from django.db.models import Q
from django.shortcuts import get_object_or_404
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 .board_services import (
    board_payload,
    create_board,
    join_board,
    submit_guess,
)
from .engine import calculate
from .models import BoardSession


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)


class BoardCreateView(APIView):
    def post(self, request):
        session = create_board(
            request.user,
            request.data.get("mode", BoardSession.Mode.COLLABORATE),
        )
        return Response(board_payload(session, request.user), status=201)


class BoardJoinView(APIView):
    def post(self, request):
        session = join_board(request.user, request.data.get("code"))
        return Response(board_payload(session, request.user))


class BoardStateView(APIView):
    def get(self, request, session_id):
        session = get_object_or_404(
            BoardSession.objects.select_related("host", "guest").filter(
                Q(host=request.user) | Q(guest=request.user)
            ),
            id=session_id,
        )
        return Response(board_payload(session, request.user))


class BoardGuessView(APIView):
    def post(self, request, session_id):
        session, correct = submit_guess(
            request.user,
            session_id,
            request.data.get("guess"),
        )
        payload = board_payload(session, request.user)
        payload["correct"] = correct
        payload["message"] = "猜对了，得 1 分" if correct else "还不对，再观察一下画板"
        return Response(payload)