import datetime

from django.db import models
from django.utils.encoding import python_2_unicode_compatible
from django.utils.translation import ugettext_lazy as _


# Inventory Models

@python_2_unicode_compatible
class Category(models.Model):
    ''' Registration product categories, used as logical groupings for Products
    in registration forms.

    Attributes:
        name (str): The display name for the category.

        description (str): Some explanatory text for the category. This is
            displayed alongside the forms where your attendees choose their
            items.

        required (bool): Requires a user to select an item from this category
            during initial registration. You can use this, e.g., for making
            sure that the user has a ticket before they select whether they
            want a t-shirt.

        render_type (int): This is used to determine what sort of form the
            attendee will be presented with when choosing Products from this
            category. These may be either of the following:

            ``RENDER_TYPE_RADIO`` presents the Products in the Category as a
            list of radio buttons. At most one item can be chosen at a time.
            This works well when setting limit_per_user to 1.

            ``RENDER_TYPE_QUANTITY`` shows each Product next to an input field,
            where the user can specify a quantity of each Product type. This is
            useful for additional extras, like Dinner Tickets.

        limit_per_user (Optional[int]): This restricts the number of items
            from this Category that each attendee may claim. This extends
            across multiple Invoices.

        display_order (int): An ascending order for displaying the Categories
            available. By convention, your Category for ticket types should
            have the lowest display order.
    '''

    class Meta:
        app_label = "registrasion"
        verbose_name = _("inventory - category")
        verbose_name_plural = _("inventory - categories")
        ordering = ("order", )

    def __str__(self):
        return self.name

    RENDER_TYPE_RADIO = 1
    RENDER_TYPE_QUANTITY = 2

    CATEGORY_RENDER_TYPES = [
        (RENDER_TYPE_RADIO, _("Radio button")),
        (RENDER_TYPE_QUANTITY, _("Quantity boxes")),
    ]

    name = models.CharField(
        max_length=65,
        verbose_name=_("Name"),
    )
    description = models.CharField(
        max_length=255,
        verbose_name=_("Description"),
    )
    limit_per_user = models.PositiveIntegerField(
        null=True,
        blank=True,
        verbose_name=_("Limit per user"),
        help_text=_("The total number of items from this category one "
                    "attendee may purchase."),
    )
    required = models.BooleanField(
        blank=True,
        help_text=_("If enabled, a user must select an "
                    "item from this category."),
    )
    order = models.PositiveIntegerField(
        verbose_name=("Display order"),
        db_index=True,
    )
    render_type = models.IntegerField(
        choices=CATEGORY_RENDER_TYPES,
        verbose_name=_("Render type"),
        help_text=_("The registration form will render this category in this "
                    "style."),
    )


@python_2_unicode_compatible
class Product(models.Model):
    ''' Registration products '''

    class Meta:
        app_label = "registrasion"
        verbose_name = _("inventory - product")
        ordering = ("category__order", "order")

    def __str__(self):
        return "%s - %s" % (self.category.name, self.name)

    name = models.CharField(
        max_length=65,
        verbose_name=_("Name"),
    )
    description = models.CharField(
        max_length=255,
        verbose_name=_("Description"),
        null=True,
        blank=True,
    )
    category = models.ForeignKey(
        Category,
        verbose_name=_("Product category")
    )
    price = models.DecimalField(
        max_digits=8,
        decimal_places=2,
        verbose_name=_("Price"),
    )
    limit_per_user = models.PositiveIntegerField(
        null=True,
        blank=True,
        verbose_name=_("Limit per user"),
    )
    reservation_duration = models.DurationField(
        default=datetime.timedelta(hours=1),
        verbose_name=_("Reservation duration"),
        help_text=_("The length of time this product will be reserved before "
                    "it is released for someone else to purchase."),
    )
    order = models.PositiveIntegerField(
        verbose_name=("Display order"),
        db_index=True,
    )


@python_2_unicode_compatible
class Voucher(models.Model):
    ''' Registration vouchers '''

    class Meta:
        app_label = "registrasion"

    # Vouchers reserve a cart for a fixed amount of time, so that
    # items may be added without the voucher being swiped by someone else
    RESERVATION_DURATION = datetime.timedelta(hours=1)

    def __str__(self):
        return "Voucher for %s" % self.recipient

    @classmethod
    def normalise_code(cls, code):
        return code.upper()

    def save(self, *a, **k):
        ''' Normalise the voucher code to be uppercase '''
        self.code = self.normalise_code(self.code)
        super(Voucher, self).save(*a, **k)

    recipient = models.CharField(max_length=64, verbose_name=_("Recipient"))
    code = models.CharField(max_length=16,
                            unique=True,
                            verbose_name=_("Voucher code"))
    limit = models.PositiveIntegerField(verbose_name=_("Voucher use limit"))