at-container-registry/pkg/hold/admin/errors.go

package admin

import (
	"encoding/json"
	"log/slog"
	"net/http"
)

// renderHTMXError sends an error response suitable for htmx. For htmx
// requests it sets HX-Trigger so the client fires a toast; the global
// htmx:responseError listener in main.js is the fallback for non-triggering
// handlers. For plain browsers it degrades to http.Error. serverErr is
// logged but never exposed — pass userMsg for anything user-visible.
func renderHTMXError(w http.ResponseWriter, r *http.Request, status int, userMsg string, serverErr error) {
	if serverErr != nil {
		slog.Error("admin htmx handler error",
			"path", r.URL.Path,
			"status", status,
			"err", serverErr,
		)
	}
	if userMsg == "" {
		userMsg = http.StatusText(status)
	}
	if r.Header.Get("HX-Request") == "true" {
		trigger := map[string]map[string]string{
			"toast": {"message": userMsg, "type": "error"},
		}
		if b, err := json.Marshal(trigger); err == nil {
			w.Header().Set("HX-Trigger", string(b))
		}
		w.Header().Set("HX-Reswap", "none")
		w.WriteHeader(status)
		return
	}
	http.Error(w, userMsg, status)
}