# Copyright (C) 2015-2019 The Software Heritage developers
# See the AUTHORS file at the top-level directory of this distribution
# License: GNU General Public License version 3, or any later version
# See top-level LICENSE file for more information

from datetime import datetime

from celery import current_app
import celery.app.task
from celery.utils.log import get_task_logger

from swh.core.statsd import Statsd


def ts():
    return int(datetime.utcnow().timestamp())


class SWHTask(celery.app.task.Task):
    """a schedulable task (abstract class)

    Current implementation is based on Celery. See
    http://docs.celeryproject.org/en/latest/reference/celery.app.task.html for
    how to use tasks once instantiated

    """

    _statsd = None
    _log = None

    reject_on_worker_lost = None
    """Inherited from :class:`celery.app.task.Task`, but we need to override
    its docstring because it uses a custom ReST role"""

    @property
    def statsd(self):
        if self._statsd:
            return self._statsd
        worker_name = current_app.conf.get("worker_name")
        if worker_name:
            self._statsd = Statsd(
                constant_tags={"task": self.name, "worker": worker_name,}
            )
            return self._statsd
        else:
            statsd = Statsd(
                constant_tags={"task": self.name, "worker": "unknown worker",}
            )
            return statsd

    def __call__(self, *args, **kwargs):
        self.statsd.increment("swh_task_called_count")
        self.statsd.gauge("swh_task_start_ts", ts())
        with self.statsd.timed("swh_task_duration_seconds"):
            result = super().__call__(*args, **kwargs)
            try:
                status = result["status"]
                if status == "success":
                    status = "eventful" if result.get("eventful") else "uneventful"
            except Exception:
                status = "eventful" if result else "uneventful"

            self.statsd.gauge("swh_task_end_ts", ts(), tags={"status": status})
            return result

    def on_failure(self, exc, task_id, args, kwargs, einfo):
        self.statsd.increment("swh_task_failure_count")

    def on_success(self, retval, task_id, args, kwargs):
        self.statsd.increment("swh_task_success_count")
        # this is a swh specific event. Used to attach the retval to the
        # task_run
        self.send_event("task-result", result=retval)

    @property
    def log(self):
        if self._log is None:
            self._log = get_task_logger(self.name)
        return self._log

    def run(self, *args, **kwargs):
        self.log.debug("%s: args=%s, kwargs=%s", self.name, args, kwargs)
        ret = super().run(*args, **kwargs)
        self.log.debug("%s: OK => %s", self.name, ret)
        return ret