Include federation latency

app/modules/latency.py

@@ -1,4 +1,6 @@
 import niobot
+import time
+import httpx
 
 
 class LatencyModule(niobot.Module):
@@ -6,4 +8,17 @@ class LatencyModule(niobot.Module):
     async def latency(self, ctx: niobot.Context):
         """See the bot's latency."""
         latency = ctx.latency
-        return await ctx.respond("Latency: {:,.2f}ms".format(latency))
+
+        homeserver = await niobot.resolve_homeserver(ctx.message.sender.split(":")[1])
+        async with httpx.AsyncClient(headers={"User-Agent": niobot.__user_agent__}) as client:
+            timings = []
+            for rnd in range(5):
+                start = time.time()
+                await client.get(f"{homeserver}/_matrix/client/v1/ping")
+                end = time.time()
+                timings.append(end - start)
+            fed_latency = sum(timings) / len(timings) * 1000
+
+        return await ctx.respond(
+            "Latency: {:,.2f}ms (federation latency to your homeserver: {:,.2f})".format(latency, fed_latency)
+        )