from django.db import models
from django.utils import timezone
import math

from config.extras import DateUUIDField
from config.extras import BREWFATHER_APP_ROOT

import logging
logger = logging.getLogger('django')


def average(lst):
    return sum(lst) / len(lst)


class AvailableYeastManager(models.Manager):
    """ Special manager for filtering out pitched yeast."""

    def get_queryset(self):
        return super(AvailableYeastManager, self)\
            .get_queryset().filter(pitched=False)


class CustomModel(models.Model):
    """ Custom model class with default fields to use. """
    created_date = models.DateTimeField(default=timezone.now)

    class Meta:
        abstract = True


class Manufacturer(CustomModel):
    """ Store manufacturer data for various yeast strains."""
    name = models.CharField(max_length=100)
    website = models.URLField(max_length=200, blank=True, null=True)

    def __str__(self):
        # Return a string that represents the instance
        return self.name


class Strain(CustomModel):
    """
    Store individual yeast strain data. :model:`yeast.Manufacturer`.
    """
    name = models.CharField(max_length=100)
    long_name = models.CharField(max_length=100, blank=True)
    manufacturer = models.ForeignKey(Manufacturer, on_delete=models.PROTECT)

    @property
    def batches_available(self):
        return [x for x in Propogation.objects.all()
                if not x.consumed and x.strain == self]

    def __str__(self):
        # Return a string that represents the instance
        return '{}: {}'.format(self.manufacturer.name, self.name)


class Storage(CustomModel):
    """
    Data for methods of yeast storage. Used for calculating viability
    in :model:`yeast.Yeast`.
    """
    name = models.CharField(max_length=100)
    viability_loss = models.DecimalField(max_digits=6, decimal_places=4)
    viability_interval = models.IntegerField(default=30)

    def __str__(self):
        # Return a string that represents the instance
        return self.name


class Propogation(CustomModel):
    """
    Stores a batch  of :model:`yeast.Yeast` of a single :model:`yeast.Strain`.

    Can be a single purchased pack, or multiple vials
    to be frozen from a starter.
    """

    BATCH_TYPES = {
        'ST': 'Store',
        'PR': 'Propogated',
        'SL': 'Slurry',
    }
    id = DateUUIDField(primary_key=True)
    parent = models.ManyToManyField('Yeast', related_name='+', blank=True)
    production_date = models.DateField()
    strain = models.ForeignKey(Strain, on_delete=models.PROTECT, default=0)
    source = models.CharField(max_length=3, choices=BATCH_TYPES, default='ST')
    source_batch = models.ForeignKey(
        'beer.Batch', null=True, blank=True, on_delete=models.PROTECT)
    notes = models.TextField(max_length=500, blank=True, null=True)

    def save(self, *args, **kwargs):
        super(Propogation, self).save(*args, **kwargs)
        if self.source_batch:
            relate_samples = [x for x in Yeast.objects.all()
                              if x.pitched_batch == self.source_batch]
            for sample in relate_samples:
                self.parent.add(sample)

    @property
    def age(self):
        return int(average([x.age for x in Yeast.available.all()
                            if x.propogation == self]))

    @property
    def max_viability(self):
        return int(max([x.viability for x in Yeast.available.all()
                        if x.propogation == self]) * 100)

    @property
    def min_viability(self):
        return int(min([x.viability for x in Yeast.available.all()
                        if x.propogation == self]) * 100)

    @property
    def generation(self):
        return int(average([x.generation_num for x in Yeast.available.all()
                            if x.propogation == self]))

    @property
    def beer_name(self):
        if self.source_batch:
            return self.source_batch.brewfather_name

    @property
    def beer_num(self):
        if self.source_batch:
            return self.source_batch.brewfather_num

    @property
    def beer_url(self):
        if self.source_batch:
            return '{}/tabs/batches/batch/{}'.format(
                BREWFATHER_APP_ROOT,
                self.source_batch.brewfather_id
            )

    @property
    def consumed(self):
        return not len(self.remaining_samples) > 0

    @property
    def remaining_samples(self):
        return [x for x in Yeast.available.all() if x.propogation == self]

    @property
    def used_samples(self):
        return [x for x in Yeast.objects.all()
                if x.propogation == self and x.pitched]

    def __str__(self):
        # Return a string that represents the instance
        return '{} [{}]'.format(
            self.strain,
            self.production_date.strftime("%Y-%m-%d")
        )


class Yeast(CustomModel):
    """
    Store an individual sample of yeast.
    """
    id = DateUUIDField(primary_key=True)
    propogation = models.ForeignKey(Propogation, on_delete=models.CASCADE)
    generation_num = models.IntegerField(default=0)
    storage = models.ForeignKey(Storage, on_delete=models.CASCADE)
    cellcount = models.IntegerField(default=100)
    pitched = models.BooleanField(default=False)
    date_pitched = models.DateField(blank=True, null=True)
    pitched_batch = models.ForeignKey(
        'beer.Batch', null=True, blank=True, on_delete=models.CASCADE)
    data_web = models.URLField(blank=True, null=True)
    lot_number = models.CharField(max_length=15, blank=True, null=True)
    notes = models.TextField(max_length=500, blank=True, null=True)
    objects = models.Manager()
    available = AvailableYeastManager()

    @property
    def name(self):
        return '{} {}'.format(self.id, self.propogation.strain.name)

    @property
    def age(self):
        """Return the age in days since the sample was propogated."""

        if self.pitched:
            end_date = self.date_pitched
        else:
            end_date = timezone.now().date()

        return abs((self.propogation.production_date-end_date).days)

    @property
    def viability(self):
        """Return the viability based on age and storage method
           (:model:`yeast.Storage`).
        """
        return 0.97 * math.exp(self.age
                               * math.log(1-self.storage.viability_loss)
                               / self.storage.viability_interval)

    def __str__(self):
        # Return a string that represents the instance
        return '{} {}'.format(self.id, self.propogation.strain.name)