Initial OCS routes, version & format handling

Signed-off-by: Jörn Friedrich Dreyer <jfd@butonic.de>

pkg/middleware/format.go

@@ -0,0 +1,24 @@
+package middleware
+
+import (
+	"context"
+	"net/http"
+
+	"github.com/go-chi/render"
+)
+
+// OCSFormatCtx middleware is used to determine the content type from
+// the format URL parameter passed in an ocs request. Defaults to XML
+func OCSFormatCtx(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Query().Get("format") {
+		case "", "xml":
+			r.Header.Set("Accept", "application/xml")
+			r = r.WithContext(context.WithValue(r.Context(), render.ContentTypeCtxKey, render.ContentTypeXML))
+		case "json":
+			r.Header.Set("Accept", "application/json")
+			r = r.WithContext(context.WithValue(r.Context(), render.ContentTypeCtxKey, render.ContentTypeJSON))
+		}
+		next.ServeHTTP(w, r)
+	})
+}