from datetime import timedelta

from django.conf import settings
from django.db import transaction
from django.http import HttpRequest, HttpResponse
from django.utils.timezone import now as timezone_now
from django.utils.translation import gettext as _

from analytics.models import RealmCount
from zerver.actions.realm_export import do_delete_realm_export, notify_realm_export
from zerver.decorator import require_realm_admin
from zerver.lib.exceptions import JsonableError
from zerver.lib.export import get_realm_exports_serialized
from zerver.lib.queue import queue_json_publish
from zerver.lib.response import json_success
from zerver.models import RealmAuditLog, UserProfile


@transaction.atomic(durable=True)
@require_realm_admin
def export_realm(request: HttpRequest, user: UserProfile) -> HttpResponse:
    # Currently only supports public-data-only exports.
    event_type = RealmAuditLog.REALM_EXPORTED
    event_time = timezone_now()
    realm = user.realm
    EXPORT_LIMIT = 5

    # Exporting organizations with a huge amount of history can
    # potentially consume a lot of disk or otherwise have accidental
    # DoS risk; for that reason, we require large exports to be done
    # manually on the command line.
    #
    # It's very possible that higher limits would be completely safe.
    MAX_MESSAGE_HISTORY = 250000
    MAX_UPLOAD_QUOTA = 10 * 1024 * 1024 * 1024

    # Filter based upon the number of events that have occurred in the delta
    # If we are at the limit, the incoming request is rejected
    event_time_delta = event_time - timedelta(days=7)
    limit_check = RealmAuditLog.objects.filter(
        realm=realm, event_type=event_type, event_time__gte=event_time_delta
    )
    if len(limit_check) >= EXPORT_LIMIT:
        raise JsonableError(_("Exceeded rate limit."))

    # The RealmCount analytics table lets us efficiently get an
    # estimate for the number of public stream messages in an
    # organization. It won't match the actual number of messages in
    # the export, because this measures the number of messages that
    # went to a public stream at the time they were sent. Thus,
    # messages that were deleted or moved between streams will be
    # treated differently for this check vs. in the export code.
    exportable_messages_estimate = sum(
        realm_count.value
        for realm_count in RealmCount.objects.filter(
            realm=realm, property="messages_sent:message_type:day", subgroup="public_stream"
        )
    )

    if (
        exportable_messages_estimate > MAX_MESSAGE_HISTORY
        or user.realm.currently_used_upload_space_bytes() > MAX_UPLOAD_QUOTA
    ):
        raise JsonableError(
            _("Please request a manual export from {email}.").format(
                email=settings.ZULIP_ADMINISTRATOR,
            )
        )

    row = RealmAuditLog.objects.create(
        realm=realm, event_type=event_type, event_time=event_time, acting_user=user
    )

    # Allow for UI updates on a pending export
    notify_realm_export(user)

    # Using the deferred_work queue processor to avoid
    # killing the process after 60s
    event = {
        "type": "realm_export",
        "time": event_time,
        "realm_id": realm.id,
        "user_profile_id": user.id,
        "id": row.id,
    }
    transaction.on_commit(lambda: queue_json_publish("deferred_work", event))
    return json_success(request, data={"id": row.id})


@require_realm_admin
def get_realm_exports(request: HttpRequest, user: UserProfile) -> HttpResponse:
    realm_exports = get_realm_exports_serialized(user)
    return json_success(request, data={"exports": realm_exports})


@require_realm_admin
def delete_realm_export(request: HttpRequest, user: UserProfile, export_id: int) -> HttpResponse:
    try:
        audit_log_entry = RealmAuditLog.objects.get(
            id=export_id, realm=user.realm, event_type=RealmAuditLog.REALM_EXPORTED
        )
    except RealmAuditLog.DoesNotExist:
        raise JsonableError(_("Invalid data export ID"))

    export_data = audit_log_entry.extra_data
    if export_data.get("deleted_timestamp") is not None:
        raise JsonableError(_("Export already deleted"))
    if export_data.get("export_path") is None:
        if export_data.get("failed_timestamp") is not None:
            raise JsonableError(_("Export failed, nothing to delete"))
        raise JsonableError(_("Export still in progress"))
    do_delete_realm_export(user, audit_log_entry)
    return json_success(request)