import json
import random

from django.http import HttpResponse
from django.shortcuts import render

MAX = 12


def _generate_problem():
    operation = random.choice(['+', '-'])
    first = random.choice(range(MAX))
    if operation == '-':
        if first == 0:
            second = 0
        else:
            second = random.choice(range(first))
    else:
            second = random.choice(range(MAX))
    return {
        'first': first,
        'operation': operation,
        'second': second,
    }


def _validate_solution(a):
    f = int(a['first'])
    o = a['operation']
    s = int(a['second'])
    if a['answer'] == '':
        g = 0
    else:
        g = int(a['answer'])
    r = False
    if o == '+':
        r = bool(f + s == g)
    else:
        r = bool(f - s == g)
    return r


def home(request):
    return render(request, 'index.html')


def attempt(request):
    d = request.POST.dict()
    r = _validate_solution(d)
    if r:
        s = request.session.get('score', 0) + 1
    else:
        s = request.session.get('score', 0) - 1
    request.session['score'] = s
    return HttpResponse(
        json.dumps({'status': r, 'score': s}),
        content_type="application/json")


def problem(request):
    d = _generate_problem()
    d['score'] = request.session.get('score', 0)
    return HttpResponse(json.dumps(d), content_type="application/json")