transformers)
        self.assertIsNone(block_structure.get_xblock_field(blocks[u'course'].location, u'course_version'))

    def test_course_version_collected_in_split(self):
        with self.store.default_store(ModuleStoreEnum.Type.split):
            blocks = self.build_course_with_problems()
        block_structure = get_course_blocks(self.student, blocks[u'course'].location, self.transformers)
        self.assertIsNotNone(block_structure.get_xblock_field(blocks[u'course'].location, u'course_version'))
        self.assertEqual(
            block_structure.get_xblock_field(blocks[u'problem'].location, u'course_version'),
            block_structure.get_xblock_field(blocks[u'course'].location, u'course_version')
        )

    def test_grading_policy_collected(self):
        # the calculated hash of the original and updated grading policies of the test course
        original_grading_policy_hash = u'ChVp0lHGQGCevD0t4njna/C44zQ='
        updated_grading_policy_hash = u'TsbX04qWOy1WRnC0NHy+94upPd4='

        blocks = self.build_course_with_problems()
        course_block = blocks[u'course']
        self._validate_grading_policy_hash(
            course_block.location,
            original_grading_policy_hash
        )

        # make sure the hash changes when the course grading policy is edited
        grading_policy_with_updates = course_block.grading_policy
        original_grading_policy = deepcopy(grading_policy_with_updates)
        for section in grading_policy_with_updates['GRADER']:
            self.assertNotEqual(section['weight'], 0.25)
            section['weight'] = 0.25

        self._update_course_grading_policy(course_block, grading_policy_with_updates)
        self._validate_grading_policy_hash(
            course_block.location,
            updated_grading_policy_hash
        )

        # reset the grading policy and ensure the hash matches the original
        self._update_course_grading_policy(course_block, original_grading_policy)
        self._validate_grading_policy_hash(
            course_block.location,
            original_grading_policy_hash
        )


@ddt.ddt
class MultiProblemModulestoreAccessTestCase(CourseStructureTestCase, SharedModuleStoreTestCase):
    """
    Test mongo usage in GradesTransformer.
    """

    TRANSFORMER_CLASS_TO_TEST = GradesTransformer

    def setUp(self):
        super(MultiProblemModulestoreAccessTestCase, self).setUp()
        password = u'test'
        self.student = UserFactory.create(is_staff=False, username=u'test_student', password=password)
        self.client.login(username=self.student.username, password=password)

    @ddt.data(
        (ModuleStoreEnum.Type.split, 3),
        (ModuleStoreEnum.Type.mongo, 2),
    )
    @ddt.unpack
    def test_modulestore_performance(self, store_type, expected_mongo_queries):
        """
        Test that a constant number of mongo calls are made regardless of how
        many grade-related blocks are in the course.
        """
        course = [
            {
                u'org': u'GradesTestOrg',
                u'course': u'GB101',
                u'run': u'cannonball',
                u'metadata': {u'format': u'homework'},
                u'#type': u'course',
                u'#ref': u'course',
                u'#children': [],
            },
        ]
        for problem_number in xrange(random.randrange(10, 20)):
            course[0][u'#children'].append(
                {
                    u'metadata': {
                        u'graded': True,
                        u'weight': 1,
                        u'due': datetime.datetime(2099, 3, 15, 12, 30, 0, tzinfo=pytz.utc),
                    },
                    u'#type': u'problem',
                    u'#ref': u'problem_{}'.format(problem_number),
                    u'data': u'''
                        <problem>
                            <numericalresponse answer="{number}">
                                <textline label="1*{number}" />
                            </numericalresponse>
                        </problem>'''.format(number=problem_number),
                }
            )
        with self.store.default_store(store_type):
            blocks = self.build_course(course)
        clear_course_from_cache(blocks[u'course'].id)
        with check_mongo_calls(expected_mongo_queries):
            get_course_blocks(self.student, blocks[u'course'].location, self.transformers)
