from django import forms
from django.core.exceptions import ValidationError
from .models import TradeOffer
from friend_codes.models import FriendCode
from cards.models import Card

class TradeOfferUpdateForm(forms.ModelForm):
    class Meta:
        model = TradeOffer
        # We now only edit the `state` field
        fields = ["state"]

    def __init__(self, *args, **kwargs):
        """
        Expects additional keyword arguments:
           - friend_codes: a list of friend code objects for the current user.
        This initializer filters the available state choices based on:
          - The current state's allowed transition.
          - Which party (initiated_by or accepted_by) is acting.
        """
        friend_codes = kwargs.pop("friend_codes")
        super().__init__(*args, **kwargs)

        instance = self.instance
        allowed_state = None

        # Define permitted transitions based on the current state and user role:
        if instance.state == TradeOffer.State.INITIATED:
            # Allow the accepted_by party to accept the trade.
            if instance.accepted_by in friend_codes:
                allowed_state = TradeOffer.State.ACCEPTED
        elif instance.state == TradeOffer.State.ACCEPTED:
            # Allow the initiated_by party to mark the trade as sent.
            if instance.initiated_by in friend_codes:
                allowed_state = TradeOffer.State.SENT
        elif instance.state == TradeOffer.State.SENT:
            # Allow the accepted_by party to mark the trade as received.
            if instance.accepted_by in friend_codes:
                allowed_state = TradeOffer.State.RECEIVED

        if allowed_state:
            # Limit the `state` field's choices to only the permitted transition.
            label = dict(TradeOffer.State.choices)[allowed_state]
            self.fields["state"].choices = [(allowed_state, label)]
        else:
            # If no valid transition is available for this user, remove the field.
            self.fields.pop("state")

    def clean_have_cards(self):
        have_cards = self.cleaned_data.get("have_cards")
        if have_cards:
            for card in have_cards.all():
                if card.rarity not in ALLOWED_RARITIES:
                    # Raising a ValidationError here will cause this error message to be shown beneath the 'have_cards' field.
                    raise ValidationError(
                        f"The card '{card}' has an invalid rarity: {card.rarity}. Allowed rarities are: {', '.join(ALLOWED_RARITIES)}."
                    )
        return have_cards

class TradeOfferAcceptForm(forms.Form):
    friend_code = forms.ModelChoiceField(
        queryset=FriendCode.objects.none(),
        label="Select a Friend Code to Accept This Trade Offer"
    )

    def __init__(self, *args, **kwargs):
        # Expecting a keyword argument `friend_codes` with the user's friend codes.
        friend_codes = kwargs.pop("friend_codes")
        super().__init__(*args, **kwargs)
        self.fields["friend_code"].queryset = friend_codes