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# 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
#
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import logging
from datetime import datetime, timedelta
from typing import Iterator

import croniter

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
                )
                execute.apply_async((active_schedule.id, schedule,), eta=schedule)


@celery_app.task(name="reports.execute")
def execute(report_schedule_id: int, scheduled_dttm: datetime) -> None:
    try:
        AsyncExecuteReportScheduleCommand(report_schedule_id, scheduled_dttm).run()
    except ReportScheduleUnexpectedError as ex:
        logger.error("An unexpected occurred while executing the report: %s", ex)
    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 CommandException as ex:
        logger.error("An exception occurred while pruning report schedule logs: %s", ex)