Initial commit: btcdata — BTC data backend service

Split from btcprice monolith. Owns DB, migrations, Binance WebSocket, Kraken OHLC pollers, and exposes a JSON API with SSE price stream. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
2026-02-23 20:07:30 +01:00
commit f64aa98b04
35 changed files with 1079 additions and 0 deletions
@@ -0,0 +1,110 @@
+(ns pmagnus.btcdata.web.routes.api
+  (:require
+   [clojure.data.json :as json]
+   [clojure.string :as str]
+   [integrant.core :as ig]
+   [pmagnus.btcdata.web.controllers.health :as health]
+   [pmagnus.btcdata.web.middleware.exception :as exception]
+   [pmagnus.btcdata.web.middleware.formats :as formats]
+   [reitit.coercion.malli :as malli]
+   [reitit.ring.coercion :as coercion]
+   [reitit.ring.middleware.muuntaja :as muuntaja]
+   [reitit.ring.middleware.parameters :as parameters]
+   [reitit.swagger :as swagger])
+  (:import
+   [io.undertow.server HttpServerExchange]
+   [io.undertow.util HttpString]
+   [java.io BufferedWriter OutputStreamWriter]
+   [java.util.concurrent LinkedBlockingQueue TimeUnit]))
+
+(defn- format-sse [event data]
+  (str "event: " event "\n"
+       (str/join "\n" (map #(str "data: " %) (str/split-lines data)))
+       "\n\n"))
+
+(defn- price->json [{:keys [price prev-price recorded-at]}]
+  (json/write-str
+   {:price       (str price)
+    :prev_price  (when prev-price (str prev-price))
+    :recorded_at (str recorded-at)}))
+
+(defn- price-stream-handler [{:keys [binance]} req]
+  (let [^HttpServerExchange exchange (:server-exchange req)
+        price-atom (:latest-price binance)
+        headers    (.getResponseHeaders exchange)
+        cors-origin (or (System/getenv "CORS_ORIGIN") "*")]
+    (.setStatusCode exchange 200)
+    (.put headers (HttpString. "Content-Type") "text/event-stream")
+    (.put headers (HttpString. "Cache-Control") "no-cache")
+    (.put headers (HttpString. "X-Accel-Buffering") "no")
+    (.put headers (HttpString. "Access-Control-Allow-Origin") cors-origin)
+    (when-not (.isBlocking exchange)
+      (.startBlocking exchange))
+    (let [out    (.getOutputStream exchange)
+          writer (BufferedWriter. (OutputStreamWriter. out "UTF-8"))
+          queue  (LinkedBlockingQueue.)
+          wkey   (keyword (gensym "sse-"))]
+      (add-watch price-atom wkey
+        (fn [_ _ _ v] (.offer queue v)))
+      (when-let [v @price-atom]
+        (.offer queue v))
+      (try
+        (loop []
+          (if-let [v (.poll queue 15 TimeUnit/SECONDS)]
+            (do (.write writer (format-sse "price-update" (price->json v)))
+                (.flush writer))
+            (do (.write writer ": heartbeat\n\n")
+                (.flush writer)))
+          (recur))
+        (catch Exception _)
+        (finally
+          (remove-watch price-atom wkey)
+          (try (.close writer) (catch Exception _)))))
+    nil))
+
+(defn- latest-price-handler [{:keys [binance]} _req]
+  (let [price-atom (:latest-price binance)
+        v          @price-atom]
+    (if v
+      {:status  200
+       :headers {"Content-Type" "application/json"}
+       :body    (price->json v)}
+      {:status  503
+       :headers {"Content-Type" "application/json"}
+       :body    (json/write-str {:error "No price data yet"})})))
+
+(defn- api-routes [opts]
+  [["/swagger.json"
+    {:get {:no-doc  true
+           :swagger {:info {:title "btcdata API"}}
+           :handler (swagger/create-swagger-handler)}}]
+   ["/health"
+    {:get health/healthcheck!}]
+   ["/price/stream"
+    {:get        (fn [req] (price-stream-handler opts req))
+     :no-doc     true
+     :middleware []}]
+   ["/price/latest"
+    {:get (fn [req] (latest-price-handler opts req))}]])
+
+(defn route-data [opts]
+  (merge
+   opts
+   {:coercion   malli/coercion
+    :muuntaja   formats/instance
+    :swagger    {:id ::api}
+    :middleware [parameters/parameters-middleware
+                muuntaja/format-negotiate-middleware
+                muuntaja/format-response-middleware
+                exception/exception-middleware
+                muuntaja/format-request-middleware
+                coercion/coerce-request-middleware
+                coercion/coerce-response-middleware]}))
+
+(derive :reitit.routes/api :reitit/routes)
+
+(defmethod ig/init-key :reitit.routes/api
+  [_ {:keys [base-path]
+      :or   {base-path ""}
+      :as   opts}]
+  [base-path (route-data opts) (api-routes opts)])