docs: add comments

main.py

@@ -6,33 +6,43 @@ from fastapi.responses import StreamingResponse
 from pydantic import BaseModel
 import datetime
 
+# Use of Pydantic class for automatic request validation in FastAPI
 class Message(BaseModel):
     message: str
 
 app = FastAPI()
 
+# This middleware allows other origins to communicate with us
 app.add_middleware(
-    CORSMiddleware,
-    allow_origins=["http://localhost:5173"],
-    allow_credentials=True,
-    allow_methods=["*"],
-    allow_headers=["*"],
+    CORSMiddleware, # https://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/CORS
+    allow_origins=["http://localhost:5173"], # address of our UI application
+    allow_methods=["*"], # GET, POST, etc.
 )
 
+# Endpoint to receive messages from the UI
 @app.post("/message")
 async def receive_message(message: Message):
+    """
+    Receives a message from the UI and prints it to the console.
+    """
     print(f"Received message: {message}")
     return { "status": "Message received" }
 
+# Endpoint for Server-Sent Events (SSE)
 @app.get("/sse")
 async def sse_endpoint(request: Request):
+    """
+    Endpoint for Server-Sent Events.
+    """
     async def event_generator():
         while True:
+            # If connection to client closes, stop sending events
             if await request.is_disconnected():
                 break
             
+            # Send message containing current time every second
             current_time = datetime.datetime.now().strftime("%H:%M:%S")
-            yield f"data: Server time: {current_time}\n\n"
+            yield f"data: Server time: {current_time}\n\n" # \n\n is needed to separate events (SSE is text-based)
             await asyncio.sleep(1)
 
-    return StreamingResponse(event_generator(), media_type="text/event-stream")
+    return StreamingResponse(event_generator(), media_type="text/event-stream") # media_type specifies that this connection is for event streams