from base64 import urlsafe_b64decode

from django import forms
from django.contrib import messages
from django.contrib.auth.decorators import login_required
from django.db.models import Count, Q
from django.http import HttpResponse
from django.shortcuts import get_object_or_404, redirect, render
from django.urls import reverse

from shiftregister.fallback.models import FallbackAssignment, TeamMember


class TradeForm(forms.Form):
    assignment_id = forms.IntegerField(
        widget=forms.NumberInput(attrs={"class": "input", "placeholder": "Schicht-ID"})
    )
    pin = forms.IntegerField(
        widget=forms.PasswordInput(attrs={"class": "input", "placeholder": "Deine PIN"})
    )


def my_fallback_shifts(request, team_member_id):
    try:
        team_member_id = int.from_bytes(
            urlsafe_b64decode(team_member_id), byteorder="big"
        )
    except Exception:
        team_member_id = None

    team_member = get_object_or_404(TeamMember, pk=team_member_id)

    is_draw = False
    trade_form = TradeForm(
        request.POST
        if request.method == "POST" and "take_shift" in request.POST
        else None
    )

    if request.method == "POST":
        if "draw_shifts" in request.POST:
            team_member.assign_random_shifts()
            is_draw = True
        elif "take_shift" in request.POST and trade_form.is_valid():
            assignment_id = trade_form.cleaned_data["assignment_id"]
            pin = trade_form.cleaned_data["pin"]

            if pin != team_member.pin:
                messages.error(request, "Ungültige PIN")
            else:
                try:
                    assignment = FallbackAssignment.objects.get(pk=assignment_id)
                    if assignment.team_member == team_member:
                        assignment.traded_to = None
                        messages.success(request, f"Schicht erfolgreich zurückgenommen")
                    elif assignment.traded_to == team_member:
                        assignment.traded_to = None
                        messages.success(request, f"Schicht erfolgreich zurückgegeben")
                    else:
                        assignment.traded_to = team_member
                        messages.success(request, f"Schicht erfolgreich übernommen")
                    assignment.save()
                    return redirect(
                        reverse(
                            "my_fallback_shifts",
                            kwargs={"team_member_id": team_member.url_id()},
                        )
                    )
                except FallbackAssignment.DoesNotExist:
                    messages.error(request, "Ungültige Schicht-ID")

    assignments = (
        FallbackAssignment.objects.filter(
            Q(team_member=team_member, traded_to__isnull=True)
            | Q(traded_to=team_member)
        )
        .prefetch_related("shift", "traded_to", "team_member")
        .order_by("shift__start_at")
    )

    context = {
        "team_member": team_member,
        "assignments": assignments,
        "is_draw": is_draw,
        "trade_form": trade_form,
    }
    return render(request, "my_fallback_shifts.html", context)


@login_required
def team_members(request):
    response = HttpResponse(
        "".join(
            f"{member.name} {member.url()}\n"
            for member in TeamMember.objects.annotate(
                shift_count=Count("fallback_shifts")
            )
            .filter(fallback_shifts__gt=0)
            .order_by("name", "id")
        )
    )
    response.headers["Content-Type"] = "text/plain; charset=utf-8"

    return response