feat(signage-manager): create and edit signage artwork with AI (PPT-2741)

apps/signage-manager/src/app/ai/ai-image.util.ts

@@ -0,0 +1,41 @@
+/** Return the API's string error without leaking response objects to the UI. */
+export function errorMessage(error: unknown, fallback: string): string {
+    if (typeof error === 'string') return error;
+    if (!isRecord(error)) return fallback;
+
+    const nested = error['error'];
+    if (typeof nested === 'string') return nested;
+    if (isRecord(nested)) {
+        const detail = nested['error'];
+        if (typeof detail === 'string') return detail;
+        const nested_message = nested['message'];
+        if (typeof nested_message === 'string') return nested_message;
+    }
+
+    const message = error['message'];
+    return typeof message === 'string' ? message : fallback;
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+    return typeof value === 'object' && value !== null;
+}
+
+/** Return an HTTP status from either the error or its wrapped API response. */
+export function errorStatus(error: unknown): number | undefined {
+    if (!isRecord(error)) return undefined;
+    const status = error['status'];
+    if (typeof status === 'number') return status;
+    const nested = error['error'];
+    if (!isRecord(nested)) return undefined;
+    const nested_status = nested['status'];
+    return typeof nested_status === 'number' ? nested_status : undefined;
+}
+
+/** Perceived sRGB brightness on a 0 to 255 scale. */
+export function perceivedLightness(
+    red: number,
+    green: number,
+    blue: number,
+): number {
+    return (red * 299 + green * 587 + blue * 114) / 1000;
+}