# Copyright (c) 2015, Frappe Technologies Pvt. Ltd. and Contributors
# MIT License. See license.txt

from __future__ import unicode_literals
import frappe
import frappe.defaults
import datetime
from frappe.utils import get_datetime

# global values -- used for caching
dateformats = {
	'yyyy-mm-dd': '%Y-%m-%d',
	'mm/dd/yyyy': '%m/%d/%Y',
	'mm-dd-yyyy': '%m-%d-%Y',
	"mm/dd/yy": "%m/%d/%y",
	'dd-mmm-yyyy': '%d-%b-%Y', # numbers app format
	'dd/mm/yyyy': '%d/%m/%Y',
	'dd.mm.yyyy': '%d.%m.%Y',
	'dd-mm-yyyy': '%d-%m-%Y',
	"dd/mm/yy": "%d/%m/%y",
}

def user_to_str(date, date_format=None):
	if not date: return date

	if not date_format:
		date_format = get_user_date_format()

	try:
		return datetime.datetime.strptime(date,
			dateformats[date_format]).strftime('%Y-%m-%d')
	except ValueError as e:
		raise ValueError("Date %s must be in format %s" % (date, date_format))

def parse_date(date):
	"""tries to parse given date to system's format i.e. yyyy-mm-dd. returns a string"""
	parsed_date = None

	if " " in date:
		# as date-timestamp, remove the time part
		date = date.split(" ")[0]

	# why the sorting? checking should be done in a predictable order
	check_formats = [None] + sorted(dateformats.keys(),
		reverse=not get_user_date_format().startswith("dd"))

	for f in check_formats:
		try:
			parsed_date = user_to_str(date, f)
			if parsed_date:
				break
		except ValueError as e:
			pass

	if not parsed_date:
		raise Exception("""Cannot understand date - '%s'.
			Try formatting it like your default format - '%s'""" % (date, get_user_date_format())
		)

	return parsed_date

def get_user_date_format():
	if getattr(frappe.local, "user_date_format", None) is None:
		frappe.local.user_date_format = frappe.defaults.get_global_default("date_format") or "yyyy-mm-dd"

	return frappe.local.user_date_format

def datetime_in_user_format(date_time):
	if not date_time:
		return ""
	if isinstance(date_time, basestring):
		date_time = get_datetime(date_time)
	from frappe.utils import formatdate
	return formatdate(date_time.date()) + " " + date_time.strftime("%H:%M")