from typing import List, Sequence

from django.http import HttpRequest, HttpResponse
from django.utils.translation import ugettext as _

from zerver.decorator import require_member_or_admin, require_user_group_edit_permission
from zerver.lib.actions import (
    bulk_add_members_to_user_group,
    check_add_user_group,
    check_delete_user_group,
    do_update_user_group_description,
    do_update_user_group_name,
    remove_members_from_user_group,
)
from zerver.lib.exceptions import JsonableError
from zerver.lib.request import REQ, has_request_variables
from zerver.lib.response import json_error, json_success
from zerver.lib.user_groups import (
    access_user_group_by_id,
    get_memberships_of_users,
    get_user_group_members,
    user_groups_in_realm_serialized,
)
from zerver.lib.users import user_ids_to_users
from zerver.lib.validator import check_int, check_list
from zerver.models import UserProfile
from zerver.views.streams import FuncKwargPair, compose_views


@require_user_group_edit_permission
@has_request_variables
def add_user_group(request: HttpRequest, user_profile: UserProfile,
                   name: str=REQ(),
                   members: Sequence[int]=REQ(validator=check_list(check_int), default=[]),
                   description: str=REQ()) -> HttpResponse:
    user_profiles = user_ids_to_users(members, user_profile.realm)
    check_add_user_group(user_profile.realm, name, user_profiles, description)
    return json_success()

@require_member_or_admin
@has_request_variables
def get_user_group(request: HttpRequest, user_profile: UserProfile) -> HttpResponse:
    user_groups = user_groups_in_realm_serialized(user_profile.realm)
    return json_success({"user_groups": user_groups})

@require_user_group_edit_permission
@has_request_variables
def edit_user_group(request: HttpRequest, user_profile: UserProfile,
                    user_group_id: int=REQ(validator=check_int),
                    name: str=REQ(default=""), description: str=REQ(default=""),
                    ) -> HttpResponse:
    if not (name or description):
        return json_error(_("No new data supplied"))

    user_group = access_user_group_by_id(user_group_id, user_profile)

    if name != user_group.name:
        do_update_user_group_name(user_group, name)

    if description != user_group.description:
        do_update_user_group_description(user_group, description)

    return json_success()

@require_user_group_edit_permission
@has_request_variables
def delete_user_group(request: HttpRequest, user_profile: UserProfile,
                      user_group_id: int=REQ(validator=check_int)) -> HttpResponse:

    check_delete_user_group(user_group_id, user_profile)
    return json_success()

@require_user_group_edit_permission
@has_request_variables
def update_user_group_backend(request: HttpRequest, user_profile: UserProfile,
                              user_group_id: int=REQ(validator=check_int),
                              delete: Sequence[int]=REQ(validator=check_list(check_int), default=[]),
                              add: Sequence[int]=REQ(validator=check_list(check_int), default=[]),
                              ) -> HttpResponse:
    if not add and not delete:
        return json_error(_('Nothing to do. Specify at least one of "add" or "delete".'))

    method_kwarg_pairs: List[FuncKwargPair] = [
        (add_members_to_group_backend,
         dict(user_group_id=user_group_id, members=add)),
        (remove_members_from_group_backend,
         dict(user_group_id=user_group_id, members=delete)),
    ]
    return compose_views(request, user_profile, method_kwarg_pairs)

def add_members_to_group_backend(request: HttpRequest, user_profile: UserProfile,
                                 user_group_id: int, members: List[int]) -> HttpResponse:
    if not members:
        return json_success()

    user_group = access_user_group_by_id(user_group_id, user_profile)
    user_profiles = user_ids_to_users(members, user_profile.realm)
    existing_member_ids = set(get_memberships_of_users(user_group, user_profiles))

    for user_profile in user_profiles:
        if user_profile.id in existing_member_ids:
            raise JsonableError(_("User {user_id} is already a member of this group").format(
                user_id=user_profile.id,
            ))

    bulk_add_members_to_user_group(user_group, user_profiles)
    return json_success()

def remove_members_from_group_backend(request: HttpRequest, user_profile: UserProfile,
                                      user_group_id: int, members: List[int]) -> HttpResponse:
    if not members:
        return json_success()

    user_profiles = user_ids_to_users(members, user_profile.realm)
    user_group = access_user_group_by_id(user_group_id, user_profile)
    group_member_ids = get_user_group_members(user_group)
    for member in members:
        if (member not in group_member_ids):
            raise JsonableError(_("There is no member '{}' in this user group").format(member))

    remove_members_from_user_group(user_group, user_profiles)
    return json_success()