Enable client to operate against different API instances (#41)

Author: glasperfan

scaleapi/__init__.py

@@ -44,8 +44,10 @@ class Batchlist(Paginator[Batch]):
 class ScaleClient:
     """Main class serves as an interface for Scale API"""
 
-    def __init__(self, api_key, source=None):
-        self.api = Api(api_key, source)
+    def __init__(self, api_key, source=None, api_instance_url=None):
+        self.api = Api(
+            api_key, user_agent_extension=source, api_instance_url=api_instance_url
+        )
 
     def get_task(self, task_id: str) -> Task:
         """Fetches a task.

scaleapi/api.py

@@ -7,7 +7,7 @@
 from ._version import __package_name__, __version__
 from .exceptions import ExceptionMap, ScaleException
 
-SCALE_ENDPOINT = "https://api.scale.com/v1"
+SCALE_API_BASE_URL_V1 = "https://api.scale.com/v1"
 
 # Parameters for HTTP retry
 HTTP_TOTAL_RETRIES = 3  # Number of total retries
@@ -19,7 +19,7 @@
 class Api:
     """Internal Api reference for handling http operations"""
 
-    def __init__(self, api_key, user_agent_extension=None):
+    def __init__(self, api_key, user_agent_extension=None, api_instance_url=None):
         if api_key == "" or api_key is None:
             raise ScaleException("Please provide a valid API Key.")
 
@@ -33,6 +33,7 @@ def __init__(self, api_key, user_agent_extension=None):
         self._headers_multipart_form_data = {
             "User-Agent": self._generate_useragent(user_agent_extension),
         }
+        self.base_api_url = api_instance_url or SCALE_API_BASE_URL_V1
 
     @staticmethod
     def _http_request(
@@ -101,7 +102,7 @@ def _api_request(
     ):
         """Generic HTTP request method with error handling."""
 
-        url = f"{SCALE_ENDPOINT}/{endpoint}"
+        url = f"{self.base_api_url}/{endpoint}"
 
         res = self._http_request(method, url, headers, auth, params, body, files, data)