from collections import OrderedDict
from datetime import timedelta
from decimal import Decimal, InvalidOperation

from django.template.loader import render_to_string
from django.utils import timezone
from liveview import liveview_handler, send

from app.expenses.models import Category, Expense, Subcategory


def _build_week_data(offset):
	today = timezone.localdate()
	monday = today - timedelta(days=today.weekday()) + timedelta(weeks=offset)
	sunday = monday + timedelta(days=6)
	expenses = Expense.objects.filter(
		created_at__date__gte=monday,
		created_at__date__lte=sunday,
	).select_related("category", "subcategory")

	categories_data = OrderedDict()
	total = Decimal("0")
	for expense in expenses:
		cat = expense.category
		if cat.id not in categories_data:
			categories_data[cat.id] = {
				"category": cat,
				"expenses": [],
				"subcategory_totals": OrderedDict(),
				"total": Decimal("0"),
			}
		entry = categories_data[cat.id]
		entry["expenses"].append(expense)
		entry["total"] += expense.amount
		total += expense.amount

		sub = expense.subcategory
		if sub.id not in entry["subcategory_totals"]:
			entry["subcategory_totals"][sub.id] = {
				"subcategory": sub,
				"total": Decimal("0"),
			}
		entry["subcategory_totals"][sub.id]["total"] += expense.amount

	return {
		"categories_data": categories_data.values(),
		"total": total,
		"monday": monday,
		"sunday": sunday,
		"offset": offset,
		"prev_offset": offset - 1,
		"next_offset": offset + 1,
		"is_current_week": offset == 0,
	}


def _render_week(offset, editing_id=None):
	context = _build_week_data(offset)
	context["editing_id"] = editing_id
	if editing_id:
		try:
			expense = Expense.objects.get(id=editing_id)
			context["editing_expense"] = expense
			context["user_categories"] = Category.objects.all()
			context["user_subcategories"] = Subcategory.objects.filter(
				category=expense.category
			)
		except Expense.DoesNotExist:
			pass
	return render_to_string("pages/expenses/partials/week_content.html", context)


@liveview_handler("delete_expense")
def delete_expense(consumer, content):
	data = content.get("data", {})
	expense_id = data.get("data_id", "")
	offset = int(data.get("data_offset", 0))

	if not expense_id:
		return

	Expense.objects.filter(id=expense_id).delete()
	html = _render_week(offset)
	send(consumer, {"target": "#week-content", "html": html})


@liveview_handler("edit_expense")
def edit_expense(consumer, content):
	data = content.get("data", {})
	expense_id = data.get("data_id", "")
	offset = int(data.get("data_offset", 0))

	if not expense_id:
		return

	html = _render_week(offset, editing_id=int(expense_id))
	send(consumer, {"target": "#week-content", "html": html})


@liveview_handler("save_expense")
def save_expense(consumer, content):
	form = content.get("form", {})
	expense_id = form.get("expense_id", "")
	offset = int(form.get("offset", 0))
	concept = form.get("expense_concept", "").strip()
	amount_raw = form.get("expense_amount", "").replace(",", ".")
	category_id = form.get("expense_category", "")
	subcategory_id = form.get("expense_subcategory", "")

	if not expense_id or not concept or not amount_raw:
		return

	try:
		expense = Expense.objects.get(id=expense_id)
		expense.concept = concept
		expense.amount = Decimal(amount_raw)
		if category_id:
			expense.category_id = int(category_id)
		if subcategory_id:
			expense.subcategory_id = int(subcategory_id)
		expense.save()
	except (Expense.DoesNotExist, ValueError, InvalidOperation):
		return

	html = _render_week(offset)
	send(consumer, {"target": "#week-content", "html": html})


@liveview_handler("update_week_subcategories")
def update_week_subcategories(consumer, content):
	form = content.get("form", {})
	category_id = form.get("expense_category", "")

	if not category_id:
		return

	try:
		subcategories = Subcategory.objects.filter(category_id=int(category_id))
	except (ValueError, Category.DoesNotExist):
		return

	options = "".join(
		f'<option value="{sub.id}">{sub.name}</option>' for sub in subcategories
	)
	html = f'<select name="expense_subcategory" class="select select-bordered select-sm flex-1 min-w-[7rem]">{options}</select>'
	send(consumer, {"target": "#week-subcategory-wrapper", "html": html})


@liveview_handler("cancel_edit_expense")
def cancel_edit_expense(consumer, content):
	data = content.get("data", {})
	offset = int(data.get("data_offset", 0))

	html = _render_week(offset)
	send(consumer, {"target": "#week-content", "html": html})