// HTTPCachingHandler middleware that provides HTTP level caching
// using the If-None-Match header. If the value of this header contains
// a matching CurrentSHA this handler will write a 304 status and return.
func HTTPCachingHandler(dcdr client.IFace) func(http.Handler) http.Handler {
return func(h http.Handler) http.Handler {
fn := func(w http.ResponseWriter, r *http.Request) {
if sha := dcdr.Info().CurrentSHA; sha != "" {
w.Header().Set(EtagHeader, sha)
}
if date := dcdr.Info().LastModifiedDate; date != 0 {
lmd := time.Unix(date, 0).Format(time.RFC1123)
w.Header().Set(LastModifiedHeader, lmd)
}
SetCacheHeaders(w, r)
if NotModified(dcdr.Info().CurrentSHA, r) {
w.WriteHeader(http.StatusNotModified)
return
}
h.ServeHTTP(w, r)
}
return http.HandlerFunc(fn)
}
}
// ScopeMapFromRequest helper method for returning a FeatureMap scoped to
// the values found in DcdrScopesHeader.
func ScopeMapFromRequest(c client.IFace, r *http.Request) *models.FeatureMap {
return c.WithScopes(GetScopes(r)...).ScopedMap()
}