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

from __future__ import unicode_literals

'''
File based locking utility
'''

import os
from time import time
from frappe.utils import get_site_path, touch_file

class LockTimeoutError(Exception):
    pass

def create_lock(name):
	'''Creates a file in the /locks folder by the given name'''
	lock_path = get_lock_path(name)
	if not check_lock(lock_path):
		return touch_file(lock_path)
	else:
		return False

def lock_exists(name):
	'''Returns True if lock of the given name exists'''
	return os.path.exists(get_lock_path(name))

def check_lock(path, timeout=600):
	if not os.path.exists(path):
		return False
	if time() - os.path.getmtime(path) > timeout:
		raise LockTimeoutError(path)
	return True

def delete_lock(name):
	lock_path = get_lock_path(name)
	try:
		os.remove(lock_path)
	except OSError:
		pass
	return True

def get_lock_path(name):
	name = name.lower()
	locks_dir = 'locks'
	lock_path = get_site_path(locks_dir, name + '.lock')
	return lock_path