http_client: add a http request wrapper

This wrapper is an object that may be used to build requests
procedurally rather than submit all request parameters in
a call to "request()", "get()", etc.  This is primarily useful for
usage in a Jinja2 context.

Signed-off-by:  Eric Callahan <arksine.code@gmail.com>

moonraker/components/http_client.py

@@ -12,8 +12,9 @@ import asyncio
 import pathlib
 import tempfile
 import logging
+import copy
 from ..utils import ServerError
-from tornado.escape import url_escape, url_unescape
+from tornado.escape import url_unescape
 from tornado.httpclient import AsyncHTTPClient, HTTPRequest, HTTPError
 from tornado.httputil import HTTPHeaders
 from typing import (
@@ -267,9 +268,59 @@ class HttpClient:
                 return dl.dest_file
         raise self.server.error(f"Retries exceeded for request: {url}")
 
+    def wrap_request(self, default_url: str, **kwargs) -> HttpRequestWrapper:
+        return HttpRequestWrapper(self, default_url, **kwargs)
+
     def close(self):
         self.client.close()
 
+class HttpRequestWrapper:
+    def __init__(
+        self, client: HttpClient, default_url: str, **kwargs
+    ) -> None:
+        self.client = client
+        self._last_response: Optional[HttpResponse] = None
+        self.default_request_args: Dict[str, Any] = {
+            "method": "GET",
+            "url": default_url,
+        }
+        self.default_request_args.update(kwargs)
+        self.request_args = copy.deepcopy(self.default_request_args)
+        self.reset()
+
+    async def send(self, **kwargs) -> HttpResponse:
+        req_args = copy.deepcopy(self.request_args)
+        req_args.update(kwargs)
+        method = req_args.pop("method", self.default_request_args["method"])
+        url = req_args.pop("url", self.default_request_args["url"])
+        self._last_response = await self.client.request(method, url, **req_args)
+        return self._last_response
+
+    def set_method(self, method: str) -> None:
+        self.request_args["method"] = method
+
+    def set_url(self, url: str) -> None:
+        self.request_args["url"] = url
+
+    def set_body(
+        self, body: Optional[Union[str, List[Any], Dict[str, Any]]]
+    ) -> None:
+        self.request_args["body"] = body
+
+    def add_header(self, name: str, value: str) -> None:
+        headers = self.request_args.get("headers", {})
+        headers[name] = value
+        self.request_args["headers"] = headers
+
+    def set_headers(self, headers: Dict[str, str]) -> None:
+        self.request_args["headers"] = headers
+
+    def reset(self) -> None:
+        self.request_args = copy.deepcopy(self.default_request_args)
+
+    def last_response(self) -> Optional[HttpResponse]:
+        return self._last_response
+
 class HttpResponse:
     def __init__(self,
                  url: str,