"""Manage diffusions using schedules, to update, clean up or check diffusions.

A generated diffusion can be unconfirmed, that means that the user must confirm
it by changing its type to "normal". The behaviour is controlled using
--approval.
"""
import datetime
import logging
from argparse import RawTextHelpFormatter

from django.core.management.base import BaseCommand
from django.db import transaction
from django.utils import timezone as tz

from aircox.models import Diffusion, Schedule

logger = logging.getLogger("aircox.commands")


class Actions:
    date = None

    def __init__(self, date):
        self.date = date or datetime.date.today()

    def update(self):
        episodes, diffusions = [], []
        for schedule in Schedule.objects.filter(
            program__active=True, initial__isnull=True
        ):
            eps, diffs = schedule.diffusions_of_month(self.date)
            if eps:
                episodes += eps
            if diffs:
                diffusions += diffs

            logger.info(
                "[update] %s: %d episodes, %d diffusions and reruns",
                str(schedule),
                len(eps),
                len(diffs),
            )

        with transaction.atomic():
            logger.info(
                "[update] save %d episodes and %d diffusions",
                len(episodes),
                len(diffusions),
            )
            for episode in episodes:
                episode.save()
            for diffusion in diffusions:
                # force episode id's update
                diffusion.episode = diffusion.episode
                diffusion.save()

    def clean(self):
        qs = Diffusion.objects.filter(
            type=Diffusion.TYPE_UNCONFIRMED, start__lt=self.date
        )
        logger.info("[clean] %d diffusions will be removed", qs.count())
        qs.delete()


class Command(BaseCommand):
    help = __doc__

    def add_arguments(self, parser):
        parser.formatter_class = RawTextHelpFormatter
        today = datetime.date.today()

        group = parser.add_argument_group("action")
        group.add_argument(
            "-u",
            "--update",
            action="store_true",
            help="generate (unconfirmed) diffusions for the given month. "
            "These diffusions must be confirmed manually by changing "
            'their type to "normal"',
        )
        group.add_argument(
            "-l",
            "--clean",
            action="store_true",
            help="remove unconfirmed diffusions older than the given month",
        )

        group = parser.add_argument_group("date")
        group.add_argument(
            "--year",
            type=int,
            default=today.year,
            help="used by update, default is today's year",
        )
        group.add_argument(
            "--month",
            type=int,
            default=today.month,
            help="used by update, default is today's month",
        )
        group.add_argument(
            "--next-month",
            action="store_true",
            help="set the date to the next month of given date"
            " (if next month from today",
        )

    def handle(self, *args, **options):
        date = datetime.date(
            year=options["year"], month=options["month"], day=1
        )
        if options.get("next_month"):
            month = options.get("month")
            date += tz.timedelta(days=28)
            if date.month == month:
                date += tz.timedelta(days=28)
            date = date.replace(day=1)

        actions = Actions(date)
        if options.get("update"):
            actions.update()
        if options.get("clean"):
            actions.clean()
        if options.get("check"):
            actions.check()