from django.shortcuts import render
from django.http import HttpResponse, HttpResponseRedirect, JsonResponse
from django.views.generic import ListView
from django.db import transaction

from .models import Sale, Product, ProductCategory, Payment, PaymentMethods
from .forms import ImportProductsForm, PurchaseForm, SaleLineFormSet, ReconciliationJarForm, PurchaseSummaryForm

import csv
import io
import json
from decimal import Decimal


class DecimalEncoder(json.JSONEncoder):
    def default(self, obj):
        if isinstance(obj, Decimal):
            return float(obj)
        return json.JSONEncoder.default(self, obj)

def index(request):
    return render(request, 'don_confiao/index.html')

def buy(request):
    if request.method == "POST":
        sale_form = PurchaseForm(request.POST)
        line_formset = SaleLineFormSet(request.POST)
        sale_summary_form = PurchaseSummaryForm(request.POST)
        forms_are_valid = all([
            sale_form.is_valid(),
            line_formset.is_valid(),
            sale_summary_form.is_valid()
        ])
        payment_method = request.POST.get('payment_method')
        valid_payment_methods = [PaymentMethods.CASH]
        valid_payment_method = payment_method in valid_payment_methods
        if forms_are_valid:
            with transaction.atomic():
                sale = sale_form.save()
                line_formset.instance = sale
                line_formset.save()
                Payment.total_payment_from_sale(
                    payment_method,
                    sale
                )
            return HttpResponseRedirect("compras")
    else:
        sale_form = PurchaseForm()
        line_formset = SaleLineFormSet()
        sale_summary_form = PurchaseSummaryForm()
    return render(
        request,
        'don_confiao/purchase.html',
        {
            'sale_form': sale_form,
            'linea_formset': line_formset,
            'summary_form': sale_summary_form,
            'list_products': json.dumps(Product.to_list(), cls=DecimalEncoder),
        }
    )


def purchases(request):
    purchases = Sale.objects.all()
    context = {
        "purchases": purchases,
    }
    return render(request, 'don_confiao/purchases.html', context)


def products(request):
    return JsonResponse(Product.to_list(), safe=False)


def import_products(request):
    if request.method == "POST":
        form = ImportProductsForm(request.POST, request.FILES)
        if form.is_valid():
            handle_import_products_file(request.FILES["csv_file"])
            return HttpResponseRedirect("productos")
    else:
        form = ImportProductsForm()
    return render(
        request,
        "don_confiao/import_products.html",
        {'form': form}
    )


def reconciliate_jar(request):
    summary = Payment.get_reconciliation_jar_summary()
    if request.method == 'POST':
        form = ReconciliationJarForm(request.POST)
        if form.is_valid():
            reconciliation = form.save()
            reconciliation.add_payments(summary.payments)
            reconciliation.clean()
            reconciliation.save()
            return HttpResponseRedirect('cuadres')
    else:
        form = ReconciliationJarForm()
    return render(
        request,
        "don_confiao/reconciliate_jar.html",
        {'summary': summary, 'form': form}
    )


def reconciliations(request):
    return HttpResponse('<h1>Reconciliaciones</h1>')

def purchase_summary(request, id):
    purchase = Sale.objects.get(pk=id)
    return render(
        request,
        "don_confiao/purchase_summary.html",
        {
            "purchase" : purchase
        }
    )

def _categories_from_csv_string(categories_string, separator="&"):
    categories = categories_string.split(separator)
    clean_categories = [c.strip() for c in categories]
    return [_category_from_name(category) for category in clean_categories]


def _category_from_name(name):
    return ProductCategory.objects.get_or_create(name=name)[0]


def handle_import_products_file(csv_file):
    data = io.StringIO(csv_file.read().decode('utf-8'))
    reader = csv.DictReader(data, quotechar='"')
    for row in reader:
        product, created = Product.objects.update_or_create(
            name=row['producto'],
            defaults={
                'price': row['precio'],
                'measuring_unit': row['unidad']
            }
        )
        categories = _categories_from_csv_string(row["categorias"])
        product.categories.clear()
        for category in categories:
            product.categories.add(category)


class ProductListView(ListView):
    model = Product
    template_model = 'don_confiao/product_list.html'

    def get_queryset(self):
        name = self.request.GET.get('name')
        if name:
            return Product.objects.filter(name__icontains=name)
        return Product.objects.all()