"""Karma logging models."""

import logging
import math
import pytz
import random

from django.conf import settings
from django.db import models


log = logging.getLogger('pi.models')


class PiLogManager(models.Manager):

    """Assemble some queries against PiLog."""

    def simulate(self):
        """Add one more entry to the log, and return it."""

        try:
            latest = self.latest()
        except PiLog.DoesNotExist:
            latest = PiLog(count_inside=0, count_total=0)
            latest.save()

        inside = latest.count_inside
        total = latest.count_total

        x = random.random()
        y = random.random()
        hit = True if math.hypot(x,y) < 1 else False

        if hit:
            newest = PiLog(count_inside=inside+1, count_total=total+1)
        else:
            newest = PiLog(count_inside=inside, count_total=total+1)
        newest.save()

        return newest, x, y, hit


class PiLog(models.Model):

    """Track pi as it is estimated over time."""

    count_inside = models.PositiveIntegerField()
    count_total = models.PositiveIntegerField()
    created = models.DateTimeField(auto_now_add=True)

    objects = PiLogManager()

    class Meta:
        get_latest_by = 'created'

    def __unicode__(self):
        """String representation."""

        tz = pytz.timezone(settings.TIME_ZONE)
        return "({0:d}/{1:d}) @ {2:s}".format(self.count_inside, self.count_total,
                                              self.created.astimezone(tz).strftime('%Y-%m-%d %H:%M:%S %Z'))

    def value(self):
        """Return this log entry's value of pi."""

        return 4.0 * int(self.count_inside) / int(self.count_total)