From a4d914c7f2c1cbcde85b41d1d81e0b509de7a593 Mon Sep 17 00:00:00 2001
From: bashmak <nerosketch@gmail.com>
Date: Sat, 30 Jun 2018 17:09:14 +0300
Subject: [PATCH] Make  metaclass for lazy init objects

---
 agent/core.py           | 10 ++--------
 agent/mod_mikrotik.py   |  6 +++---
 djing/lib/decorators.py | 37 +++++++++++++++++++++++++++++++++++++
 3 files changed, 42 insertions(+), 11 deletions(-)

diff --git a/agent/core.py b/agent/core.py
index def183f..2ed3110 100644
--- a/agent/core.py
+++ b/agent/core.py
@@ -1,4 +1,4 @@
-from abc import ABCMeta, abstractmethod
+from abc import ABC, abstractmethod
 from typing import Iterator, Any, Tuple, Optional
 
 from .structs import AbonStruct, TariffStruct, VectorAbon, VectorTariff, IpStruct
@@ -15,7 +15,7 @@ class NasNetworkError(Exception):
 
 
 # Communicate with NAS
-class BaseTransmitter(metaclass=ABCMeta):
+class BaseTransmitter(ABC):
     @abstractmethod
     def add_user_range(self, user_list: VectorAbon):
         """add subscribers list to NAS"""
@@ -106,12 +106,6 @@ class BaseTransmitter(metaclass=ABCMeta):
     def sync_nas(self, users_from_db: Iterator):
         list_for_add, list_for_del = self._diff_users(users_from_db)
         if len(list_for_del) > 0:
-            print('FOR DELETE')
-            for ld in list_for_del:
-                print(ld)
             self.remove_user_range(list_for_del)
         if len(list_for_add) > 0:
-            print('FOR ADD')
-            for la in list_for_add:
-                print(la)
             self.add_user_range(list_for_add)
diff --git a/agent/mod_mikrotik.py b/agent/mod_mikrotik.py
index d430632..ca5b9f4 100644
--- a/agent/mod_mikrotik.py
+++ b/agent/mod_mikrotik.py
@@ -1,10 +1,12 @@
 import re
 import socket
 import binascii
+from abc import ABCMeta
 from hashlib import md5
 from ipaddress import ip_network
 from typing import Iterable, Optional, Tuple, Generator, Dict
 
+from djing.lib.decorators import LazyInitMetaclass
 from .structs import TariffStruct, AbonStruct, IpStruct, VectorAbon, VectorTariff
 from . import settings as local_settings
 from django.conf import settings
@@ -30,8 +32,6 @@ class ApiRos(object):
             sk.connect((ip, port or 8728))
             self.sk = sk
 
-        self.currenttag = 0
-
     def login(self, username, pwd):
         if self.is_login:
             return
@@ -172,7 +172,7 @@ class IpAddressListObj(IpStruct):
         self.mk_id = str(mk_id).replace('*', '')
 
 
-class MikrotikTransmitter(BaseTransmitter, ApiRos):
+class MikrotikTransmitter(BaseTransmitter, ApiRos, metaclass=type('_ABC_Lazy_mcs', (ABCMeta, LazyInitMetaclass), {})):
 
     def __init__(self, login=None, password=None, ip=None, port=None):
         ip = ip or getattr(local_settings, 'NAS_IP')
diff --git a/djing/lib/decorators.py b/djing/lib/decorators.py
index 2a69fed..f7c2aad 100644
--- a/djing/lib/decorators.py
+++ b/djing/lib/decorators.py
@@ -55,3 +55,40 @@ def hash_auth_view(fn):
         else:
             return HttpResponseForbidden('Access Denied')
     return wrapped
+
+
+# Lazy initialize metaclass
+class LazyInitMetaclass(type):
+    """
+    Type this metaclass if you want to make your object with lazy initialize.
+    Method __init__ called only when you try to call something method
+    from object of your class.
+    """
+    def __new__(mcs, name: str, bases: tuple, attrs: dict):
+        new_class_new = super(LazyInitMetaclass, mcs).__new__
+
+        def _lazy_call_decorator(fn):
+            def wrapped(self, *args, **kwargs):
+                if not self._is_initialized:
+                    self._lazy_init(*self._args, **self._kwargs)
+                return fn(self, *args, **kwargs)
+
+            return wrapped
+
+        # Apply decorator to all public class methods
+        new_attrs = {k: _lazy_call_decorator(v) for k, v in attrs.items() if not k.startswith('__') and not k.endswith('__') and callable(v)}
+        if new_attrs:
+            attrs.update(new_attrs)
+        attrs['_is_initialized'] = False
+
+        new_class = new_class_new(mcs, name, bases, attrs)
+
+        real_init = getattr(new_class, '__init__')
+
+        def _lazy_init(self, *args, **kwargs):
+            self._args = args
+            self._kwargs = kwargs
+        setattr(new_class, '__init__', _lazy_init)
+        setattr(new_class, '_lazy_init', real_init)
+
+        return new_class