From 6d20598706c250fd2bbe88b26ddd247e97754740 Mon Sep 17 00:00:00 2001
From: Dmitry Kokorin <d.kokorin@npp-crts.ru>
Date: Mon, 5 Jul 2021 17:40:45 +0300
Subject: [PATCH] Python: rest_api

---
 python/rest-api/rest_api.py | 104 ++++++++++++++++++++----------------
 1 file changed, 58 insertions(+), 46 deletions(-)

diff --git a/python/rest-api/rest_api.py b/python/rest-api/rest_api.py
index d798626..cc709df 100644
--- a/python/rest-api/rest_api.py
+++ b/python/rest-api/rest_api.py
@@ -1,11 +1,56 @@
 import json
 from collections import defaultdict
+from copy import copy
 from functools import wraps
 from operator import attrgetter
 
 VALID_HTTP_METHODS = ['GET', 'POST']
 
 
+class ApiMethodRegistry:
+    def __init__(self):
+        self.methods = {k: {} for k in VALID_HTTP_METHODS}
+
+    def register_url(self, url, http_method):
+
+        def actual_decorator(f):
+
+            @wraps(f)
+            def _wrapper(f_self, payload):
+
+                if payload:
+                    payload = json.loads(payload)
+                    #  It would be essential to validate JSON schema here
+
+                f_result = f(f_self, payload)
+
+                return json.dumps(f_result,
+                                  default=lambda obj: obj.__dict__,
+                                  sort_keys=True)
+
+            self.methods[http_method][url] = _wrapper
+
+        return actual_decorator
+
+
+class RestApiBase:
+
+    registry = ApiMethodRegistry()
+
+    def _process_request(self, method, url, payload):
+        methods = self.registry.methods[method]
+
+        #  It would be natural to handle exceptions here
+        if url in methods.keys():
+            return methods[url](self, payload)
+
+    def get(self, url, payload=None):
+        return self._process_request('GET', url, payload)
+
+    def post(self, url, payload=None):
+        return self._process_request('POST', url, payload)
+
+
 class User:
     def __init__(self, name):
         self.name = name
@@ -40,59 +85,26 @@ class User:
         return user
 
 
-class MethodRegistry:
-    def __init__(self):
-        self.methods = {k: {} for k in VALID_HTTP_METHODS }
+class RestAPI(RestApiBase):
 
-    def register_url(self, url, http_method):
-
-        def actual_decorator(f):
-
-            @wraps(f)
-            def _wrapper(f_self, payload):
-
-                if payload:
-                    payload = json.loads(payload)
-                    #It would be essential to validate JSON schema here
-
-                f_result = f(f_self, payload)
-
-                return json.dumps(f_result, default=lambda obj: obj.__dict__, sort_keys=True)
-
-            self.methods[http_method][url] = _wrapper
-
-        return actual_decorator
-
-
-class RestAPI:
-
-    registry = MethodRegistry()
+    registry = copy(RestApiBase.registry)
 
     def __init__(self, database=None):
-        self._users = {user['name'] : User.from_dict(user) for user in database['users']} if database else {}
-
-    def _process_request(self, method, url, payload):
-        methods = self.registry.methods[method]
-
-        #It would be natural to handle exceptions here
-        if url in methods.keys():
-            return methods[url](self, payload)
-
-    def get(self, url, payload=None):
-        return self._process_request('GET', url, payload)
-
-    def post(self, url, payload=None):
-        return self._process_request('POST', url, payload)
+        self._users = {user['name']: User.from_dict(user)
+                       for user in database['users']} if database else {}
 
     @registry.register_url('/users', 'GET')
     def users(self, payload=None):
         if payload:
-            requested_users = payload['users']
-            response = [user for user in self._users.values() if user.name in requested_users]
+            requested_user_names = payload['users']
+            users = [user for user in self._users.values()
+                     if user.name in requested_user_names]
         else:
-            response = [user for user in self._users.values()]
+            users = [user for user in self._users.values()]
 
-        return {'users': response}
+        users = sorted(users, key=attrgetter('name'))
+
+        return {'users': users}
 
     @registry.register_url('/add', 'POST')
     def add(self, payload=None):
@@ -112,5 +124,5 @@ class RestAPI:
         self._users[lender].lend(borrower, amount)
         self._users[borrower].borrow(lender, amount)
 
-        return {'users': sorted([self._users[lender], self._users[borrower]], key=attrgetter('name'))}
-
+        return {'users': sorted([self._users[lender], self._users[borrower]],
+                                key=attrgetter('name'))}