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# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
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import logging
from datetime import datetime, timedelta
from typing import Iterator

import croniter
from celery.exceptions import SoftTimeLimitExceeded
from dateutil import parser

from superset import app
from superset.commands.exceptions import CommandException
from superset.extensions import celery_app
from superset.reports.commands.exceptions import ReportScheduleUnexpectedError
from superset.reports.commands.execute import AsyncExecuteReportScheduleCommand
from superset.reports.commands.log_prune import AsyncPruneReportScheduleLogCommand
from superset.reports.dao import ReportScheduleDAO
from superset.utils.celery import session_scope

logger = logging.getLogger(__name__)


def cron_schedule_window(cron: str) -> Iterator[datetime]:
    window_size = app.config["ALERT_REPORTS_CRON_WINDOW_SIZE"]
    utc_now = datetime.utcnow()
    start_at = utc_now - timedelta(seconds=1)
    stop_at = utc_now + timedelta(seconds=window_size)
    crons = croniter.croniter(cron, start_at)
    for schedule in crons.all_next(datetime):
        if schedule >= stop_at:
            break
        yield schedule


@celery_app.task(name="reports.scheduler")
def scheduler() -> None:
    """
    Celery beat main scheduler for reports
    """
    with session_scope(nullpool=True) as session:
        active_schedules = ReportScheduleDAO.find_active(session)
        for active_schedule in active_schedules:
            for schedule in cron_schedule_window(active_schedule.crontab):
                logger.info(
                    "Scheduling alert %s eta: %s", active_schedule.name, schedule
                )
                async_options = {"eta": schedule}
                if (
                    active_schedule.working_timeout is not None
                    and app.config["ALERT_REPORTS_WORKING_TIME_OUT_KILL"]
                ):
                    async_options["time_limit"] = (
                        active_schedule.working_timeout
                        + app.config["ALERT_REPORTS_WORKING_TIME_OUT_LAG"]
                    )
                    async_options["soft_time_limit"] = (
                        active_schedule.working_timeout
                        + app.config["ALERT_REPORTS_WORKING_SOFT_TIME_OUT_LAG"]
                    )
                execute.apply_async((active_schedule.id, schedule,), **async_options)


@celery_app.task(name="reports.execute")
def execute(report_schedule_id: int, scheduled_dttm: str) -> None:
    try:
        task_id = execute.request.id
        scheduled_dttm_ = parser.parse(scheduled_dttm)
        AsyncExecuteReportScheduleCommand(
            task_id, report_schedule_id, scheduled_dttm_,
        ).run()
    except ReportScheduleUnexpectedError as ex:
        logger.error(
            "An unexpected occurred while executing the report: %s", ex, exc_info=True
        )
    except CommandException as ex:
        logger.info("Report state: %s", ex)


@celery_app.task(name="reports.prune_log")
def prune_log() -> None:
    try:
        AsyncPruneReportScheduleLogCommand().run()
    except SoftTimeLimitExceeded as ex:
        logger.warning("A timeout occurred while pruning report schedule logs: %s", ex)
    except CommandException as ex:
        logger.error(
            "An exception occurred while pruning report schedule logs: %s",
            ex,
            exc_info=True,
        )