from typing import Any, Dict, List, Set

from ..utils.access_permissions import BaseAccessPermissions, required_user
from ..utils.auth import async_has_perm
from ..utils.utils import get_model_from_collection_string


class UserAccessPermissions(BaseAccessPermissions):
    """
    Access permissions container for User and UserViewSet.
    """

    async def get_restricted_data(
            self,
            full_data: List[Dict[str, Any]],
            user_id: int) -> List[Dict[str, Any]]:
        """
        Returns the restricted serialized data for the instance prepared
        for the user. Removes several fields for non admins so that they do
        not get the fields they should not get.
        """
        from .serializers import USERCANSEESERIALIZER_FIELDS, USERCANSEEEXTRASERIALIZER_FIELDS

        def filtered_data(full_data, whitelist):
            """
            Returns a new dict like full_data but only with whitelisted keys.
            """
            return {key: full_data[key] for key in whitelist}

        # We have five sets of data to be sent:
        # * full data i. e. all fields (including session_auth_hash),
        # * all data i. e. all fields but not session_auth_hash,
        # * many data i. e. all fields but not the default password and session_auth_hash,
        # * little data i. e. all fields but not the default password, session_auth_hash, comments and active status,
        # * no data.

        # Prepare field set for users with "all" data, "many" data and with "little" data.
        all_data_fields = set(USERCANSEEEXTRASERIALIZER_FIELDS)
        all_data_fields.add('groups_id')
        all_data_fields.discard('groups')
        all_data_fields.add('default_password')
        many_data_fields = all_data_fields.copy()
        many_data_fields.discard('default_password')
        litte_data_fields = set(USERCANSEESERIALIZER_FIELDS)
        litte_data_fields.add('groups_id')
        litte_data_fields.discard('groups')

        # Check user permissions.
        if await async_has_perm(user_id, 'users.can_see_name'):
            if await async_has_perm(user_id, 'users.can_see_extra_data'):
                if await async_has_perm(user_id, 'users.can_manage'):
                    data = [filtered_data(full, all_data_fields) for full in full_data]
                else:
                    data = [filtered_data(full, many_data_fields) for full in full_data]
            else:
                data = [filtered_data(full, litte_data_fields) for full in full_data]
        else:
            # Build a list of users, that can be seen without any permissions (with little fields).

            # Everybody can see himself. Also everybody can see every user
            # that is required e. g. as speaker, motion submitter or
            # assignment candidate.

            can_see_collection_strings: Set[str] = set()
            for collection_string in required_user.get_collection_strings():
                if await async_has_perm(user_id, get_model_from_collection_string(collection_string).can_see_permission):
                    can_see_collection_strings.add(collection_string)

            user_ids = await required_user.get_required_users(can_see_collection_strings)

            # Add oneself.
            if user_id:
                user_ids.add(user_id)

            # Parse data.
            data = [
                filtered_data(full, litte_data_fields)
                for full
                in full_data
                if full['id'] in user_ids]

        return data


class GroupAccessPermissions(BaseAccessPermissions):
    """
    Access permissions container for Groups. Everyone can see them
    """


class PersonalNoteAccessPermissions(BaseAccessPermissions):
    """
    Access permissions container for personal notes. Every authenticated user
    can handle personal notes.
    """

    async def get_restricted_data(
            self,
            full_data: List[Dict[str, Any]],
            user_id: int) -> List[Dict[str, Any]]:
        """
        Returns the restricted serialized data for the instance prepared
        for the user. Everybody gets only his own personal notes.
        """
        # Parse data.
        if not user_id:
            data: List[Dict[str, Any]] = []
        else:
            for full in full_data:
                if full['user_id'] == user_id:
                    data = [full]
                    break
            else:
                data = []

        return data