from django.shortcuts import redirect
from django.contrib import messages
from django.db.models import Q
from django.views.generic import TemplateView
from web_project import TemplateLayout
from apps.transactions.forms import TransactionForm
from apps.transactions.models import Transaction
from django.contrib.auth.mixins import PermissionRequiredMixin

class TransactionUpdateView(PermissionRequiredMixin, TemplateView):
    permission_required = ("transactions.update_transaction")

    def get_context_data(self, **kwargs):
        context = TemplateLayout.init(self, super().get_context_data(**kwargs))
        context['transaction_id'] = self.get_transaction(self.kwargs['pk'])
        return context

    def post(self, request, pk):
        transaction = self.get_transaction(pk)
        form = TransactionForm(request.POST, instance=transaction)
        if form.is_valid():
            if not self.transaction_exists(form.cleaned_data, transaction):
                form.save()
                messages.success(request, 'Transaction Updated')
            else:
                messages.error(request, 'Transaction Already Exists')
        else:
            messages.error(request, 'Transaction Failed')
        return redirect('transactions')

    def get_transaction(self, pk):
        return Transaction.objects.get(pk=pk)

    def transaction_exists(self, cleaned_data, current_transaction):
        matching_transactions = Transaction.objects.filter(
            Q(customer__iexact=cleaned_data['customer']) &
            Q(transaction_date=cleaned_data['transaction_date']) &
            Q(due_date=cleaned_data['due_date']) &
            Q(total=cleaned_data['total']) &
            Q(status=cleaned_data['status'])
        ).exclude(pk=current_transaction.pk)
        return matching_transactions.exists()