# Copyright (c) 2013, Web Notes Technologies Pvt. Ltd.
# License: GNU General Public License v3. See license.txt

from __future__ import unicode_literals
import frappe
from frappe import _
from frappe.utils import getdate, nowdate, flt, cint

class AccountsReceivableReport(object):
	def __init__(self, filters=None):
		self.filters = frappe._dict(filters or {})
		self.filters.report_date = getdate(self.filters.report_date or nowdate())
		self.age_as_on = getdate(nowdate()) \
			if self.filters.report_date > getdate(nowdate()) \
			else self.filters.report_date

	def run(self):
		customer_naming_by = frappe.db.get_value("Selling Settings", None, "cust_master_name")
		return self.get_columns(customer_naming_by), self.get_data(customer_naming_by)

	def get_columns(self, customer_naming_by):
		columns = [_("Posting Date") + ":Date:80", _("Customer") + ":Link/Customer:200"]

		if customer_naming_by == "Naming Series":
			columns += ["Customer Name::110"]

		columns += [_("Voucher Type") + "::110", _("Voucher No") + ":Dynamic Link/Voucher Type:120",
			_("Due Date") + ":Date:80", _("Invoiced Amount") + ":Currency:100",
			_("Payment Received") + ":Currency:100", _("Outstanding Amount") + ":Currency:100",
			_("Age") + ":Int:50", "0-" + self.filters.range1 + ":Currency:100",
			self.filters.range1 + "-" + self.filters.range2 + ":Currency:100",
			self.filters.range2 + "-" + self.filters.range3 + ":Currency:100",
			self.filters.range3 + _("-Above") + ":Currency:100",
			_("Territory") + ":Link/Territory:80", _("Remarks") + "::200"
		]

		return columns

	def get_data(self, customer_naming_by):
		from erpnext.accounts.utils import get_currency_precision
		currency_precision = get_currency_precision() or 2

		data = []
		future_vouchers = self.get_entries_after(self.filters.report_date)
		for gle in self.get_entries_till(self.filters.report_date):
			if self.is_receivable(gle, future_vouchers):
				outstanding_amount = self.get_outstanding_amount(gle, self.filters.report_date)
				if abs(outstanding_amount) > 0.1/10**currency_precision:
					due_date = self.get_due_date(gle)
					invoiced_amount = gle.debit if (gle.debit > 0) else 0
					payment_received = invoiced_amount - outstanding_amount

					row = [gle.posting_date, gle.party]
					if customer_naming_by == "Naming Series":
						row += [self.get_customer_name(gle.party)]

					row += [gle.voucher_type, gle.voucher_no, due_date, invoiced_amount,
						payment_received, outstanding_amount]

					entry_date = due_date if self.filters.ageing_based_on == "Due Date" else gle.posting_date
					row += get_ageing_data(cint(self.filters.range1), cint(self.filters.range2), \
						cint(self.filters.range3), self.age_as_on, entry_date, outstanding_amount) + \
						[self.get_territory(gle.account), gle.remarks]

					data.append(row)

		return data

	def get_entries_after(self, report_date):
		# returns a distinct list
		return list(set([(e.voucher_type, e.voucher_no) for e in self.get_gl_entries()
			if getdate(e.posting_date) > report_date]))

	def get_entries_till(self, report_date):
		# returns a generator
		return (e for e in self.get_gl_entries()
			if getdate(e.posting_date) <= report_date)

	def is_receivable(self, gle, future_vouchers):
		return (
			# advance
			(not gle.against_voucher) or

			# against sales order
			(gle.against_voucher_type == "Sales Order") or

			# sales invoice
			(gle.against_voucher==gle.voucher_no and gle.debit > 0) or

			# entries adjusted with future vouchers
			((gle.against_voucher_type, gle.against_voucher) in future_vouchers)
		)

	def get_outstanding_amount(self, gle, report_date):
		payment_received = 0.0
		for e in self.get_gl_entries_for(gle.party, gle.voucher_type, gle.voucher_no):
			if getdate(e.posting_date) <= report_date and e.name!=gle.name:
				payment_received += (flt(e.credit) - flt(e.debit))

		return flt(gle.debit) - flt(gle.credit) - payment_received

	def get_customer_name(self, customer):
		return self.get_customer_map().get(customer, {}).get("customer_name") or ""

	def get_territory(self, customer):
		return self.get_customer_map().get(customer, {}).get("territory") or ""

	def get_customer_map(self):
		if not hasattr(self, "customer_map"):
			self.customer_map = dict(((r.name, r) for r in frappe.db.sql("""select
				name, customer_name, territory from `tabCustomer`""", as_dict=True)))

		return self.customer_map

	def get_due_date(self, gle):
		if not hasattr(self, "invoice_due_date_map"):
			# TODO can be restricted to posting date
			self.invoice_due_date_map = dict(frappe.db.sql("""select name, due_date
				from `tabSales Invoice` where docstatus=1"""))

		return gle.voucher_type == "Sales Invoice" \
			and self.invoice_due_date_map.get(gle.voucher_no) or ""

	def get_gl_entries(self):
		if not hasattr(self, "gl_entries"):
			conditions, values = self.prepare_conditions()
			self.gl_entries = frappe.db.sql("""select * from `tabGL Entry`
				where docstatus < 2 and party_type='Customer' {0}
				order by posting_date, party""".format(conditions), values, as_dict=True)

		return self.gl_entries

	def prepare_conditions(self):
		conditions = [""]
		values = {}

		if self.filters.company:
			conditions.append("company=%(company)s")
			values["company"] = self.filters.company

		if self.filters.customer:
			conditions.append("party=%(customer)s")
			values["customer"] = self.filters.customer

		return " and ".join(conditions), values

	def get_gl_entries_for(self, party, against_voucher_type, against_voucher):
		if not hasattr(self, "gl_entries_map"):
			self.gl_entries_map = {}
			for gle in self.get_gl_entries():
				if gle.against_voucher_type and gle.against_voucher:
					self.gl_entries_map.setdefault(gle.party, {})\
						.setdefault(gle.against_voucher_type, {})\
						.setdefault(gle.against_voucher, [])\
						.append(gle)

		return self.gl_entries_map.get(party, {})\
			.get(against_voucher_type, {})\
			.get(against_voucher, [])

def execute(filters=None):
	return AccountsReceivableReport(filters).run()

def get_ageing_data(first_range, second_range, third_range, age_as_on, entry_date, outstanding_amount):
	# [0-30, 30-60, 60-90, 90-above]
	outstanding_range = [0.0, 0.0, 0.0, 0.0]

	if not (age_as_on and entry_date):
		return [0] + outstanding_range

	age = (getdate(age_as_on) - getdate(entry_date)).days or 0
	index = None
	for i, days in enumerate([first_range, second_range, third_range]):
		if age <= days:
			index = i
			break

	if index is None: index = 3
	outstanding_range[index] = outstanding_amount

	return [age] + outstanding_range