from __future__ import unicode_literals

import datetime

from django.core.exceptions import ObjectDoesNotExist

from django.core.exceptions import ValidationError

from django.contrib.auth.models import User

from django.db import models

from django.db.models import F, Q

from django.utils import timezone

from django.utils.encoding import python_2_unicode_compatible

from django.utils.translation import ugettext_lazy as _

from model_utils.managers import InheritanceManager

from symposion.markdown_parser import parse

from symposion.proposals.models import ProposalBase

# User models

@python_2_unicode_compatible

class Profile(models.Model):

    ''' Miscellaneous user-related data. '''

    def __str__(self):

        return "%s" % self.user

    user = models.OneToOneField(User, on_delete=models.CASCADE)

    # Badge is linked

    completed_registration = models.BooleanField(default=False)

    highest_complete_category = models.IntegerField(default=0)

@python_2_unicode_compatible

class Badge(models.Model):

    ''' Information for an attendee's badge. '''

    def __str__(self):

        return "Badge for: %s of %s" % (self.name, self.company)

    profile = models.OneToOneField(Profile, on_delete=models.CASCADE)

    name = models.CharField(max_length=256)

    company = models.CharField(max_length=256)

# Inventory Models

@python_2_unicode_compatible

class Category(models.Model):

    ''' Registration product categories '''

    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"))

    order = models.PositiveIntegerField(verbose_name=("Display order"))

    render_type = models.IntegerField(choices=CATEGORY_RENDER_TYPES, verbose_name=_("Render type"))

@python_2_unicode_compatible

class Product(models.Model):

    ''' Registration products '''

    def __str__(self):

        return self.name

    name = models.CharField(max_length=65, verbose_name=_("Name"))

    description = models.CharField(max_length=255, verbose_name=_("Description"))

    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(blank=True, verbose_name=_("Limit per user"))

    reservation_duration = models.DurationField(

        default=datetime.timedelta(hours=1),

        verbose_name=_("Reservation duration"))

    order = models.PositiveIntegerField(verbose_name=("Display order"))

@python_2_unicode_compatible

class Voucher(models.Model):

    ''' Registration vouchers '''

    # 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

    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"))

# Product Modifiers

@python_2_unicode_compatible

class DiscountBase(models.Model):

    ''' Base class for discounts. Each subclass has controller code that

    determines whether or not the given discount is available to be added to the

    current cart. '''

    objects = InheritanceManager()

    def __str__(self):

        return "Discount: " + self.description

    description = models.CharField(max_length=255,

        verbose_name=_("Description"))

@python_2_unicode_compatible

class DiscountForProduct(models.Model):

    ''' Represents a discount on an individual product. Each Discount can

    contain multiple products and categories. Discounts can either be a

    percentage or a fixed amount, but not both. '''

    def __str__(self):

        if self.percentage:

            return "%s%% off %s" % (self.percentage, self.product)

        elif self.price:

            return "$%s off %s" % (self.price, self.product)

    def clean(self):

        if self.percentage is None and self.price is None:

            raise ValidationError(

                _("Discount must have a percentage or a price."))

        elif self.percentage is not None and self.price is not None:

            raise ValidationError(

                _("Discount may only have a percentage or only a price."))

    discount = models.ForeignKey(DiscountBase, on_delete=models.CASCADE)

    product = models.ForeignKey(Product, on_delete=models.CASCADE)

    percentage = models.DecimalField(max_digits=4, decimal_places=1, null=True)

    price = models.DecimalField(max_digits=8, decimal_places=2, null=True)

    quantity = models.PositiveIntegerField()

@python_2_unicode_compatible

class DiscountForCategory(models.Model):

    ''' Represents a discount for a category of products. Each discount can

    contain multiple products. Category discounts can only be a percentage. '''

    def __str__(self):

        return "%s%% off %s" % (self.percentage, self.category)

    discount = models.ForeignKey(DiscountBase, on_delete=models.CASCADE)

    category = models.ForeignKey(Category, on_delete=models.CASCADE)

    percentage = models.DecimalField(max_digits=4, decimal_places=1, blank=True)

    quantity = models.PositiveIntegerField()

class TimeOrStockLimitDiscount(DiscountBase):

    ''' Discounts that are generally available, but are limited by timespan or

    usage count. This is for e.g. Early Bird discounts. '''

    class Meta:

        verbose_name = _("Promotional discount")

    start_time = models.DateTimeField(null=True, verbose_name=_("Start time"))

    end_time = models.DateTimeField(null=True, verbose_name=_("End time"))

    limit = models.PositiveIntegerField(null=True, verbose_name=_("Limit"))

class VoucherDiscount(DiscountBase):

    ''' Discounts that are enabled when a voucher code is in the current

    cart. '''

    voucher = models.OneToOneField(Voucher, on_delete=models.CASCADE,

        verbose_name=_("Voucher"))

class IncludedProductDiscount(DiscountBase):

    ''' Discounts that are enabled because another product has been purchased.

    e.g. A conference ticket includes a free t-shirt. '''

    class Meta:

        verbose_name = _("Product inclusion")

    enabling_products = models.ManyToManyField(Product,

        verbose_name=_("Including product"))

class RoleDiscount(object):

    ''' Discounts that are enabled because the active user has a specific

    role. This is for e.g. volunteers who can get a discount ticket. '''

    ## TODO: implement RoleDiscount

    pass

@python_2_unicode_compatible

class EnablingConditionBase(models.Model):

    ''' This defines a condition which allows products or categories to

    be made visible. If there is at least one mandatory enabling condition

    defined on a Product or Category, it will only be enabled if *all*

    mandatory conditions are met, otherwise, if there is at least one enabling

    condition defined on a Product or Category, it will only be enabled if at

    least one condition is met. '''

    objects = InheritanceManager()

    def __str__(self):

        return self.name

    description = models.CharField(max_length=255)

    mandatory = models.BooleanField(default=False)

    products = models.ManyToManyField(Product)

    categories = models.ManyToManyField(Category)

class TimeOrStockLimitEnablingCondition(EnablingConditionBase):

    ''' Registration product ceilings '''

    start_time = models.DateTimeField(null=True, verbose_name=_("Start time"))

    end_time = models.DateTimeField(null=True, verbose_name=_("End time"))

    limit = models.PositiveIntegerField(null=True, verbose_name=_("Limit"))

@python_2_unicode_compatible

class ProductEnablingCondition(EnablingConditionBase):

    ''' The condition is met because a specific product is purchased. '''

    def __str__(self):

        return "Enabled by product: "

    enabling_products = models.ManyToManyField(Product)

@python_2_unicode_compatible

class CategoryEnablingCondition(EnablingConditionBase):

    ''' The condition is met because a product in a particular product is

    purchased. '''

    def __str__(self):

        return "Enabled by product in category: "

    enabling_category = models.ForeignKey(Category)

@python_2_unicode_compatible

class VoucherEnablingCondition(EnablingConditionBase):

    ''' The condition is met because a Voucher is present. This is for e.g.

    enabling sponsor tickets. '''

    def __str__(self):

        return "Enabled by voucher: %s" % voucher

    voucher = models.OneToOneField(Voucher)

#@python_2_unicode_compatible

class RoleEnablingCondition(object):

    ''' The condition is met because the active user has a particular Role.

    This is for e.g. enabling Team tickets. '''

    ## TODO: implement RoleEnablingCondition

    pass

# Commerce Models

@python_2_unicode_compatible

class Cart(models.Model):

    ''' Represents a set of product items that have been purchased, or are

    pending purchase. '''

    def __str__(self):

        return "%d rev #%d" % (self.id, self.revision)

    user = models.ForeignKey(User)

    # ProductItems (foreign key)

    vouchers = models.ManyToManyField(Voucher, blank=True)

    time_last_updated = models.DateTimeField()

    reservation_duration = models.DurationField()

    revision = models.PositiveIntegerField(default=1)

    active = models.BooleanField(default=True)

    @classmethod

    def reserved_carts(cls):

        ''' Gets all carts that are 'reserved' '''

        return Cart.objects.filter(

            (Q(active=True) &

                Q(time_last_updated__gt=timezone.now()-F('reservation_duration')

            )) |

            Q(active=False)

        )

@python_2_unicode_compatible

class ProductItem(models.Model):

    ''' Represents a product-quantity pair in a Cart. '''

    def __str__(self):

        return "product: %s * %d in Cart: %s" % (

            self.product, self.quantity, self.cart)

    cart = models.ForeignKey(Cart)

    product = models.ForeignKey(Product)

    quantity = models.PositiveIntegerField()

@python_2_unicode_compatible

class DiscountItem(models.Model):

    ''' Represents a discount-product-quantity relation in a Cart. '''

    def __str__(self):

        return "%s: %s * %d in Cart: %s" % (

            self.discount, self.product, self.quantity, self.cart)

    cart = models.ForeignKey(Cart)

    product = models.ForeignKey(Product)

    discount = models.ForeignKey(DiscountBase)

    quantity = models.PositiveIntegerField()

@python_2_unicode_compatible

class Invoice(models.Model):

    ''' An invoice. Invoices can be automatically generated when checking out

    a Cart, in which case, it is attached to a given revision of a Cart. '''

    def __str__(self):

        return "Invoice #%d" % self.id

    def clean(self):

        if self.cart is not None and self.cart_revision is None:

            raise ValidationError(

                "If this is a cart invoice, it must have a revision")

    # Invoice Number

    user = models.ForeignKey(User)

    cart = models.ForeignKey(Cart, null=True)

    cart_revision = models.IntegerField(null=True)

    # Line Items (foreign key)

    void = models.BooleanField(default=False)

    paid = models.BooleanField(default=False)

    value = models.DecimalField(max_digits=8, decimal_places=2)

@python_2_unicode_compatible

class LineItem(models.Model):

    ''' Line items for an invoice. These are denormalised from the ProductItems

    and DiscountItems that belong to a cart (for consistency), but also allow

    for arbitrary line items when required. '''

    def __str__(self):

        return "Line: %s * %d @ %s" % (

            self.description, self.quantity, self.price)

    invoice = models.ForeignKey(Invoice)

    description = models.CharField(max_length=255)

    quantity = models.PositiveIntegerField()

    price = models.DecimalField(max_digits=8, decimal_places=2)

@python_2_unicode_compatible

class Payment(models.Model):

    ''' A payment for an invoice. Each invoice can have multiple payments

    attached to it.'''

    def __str__(self):

        return "Payment: ref=%s amount=%s" % (self.reference, self.amount)

    invoice = models.ForeignKey(Invoice)

    time = models.DateTimeField(default=timezone.now)

    reference = models.CharField(max_length=64)

    amount = models.DecimalField(max_digits=8, decimal_places=2)