"""
Test for lms courseware app, module data (runtime data storage for XBlocks)
"""
import json
from mock import Mock, patch
from functools import partial

from courseware.model_data import DjangoKeyValueStore
from courseware.model_data import InvalidScopeError, FieldDataCache
from courseware.models import StudentModule
from courseware.models import XModuleStudentInfoField, XModuleStudentPrefsField

from student.tests.factories import UserFactory
from courseware.tests.factories import StudentModuleFactory as cmfStudentModuleFactory, location, course_id
from courseware.tests.factories import UserStateSummaryFactory
from courseware.tests.factories import StudentPrefsFactory, StudentInfoFactory

from xblock.fields import Scope, BlockScope, ScopeIds
from django.test import TestCase
from django.db import DatabaseError
from xblock.core import KeyValueMultiSaveError


def mock_field(scope, name):
    field = Mock()
    field.scope = scope
    field.name = name
    return field


def mock_descriptor(fields=[]):
    descriptor = Mock()
    descriptor.scope_ids = ScopeIds('user1', 'mock_problem', location('def_id'), location('usage_id'))
    descriptor.module_class.fields.values.return_value = fields
    descriptor.fields.values.return_value = fields
    descriptor.module_class.__name__ = 'MockProblemModule'
    return descriptor

# The user ids here are 1 because we make a student in the setUp functions, and
# they get an id of 1.  There's an assertion in setUp to ensure that assumption
# is still true.
user_state_summary_key = partial(DjangoKeyValueStore.Key, Scope.user_state_summary, None, location('usage_id'))
settings_key = partial(DjangoKeyValueStore.Key, Scope.settings, None, location('usage_id'))
user_state_key = partial(DjangoKeyValueStore.Key, Scope.user_state, 1, location('usage_id'))
prefs_key = partial(DjangoKeyValueStore.Key, Scope.preferences, 1, 'mock_problem')
user_info_key = partial(DjangoKeyValueStore.Key, Scope.user_info, 1, None)


class StudentModuleFactory(cmfStudentModuleFactory):
    module_state_key = location('usage_id')
    course_id = course_id


class TestInvalidScopes(TestCase):
    def setUp(self):
        self.user = UserFactory.create(username='user')
        self.field_data_cache = FieldDataCache([mock_descriptor([mock_field(Scope.user_state, 'a_field')])], course_id, self.user)
        self.kvs = DjangoKeyValueStore(self.field_data_cache)

    def test_invalid_scopes(self):
        for scope in (Scope(user=True, block=BlockScope.DEFINITION),
                      Scope(user=False, block=BlockScope.TYPE),
                      Scope(user=False, block=BlockScope.ALL)):
            key = DjangoKeyValueStore.Key(scope, None, None, 'field')

            self.assertRaises(InvalidScopeError, self.kvs.get, key)
            self.assertRaises(InvalidScopeError, self.kvs.set, key, 'value')
            self.assertRaises(InvalidScopeError, self.kvs.delete, key)
            self.assertRaises(InvalidScopeError, self.kvs.has, key)
            self.assertRaises(InvalidScopeError, self.kvs.set_many, {key: 'value'})


class OtherUserFailureTestMixin(object):
    """
    Mixin class to add test cases for failures when a user trying to use the kvs is not
    the one that instantiated the kvs.
    Doing a mixin rather than modifying StorageTestBase (below) because some scopes don't fail in this case, because
    they aren't bound to a particular user

    assumes that this is mixed into a class that defines other_key_factory and existing_field_name
    """
    def test_other_user_kvs_get_failure(self):
        """
        Test for assert failure when a user who didn't create the kvs tries to get from it it
        """
        with self.assertRaises(AssertionError):
            self.kvs.get(self.other_key_factory(self.existing_field_name))

    def test_other_user_kvs_set_failure(self):
        """
        Test for assert failure when a user who didn't create the kvs tries to get from it it
        """
        with self.assertRaises(AssertionError):
            self.kvs.set(self.other_key_factory(self.existing_field_name), "new_value")


class TestStudentModuleStorage(OtherUserFailureTestMixin, TestCase):
    """Tests for user_state storage via StudentModule"""
    other_key_factory = partial(DjangoKeyValueStore.Key, Scope.user_state, 2, location('usage_id'))  # user_id=2, not 1
    existing_field_name = "a_field"

    def setUp(self):
        student_module = StudentModuleFactory(state=json.dumps({'a_field': 'a_value', 'b_field': 'b_value'}))
        self.user = student_module.student
        self.assertEqual(self.user.id, 1)   # check our assumption hard-coded in the key functions above.
        self.field_data_cache = FieldDataCache([mock_descriptor([mock_field(Scope.user_state, 'a_field')])], course_id, self.user)
        self.kvs = DjangoKeyValueStore(self.field_data_cache)

    def test_get_existing_field(self):
        "Test that getting an existing field in an existing StudentModule works"
        self.assertEquals('a_value', self.kvs.get(user_state_key('a_field')))

    def test_get_missing_field(self):
        "Test that getting a missing field from an existing StudentModule raises a KeyError"
        self.assertRaises(KeyError, self.kvs.get, user_state_key('not_a_field'))

    def test_set_existing_field(self):
        "Test that setting an existing user_state field changes the value"
        self.kvs.set(user_state_key('a_field'), 'new_value')
        self.assertEquals(1, StudentModule.objects.all().count())
        self.assertEquals({'b_field': 'b_value', 'a_field': 'new_value'}, json.loads(StudentModule.objects.all()[0].state))

    def test_set_missing_field(self):
        "Test that setting a new user_state field changes the value"
        self.kvs.set(user_state_key('not_a_field'), 'new_value')
        self.assertEquals(1, StudentModule.objects.all().count())
        self.assertEquals({'b_field': 'b_value', 'a_field': 'a_value', 'not_a_field': 'new_value'}, json.loads(StudentModule.objects.all()[0].state))

    def test_delete_existing_field(self):
        "Test that deleting an existing field removes it from the StudentModule"
        self.kvs.delete(user_state_key('a_field'))
        self.assertEquals(1, StudentModule.objects.all().count())
        self.assertRaises(KeyError, self.kvs.get, user_state_key('not_a_field'))

    def test_delete_missing_field(self):
        "Test that deleting a missing field from an existing StudentModule raises a KeyError"
        self.assertRaises(KeyError, self.kvs.delete, user_state_key('not_a_field'))
        self.assertEquals(1, StudentModule.objects.all().count())
        self.assertEquals({'b_field': 'b_value', 'a_field': 'a_value'}, json.loads(StudentModule.objects.all()[0].state))

    def test_has_existing_field(self):
        "Test that `has` returns True for existing fields in StudentModules"
        self.assertTrue(self.kvs.has(user_state_key('a_field')))

    def test_has_missing_field(self):
        "Test that `has` returns False for missing fields in StudentModule"
        self.assertFalse(self.kvs.has(user_state_key('not_a_field')))

    def construct_kv_dict(self):
        """Construct a kv_dict that can be passed to set_many"""
        key1 = user_state_key('field_a')
        key2 = user_state_key('field_b')
        new_value = 'new value'
        newer_value = 'newer value'
        return {key1: new_value, key2: newer_value}

    def test_set_many(self):
        "Test setting many fields that are scoped to Scope.user_state"
        kv_dict = self.construct_kv_dict()
        self.kvs.set_many(kv_dict)

        for key in kv_dict:
            self.assertEquals(self.kvs.get(key), kv_dict[key])

    def test_set_many_failure(self):
        "Test failures when setting many fields that are scoped to Scope.user_state"
        kv_dict = self.construct_kv_dict()
        # because we're patching the underlying save, we need to ensure the
        # fields are in the cache
        for key in kv_dict:
            self.kvs.set(key, 'test_value')

        with patch('django.db.models.Model.save', side_effect=DatabaseError):
            with self.assertRaises(KeyValueMultiSaveError) as exception_context:
                self.kvs.set_many(kv_dict)
        self.assertEquals(len(exception_context.exception.saved_field_names), 0)


class TestMissingStudentModule(TestCase):
    def setUp(self):
        self.user = UserFactory.create(username='user')
        self.assertEqual(self.user.id, 1)   # check our assumption hard-coded in the key functions above.
        self.field_data_cache = FieldDataCache([mock_descriptor()], course_id, self.user)
        self.kvs = DjangoKeyValueStore(self.field_data_cache)

    def test_get_field_from_missing_student_module(self):
        "Test that getting a field from a missing StudentModule raises a KeyError"
        self.assertRaises(KeyError, self.kvs.get, user_state_key('a_field'))

    def test_set_field_in_missing_student_module(self):
        "Test that setting a field in a missing StudentModule creates the student module"
        self.assertEquals(0, len(self.field_data_cache.cache))
        self.assertEquals(0, StudentModule.objects.all().count())

        self.kvs.set(user_state_key('a_field'), 'a_value')

        self.assertEquals(1, len(self.field_data_cache.cache))
        self.assertEquals(1, StudentModule.objects.all().count())

        student_module = StudentModule.objects.all()[0]
        self.assertEquals({'a_field': 'a_value'}, json.loads(student_module.state))
        self.assertEquals(self.user, student_module.student)
        self.assertEquals(location('usage_id').replace(run=None), student_module.module_state_key)
        self.assertEquals(course_id, student_module.course_id)

    def test_delete_field_from_missing_student_module(self):
        "Test that deleting a field from a missing StudentModule raises a KeyError"
        self.assertRaises(KeyError, self.kvs.delete, user_state_key('a_field'))

    def test_has_field_for_missing_student_module(self):
        "Test that `has` returns False for missing StudentModules"
        self.assertFalse(self.kvs.has(user_state_key('a_field')))


class StorageTestBase(object):
    """
    A base class for that gets subclassed when testing each of the scopes.

    """
    # Disable pylint warnings that arise because of the way the child classes call
    # this base class -- pylint's static analysis can't keep up with it.
    # pylint: disable=E1101, E1102

    factory = None
    scope = None
    key_factory = None
    storage_class = None

    def setUp(self):
        field_storage = self.factory.create()
        if hasattr(field_storage, 'student'):
            self.user = field_storage.student
        else:
            self.user = UserFactory.create()
        self.mock_descriptor = mock_descriptor([
            mock_field(self.scope, 'existing_field'),
            mock_field(self.scope, 'other_existing_field')])
        self.field_data_cache = FieldDataCache([self.mock_descriptor], course_id, self.user)
        self.kvs = DjangoKeyValueStore(self.field_data_cache)


    def test_set_and_get_existing_field(self):
        self.kvs.set(self.key_factory('existing_field'), 'test_value')
        self.assertEquals('test_value', self.kvs.get(self.key_factory('existing_field')))

    def test_get_existing_field(self):
        "Test that getting an existing field in an existing Storage Field works"
        self.assertEquals('old_value', self.kvs.get(self.key_factory('existing_field')))

    def test_get_missing_field(self):
        "Test that getting a missing field from an existing Storage Field raises a KeyError"
        self.assertRaises(KeyError, self.kvs.get, self.key_factory('missing_field'))

    def test_set_existing_field(self):
        "Test that setting an existing field changes the value"
        self.kvs.set(self.key_factory('existing_field'), 'new_value')
        self.assertEquals(1, self.storage_class.objects.all().count())
        self.assertEquals('new_value', json.loads(self.storage_class.objects.all()[0].value))

    def test_set_missing_field(self):
        "Test that setting a new field changes the value"
        self.kvs.set(self.key_factory('missing_field'), 'new_value')
        self.assertEquals(2, self.storage_class.objects.all().count())
        self.assertEquals('old_value', json.loads(self.storage_class.objects.get(field_name='existing_field').value))
        self.assertEquals('new_value', json.loads(self.storage_class.objects.get(field_name='missing_field').value))

    def test_delete_existing_field(self):
        "Test that deleting an existing field removes it"
        self.kvs.delete(self.key_factory('existing_field'))
        self.assertEquals(0, self.storage_class.objects.all().count())

    def test_delete_missing_field(self):
        "Test that deleting a missing field from an existing Storage Field raises a KeyError"
        self.assertRaises(KeyError, self.kvs.delete, self.key_factory('missing_field'))
        self.assertEquals(1, self.storage_class.objects.all().count())

    def test_has_existing_field(self):
        "Test that `has` returns True for an existing Storage Field"
        self.assertTrue(self.kvs.has(self.key_factory('existing_field')))

    def test_has_missing_field(self):
        "Test that `has` return False for an existing Storage Field"
        self.assertFalse(self.kvs.has(self.key_factory('missing_field')))

    def construct_kv_dict(self):
        """Construct a kv_dict that can be passed to set_many"""
        key1 = self.key_factory('existing_field')
        key2 = self.key_factory('other_existing_field')
        new_value = 'new value'
        newer_value = 'newer value'
        return {key1: new_value, key2: newer_value}

    def test_set_many(self):
        """Test that setting many regular fields at the same time works"""
        kv_dict = self.construct_kv_dict()

        self.kvs.set_many(kv_dict)
        for key in kv_dict:
            self.assertEquals(self.kvs.get(key), kv_dict[key])

    def test_set_many_failure(self):
        """Test that setting many regular fields with a DB error """
        kv_dict = self.construct_kv_dict()
        for key in kv_dict:
            self.kvs.set(key, 'test value')

        with patch('django.db.models.Model.save', side_effect=[None, DatabaseError]):
            with self.assertRaises(KeyValueMultiSaveError) as exception_context:
                self.kvs.set_many(kv_dict)

        exception = exception_context.exception
        self.assertEquals(len(exception.saved_field_names), 1)
        self.assertEquals(exception.saved_field_names[0], 'existing_field')


class TestUserStateSummaryStorage(StorageTestBase, TestCase):
    """Tests for UserStateSummaryStorage"""
    factory = UserStateSummaryFactory
    scope = Scope.user_state_summary
    key_factory = user_state_summary_key
    storage_class = factory.FACTORY_FOR


class TestStudentPrefsStorage(OtherUserFailureTestMixin, StorageTestBase, TestCase):
    """Tests for StudentPrefStorage"""
    factory = StudentPrefsFactory
    scope = Scope.preferences
    key_factory = prefs_key
    storage_class = XModuleStudentPrefsField
    other_key_factory = partial(DjangoKeyValueStore.Key, Scope.preferences, 2, 'mock_problem')  # user_id=2, not 1
    existing_field_name = "existing_field"


class TestStudentInfoStorage(OtherUserFailureTestMixin, StorageTestBase, TestCase):
    """Tests for StudentInfoStorage"""
    factory = StudentInfoFactory
    scope = Scope.user_info
    key_factory = user_info_key
    storage_class = XModuleStudentInfoField
    other_key_factory = partial(DjangoKeyValueStore.Key, Scope.user_info, 2, 'mock_problem')  # user_id=2, not 1
    existing_field_name = "existing_field"