from __future__ import unicode_literals

import datetime

import itertools

from django.core.exceptions import ValidationError

from django.core.exceptions import ObjectDoesNotExist

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

# User models

@python_2_unicode_compatible

class Attendee(models.Model):

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

    def __str__(self):

        return "%s" % self.user

    @staticmethod

    def get_instance(user):

        ''' Returns the instance of attendee for the given user, or creates

        a new one. '''

        attendees = Attendee.objects.filter(user=user)

        if len(attendees) > 0:

            return attendees[0]

        else:

            attendee = Attendee(user=user)

            attendee.save()

            return attendee

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

    # Badge/profile is linked

    completed_registration = models.BooleanField(default=False)

    highest_complete_category = models.IntegerField(default=0)

class AttendeeProfileBase(models.Model):

    ''' Information for an attendee's badge and related preferences.

    Subclass this in your Django site to ask for attendee information in your

    registration progess.

     '''

    attendee = models.OneToOneField(Attendee, on_delete=models.CASCADE)

# Inventory Models

@python_2_unicode_compatible

class Category(models.Model):

    ''' Registration product categories '''

    class Meta:

        verbose_name_plural = _("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"),

    )

    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"),

    )

    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 '''

    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"),

    )

@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

    @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"))

# 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

    def effects(self):

        ''' Returns all of the effects of this discount. '''

        products = self.discountforproduct_set.all()

        categories = self.discountforcategory_set.all()

        return itertools.chain(products, categories)

    description = models.CharField(

        max_length=255,

        verbose_name=_("Description"),

        help_text=_("A description of this discount. This will be included on "

                    "invoices where this discount is applied."),

        )

@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."))

        prods = DiscountForProduct.objects.filter(

            discount=self.discount,

            product=self.product)

        cats = DiscountForCategory.objects.filter(

            discount=self.discount,

            category=self.product.category)

        if len(prods) > 1:

            raise ValidationError(

                _("You may only have one discount line per product"))

        if len(cats) != 0:

            raise ValidationError(

                _("You may only have one discount for "

                    "a product or its category"))

    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, blank=True)

    price = models.DecimalField(

        max_digits=8, decimal_places=2, null=True, blank=True)

    quantity = models.PositiveIntegerField()

import sys

from registrasion import forms

from registrasion import models as rego

from registrasion.controllers import discount

from registrasion.controllers.cart import CartController

from registrasion.controllers.invoice import InvoiceController

from registrasion.controllers.product import ProductController

from collections import namedtuple

from django.conf import settings

from django.contrib.auth.decorators import login_required

from django.contrib import messages

from django.core.exceptions import ObjectDoesNotExist

from django.core.exceptions import ValidationError

from django.db import transaction

from django.http import Http404

from django.shortcuts import redirect

from django.shortcuts import render

GuidedRegistrationSection = namedtuple(

    "GuidedRegistrationSection",

    (

        "title",

        "discounts",

        "description",

        "form",

    )

)

GuidedRegistrationSection.__new__.__defaults__ = (

    (None,) * len(GuidedRegistrationSection._fields)

)

def get_form(name):

    dot = name.rindex(".")

    mod_name, form_name = name[:dot], name[dot + 1:]

    __import__(mod_name)

    return getattr(sys.modules[mod_name], form_name)

@login_required

def guided_registration(request, page_id=0):

    ''' Goes through the registration process in order,

    making sure user sees all valid categories.

    WORK IN PROGRESS: the finalised version of this view will allow

    grouping of categories into a specific page. Currently, it just goes

    through each category one by one

    '''

    dashboard = redirect("dashboard")

    next_step = redirect("guided_registration")

    sections = []

    attendee = rego.Attendee.get_instance(request.user)

    if attendee.completed_registration:

        return render(

            request,

            "registrasion/guided_registration_complete.html",

            {},

        )

    # Step 1: Fill in a badge and collect a voucher code

    try:

        profile = attendee.attendeeprofilebase

    except ObjectDoesNotExist:

        profile = None

    if not profile:

        # TODO: if voucherform is invalid, make sure that profileform does not save

        voucher_form, voucher_handled = handle_voucher(request, "voucher")

        profile_form, profile_handled = handle_profile(request, "profile")

        voucher_section = GuidedRegistrationSection(

            title="Voucher Code",

            form=voucher_form,

        )

        profile_section = GuidedRegistrationSection(

            title="Profile and Personal Information",

            form=profile_form,

        )

        title = "Attendee information"

        current_step = 1

        sections.append(voucher_section)

        sections.append(profile_section)

    else:

        # We're selling products

        last_category = attendee.highest_complete_category

        # Get the next category

        cats = rego.Category.objects

        cats = cats.filter(id__gt=last_category).order_by("order")

        if cats.count() == 0:

            # We've filled in every category

            attendee.completed_registration = True

            attendee.save()

            return next_step

        if last_category == 0:

            # Only display the first Category

            title = "Select ticket type"

            current_step = 2

            cats = [cats[0]]

        else:

            # Set title appropriately for remaining categories

            current_step = 3

            title = "Additional items"

        for category in cats:

            products = ProductController.available_products(

                request.user,

                category=category,

            )

            prefix = "category_" + str(category.id)

            p = handle_products(request, category, products, prefix)

            products_form, discounts, products_handled = p

            section = GuidedRegistrationSection(

                title=category.name,

                description=category.description,

                discounts=discounts,

                form=products_form,

            )

            sections.append(section)

            if request.method == "POST" and not products_form.errors:

                if category.id > attendee.highest_complete_category:

                    # This is only saved if we pass each form with no errors.

                    attendee.highest_complete_category = category.id

    if sections and request.method == "POST":

        for section in sections:

            if section.form.errors:

                break

        else:

            attendee.save()

            # We've successfully processed everything

            return next_step

    data = {

        "current_step": current_step,

        "sections": sections,

        "title" : title,

        "total_steps": 3,

    }

    return render(request, "registrasion/guided_registration.html", data)

@login_required

def edit_profile(request):

    form, handled = handle_profile(request, "profile")

    data = {

        "form": form,

    }

    return render(request, "registrasion/profile_form.html", data)

def handle_profile(request, prefix):

    ''' Returns a profile form instance, and a boolean which is true if the

    form was handled. '''

    attendee = rego.Attendee.get_instance(request.user)

    try:

        profile = attendee.attendeeprofilebase

    except ObjectDoesNotExist:

        profile = None

    ProfileForm = get_form(settings.ATTENDEE_PROFILE_FORM)

    form = ProfileForm(

        request.POST or None,

        instance=profile,

        prefix=prefix

    )

    handled = True if request.POST else False

    if request.POST and form.is_valid():

        form.instance.attendee = attendee

        form.save()

    return form, handled

@login_required

def product_category(request, category_id):

    ''' Registration selections form for a specific category of items.

    '''

    PRODUCTS_FORM_PREFIX = "products"

    VOUCHERS_FORM_PREFIX = "vouchers"

    # Handle the voucher form *before* listing products.

    # Products can change as vouchers are entered.

    v = handle_voucher(request, VOUCHERS_FORM_PREFIX)

    voucher_form, voucher_handled = v

    category_id = int(category_id)  # Routing is [0-9]+

    category = rego.Category.objects.get(pk=category_id)

    products = ProductController.available_products(

        request.user,

        category=category,

    )

    p = handle_products(request, category, products, PRODUCTS_FORM_PREFIX)

    products_form, discounts, products_handled = p

    if request.POST and not voucher_handled and not products_form.errors:

        # Only return to the dashboard if we didn't add a voucher code

        # and if there's no errors in the products form

        return redirect("dashboard")

    data = {

        "category": category,

        "discounts": discounts,

        "form": products_form,

        "voucher_form": voucher_form,

    }

    return render(request, "registrasion/product_category.html", data)

def handle_products(request, category, products, prefix):

    ''' Handles a products list form in the given request. Returns the

    form instance, the discounts applicable to this form, and whether the

    contents were handled. '''

    current_cart = CartController.for_user(request.user)

    ProductsForm = forms.ProductsForm(category, products)

    # Create initial data for each of products in category

    items = rego.ProductItem.objects.filter(

        product__in=products,

        cart=current_cart.cart,

    )

    quantities = []

    for product in products:

        # Only add items that are enabled.

        try:

            quantity = items.get(product=product).quantity

        except ObjectDoesNotExist:

            quantity = 0

        quantities.append((product, quantity))

    products_form = ProductsForm(

        request.POST or None,

        product_quantities=quantities,

        prefix=prefix,

    )

    if request.method == "POST" and products_form.is_valid():

        try:

            if products_form.has_changed():

                set_quantities_from_products_form(products_form, current_cart)

        except ValidationError:

            # There were errors, but they've already been added to the form.

            pass

        # If category is required, the user must have at least one

        # in an active+valid cart

        if category.required:

            carts = rego.Cart.objects.filter(user=request.user)

            items = rego.ProductItem.objects.filter(

                product__category=category,

                cart=carts,

            )

            if len(items) == 0:

                products_form.add_error(

                    None,

                    "You must have at least one item from this category",

                )

    handled = False if products_form.errors else True

    discounts = discount.available_discounts(request.user, [], products)

    return products_form, discounts, handled

@transaction.atomic

def set_quantities_from_products_form(products_form, current_cart):

    # TODO: issue #8 is a problem here.

    quantities = list(products_form.product_quantities())

    quantities.sort(key=lambda item: item[1])

    for product_id, quantity, field_name in quantities:

        product = rego.Product.objects.get(pk=product_id)

        try:

            current_cart.set_quantity(product, quantity, batched=True)

        except ValidationError as ve:

            products_form.add_error(field_name, ve)

    if products_form.errors:

        raise ValidationError("Cannot add that stuff")

    current_cart.end_batch()

def handle_voucher(request, prefix):

    ''' Handles a voucher form in the given request. Returns the voucher

    form instance, and whether the voucher code was handled. '''

    voucher_form = forms.VoucherForm(request.POST or None, prefix=prefix)

    current_cart = CartController.for_user(request.user)

    if (voucher_form.is_valid() and

            voucher_form.cleaned_data["voucher"].strip()):

        voucher = voucher_form.cleaned_data["voucher"]

        voucher = rego.Voucher.normalise_code(voucher)

        if len(current_cart.cart.vouchers.filter(code=voucher)) > 0:

            # This voucher has already been applied to this cart.

            # Do not apply code

            handled = False

        else:

            try:

                current_cart.apply_voucher(voucher)

            except Exception as e:

                voucher_form.add_error("voucher", e)

            handled = True

    else:

        handled = False

    return (voucher_form, handled)

@login_required

def checkout(request):

    ''' Runs checkout for the current cart of items, ideally generating an

    invoice. '''

    current_cart = CartController.for_user(request.user)

    current_invoice = InvoiceController.for_cart(current_cart.cart)

    return redirect("invoice", current_invoice.invoice.id)

@login_required

def invoice(request, invoice_id):

    ''' Displays an invoice for a given invoice id. '''

    invoice_id = int(invoice_id)

    inv = rego.Invoice.objects.get(pk=invoice_id)

    if request.user != inv.cart.user and not request.user.is_staff:

        raise Http404()

    current_invoice = InvoiceController(inv)

    data = {

        "invoice": current_invoice.invoice,

    }

    return render(request, "registrasion/invoice.html", data)

@login_required

def pay_invoice(request, invoice_id):

    ''' Marks the invoice with the given invoice id as paid.

    WORK IN PROGRESS FUNCTION. Must be replaced with real payment workflow.

    '''

    invoice_id = int(invoice_id)

    inv = rego.Invoice.objects.get(pk=invoice_id)

    current_invoice = InvoiceController(inv)