# ======= SHARED HELPERS =======

import frappe
from datetime import datetime


def resolve_customer_group(preferred=None):
	"""Return a usable (non-group) Customer Group, or None.

	Newer ERPNext rejects assigning a Customer to a "group" type Customer Group
	(e.g. the root "All Customer Groups"), and `customer_group` is no longer a
	mandatory field. So:
	  - if a valid, non-group Customer Group is configured -> use it
	  - otherwise return None and let the Customer be created without a group
	"""
	if preferred and frappe.db.exists("Customer Group", preferred):
		if not frappe.db.get_value("Customer Group", preferred, "is_group"):
			return preferred
	return None


def resolve_territory(preferred=None):
	"""Return a usable Territory, or None if the configured one is missing.

	Mirrors :func:`resolve_customer_group`; Territory root nodes are still
	accepted by ERPNext, so we only validate existence.
	"""
	if preferred and frappe.db.exists("Territory", preferred):
		return preferred
	return None


def _parse_load_date(value):
	"""Parse the date formats the e-taxes loaders use ('YYYY-MM-DD' or
	'DD-MM-YYYY[ HH:MM]'). Returns a datetime.date or None."""
	if not value:
		return None
	token = str(value).strip().split(" ")[0]
	for fmt in ("%Y-%m-%d", "%d-%m-%Y"):
		try:
			return datetime.strptime(token, fmt).date()
		except ValueError:
			continue
	return None


def exceeds_one_year(date_from, date_to):
	"""True if [date_from, date_to] spans more than one year (366 days).

	Used to forbid loading more than a year of data in a single run — applies to
	every e-taxes load (invoices, reference data, VAT) EXCEPT Company data."""
	df = _parse_load_date(date_from)
	dt = _parse_load_date(date_to)
	return bool(df and dt and (dt - df).days > 366)