# Copyright (c) 2015, Frappe Technologies Pvt. Ltd. and Contributors
# License: GNU General Public License v3. See license.txt

from __future__ import unicode_literals
import frappe
import math
from frappe import _
from frappe.utils import (flt, getdate, get_first_day, get_last_day, date_diff,
	add_months, add_days, formatdate, cint)

def get_period_list(from_fiscal_year, to_fiscal_year, periodicity):
	"""Get a list of dict {"from_date": from_date, "to_date": to_date, "key": key, "label": label}
		Periodicity can be (Yearly, Quarterly, Monthly)"""

	fiscal_year = get_fiscal_year_data(from_fiscal_year, to_fiscal_year)
	validate_fiscal_year(fiscal_year, from_fiscal_year, to_fiscal_year)

	# start with first day, so as to avoid year to_dates like 2-April if ever they occur]
	year_start_date = getdate(fiscal_year.year_start_date)
	year_end_date = getdate(fiscal_year.year_end_date)

	months_to_add = {
		"Yearly": 12,
		"Half-Yearly": 6,
		"Quarterly": 3,
		"Monthly": 1
	}[periodicity]

	period_list = []

	start_date = year_start_date
	months = get_months(year_start_date, year_end_date)

	for i in xrange(months / months_to_add):
		period = frappe._dict({
			"from_date": start_date
		})

		to_date = add_months(start_date, months_to_add)
		start_date = to_date

		if to_date == get_first_day(to_date):
			# if to_date is the first day, get the last day of previous month
			to_date = add_days(to_date, -1)
		else:
			# to_date should be the last day of the new to_date's month
			to_date = get_last_day(to_date)

		if to_date <= year_end_date:
			# the normal case
			period.to_date = to_date
		else:
			# if a fiscal year ends before a 12 month period
			period.to_date = year_end_date

		period.to_date_fiscal_year = get_date_fiscal_year(period.to_date)

		period_list.append(period)

		if period.to_date == year_end_date:
			break

	# common processing
	for opts in period_list:
		key = opts["to_date"].strftime("%b_%Y").lower()
		if periodicity == "Monthly":
			label = formatdate(opts["to_date"], "MMM YYYY")
		else:
			label = get_label(periodicity, opts["from_date"], opts["to_date"])
			
		opts.update({
			"key": key.replace(" ", "_").replace("-", "_"),
			"label": label,
			"year_start_date": year_start_date,
			"year_end_date": year_end_date
		})

	return period_list

def get_fiscal_year_data(from_fiscal_year, to_fiscal_year):
	fiscal_year = frappe.db.sql("""select min(year_start_date) as year_start_date, 
		max(year_end_date) as year_end_date from `tabFiscal Year` where 
		name between %(from_fiscal_year)s and %(to_fiscal_year)s""",
		{'from_fiscal_year': from_fiscal_year, 'to_fiscal_year': to_fiscal_year}, as_dict=1)

	return fiscal_year[0] if fiscal_year else {}

def validate_fiscal_year(fiscal_year, from_fiscal_year, to_fiscal_year):
	if not fiscal_year.get('year_start_date') and not fiscal_year.get('year_end_date'):
		frappe.throw(_("End Year cannot be before Start Year"))

def get_months(start_date, end_date):
	diff = (12 * end_date.year + end_date.month) - (12 * start_date.year + start_date.month)
	return diff + 1

def get_label(periodicity, from_date, to_date):
	if periodicity=="Yearly":
		if formatdate(from_date, "YYYY") == formatdate(to_date, "YYYY"):
			label = formatdate(from_date, "YYYY")
		else:
			label = formatdate(from_date, "YYYY") + "-" + formatdate(to_date, "YYYY")
	else:
		label = formatdate(from_date, "MMM YY") + "-" + formatdate(to_date, "MMM YY")

	return label
	
def get_data(company, root_type, balance_must_be, period_list, filters=None,
		accumulated_values=1, only_current_fiscal_year=True, ignore_closing_entries=False,
		ignore_accumulated_values_for_fy=False):
	accounts = get_accounts(company, root_type)
	if not accounts:
		return None

	accounts, accounts_by_name, parent_children_map = filter_accounts(accounts)
	
	company_currency = frappe.db.get_value("Company", company, "default_currency")

	gl_entries_by_account = {}
	for root in frappe.db.sql("""select lft, rgt from tabAccount
			where root_type=%s and ifnull(parent_account, '') = ''""", root_type, as_dict=1):
			
		set_gl_entries_by_account(company, 
			period_list[0]["year_start_date"] if only_current_fiscal_year else None,
			period_list[-1]["to_date"], 
			root.lft, root.rgt, filters,
			gl_entries_by_account, ignore_closing_entries=ignore_closing_entries)

	calculate_values(accounts_by_name, gl_entries_by_account, period_list, accumulated_values, ignore_accumulated_values_for_fy)
	accumulate_values_into_parents(accounts, accounts_by_name, period_list, accumulated_values)
	out = prepare_data(accounts, balance_must_be, period_list, company_currency)
	out = filter_out_zero_value_rows(out, parent_children_map)
	
	if out:
		add_total_row(out, root_type, balance_must_be, period_list, company_currency)

	return out

def calculate_values(accounts_by_name, gl_entries_by_account, period_list, accumulated_values, ignore_accumulated_values_for_fy):
	for entries in gl_entries_by_account.values():
		for entry in entries:
			d = accounts_by_name.get(entry.account)
			for period in period_list:
				# check if posting date is within the period

				if entry.posting_date <= period.to_date:
					if (accumulated_values or entry.posting_date >= period.from_date) and \
						(entry.fiscal_year == period.to_date_fiscal_year or not ignore_accumulated_values_for_fy):
						d[period.key] = d.get(period.key, 0.0) + flt(entry.debit) - flt(entry.credit)

			if entry.posting_date < period_list[0].year_start_date:
				d["opening_balance"] = d.get("opening_balance", 0.0) + flt(entry.debit) - flt(entry.credit)
				
def get_date_fiscal_year(date):
	from erpnext.accounts.utils import get_fiscal_year
	
	return get_fiscal_year(date)[0]

def accumulate_values_into_parents(accounts, accounts_by_name, period_list, accumulated_values):
	"""accumulate children's values in parent accounts"""
	for d in reversed(accounts):
		if d.parent_account:
			for period in period_list:
				accounts_by_name[d.parent_account][period.key] = \
					accounts_by_name[d.parent_account].get(period.key, 0.0) + d.get(period.key, 0.0)
			
			accounts_by_name[d.parent_account]["opening_balance"] = \
				accounts_by_name[d.parent_account].get("opening_balance", 0.0) + d.get("opening_balance", 0.0)

def prepare_data(accounts, balance_must_be, period_list, company_currency):
	data = []
	year_start_date = period_list[0]["year_start_date"].strftime("%Y-%m-%d")
	year_end_date = period_list[-1]["year_end_date"].strftime("%Y-%m-%d")
	
	for d in accounts:
		# add to output
		has_value = False
		total = 0
		row = frappe._dict({
			"account_name": d.account_name,
			"account": d.name,
			"parent_account": d.parent_account,
			"indent": flt(d.indent),
			"year_start_date": year_start_date,
			"year_end_date": year_end_date,
			"currency": company_currency,
			"opening_balance": d.get("opening_balance", 0.0) * (1 if balance_must_be=="Debit" else -1)
		})
		for period in period_list:
			if d.get(period.key) and balance_must_be=="Credit":
				# change sign based on Debit or Credit, since calculation is done using (debit - credit)
				d[period.key] *= -1
		
			row[period.key] = flt(d.get(period.key, 0.0), 3)

			if abs(row[period.key]) >= 0.005:
				# ignore zero values
				has_value = True
				total += flt(row[period.key])

		row["has_value"] = has_value
		row["total"] = total
		data.append(row)
		
	return data
	
def filter_out_zero_value_rows(data, parent_children_map, show_zero_values=False):
	data_with_value = []
	for d in data:
		if show_zero_values or d.get("has_value"):
			data_with_value.append(d)
		else:
			# show group with zero balance, if there are balances against child
			children = [child.name for child in parent_children_map.get(d.get("account")) or []]
			if children:
				for row in data:
					if row.get("account") in children and row.get("has_value"):
						data_with_value.append(d)
						break

	return data_with_value

def add_total_row(out, root_type, balance_must_be, period_list, company_currency):
	total_row = {
		"account_name": "'" + _("Total {0} ({1})").format(root_type, balance_must_be) + "'",
		"account": None,
		"currency": company_currency
	}

	for row in out:
		if not row.get("parent_account"):
			for period in period_list:
				total_row.setdefault(period.key, 0.0)
				total_row[period.key] += row.get(period.key, 0.0)
				row[period.key] = ""
			
			total_row.setdefault("total", 0.0)
			total_row["total"] += flt(row["total"])
			row["total"] = ""
	
	if total_row.has_key("total"):
		out.append(total_row)

		# blank row after Total
		out.append({})

def get_accounts(company, root_type):
	return frappe.db.sql("""select name, parent_account, lft, rgt, root_type, report_type, account_name from `tabAccount`
		where company=%s and root_type=%s order by lft""", (company, root_type), as_dict=True)

def filter_accounts(accounts, depth=10):
	parent_children_map = {}
	accounts_by_name = {}
	for d in accounts:
		accounts_by_name[d.name] = d
		parent_children_map.setdefault(d.parent_account or None, []).append(d)

	filtered_accounts = []

	def add_to_list(parent, level):
		if level < depth:
			children = parent_children_map.get(parent) or []
			if parent == None:
				sort_root_accounts(children)

			for child in children:
				child.indent = level
				filtered_accounts.append(child)
				add_to_list(child.name, level + 1)

	add_to_list(None, 0)

	return filtered_accounts, accounts_by_name, parent_children_map

def sort_root_accounts(roots):
	"""Sort root types as Asset, Liability, Equity, Income, Expense"""

	def compare_roots(a, b):
		if a.report_type != b.report_type and a.report_type == "Balance Sheet":
			return -1
		if a.root_type != b.root_type and a.root_type == "Asset":
			return -1
		if a.root_type == "Liability" and b.root_type == "Equity":
			return -1
		if a.root_type == "Income" and b.root_type == "Expense":
			return -1
		return 1

	roots.sort(compare_roots)

def set_gl_entries_by_account(company, from_date, to_date, root_lft, root_rgt, filters, gl_entries_by_account,
		ignore_closing_entries=False):
	"""Returns a dict like { "account": [gl entries], ... }"""

	additional_conditions = get_additional_conditions(from_date, ignore_closing_entries, filters)

	gl_entries = frappe.db.sql("""select posting_date, account, debit, credit, is_opening, fiscal_year from `tabGL Entry`
		where company=%(company)s
		{additional_conditions}
		and posting_date <= %(to_date)s
		and account in (select name from `tabAccount`
			where lft >= %(lft)s and rgt <= %(rgt)s)
		order by account, posting_date""".format(additional_conditions=additional_conditions),
		{
			"company": company,
			"from_date": from_date,
			"to_date": to_date,
			"lft": root_lft,
			"rgt": root_rgt
		},
		as_dict=True)

	for entry in gl_entries:
		gl_entries_by_account.setdefault(entry.account, []).append(entry)

	return gl_entries_by_account

def get_additional_conditions(from_date, ignore_closing_entries, filters):
	additional_conditions = []

	if ignore_closing_entries:
		additional_conditions.append("ifnull(voucher_type, '')!='Period Closing Voucher'")

	if from_date:
		additional_conditions.append("posting_date >= %(from_date)s")

	if filters:
		for key in ['cost_center', 'project']:
			if filters.get(key):
				additional_conditions.append("%s = '%s'"%(key, filters.get(key)))

	return " and {}".format(" and ".join(additional_conditions)) if additional_conditions else ""

def get_columns(periodicity, period_list, accumulated_values=1, company=None):
	columns = [{
		"fieldname": "account",
		"label": _("Account"),
		"fieldtype": "Link",
		"options": "Account",
		"width": 300
	}]
	if company:
		columns.append({
			"fieldname": "currency",
			"label": _("Currency"),
			"fieldtype": "Link",
			"options": "Currency",
			"hidden": 1
		})
	for period in period_list:
		columns.append({
			"fieldname": period.key,
			"label": period.label,
			"fieldtype": "Currency",
			"options": "currency",
			"width": 150
		})
	if periodicity!="Yearly":
		if not accumulated_values:
			columns.append({
				"fieldname": "total",
				"label": _("Total"),
				"fieldtype": "Currency",
				"width": 150
			})

	return columns