from django.contrib import messages
from django.contrib.auth.mixins import LoginRequiredMixin
from django.urls import reverse_lazy
from django.shortcuts import redirect, get_object_or_404
from django.views.generic import ListView, CreateView, DeleteView, View
from accounts.models import FriendCode
from accounts.forms import FriendCodeForm

class ListFriendCodesView(LoginRequiredMixin, ListView):
    """
    Display the current user's friend codes.
    """
    model = FriendCode
    template_name = "friend_codes/list_friend_codes.html"
    context_object_name = "friend_codes"

    def get_queryset(self):
        return self.request.user.friend_codes.all()

class AddFriendCodeView(LoginRequiredMixin, CreateView):
    """
    Add a new friend code for the current user. If the user does not yet have a default,
    the newly added code will automatically become the default.
    """
    model = FriendCode
    form_class = FriendCodeForm
    template_name = "friend_codes/add_friend_code.html"
    success_url = reverse_lazy("list_friend_codes")

    def form_valid(self, form):
        form.instance.user = self.request.user
        messages.success(self.request, "Friend code added successfully.")
        return super().form_valid(form)

class DeleteFriendCodeView(LoginRequiredMixin, DeleteView):
    """
    Remove an existing friend code.
    Prevent deletion if the friend code is bound to any trade offers.
    Also, prevent deletion if the friend code is either the only one or
    is set as the default friend code.
    """
    model = FriendCode
    template_name = "friend_codes/confirm_delete_friend_code.html"
    context_object_name = "friend_code"
    success_url = reverse_lazy("list_friend_codes")

    def get_queryset(self):
        # Only allow deletion of friend codes owned by the current user.
        return FriendCode.objects.filter(user=self.request.user)

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        friend_code = self.get_object()
        user = self.request.user

        # Determine if the deletion should be disabled.
        disable_delete = False
        error_message = None

        if user.friend_codes.count() == 1:
            disable_delete = True
            error_message = "Cannot delete your only friend code."
        elif user.default_friend_code == friend_code:
            disable_delete = True
            error_message = (
                "Cannot delete your default friend code. "
                "Please set a different default first."
            )

        context["disable_delete"] = disable_delete
        context["error_message"] = error_message
        return context

    def post(self, request, *args, **kwargs):
        self.object = self.get_object()
        user = self.object.user

        # Check if the friend code is the only one; prevent deletion.
        if user.friend_codes.count() == 1:
            messages.error(request, "Cannot remove your only friend code.")
            return redirect(self.success_url)

        # Check if the friend code is set as default; prevent deletion.
        if user.default_friend_code == self.object:
            messages.error(
                request,
                "Cannot delete your default friend code. Please set a different default first."
            )
            return redirect(self.success_url)

        # Also check if this friend code is referenced by any trade offer.
        if self.object.initiated_by.exists() or self.object.accepted_by.exists():
            messages.error(
                request,
                "Cannot remove this friend code because there are existing trade offers associated with it."
            )
            return redirect(self.success_url)
        
        # Proceed to safe deletion.
        self.object.delete()
        messages.success(request, "Friend code removed successfully.")
        return redirect(self.success_url + "?deleted=true")

class ChangeDefaultFriendCodeView(LoginRequiredMixin, View):
    """
    Change the default friend code for the current user.
    """
    def post(self, request, *args, **kwargs):
        friend_code_id = kwargs.get("pk")
        friend_code = get_object_or_404(FriendCode, pk=friend_code_id, user=request.user)
        request.user.set_default_friend_code(friend_code)
        messages.success(request, "Default friend code updated successfully.")
        return redirect("list_friend_codes")