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

from zerver.decorator import to_non_negative_int
from zerver.lib.actions import do_update_pointer
from zerver.lib.request import has_request_variables, JsonableError, REQ
from zerver.lib.response import json_success
from zerver.models import UserProfile, UserMessage

def get_pointer_backend(request: HttpRequest, user_profile: UserProfile) -> HttpResponse:
    return json_success({'pointer': user_profile.pointer})

@has_request_variables
def update_pointer_backend(request, user_profile,
                           pointer=REQ(converter=to_non_negative_int)):
    # type: (HttpRequest, UserProfile, int) -> HttpResponse
    if pointer <= user_profile.pointer:
        return json_success()

    try:
        UserMessage.objects.get(
            user_profile=user_profile,
            message__id=pointer
        )
    except UserMessage.DoesNotExist:
        raise JsonableError(_("Invalid message ID"))

    request._log_data["extra"] = "[%s]" % (pointer,)
    update_flags = (request.client.name.lower() in ['android', "zulipandroid"])
    do_update_pointer(user_profile, pointer, update_flags=update_flags)

    return json_success()


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

from zerver.decorator import to_non_negative_int
from zerver.lib.actions import do_update_pointer
from zerver.lib.request import has_request_variables, JsonableError, REQ
from zerver.lib.response import json_success
from zerver.models import UserProfile, UserMessage

def get_pointer_backend(request: HttpRequest, user_profile: UserProfile) -> HttpResponse:
    return json_success({'pointer': user_profile.pointer})

@has_request_variables
def update_pointer_backend(request: HttpRequest, user_profile: UserProfile,
                           pointer: int=REQ(converter=to_non_negative_int)) -> HttpResponse:
    if pointer <= user_profile.pointer:
        return json_success()

    try:
        UserMessage.objects.get(
            user_profile=user_profile,
            message__id=pointer
        )
    except UserMessage.DoesNotExist:
        raise JsonableError(_("Invalid message ID"))

    request._log_data["extra"] = "[%s]" % (pointer,)
    update_flags = (request.client.name.lower() in ['android', "zulipandroid"])
    do_update_pointer(user_profile, pointer, update_flags=update_flags)

    return json_success()

Use Python 3 type syntax in views/pointer.py.