#    Copyright (C) 2018  Alban Gruin
#
#    celcatsanitizer is free software: you can redistribute it and/or modify
#    it under the terms of the GNU Affero General Public License as published
#    by the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    celcatsanitizer is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU Affero General Public License for more details.
#
#    You should have received a copy of the GNU Affero General Public License
#    along with celcatsanitizer.  If not, see <http://www.gnu.org/licenses/>.

from datetime import datetime, timedelta

import asyncio
import calendar
import json

from django.utils import timezone

import lxml.html
import requests

from ...models import Course, Group, Room
from ...utils import get_current_week, get_week
from .abstractparser import AbstractParser

VARNAME = "v.events.list = "


def find_events_list(soup):
    res = []
    for script in soup.xpath("//script/text()"):
        if VARNAME in script:
            for var in script.split('\n'):
                if var.startswith(VARNAME):
                    res = json.loads(var[len(VARNAME):-2])

    return res


def get_next_month(dt):
    n = dt.replace(day=1) + timedelta(days=32)
    return n.replace(day=1)


class Parser(AbstractParser):
    def __init__(self, source):
        super(Parser, self).__init__(source)

        # En-tête tiré de mon Firefox…
        base_req = self._make_request(
            source.url, headers={"Accept-Language": "en-US,en;q=0.5"}
        )

        parser = lxml.html.HTMLParser(encoding="utf-8")
        self.soup = lxml.html.document_fromstring(
            base_req.content, parser=parser
        )

        self.months = []
        for option in self.soup.xpath("//option"):
            if option.get("selected") is not None or len(self.months) > 0:
                self.months.append(option.text)

    def __get_event(self, event, today,
                    beginning_of_month, end_of_month,
                    year, week):
        begin = timezone.make_aware(
            datetime.strptime(event["start"], "%Y-%m-%dT%H:%M:%S")
        )
        end = timezone.make_aware(
            datetime.strptime(event["end"], "%Y-%m-%dT%H:%M:%S")
        )

        if begin < beginning_of_month or begin >= end_of_month or \
           (today is not None and begin < today):
            return

        if year is not None and week is not None:
            event_year, event_week, _ = begin.isocalendar()
            if event_year != year or event_week != week:
                return

        course = Course.objects.create(
            source=self.source, begin=begin, end=end
        )

        data = event["text"].split("<br>")
        rooms = None
        if data[0] == "Global Event":
            return

        i = 0
        while i < len(data) and not data[i].startswith(
                ("L1 ", "L2 ", "L3 ", "L3P ", "M1 ", "M2 ", "DEUST ", "MAG1 ",
                 "1ERE ANNEE ", "2EME ANNEE ", "3EME ANNEE ",
                 "MAT-Agreg Interne ")
        ):
            i += 1

        groups = data[i]
        if i - 1 >= 0:
            course.name = ", ".join(set(data[i - 1].split(';')))
        else:
            course.name = "Sans nom"
        if i - 2 >= 0:
            course.type = data[i - 2]
        if len(data) >= i + 2:
            rooms = data[i + 1]
        if len(data) >= i + 3:
            course.notes = data[i + 2]

        groups = [
            Group.objects.get_or_create(
                source=self.source, celcat_name=name
            )[0]
            for name in groups.split(';')
        ]
        course.groups.add(*groups)

        if rooms is not None:
            rooms_objs = Room.objects.filter(name__in=rooms.split(';'))
            if rooms_objs.count() > 0:
                course.rooms.add(*rooms_objs)
            elif course.notes:
                course.notes = "{0}\n{1}".format(rooms, course.notes)
            else:
                course.notes = rooms

        if course.notes is not None:
            course.notes = course.notes.strip()

        return course

    def get_events(self, today, year=None, week=None):
        for i, month in enumerate(self.events):
            beginning_of_month = timezone.make_aware(
                datetime.strptime(self.months[i], "%B, %Y")
            )
            end_of_month = get_next_month(beginning_of_month)

            for event in month:
                course = self.__get_event(event, today,
                                          beginning_of_month, end_of_month,
                                          year, week)
                if course is not None:
                    yield course

    def get_update_date(self):
        return None  # Pas de date de mise à jour dans ce format

    def get_weeks(self):
        # FIXME: détection automatique à partir des événements présents
        beginning, _ = get_week(*get_current_week())
        self.weeks = {"1": beginning}

        return self.weeks

    def ajax_req(self, month):
        month = datetime.strptime(month, "%B, %Y")
        first_monday = min(
            week[calendar.MONDAY]
            for week in calendar.monthcalendar(month.year, month.month)
            if week[calendar.MONDAY] > 0
        )
        month_str = month.replace(day=first_monday).strftime("%Y%m%d")

        req = self._make_request(
            self.source.url,
            headers={
                "Accept-Language": "en-US,en;q=0.5",
            },
            params={"Date": month_str},
        )
        req.raise_for_status()

        parser = lxml.html.HTMLParser(encoding="utf8")
        soup = lxml.html.document_fromstring(req.content, parser=parser)

        return find_events_list(soup)

    @asyncio.coroutine
    def get_months_async(self):
        loop = asyncio.get_event_loop()
        futures = []

        for month in self.months[1:]:
            futures.append(loop.run_in_executor(None, self.ajax_req, month))

        responses = yield from asyncio.gather(*futures)
        return responses

    def get_source_from_months(self, async=True):
        events = []

        if async:
            loop = asyncio.get_event_loop()
            events = loop.run_until_complete(self.get_months_async())
        else:
            for month in self.months[1:]:
                events.append(self.ajax_req(month))

        return events

    def get_source(self):
        self.events = [
            find_events_list(self.soup)
        ] + self.get_source_from_months()
        return self.events