1 files changed, 79 insertions, 0 deletions
diff --git a/system/db/cache.go b/system/db/cache.go
new file mode 100644
index 0000000..5f2dd03
--- /dev/null
+++ b/system/db/cache.go
@@ -0,0 +1,79 @@
+package db
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+)
+
+// CacheControl sets the default cache policy on static asset responses
+func CacheControl(next http.Handler) http.HandlerFunc {
+	return http.HandlerFunc(func(res http.ResponseWriter, req *http.Request) {
+		etag := ConfigCache("etag")
+		policy := fmt.Sprintf("max-age=%d, public", 60*60*24*30)
+		res.Header().Add("ETag", etag)
+		res.Header().Add("Cache-Control", policy)
+
+		if match := req.Header.Get("If-None-Match"); match != "" {
+			if strings.Contains(match, etag) {
+				res.WriteHeader(http.StatusNotModified)
+				return
+			}
+		}
+
+		next.ServeHTTP(res, req)
+	})
+}
+
+// NewEtag generates a new Etag for response caching
+func NewEtag() string {
+	now := fmt.Sprintf("%d", time.Now().Unix())
+	etag := base64.StdEncoding.EncodeToString([]byte(now))
+
+	return etag
+}
+
+// InvalidateCache sets a new Etag for http responses
+func InvalidateCache() error {
+	kv := make(map[string]interface{})
+
+	c, err := ConfigAll()
+	if err != nil {
+		return err
+	}
+
+	err = json.Unmarshal(c, &kv)
+	if err != nil {
+		return err
+	}
+
+	kv["etag"] = NewEtag()
+
+	data := make(url.Values)
+	for k, v := range kv {
+		switch v.(type) {
+		case string:
+			data.Set(k, v.(string))
+		case []string:
+			vv := v.([]string)
+			for i := range vv {
+				if i == 0 {
+					data.Set(k, vv[i])
+				} else {
+					data.Add(k, vv[i])
+				}
+			}
+		}
+	}
+
+	err = SetConfig(data)
+	if err != nil {
+
+	}
+
+	return nil
+}