import sys

from registrasion import forms

from registrasion import util

from registrasion.models import commerce

from registrasion.models import inventory

from registrasion.models import people

from registrasion.controllers.batch import BatchController

from registrasion.controllers.cart import CartController

from registrasion.controllers.credit_note import CreditNoteController

from registrasion.controllers.discount import DiscountController

from registrasion.controllers.invoice import InvoiceController

from registrasion.controllers.product import ProductController

from registrasion.exceptions import CartValidationError

from collections import namedtuple

from django.conf import settings

from django.contrib.auth.decorators import login_required

from django.contrib.auth.decorators import user_passes_test

from django.contrib.auth.models import User

from django.contrib import messages

from django.core.exceptions import ObjectDoesNotExist

from django.core.exceptions import ValidationError

from django.http import Http404

from django.shortcuts import redirect

from django.shortcuts import render

_GuidedRegistrationSection = namedtuple(

    "GuidedRegistrationSection",

    (

        "title",

        "discounts",

        "description",

        "form",

    )

)

@util.all_arguments_optional

class GuidedRegistrationSection(_GuidedRegistrationSection):

    ''' Represents a section of a guided registration page.

    Attributes:

       title (str): The title of the section.

       discounts ([registrasion.contollers.discount.DiscountAndQuantity, ...]):

            A list of discount objects that are available in the section. You

            can display ``.clause`` to show what the discount applies to, and

            ``.quantity`` to display the number of times that discount can be

            applied.

       description (str): A description of the section.

       form (forms.Form): A form to display.

    '''

    pass

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):

    ''' Goes through the registration process in order, making sure user sees

    all valid categories.

    The user must be logged in to see this view.

    Returns:

        render: Renders ``registrasion/guided_registration.html``,

            with the following data::

                {

                    "current_step": int(),  # The current step in the

                                            # registration

                    "sections": sections,   # A list of

                                            # GuidedRegistrationSections

                    "title": str(),         # The title of the page

                    "total_steps": int(),   # The total number of steps

                }

    '''

    SESSION_KEY = "guided_registration_categories"

    ASK_FOR_PROFILE = 777  # Magic number. Meh.

    next_step = redirect("guided_registration")

    sections = []

    attendee = people.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

    current_invoice = InvoiceController.for_id_or_404(invoice_id)

    try:

        current_invoice.refund()

        messages.success(request, "This invoice has been refunded.")

    except ValidationError as ve:

        messages.error(request, ve)

    return redirect("invoice", invoice_id)

@user_passes_test(_staff_only)

def credit_note(request, note_id, access_code=None):

    ''' Displays a credit note.

    If ``request`` is a ``POST`` request, forms for applying or refunding

    a credit note will be processed.

    This view requires a login, and the logged in user must be staff.

    Arguments:

        note_id (castable to int): The ID of the credit note to view.

    Returns:

        render or redirect:

            If the "apply to invoice" form is correctly processed, redirect to

            that invoice, otherwise, render ``registration/credit_note.html``

            with the following data::

                {

                    "credit_note": models.commerce.CreditNote(),

                    "apply_form": form,  # A form for applying credit note

                                         # to an invoice.

                    "refund_form": form, # A form for applying a *manual*

                                         # refund of the credit note.

                }

    '''

    note_id = int(note_id)

    current_note = CreditNoteController.for_id_or_404(note_id)

    apply_form = forms.ApplyCreditNoteForm(

        current_note.credit_note.invoice.user,

        request.POST or None,

        prefix="apply_note"

    )

    refund_form = forms.ManualCreditNoteRefundForm(

        request.POST or None,

        prefix="refund_note"

    )

    if request.POST and apply_form.is_valid():

        inv_id = apply_form.cleaned_data["invoice"]

        invoice = commerce.Invoice.objects.get(pk=inv_id)

        current_note.apply_to_invoice(invoice)

        messages.success(

            request,

            "Applied credit note %d to invoice." % note_id,

        )

        return redirect("invoice", invoice.id)

    elif request.POST and refund_form.is_valid():

        refund_form.instance.entered_by = request.user

        refund_form.instance.parent = current_note.credit_note

        refund_form.save()

        messages.success(

            request,

            "Applied manual refund to credit note."

        )

        refund_form = forms.ManualCreditNoteRefundForm(

            prefix="refund_note",

        )

    data = {

        "credit_note": current_note.credit_note,

        "apply_form": apply_form,

        "refund_form": refund_form,

    }

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

@user_passes_test(_staff_only)

def amend_registration(request, user_id):

    ''' Allows staff to amend a user's current registration cart, and etc etc.

    '''

    user = User.objects.get(id=int(user_id))

    current_cart = CartController.for_user(user)

    items = commerce.ProductItem.objects.filter(

        cart=current_cart.cart,

    ).select_related("product")

    initial = [{"product": i.product, "quantity": i.quantity} for i in items]

        request.POST or None,

        initial=initial,

        prefix="products",

    )

    data = {

    }

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