back-end communication set up, base screen implemented

src/justgetit/backend.py

@@ -0,0 +1,52 @@
+from justgetit.constants import *
+import httpx
+import json
+import toga
+
+
+class BackEnd():
+    """
+    This is the interface for the backend.
+    Its a bit over the top to subclass it from a widget, but this way it has access to the app
+    """
+    application = None
+
+    def __init__(self, app):
+        self.application = app
+
+
+    async def post(self, endpoint, parameters, callback):
+        """
+        Call the server, always with a POST, for a specific endpoint and the parameters
+        in the body
+        
+        :param endpoint: the endpoint without /api/ (no slashes)
+        :param parameters: A dict with the parameters for the call
+        :param callback: def in the calling function to return to
+        """
+        self.status = 0
+        self.payload = None
+        if len(endpoint)>2:
+            try:
+                async with httpx.AsyncClient() as client:
+                    response = await client.post(f"{API}/{endpoint}", data=parameters)
+                self.payload = response.json()
+                self.status = int(self.payload['status'])
+                print(f" payload {self.payload}")
+            except httpx.RequestError as exc:
+                self.status = -2
+            
+            # status 2 means we are in offline mode
+            if self.status == -2:
+                pass
+            elif self.status == 0:
+                await self.application.main_window.dialog(
+                    toga.InfoDialog("Oops", self.payload['message'])            
+                )
+            elif self.status == 2:
+                await self.application.main_window.dialog(
+                    toga.InfoDialog("Thank you", self.payload['message'])            
+                )
+
+            callback(parameters, self.payload)
+