Feature/stats endpoint (#631)

* Idea for stats endpoint

* Introduced /stats endpoint replacing sending data to metrics server

* Removed metrics client

* Removed old metrics file

* cargo fmt

mixnode/src/node/http/mod.rs

@@ -1,4 +1,5 @@
 pub(crate) mod description;
+pub(crate) mod stats;
 pub(crate) mod verloc;
 
 use rocket::Request;

mixnode/src/node/http/stats.rs

@@ -0,0 +1,29 @@
+use crate::node::node_statistics::{NodeStats, NodeStatsSimple, NodeStatsWrapper};
+use rocket::State;
+use rocket_contrib::json::Json;
+use serde::Serialize;
+
+#[derive(Serialize)]
+#[serde(untagged)]
+pub(crate) enum NodeStatsResponse {
+    Full(NodeStats),
+    Simple(NodeStatsSimple),
+}
+
+/// Returns a running stats of the node.
+#[get("/stats?<debug>")]
+pub(crate) async fn stats(
+    stats: State<'_, NodeStatsWrapper>,
+    debug: Option<bool>,
+) -> Json<NodeStatsResponse> {
+    let snapshot_data = stats.clone_data().await;
+
+    // there's no point in returning the entire hashmap of sending destinations in regular mode
+    if let Some(debug) = debug {
+        if debug {
+            return Json(NodeStatsResponse::Full(snapshot_data));
+        }
+    }
+
+    Json(NodeStatsResponse::Simple(snapshot_data.simplify()))
+}