import erpnext
import frappe
from erpnext.accounts.doctype.shipping_rule.shipping_rule import ShippingRule

from default_thai_company.tax_withholding import company_ready, get_or_create_account, thai_companies

# Shipping Rule is named by its label (site-wide unique) but bound to one company,
# so each Thai company gets "<LABEL> - <abbr>", the way ERPNext names accounts and
# tax templates. The label doubles as the charge description on the transaction.
LABEL = "Shipping Charges"

# Shipping billed to customers is revenue; the courier's bill stays an expense.
SHIPPING_ACCOUNT = "Shipping Charges"
SHIPPING_ACCOUNT_GROUPS = ("Direct Income", "Income")


class ThaiShippingRule(ShippingRule):
	def add_shipping_rule_to_tax_table(self, doc, shipping_amount):
		"""A Fixed rule without an amount only seeds the charge row; the amount is
		entered on the transaction. ERPNext re-applies the rule on every
		recalculation, which would otherwise reset the row to 0."""
		manual = self.calculate_based_on == "Fixed" and not self.shipping_amount
		entered = [(row, row.tax_amount) for row in doc.get("taxes")] if manual else ()
		super().add_shipping_rule_to_tax_table(doc, shipping_amount)
		for row, amount in entered:
			row.tax_amount = amount


def shipping_rule_name(company):
	abbr = frappe.get_cached_value("Company", company, "abbr")
	return f"{LABEL} - {abbr}"


def ensure_shipping_rule(company):
	"""Selling Shipping Rule for `company` with the amount entered per
	transaction (see ThaiShippingRule). No-op when the rule exists."""
	name = shipping_rule_name(company)
	if frappe.db.exists("Shipping Rule", name):
		return
	frappe.get_doc(
		{
			"doctype": "Shipping Rule",
			"label": name,
			"company": company,
			"shipping_rule_type": "Selling",
			"calculate_based_on": "Fixed",
			"shipping_amount": 0,
			"account": get_or_create_account(
				company, SHIPPING_ACCOUNT, "Income", "Income Account", SHIPPING_ACCOUNT_GROUPS
			),
			"cost_center": erpnext.get_default_cost_center(company),
		}
	).insert(ignore_permissions=True)


def setup_company(doc, method=None):
	"""Company.on_update: default Shipping Rule for a Thai company."""
	if company_ready(doc):
		ensure_shipping_rule(doc.name)


def setup_companies():
	"""after_install and the create_shipping_rules patch: companies that exist
	before this code did never pass through `setup_company`."""
	for company in thai_companies():
		ensure_shipping_rule(company)