Get days remaining or passed for particular date. Can add dates/events in json file

daysfor.py

#!/usr/bin/env python
# -*- encoding: utf-8 -*-

import time
import string
from datetime import datetime
from os.path import expanduser, join

import json

json_data_file_name = "days_for.json"
json_data_file_path = expanduser("~")


def is_valid_event_name(event):
	if event[0] in string.digits:
		print "Error: invalid event name '%s'"
		return False

	return True

def is_date_valid(eday):
	try:
		day, month, year = [int(x) for x in eday.split('/')]
		if year < 1900:
			raise InvalidInputException
		ed = datetime(year=year, month=month, day=day)
		return True
	except:
		print "Error: Incorret input: '%s'. Enter valid date in dd/mm/yyyy format." % (eday)
		return False


def get_days_for(eday, from_day=datetime.now()):
	if not is_date_valid:
		return

	day, month, year = [int(x) for x in eday.split('/')]
	ed = datetime(year=year, month=month, day=day)

	if ed > from_day:
		diff_date = ed - from_day
		if diff_date.days > 0:
			print "%d day(s) remaining" % (diff_date.days)
		else:
			print "<1 day remaining"
	else:
		diff_date = from_day - ed
		print "%d day(s) ago" % (diff_date.days)


def read_data():
	return json.load(open( join(json_data_file_path, json_data_file_name) ))


def show_data():
	l = read_data()
	for e in l.keys():
		show_data_for(e, l)


def add_days_for(eday):
	if not is_date_valid(eday):
		return

	event = raw_input("Event: ")
	if not is_valid_event_name(event):
		return
	description = raw_input("Description: ")

	data = {
		"date": eday,
		"description": description,
	}

	l = read_data()
	l[event] = data

	ofile = open(join(json_data_file_path, json_data_file_name), "w")

	print json.dump(l, ofile)


def test_all():

	idays = [
		"26/07/2016", 
		"26/12/2015",
		"26/13/2015",
		"31/12/2016",
		]

	for d in idays:
		get_days_for(d)


def show_data_for(event, data=None):
	if not data:
		data = read_data()

	if event not in data.keys():
		print "Error: event '%s' not found!" % (event)
		return

	print "%s '%s': %s" % (
		data[event]['date'],
		event,
		data[event]['description'],
	)
	get_days_for(data[event]['date'])
	print 


if __name__ == "__main__":
	import sys
	if len(sys.argv) > 1:
		if (sys.argv[1][0] in string.digits) and is_date_valid(sys.argv[1]):
			add_days_for(sys.argv[1])
			show_data()
		else:
			show_data_for(sys.argv[1])
	else:
		show_data()