from datetime import datetime
from django.db import models
from django.utils.translation import ugettext as _


class Collection(models.Model):
    name = models.CharField(max_length=255, verbose_name=_('name'))

    def __str__(self):
        return '%s' % self.name

    class Meta:
        abstract = True
        ordering = ['name']


class Item(models.Model):
    TARGET_MODEL = None
    TARGET_VERBOSE_NAME = None

    # status choices
    CREATED = 'created'
    STATUS_CHOICES = (
        (CREATED, _('New')),
    )
    DEFAULT_CHOICE = CREATED

    name = models.CharField(max_length=255, verbose_name=_('name'))

    def __str__(self):
        return '%s' % self.name

    @classmethod
    def on_class_prepared(cls):
        """
        Add new field 'collection' which is a link to TARGET_MODEL.
        Add new field 'status' which is a list of choices. With CREATED.
        """
        target_field = models.ForeignKey(
            cls.TARGET_MODEL,
            related_name=cls.RELATED_TARGET_NAME,
            verbose_name=_(cls.TARGET_VERBOSE_NAME))
        target_field.contribute_to_class(cls, 'collection')
        status_field = models.CharField(
            max_length=30,
            choices=Item.STATUS_CHOICES + cls.STATUS_CHOICES,
            default=cls.DEFAULT_CHOICE,
            verbose_name=_('status'))
        status_field.contribute_to_class(cls, 'status')

    class Meta:
        abstract = True
        ordering = ['name']


class Timeline(models.Model):
    """
    Keep changes on collection.
    For an example, a game cretion date. Or when you completed a game.
    """
    TARGET_MODEL = None
    TARGET_VERBOSE_NAME = None
    STATUS_CHOICES = Item.STATUS_CHOICES
    DEFAULT_CHOICE = Item.CREATED
    date = models.DateField(default=datetime.now, verbose_name=_('date'))

    @classmethod
    def on_class_prepared(cls):
        """
        Add new field 'item' which is a link to TARGET_MODEL
        """
        target_field = models.ForeignKey(
            cls.TARGET_MODEL,
            verbose_name=_(cls.TARGET_VERBOSE_NAME))
        target_field.contribute_to_class(cls, 'item')
        status_field = models.CharField(
            max_length=30,
            choices=Item.STATUS_CHOICES + cls.STATUS_CHOICES,
            default=cls.DEFAULT_CHOICE,
            verbose_name=_('status'))
        status_field.contribute_to_class(cls, 'status')

    def __str__(self):
        return '%s: %s - %s' % (
            self.date.strftime('%Y-%m-%d'),
            self.status,
            self.item)

    class Meta:
        abstract = True
        ordering = ('-date',)