import forms

from django.contrib.auth.decorators import user_passes_test
from django.core.urlresolvers import reverse
from django.db import models
from django.db.models import F, Q
from django.db.models import Sum
from django.db.models import Case, When, Value
from django.shortcuts import render

from registrasion.models import commerce
from registrasion import views

from reports import get_all_reports
from reports import Report
from reports import report_view


@user_passes_test(views._staff_only)
def reports_list(request):
    ''' Lists all of the reports currently available. '''

    reports = []

    for report in get_all_reports():
        reports.append({
            "name": report.__name__,
            "url": reverse(report),
            "description": report.__doc__,
        })

    reports.sort(key=lambda report: report["name"])

    ctx = {
        "reports": reports,
    }

    return render(request, "registrasion/reports_list.html", ctx)


# Report functions


@report_view("Paid items", form_type=forms.ProductAndCategoryForm)
def items_sold(request, form):
    ''' Summarises the items sold and discounts granted for a given set of
    products, or products from categories. '''

    data = None
    headings = None

    products = form.cleaned_data["product"]
    categories = form.cleaned_data["category"]

    line_items = commerce.LineItem.objects.filter(
        Q(product__in=products) | Q(product__category__in=categories),
        invoice__status=commerce.Invoice.STATUS_PAID,
    ).select_related("invoice")

    line_items = line_items.order_by(
        # sqlite requires an order_by for .values() to work
        "-price", "description",
    ).values(
        "price", "description",
    ).annotate(
        total_quantity=Sum("quantity"),
    )

    print line_items

    headings = ["Description", "Quantity", "Price", "Total"]

    data = []
    total_income = 0
    for line in line_items:
        cost = line["total_quantity"] * line["price"]
        data.append([
            line["description"], line["total_quantity"],
            line["price"], cost,
        ])
        total_income += cost

    data.append([
        "(TOTAL)", "--", "--", total_income,
    ])

    return Report("Paid items", headings, data)


@report_view("Product status", form_type=forms.ProductAndCategoryForm)
def product_status(request, form):
    ''' Summarises the inventory status of the given items, grouping by
    invoice status. '''

    products = form.cleaned_data["product"]
    categories = form.cleaned_data["category"]

    items = commerce.ProductItem.objects.filter(
        Q(product__in=products) | Q(product__category__in=categories),
    ).select_related("cart", "product")

    items = items.annotate(
        is_reserved=Case(
            When(cart__in=commerce.Cart.reserved_carts(), then=Value(1)),
            default=Value(0),
            output_field=models.BooleanField(),
        ),
    )

    items = items.order_by(
        "product__category__order",
        "product__order",
    ).values(
        "product",
        "product__category__name",
        "product__name",
    ).annotate(
        total_paid=Sum(Case(
            When(
                cart__status=commerce.Cart.STATUS_PAID,
                then=F("quantity"),
            ),
            default=Value(0),
        )),
        total_refunded=Sum(Case(
            When(
                cart__status=commerce.Cart.STATUS_RELEASED,
                then=F("quantity"),
            ),
            default=Value(0),
        )),
        total_unreserved=Sum(Case(
            When(
                (
                    Q(cart__status=commerce.Cart.STATUS_ACTIVE) &
                    Q(is_reserved=False)
                ),
                then=F("quantity"),
            ),
            default=Value(0),
        )),
        total_reserved=Sum(Case(
            When(
                (
                    Q(cart__status=commerce.Cart.STATUS_ACTIVE) &
                    Q(is_reserved=True)
                ),
                then=F("quantity"),
            ),
            default=Value(0),
        )),
    )

    headings = [
        "Product", "Paid", "Reserved", "Unreserved", "Refunded",
    ]
    data = []

    for item in items:
        data.append([
            "%s - %s" % (
                item["product__category__name"], item["product__name"]
            ),
            item["total_paid"],
            item["total_reserved"],
            item["total_unreserved"],
            item["total_refunded"],
        ])

    return Report("Inventory", headings, data)


@report_view("Credit notes")
def credit_notes(request, form):
    ''' Shows all of the credit notes in the system. '''

    notes = commerce.CreditNote.objects.all().select_related(
        "creditnoterefund",
        "creditnoteapplication",
        "invoice",
        "invoice__user__attendee__attendeeprofilebase",
    )

    headings = [
        "id", "Owner", "Status", "Value",
    ]

    data = []
    for note in notes:
        data.append([
            note.id,
            note.invoice.user.attendee.attendeeprofilebase.invoice_recipient(),
            note.status,
            note.value,
        ])

    return Report("Credit Notes", headings, data, link_view="credit_note")