from django.contrib import messages
from django.contrib.auth.mixins import LoginRequiredMixin
from django.http import HttpResponseRedirect
from django.template import Template, Context
from django.views.generic import (
    View,
    CreateView,
    UpdateView,
    ListView,
    FormView,
    DeleteView,
    TemplateView
)
from django import forms
from django.utils import timezone
from django.urls import reverse

from psycopg2.extras import DateTimeTZRange

from camps.mixins import CampViewMixin

from ..models import (
    Team,
    TeamMember,
    TeamShift,
)


class ShiftListView(LoginRequiredMixin, CampViewMixin, ListView):
    model = TeamShift
    template_name = "team_shift_list.html"
    context_object_name = "shifts"
    active_menu = "shifts"

    def get_queryset(self):
        queryset = super().get_queryset()
        return queryset.filter(team__slug=self.kwargs['team_slug'])

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context['team'] = Team.objects.get(
            camp=self.camp,
            slug=self.kwargs['team_slug']
        )
        return context


def date_choices(camp):

    index = 0
    minute_choices = []
    # To begin with we assume a shift can not be shorter than an hour
    SHIFT_MINIMUM_LENGTH = 60
    while index * SHIFT_MINIMUM_LENGTH < 60:
        minutes = int(index * SHIFT_MINIMUM_LENGTH)
        minute_choices.append(minutes)
        index += 1

    def get_time_choices(date):
        time_choices = []
        for hour in range(0, 24):
            for minute in minute_choices:
                time_label = "{hour:02d}:{minutes:02d}".format(
                    hour=hour,
                    minutes=minute
                )
                choice_value = "{} {}".format(date, time_label)
                time_choices.append((choice_value, choice_value))
        return time_choices

    choices = []

    current_date = camp.buildup.lower.date()
    while current_date != camp.teardown.upper.date():
        choices.append(
            (
                current_date,
                get_time_choices(current_date.strftime("%Y-%m-%d"))
            )
        )
        current_date += timezone.timedelta(days=1)
    return choices


class ShiftForm(forms.ModelForm):
    class Meta:
        model = TeamShift
        fields = [
            'from_datetime',
            'to_datetime',
            'people_required'
        ]

    def __init__(self, instance=None, **kwargs):
        camp = kwargs.pop('camp')
        super().__init__(instance=instance, **kwargs)
        self.fields['from_datetime'].widget = forms.Select(choices=date_choices(camp))
        self.fields['to_datetime'].widget = forms.Select(choices=date_choices(camp))
        if instance:
            current_tz = timezone.get_current_timezone()
            lower = instance.shift_range.lower.astimezone(current_tz).strftime("%Y-%m-%d %H:%M")
            upper = instance.shift_range.upper.astimezone(current_tz).strftime("%Y-%m-%d %H:%M")
            self.fields['from_datetime'].initial = lower
            self.fields['to_datetime'].initial = upper

    from_datetime = forms.DateTimeField()
    to_datetime = forms.DateTimeField()

    def _get_from_datetime(self):
        current_timezone = timezone.get_current_timezone()
        return (
            self.cleaned_data['from_datetime']
            .astimezone(current_timezone)
        )

    def _get_to_datetime(self):
        current_timezone = timezone.get_current_timezone()
        return (
            self.cleaned_data['to_datetime']
            .astimezone(current_timezone)
        )

    def clean(self):
        self.lower = self._get_from_datetime()
        self.upper = self._get_to_datetime()
        if self.lower > self.upper:
            raise forms.ValidationError('Start can not be after end.')

    def save(self, commit=True):
        # self has .lower and .upper from .clean()
        self.instance.shift_range = DateTimeTZRange(self.lower, self.upper)
        return super().save(commit=commit)


class ShiftCreateView(LoginRequiredMixin, CampViewMixin, CreateView):
    model = TeamShift
    template_name = "team_shift_form.html"
    form_class = ShiftForm
    active_menu = "shifts"

    def get_form_kwargs(self):
        kwargs = super().get_form_kwargs()
        kwargs['camp'] = self.camp
        return kwargs

    def form_valid(self, form):
        shift = form.save(commit=False)
        shift.team = Team.objects.get(
            camp=self.camp,
            slug=self.kwargs['team_slug']
        )
        return super().form_valid(form)

    def get_success_url(self):
        return reverse(
            'teams:shifts',
            kwargs=self.kwargs
        )

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context['team'] = Team.objects.get(
            camp=self.camp,
            slug=self.kwargs['team_slug']
        )
        return context


class ShiftUpdateView(LoginRequiredMixin, CampViewMixin, UpdateView):
    model = TeamShift
    template_name = "team_shift_form.html"
    form_class = ShiftForm
    active_menu = "shifts"

    def get_form_kwargs(self):
        kwargs = super().get_form_kwargs()
        kwargs['camp'] = self.camp
        return kwargs

    def get_success_url(self):
        self.kwargs.pop('pk')
        return reverse(
            'teams:shifts',
            kwargs=self.kwargs
        )

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context['team'] = self.object.team
        return context


class ShiftDeleteView(LoginRequiredMixin, CampViewMixin, DeleteView):
    model = TeamShift
    template_name = "team_shift_confirm_delete.html"
    active_menu = "shifts"

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context['team'] = Team.objects.get(
            camp=self.camp,
            slug=self.kwargs['team_slug']
        )
        return context

    def get_success_url(self):
        self.kwargs.pop('pk')
        return reverse(
            'teams:shifts',
            kwargs=self.kwargs
        )


class MultipleShiftForm(forms.Form):

    def __init__(self, instance=None, **kwargs):
        camp = kwargs.pop('camp')
        super().__init__(**kwargs)
        self.fields['from_datetime'].widget = forms.Select(choices=date_choices(camp))

    from_datetime = forms.DateTimeField()

    number_of_shifts = forms.IntegerField(
        help_text="How many shifts?"
    )

    shift_length = forms.IntegerField(
        help_text="How long should a shift be in minutes?"
    )

    people_required = forms.IntegerField()


class ShiftCreateMultipleView(LoginRequiredMixin, CampViewMixin, FormView):
    template_name = "team_shift_form.html"
    form_class = MultipleShiftForm
    active_menu = "shifts"

    def get_form_kwargs(self):
        kwargs = super().get_form_kwargs()
        kwargs['camp'] = self.camp
        return kwargs

    def form_valid(self, form):
        team = Team.objects.get(
            camp=self.camp,
            slug=self.kwargs['team_slug']
        )
        current_timezone = timezone.get_current_timezone()

        start_datetime = (
            form.cleaned_data['from_datetime']
            .astimezone(current_timezone)
        )
        number_of_shifts = form.cleaned_data['number_of_shifts']
        shift_length = form.cleaned_data['shift_length']
        people_required = form.cleaned_data['people_required']

        shifts = []
        for index in range(number_of_shifts):
            shift_range = DateTimeTZRange(
                start_datetime,
                start_datetime + timezone.timedelta(minutes=shift_length),
            )
            shifts.append(TeamShift(
                team=team,
                people_required=people_required,
                shift_range=shift_range
            ))
            start_datetime += timezone.timedelta(minutes=shift_length)

        TeamShift.objects.bulk_create(shifts)

        return super().form_valid(form)

    def get_success_url(self):
        return reverse(
            'teams:shifts',
            kwargs=self.kwargs
        )

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context['team'] = Team.objects.get(
            camp=self.camp,
            slug=self.kwargs['team_slug']
        )
        return context


class MemberTakesShift(LoginRequiredMixin, CampViewMixin, View):

    http_methods = ['get']

    def get(self, request, **kwargs):
        shift = TeamShift.objects.get(id=kwargs['pk'])
        team = Team.objects.get(
            camp=self.camp,
            slug=kwargs['team_slug']
        )

        team_member = TeamMember.objects.get(team=team, user=request.user)

        overlapping_shifts = TeamShift.objects.filter(
            team__camp=self.camp,
            team_members__user=request.user,
            shift_range__overlap=shift.shift_range
        )

        if overlapping_shifts.exists():
            template = Template("""You have shifts overlapping with the one you are trying to assign:<br/> <ul>
            {% for shift in shifts %}
            <li>{{ shift }}</li>
            {% endfor %}
            </ul>
            """)
            messages.error(
                request,
                template.render(Context({"shifts": overlapping_shifts}))
            )
        else:
            shift.team_members.add(team_member)

        kwargs.pop('pk')

        return HttpResponseRedirect(
            reverse(
                'teams:shifts',
                kwargs=kwargs
            )
        )


class MemberDropsShift(LoginRequiredMixin, CampViewMixin, View):

    http_methods = ['get']

    def get(self, request, **kwargs):
        shift = TeamShift.objects.get(id=kwargs['pk'])
        team = Team.objects.get(
            camp=self.camp,
            slug=kwargs['team_slug']
        )

        team_member = TeamMember.objects.get(team=team, user=request.user)

        shift.team_members.remove(team_member)

        kwargs.pop('pk')

        return HttpResponseRedirect(
            reverse(
                'teams:shifts',
                kwargs=kwargs
            )
        )


class UserShifts(CampViewMixin, TemplateView):
    template_name = 'team_user_shifts.html'

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context['user_teams'] = self.request.user.teammember_set.filter(team__camp=self.camp)
        context['user_shifts'] = TeamShift.objects.filter(
            team__camp=self.camp,
            team_members__user=self.request.user
        )
        return context