"""
Django module for Course Metadata class -- manages advanced settings and related parameters
"""


import six
from crum import get_current_user
from django.conf import settings
from django.utils.translation import ugettext as _
from six import text_type
from xblock.fields import Scope

from cms.djangoapps.contentstore.config.waffle import ENABLE_PROCTORING_PROVIDER_OVERRIDES
from openedx.features.course_experience import COURSE_ENABLE_UNENROLLED_ACCESS_FLAG
from student.roles import GlobalStaff
from xblock_django.models import XBlockStudioConfigurationFlag
from xmodule.modulestore.django import modulestore


class CourseMetadata(object):
    '''
    For CRUD operations on metadata fields which do not have specific editors
    on the other pages including any user generated ones.
    The objects have no predefined attrs but instead are obj encodings of the
    editable metadata.
    '''
    # The list of fields that wouldn't be shown in Advanced Settings.
    # Should not be used directly. Instead the get_blacklist_of_fields method should
    # be used if the field needs to be filtered depending on the feature flag.
    FIELDS_BLACK_LIST = [
        'cohort_config',
        'xml_attributes',
        'start',
        'end',
        'enrollment_start',
        'enrollment_end',
        'certificate_available_date',
        'tabs',
        'graceperiod',
        'show_timezone',
        'format',
        'graded',
        'hide_from_toc',
        'pdf_textbooks',
        'user_partitions',
        'name',  # from xblock
        'tags',  # from xblock
        'visible_to_staff_only',
        'group_access',
        'pre_requisite_courses',
        'entrance_exam_enabled',
        'entrance_exam_minimum_score_pct',
        'entrance_exam_id',
        'is_entrance_exam',
        'in_entrance_exam',
        'language',
        'certificates',
        'minimum_grade_credit',
        'default_time_limit_minutes',
        'is_proctored_enabled',
        'is_time_limited',
        'is_practice_exam',
        'exam_review_rules',
        'hide_after_due',
        'self_paced',
        'show_correctness',
        'chrome',
        'default_tab',
        'highlights_enabled_for_messaging',
        'is_onboarding_exam',
    ]

    @classmethod
    def get_blacklist_of_fields(cls, course_key):
        """
        Returns a list of fields to not include in Studio Advanced settings based on a
        feature flag (i.e. enabled or disabled).
        """
        # Copy the filtered list to avoid permanently changing the class attribute.
        black_list = list(cls.FIELDS_BLACK_LIST)

        # Do not show giturl if feature is not enabled.
        if not settings.FEATURES.get('ENABLE_EXPORT_GIT'):
            black_list.append('giturl')

        # Do not show edxnotes if the feature is disabled.
        if not settings.FEATURES.get('ENABLE_EDXNOTES'):
            black_list.append('edxnotes')

        # Do not show video auto advance if the feature is disabled
        if not settings.FEATURES.get('ENABLE_OTHER_COURSE_SETTINGS'):
            black_list.append('other_course_settings')

        # Do not show video_upload_pipeline if the feature is disabled.
        if not settings.FEATURES.get('ENABLE_VIDEO_UPLOAD_PIPELINE'):
            black_list.append('video_upload_pipeline')

        # Do not show video auto advance if the feature is disabled
        if not settings.FEATURES.get('ENABLE_AUTOADVANCE_VIDEOS'):
            black_list.append('video_auto_advance')

        # Do not show social sharing url field if the feature is disabled.
        if (not hasattr(settings, 'SOCIAL_SHARING_SETTINGS') or
                not getattr(settings, 'SOCIAL_SHARING_SETTINGS', {}).get("CUSTOM_COURSE_URLS")):
            black_list.append('social_sharing_url')

        # Do not show teams configuration if feature is disabled.
        if not settings.FEATURES.get('ENABLE_TEAMS'):
            black_list.append('teams_configuration')

        if not settings.FEATURES.get('ENABLE_VIDEO_BUMPER'):
            black_list.append('video_bumper')

        # Do not show enable_ccx if feature is not enabled.
        if not settings.FEATURES.get('CUSTOM_COURSES_EDX'):
            black_list.append('enable_ccx')
            black_list.append('ccx_connector')

        # Do not show "Issue Open Badges" in Studio Advanced Settings
        # if the feature is disabled.
        if not settings.FEATURES.get('ENABLE_OPENBADGES'):
            black_list.append('issue_badges')

        # If the XBlockStudioConfiguration table is not being used, there is no need to
        # display the "Allow Unsupported XBlocks" setting.
        if not XBlockStudioConfigurationFlag.is_enabled():
            black_list.append('allow_unsupported_xblocks')

        # If the ENABLE_PROCTORING_PROVIDER_OVERRIDES waffle flag is not enabled,
        # do not show "Proctoring Configuration" in Studio Advanced Settings.
        if not ENABLE_PROCTORING_PROVIDER_OVERRIDES.is_enabled(course_key):
            black_list.append('proctoring_provider')

        # Do not show "Course Visibility For Unenrolled Learners" in Studio Advanced Settings
        # if the enable_anonymous_access flag is not enabled
        if not COURSE_ENABLE_UNENROLLED_ACCESS_FLAG.is_enabled(course_key=course_key):
            black_list.append('course_visibility')

        # Do not show "Create Zendesk Tickets For Suspicious Proctored Exam Attempts" in
        # Studio Advanced Settings if the user is not edX staff.
        if not GlobalStaff().has_user(get_current_user()):
            black_list.append('create_zendesk_tickets')

        return black_list

    @classmethod
    def fetch(cls, descriptor):
        """
        Fetch the key:value editable course details for the given course from
        persistence and return a CourseMetadata model.
        """
        result = {}
        metadata = cls.fetch_all(descriptor)
        black_list_of_fields = cls.get_blacklist_of_fields(descriptor.id)

        for key, value in six.iteritems(metadata):
            if key in black_list_of_fields:
                continue
            result[key] = value
        return result

    @classmethod
    def fetch_all(cls, descriptor):
        """
        Fetches all key:value pairs from persistence and returns a CourseMetadata model.
        """
        result = {}
        for field in descriptor.fields.values():
            if field.scope != Scope.settings:
                continue

            field_help = _(field.help)
            help_args = field.runtime_options.get('help_format_args')
            if help_args is not None:
                field_help = field_help.format(**help_args)

            result[field.name] = {
                'value': field.read_json(descriptor),
                'display_name': _(field.display_name),
                'help': field_help,
                'deprecated': field.runtime_options.get('deprecated', False),
                'hide_on_enabled_publisher': field.runtime_options.get('hide_on_enabled_publisher', False)
            }
        return result

    @classmethod
    def update_from_json(cls, descriptor, jsondict, user, filter_tabs=True):
        """
        Decode the json into CourseMetadata and save any changed attrs to the db.

        Ensures none of the fields are in the blacklist.
        """
        blacklist_of_fields = cls.get_blacklist_of_fields(descriptor.id)
        # Don't filter on the tab attribute if filter_tabs is False.
        if not filter_tabs:
            blacklist_of_fields.remove("tabs")

        # Validate the values before actually setting them.
        key_values = {}

        for key, model in six.iteritems(jsondict):
            # should it be an error if one of the filtered list items is in the payload?
            if key in blacklist_of_fields:
                continue
            try:
                val = model['value']
                if hasattr(descriptor, key) and getattr(descriptor, key) != val:
                    key_values[key] = descriptor.fields[key].from_json(val)
            except (TypeError, ValueError) as err:
                raise ValueError(_(u"Incorrect format for field '{name}'. {detailed_message}").format(
                    name=model['display_name'], detailed_message=text_type(err)))

        return cls.update_from_dict(key_values, descriptor, user)

    @classmethod
    def validate_and_update_from_json(cls, descriptor, jsondict, user, filter_tabs=True):
        """
        Validate the values in the json dict (validated by xblock fields from_json method)

        If all fields validate, go ahead and update those values on the object and return it without
        persisting it to the DB.
        If not, return the error objects list.

        Returns:
            did_validate: whether values pass validation or not
            errors: list of error objects
            result: the updated course metadata or None if error
        """
        blacklist_of_fields = cls.get_blacklist_of_fields(descriptor.id)

        if not filter_tabs:
            blacklist_of_fields.remove("tabs")

        filtered_dict = dict((k, v) for k, v in six.iteritems(jsondict) if k not in blacklist_of_fields)
        did_validate = True
        errors = []
        key_values = {}
        updated_data = None

        for key, model in six.iteritems(filtered_dict):
            try:
                val = model['value']
                if hasattr(descriptor, key) and getattr(descriptor, key) != val:
                    key_values[key] = descriptor.fields[key].from_json(val)
            except (TypeError, ValueError) as err:
                did_validate = False
                errors.append({'message': text_type(err), 'model': model})

        # If did validate, go ahead and update the metadata
        if did_validate:
            updated_data = cls.update_from_dict(key_values, descriptor, user, save=False)

        return did_validate, errors, updated_data

    @classmethod
    def update_from_dict(cls, key_values, descriptor, user, save=True):
        """
        Update metadata descriptor from key_values. Saves to modulestore if save is true.
        """
        for key, value in six.iteritems(key_values):
            setattr(descriptor, key, value)

        if save and key_values:
            modulestore().update_item(descriptor, user.id)

        return cls.fetch(descriptor)
