CHANGE: Change Error To ProblemDetails

cms/internal/handlers/handlers.go

@@ -10,14 +10,35 @@ func Health(w http.ResponseWriter, r *http.Request) {
 	writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
 }
 
+// problemDetails is an error body in the RFC 9457 "Problem Details for HTTP
+// APIs" format. Type stays "about:blank" — the value RFC 9457 defines for
+// problems with no dedicated documentation URI — which is why Title carries
+// the plain HTTP status phrase and Detail carries the occurrence-specific
+// explanation.
+type problemDetails struct {
+	Type   string `json:"type"`
+	Title  string `json:"title"`
+	Status int    `json:"status"`
+	Detail string `json:"detail,omitempty"`
+}
+
 func writeJSON(w http.ResponseWriter, status int, body any) {
-	w.Header().Set("Content-Type", "application/json")
+	writeJSONContent(w, "application/json", status, body)
+}
+
+func writeProblem(w http.ResponseWriter, status int, detail string) {
+	writeJSONContent(w, "application/problem+json", status, problemDetails{
+		Type:   "about:blank",
+		Title:  http.StatusText(status),
+		Status: status,
+		Detail: detail,
+	})
+}
+
+func writeJSONContent(w http.ResponseWriter, contentType string, status int, body any) {
+	w.Header().Set("Content-Type", contentType)
 	w.WriteHeader(status)
 	if err := json.NewEncoder(w).Encode(body); err != nil {
 		log.Printf("Something Went Wrong Writing The Response: %s", err)
 	}
 }
-
-func writeJSONError(w http.ResponseWriter, status int, message string) {
-	writeJSON(w, status, map[string]string{"error": message})
-}