Port `kucoin` backend to `httpx`

piker/brokers/kucoin.py

@@ -16,10 +16,9 @@
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 '''
-Kucoin broker backend
+Kucoin cex API backend.
 
 '''
-
 from contextlib import (
     asynccontextmanager as acm,
     aclosing,
@@ -42,7 +41,7 @@ import wsproto
 from uuid import uuid4
 
 from trio_typing import TaskStatus
-import asks
+import httpx
 from bidict import bidict
 import numpy as np
 import pendulum
@@ -212,7 +211,11 @@ def get_config() -> BrokerConfig | None:
 
 class Client:
 
-    def __init__(self) -> None:
+    def __init__(
+        self,
+        httpx_client: httpx.AsyncClient,
+    ) -> None:
+        self._http: httpx.AsyncClient = httpx_client
         self._config: BrokerConfig|None = get_config()
         self._pairs: dict[str, KucoinMktPair] = {}
         self._fqmes2mktids: bidict[str, str] = bidict()
@@ -227,18 +230,24 @@ class Client:
 
     ) -> dict[str, str | bytes]:
         '''
-        Generate authenticated request headers
+        Generate authenticated request headers:
+
         https://docs.kucoin.com/#authentication
+        https://www.kucoin.com/docs/basic-info/connection-method/authentication/creating-a-request
+        https://www.kucoin.com/docs/basic-info/connection-method/authentication/signing-a-message
 
         '''
-
         if not self._config:
             raise ValueError(
-                'No config found when trying to send authenticated request')
+                'No config found when trying to send authenticated request'
+            )
 
         str_to_sign = (
             str(int(time.time() * 1000))
-            + action + f'/api/{api}/{endpoint.lstrip("/")}'
+            +
+            action
+            +
+            f'/api/{api}/{endpoint.lstrip("/")}'
         )
 
         signature = base64.b64encode(
@@ -249,6 +258,7 @@ class Client:
             ).digest()
         )
 
+        # TODO: can we cache this between calls?
         passphrase = base64.b64encode(
             hmac.new(
                 self._config.key_secret.encode('utf-8'),
@@ -270,8 +280,10 @@ class Client:
         self,
         action: Literal['POST', 'GET'],
         endpoint: str,
+
         api: str = 'v2',
         headers: dict = {},
+
     ) -> Any:
         '''
         Generic request wrapper for Kucoin API
@@ -284,13 +296,17 @@ class Client:
                 api,
             )
 
-        api_url = f'https://api.kucoin.com/api/{api}/{endpoint}'
-
-        res = await asks.request(action, api_url, headers=headers)
-
-        json = res.json()
-        if 'data' in json:
-            return json['data']
+        req_meth: Callable = getattr(
+            self._http,
+            action.lower(),
+        )
+        res = await req_meth(
+            url=f'/{api}/{endpoint}',
+            headers=headers,
+        )
+        json: dict = res.json()
+        if data := json.get('data'):
+            return data
         else:
             log.error(
                 f'Error making request to {api_url} ->\n'
@@ -349,8 +365,8 @@ class Client:
             currencies: dict[str, Currency] = {}
             entries: list[dict] = await self._request(
                 'GET',
-                api='v1',
                 endpoint='currencies',
+                api='v1',
             )
             for entry in entries:
                 curr = Currency(**entry).copy()
@@ -366,7 +382,10 @@ class Client:
         dict[str, KucoinMktPair],
         bidict[str, KucoinMktPair],
     ]:
-        entries = await self._request('GET', 'symbols')
+        entries = await self._request(
+            'GET',
+            endpoint='symbols',
+        )
         log.info(f' {len(entries)} Kucoin market pairs fetched')
 
         pairs: dict[str, KucoinMktPair] = {}
@@ -567,10 +586,18 @@ def fqme_to_kucoin_sym(
 
 @acm
 async def get_client() -> AsyncGenerator[Client, None]:
-    client = Client()
+    '''
+    Load an API `Client` preconfigured from user settings
 
-    async with trio.open_nursery() as n:
-        n.start_soon(client.get_mkt_pairs)
+    '''
+    async with (
+        httpx.AsyncClient(
+            base_url=f'https://api.kucoin.com/api',
+        ) as trio_client,
+    ):
+        client = Client(httpx_client=trio_client)
+        async with trio.open_nursery() as tn:
+            tn.start_soon(client.get_mkt_pairs)
             await client.get_currencies()
 
         yield client