import frappe, re
from frappe import _
from frappe.utils import cstr
from erpnext.regional.india import states, state_numbers
from erpnext.controllers.taxes_and_totals import get_itemised_tax, get_itemised_taxable_amount

def validate_gstin_for_india(doc, method):
	if not hasattr(doc, 'gstin') or not doc.gstin:
		return

	doc.gstin = doc.gstin.upper().strip()
	if not doc.gstin or doc.gstin == 'NA':
		return

	if len(doc.gstin) != 15:
		frappe.throw(_("Invalid GSTIN! A GSTIN must have 15 characters."))

	p = re.compile("^[0-9]{2}[A-Z]{4}[0-9A-Z]{1}[0-9]{4}[A-Z]{1}[1-9A-Z]{1}[1-9A-Z]{1}[0-9A-Z]{1}$")
	if not p.match(doc.gstin):
		frappe.throw(_("Invalid GSTIN! The input you've entered doesn't match the format of GSTIN."))

	validate_gstin_check_digit(doc.gstin)

	if not doc.gst_state:
		if not doc.state:
			return
		state = doc.state.lower()
		states_lowercase = {s.lower():s for s in states}
		if state in states_lowercase:
			doc.gst_state = states_lowercase[state]
		else:
			return

	doc.gst_state_number = state_numbers[doc.gst_state]
	if doc.gst_state_number != doc.gstin[:2]:
		frappe.throw(_("Invalid GSTIN! First 2 digits of GSTIN should match with State number {0}.")
			.format(doc.gst_state_number))

def validate_gstin_check_digit(gstin):
	''' Function to validate the check digit of the GSTIN.'''
	factor = 1
	total = 0
	code_point_chars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ'
	mod = len(code_point_chars)
	input_chars = gstin[:-1]
	for char in input_chars:
		digit = factor * code_point_chars.find(char)
		digit = (digit // mod) + (digit % mod)
		total += digit
		factor = 2 if factor == 1 else 1
	if gstin[-1] != code_point_chars[((mod - (total % mod)) % mod)]:
		frappe.throw(_("Invalid GSTIN! The check digit validation has failed. " +
			"Please ensure you've typed the GSTIN correctly."))

def get_itemised_tax_breakup_header(item_doctype, tax_accounts):
	if frappe.get_meta(item_doctype).has_field('gst_hsn_code'):
		return [_("HSN/SAC"), _("Taxable Amount")] + tax_accounts
	else:
		return [_("Item"), _("Taxable Amount")] + tax_accounts

def get_itemised_tax_breakup_data(doc):
	itemised_tax = get_itemised_tax(doc.taxes)

	itemised_taxable_amount = get_itemised_taxable_amount(doc.items)

	if not frappe.get_meta(doc.doctype + " Item").has_field('gst_hsn_code'):
		return itemised_tax, itemised_taxable_amount

	item_hsn_map = frappe._dict()
	for d in doc.items:
		item_hsn_map.setdefault(d.item_code or d.item_name, d.get("gst_hsn_code"))

	hsn_tax = {}
	for item, taxes in itemised_tax.items():
		hsn_code = item_hsn_map.get(item)
		hsn_tax.setdefault(hsn_code, frappe._dict())
		for tax_account, tax_detail in taxes.items():
			hsn_tax[hsn_code].setdefault(tax_account, {"tax_rate": 0, "tax_amount": 0})
			hsn_tax[hsn_code][tax_account]["tax_rate"] = tax_detail.get("tax_rate")
			hsn_tax[hsn_code][tax_account]["tax_amount"] += tax_detail.get("tax_amount")

	# set taxable amount
	hsn_taxable_amount = frappe._dict()
	for item, taxable_amount in itemised_taxable_amount.items():
		hsn_code = item_hsn_map.get(item)
		hsn_taxable_amount.setdefault(hsn_code, 0)
		hsn_taxable_amount[hsn_code] += itemised_taxable_amount.get(item)

	return hsn_tax, hsn_taxable_amount

def set_place_of_supply(doc, method):
	if not frappe.get_meta('Address').has_field('gst_state'): return

	if doc.doctype in ("Sales Invoice", "Delivery Note"):
		address_name = doc.shipping_address_name or doc.customer_address
	elif doc.doctype == "Purchase Invoice":
		address_name = doc.shipping_address or doc.supplier_address

	if address_name:
		address = frappe.db.get_value("Address", address_name, ["gst_state", "gst_state_number"], as_dict=1)
		doc.place_of_supply = cstr(address.gst_state_number) + "-" + cstr(address.gst_state)

# don't remove this function it is used in tests
def test_method():
	'''test function'''
	return 'overridden'