feat: add instances handler

handlers/cache.go

@@ -1,6 +1,7 @@
 package handlers
 
 import (
+	"context"
 	"encoding/json"
 	"time"
 
@@ -9,10 +10,10 @@ import (
 )
 
 type cachable interface {
-	data.Album | data.Song | data.Annotation
+	data.Album | data.Song | data.Annotation | []byte
 }
 
-var c, _ = bigcache.NewBigCache(bigcache.DefaultConfig(time.Hour * 24))
+var c, _ = bigcache.New(context.Background(), bigcache.DefaultConfig(time.Hour*24))
 
 func setCache(key string, entry interface{}) error {
 	data, err := json.Marshal(&entry)

handlers/instances.go

@@ -0,0 +1,56 @@
+package handlers
+
+import (
+	"context"
+	"io"
+	"net/http"
+
+	"github.com/rramiachraf/dumb/views"
+	"github.com/sirupsen/logrus"
+)
+
+const ContentTypeJSON = "application/json"
+
+// TODO: move this to utils, so it can be used by other handlers.
+func sendError(err error, status int, msg string, l *logrus.Logger, w http.ResponseWriter) {
+	l.Errorln(err)
+	w.WriteHeader(status)
+	if err := views.ErrorPage(status, msg).Render(context.Background(), w); err != nil {
+		l.Errorln(err)
+	}
+}
+
+func Instances(l *logrus.Logger) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		if instances, err := getCache[[]byte]("instances"); err == nil {
+			w.Header().Set("content-type", ContentTypeJSON)
+			_, err = w.Write(instances)
+			if err == nil {
+				return
+			}
+		}
+
+		res, err := sendRequest("https://raw.githubusercontent.com/rramiachraf/dumb/main/instances.json")
+		if err != nil {
+			sendError(err, http.StatusInternalServerError, "something went wrong", l, w)
+			return
+		}
+
+		defer res.Body.Close()
+
+		instances, err := io.ReadAll(res.Body)
+		if err != nil {
+			sendError(err, http.StatusInternalServerError, "something went wrong", l, w)
+			return
+		}
+
+		w.Header().Set("content-type", ContentTypeJSON)
+		if _, err = w.Write(instances); err != nil {
+			l.Errorln(err)
+		}
+
+		if err = setCache("instances", instances); err != nil {
+			l.Errorln(err)
+		}
+	}
+}