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)

@python_2_unicode_compatible

class BadgeAndProfile(models.Model):

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

    def __str__(self):

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

    @staticmethod

    def get_instance(attendee):

        ''' Returns either None, or the instance that belongs

        to this attendee. '''

        try:

            return BadgeAndProfile.objects.get(attendee=attendee)

        except ObjectDoesNotExist:

            return None

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

    # Things that appear on badge

    name = models.CharField(

        verbose_name="Your name (for your conference nametag)",

        max_length=64,

        help_text="Your name, as you'd like it to appear on your badge. ",

    )

    company = models.CharField(

        max_length=64,

        help_text="The name of your company, as you'd like it on your badge",

        blank=True,

    )

    free_text_1 = models.CharField(

        max_length=64,

        verbose_name="Free text line 1",

        help_text="A line of free text that will appear on your badge. Use "

                  "this for your Twitter handle, IRC nick, your preferred "

                  "pronouns or anything else you'd like people to see on "

                  "your badge.",

        blank=True,

    )

    free_text_2 = models.CharField(

        max_length=64,

        verbose_name="Free text line 2",

        blank=True,

    )

    # Other important Information

    name_per_invoice = models.CharField(

        verbose_name="Your legal name (for invoicing purposes)",

        max_length=64,

        help_text="If your legal name is different to the name on your badge, "

                  "fill this in, and we'll put it on your invoice. Otherwise, "

                  "leave it blank.",

        blank=True,

        )

    of_legal_age = models.BooleanField(

        default=False,

        verbose_name="18+?",

        blank=True,

    )

    dietary_requirements = models.CharField(

        max_length=256,

        blank=True,

    )

    accessibility_requirements = models.CharField(

        max_length=256,

        blank=True,

    )

    gender = models.CharField(

        max_length=64,

        blank=True,

    )

# 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."),

    )

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.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.shortcuts import redirect

from django.shortcuts import render

GuidedRegistrationSection = namedtuple(

    "GuidedRegistrationSection",

    (

        "title",

        "discounts",

        "description",

        "form",

    )

)

GuidedRegistrationSection.__new__.__defaults__ = (

    (None,) * len(GuidedRegistrationSection._fields)

)

@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

    profile = rego.BadgeAndProfile.get_instance(attendee)

    if profile is None:

        # 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 = 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)

    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)

        current_invoice.pay("Demo invoice payment", inv.value)

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