import secrets
from typing import Any

from django import forms
from django.core.exceptions import ValidationError
from django.utils.translation import gettext_lazy as _

from core.models import User
from core.views.forms import SelectDate, SelectDateTime
from core.views.widgets.select import AutoCompleteSelectUser
from subscription.models import Subscription


class SelectionDateForm(forms.Form):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.fields["start_date"] = forms.DateTimeField(
            label=_("Start date"), widget=SelectDateTime, required=True
        )
        self.fields["end_date"] = forms.DateTimeField(
            label=_("End date"), widget=SelectDateTime, required=True
        )


class SubscriptionForm(forms.ModelForm):
    def save(self, *args, **kwargs):
        if self.errors:
            # let django deal with the error messages
            return super().save(*args, **kwargs)

        duration, user = self.instance.semester_duration, self.instance.member
        self.instance.subscription_start = self.instance.compute_start(
            duration=duration, user=user
        )
        self.instance.subscription_end = self.instance.compute_end(
            duration=duration, start=self.instance.subscription_start, user=user
        )
        return super().save(*args, **kwargs)


class SubscriptionNewUserForm(SubscriptionForm):
    """Form to create subscriptions with the user they belong to.

    Examples:
        ```py
        assert not User.objects.filter(email=request.POST.get("email")).exists()
        form = SubscriptionNewUserForm(request.POST)
        if form.is_valid():
            form.save()

        # now the user exists and is subscribed
        user = User.objects.get(email=request.POST.get("email"))
        assert user.is_subscribed
    """

    __user_fields = forms.fields_for_model(
        User,
        ["first_name", "last_name", "email", "date_of_birth"],
        widgets={"date_of_birth": SelectDate},
    )
    first_name = __user_fields["first_name"]
    last_name = __user_fields["last_name"]
    email = __user_fields["email"]
    date_of_birth = __user_fields["date_of_birth"]

    class Meta:
        model = Subscription
        fields = ["subscription_type", "payment_method", "location"]

    field_order = [
        "first_name",
        "last_name",
        "email",
        "date_of_birth",
        "subscription_type",
        "payment_method",
        "location",
    ]

    def clean_email(self):
        email = self.cleaned_data["email"]
        if User.objects.filter(email=email).exists():
            raise ValidationError(_("A user with that email address already exists"))
        return email

    def clean(self) -> dict[str, Any]:
        member = User(
            first_name=self.cleaned_data.get("first_name"),
            last_name=self.cleaned_data.get("last_name"),
            email=self.cleaned_data.get("email"),
            date_of_birth=self.cleaned_data.get("date_of_birth"),
        )
        member.generate_username()
        member.set_password(secrets.token_urlsafe(nbytes=10))
        self.instance.member = member
        return super().clean()

    def save(self, *args, **kwargs):
        if self.errors:
            # let django deal with the error messages
            return super().save(*args, **kwargs)
        self.instance.member.save()
        return super().save(*args, **kwargs)


class SubscriptionExistingUserForm(SubscriptionForm):
    """Form to add a subscription to an existing user."""

    class Meta:
        model = Subscription
        fields = ["member", "subscription_type", "payment_method", "location"]
        widgets = {"member": AutoCompleteSelectUser}