Add factory class to create HTTP Clients

Author: samwelkanda

msgraphcore/client_factory.py

@@ -0,0 +1,66 @@
+import functools
+from typing import Optional
+
+from requests import Session
+
+from msgraphcore.constants import CONNECTION_TIMEOUT, REQUEST_TIMEOUT
+from msgraphcore.enums import APIVersion, NationalClouds
+from msgraphcore.middleware.abc_token_credential import TokenCredential
+from msgraphcore.middleware.authorization import AuthorizationHandler
+from msgraphcore.middleware.middleware import BaseMiddleware, MiddlewarePipeline
+
+
+class HTTPClientFactory:
+    """
+    Constructs HTTP Client(session) instances configured with either custom or default
+    pipeline of middleware.
+    """
+    def __init__(self, session: Optional[Session], **kwargs):
+        """Class constructor that accepts a user provided session object and kwargs
+        to configure the request handling behaviour of the client"""
+        self.api_version = kwargs.get("api_version", APIVersion.v1)
+        self.endpoint = kwargs.get('cloud', NationalClouds.Global)
+        self.timeout = kwargs.get('timeout', (CONNECTION_TIMEOUT, REQUEST_TIMEOUT))
+        self.base_url = self._get_base_url()
+        if session:
+            self.session = session
+        else:
+            self.session = Session()
+            self._set_default_timeout()
+
+    # should this be a class method
+    def create_with_default_middleware(self, credential: TokenCredential, **kwargs) -> Session:
+        """Applies the default middleware chain to the HTTP Client"""
+        middleware = [
+            AuthorizationHandler(credential, **kwargs),
+        ]
+        self._register(middleware)
+        return self.session
+
+    def create_with_custom_middleware(self, middleware: [BaseMiddleware]) -> Session:
+        """Applies a custom middleware chain to the HTTP Client """
+        if not middleware:
+            raise ValueError("Please provide a list of custom middleware")
+        self._register(middleware)
+        return self.session
+
+    def _get_base_url(self):
+        """Helper method to get the base url"""
+        return self.endpoint + '/' + self.api_version
+
+    def _set_default_timeout(self):
+        """Helper method to set a default timeout for the session
+        Reference: https://github.com/psf/requests/issues/2011
+        """
+        self.session.request = functools.partial(self.session.request, timeout=self.timeout)
+
+    def _register(self, middleware: [BaseMiddleware]) -> None:
+        """
+        Helper method that constructs a middleware_pipeline with the specified middleware
+        """
+        if middleware:
+            middleware_pipeline = MiddlewarePipeline()
+            for ware in middleware:
+                middleware_pipeline.add_middleware(ware)
+
+            self.session.mount('https://', middleware_pipeline)

msgraphcore/enums.py

@@ -1,3 +1,5 @@
+#pylint: disable=invalid-name
+
 from enum import Enum