picture-tournament/pt/views.py

import logging
import random

from django.urls              import reverse
from django.db.models         import Max
from django.http              import HttpResponse, HttpResponseRedirect
from django.shortcuts         import render

from . import models

log = logging.getLogger('picture_tournament')

# Create your views here.
def compare(request):
    if "left" not in request.session:
        left_pic = random_pic()
        request.session["left"] = left_pic.id
    if "right" not in request.session:
        right_pic = random_pic()
        request.session["right"] = right_pic.id
    left_pic = models.Picture.objects.get(id=request.session["left"])
    right_pic = models.Picture.objects.get(id=request.session["right"])
    context = {
        "left": left_pic,
        "right": right_pic,
    }
    return HttpResponse(render(request, 'pt/compare.html', context))

def random_pic():
    max_id = models.Picture.objects.all().aggregate(Max('id'))["id__max"]
    log.debug("max_id = %s", max_id)
    while True:
        id = random.randint(1, max_id)
        pics = models.Picture.objects.filter(id=id)
        if len(pics) == 1:
            return pics[0]


def left_wins(request):
    left = models.Picture.objects.get(id=request.session["left"])
    right = models.Picture.objects.get(id=request.session["right"])

    expected = 1 / (1 + 10**((right.elo - left.elo) / 400))
    log.info("before: left=%f, right=%f, expected=%f", left.elo, right.elo, expected)
    adjust = (1 - expected) * 20
    left.elo += adjust
    left.save()
    right.elo -= adjust
    right.save()
    log.info("after: left=%f, right=%f", left.elo, right.elo)
    del request.session["right"]

    return HttpResponseRedirect(reverse('compare'))


def right_wins(request):
    left = models.Picture.objects.get(id=request.session["left"])
    right = models.Picture.objects.get(id=request.session["right"])

    expected = 1 / (1 + 10**((left.elo - right.elo) / 400))
    log.info("before: left=%f, right=%f, expected=%f", left.elo, right.elo, expected)
    adjust = (1 - expected) * 20
    left.elo -= adjust
    left.save()
    right.elo += adjust
    right.save()
    log.info("after: left=%f, right=%f", left.elo, right.elo)
    del request.session["left"]

    return HttpResponseRedirect(reverse('compare'))


def refresh(request):
    del request.session["left"]
    del request.session["right"]

    return HttpResponseRedirect(reverse('compare'))


def top(request):
    top = models.Picture.objects.all().order_by("-elo")[0:10]
    context = { "top": top }
    return HttpResponse(render(request, 'pt/top.html', context))