from rest_framework import permissions
from rest_framework.exceptions import ValidationError
from rest_framework.response import Response
from rest_framework.throttling import ScopedRateThrottle
from rest_framework.views import APIView

from .engine import calculate


class CalculatorView(APIView):
    permission_classes = [permissions.AllowAny]
    throttle_classes = [ScopedRateThrottle]
    throttle_scope = "calculator"

    def post(self, request):
        try:
            payload = calculate(request.data)
        except ValidationError:
            raise
        except (ArithmeticError, NotImplementedError, TypeError, ValueError) as exc:
            raise ValidationError({"expression": "该计算暂时无法完成，请缩小表达式范围"}) from exc
        return Response(payload)