feat: api

app/citizen-frontend/src/utils/api-error.ts

@@ -0,0 +1,47 @@
+import { HTTPError } from "ky";
+
+export interface ApiErrorBody {
+  message?: string;
+  errors?: Record<string, string[]>;
+}
+
+/** 讀取 ky 已解析的 API 錯誤，不重複消耗 response body。 */
+export function getApiErrorBody(error: unknown): ApiErrorBody | null {
+  if (
+    error instanceof HTTPError &&
+    error.data &&
+    typeof error.data === "object"
+  ) {
+    return error.data as ApiErrorBody;
+  }
+
+  return null;
+}
+
+export function getApiErrorStatus(error: unknown): number | null {
+  return error instanceof HTTPError ? error.response.status : null;
+}
+
+export function getApiErrorMessage(
+  error: unknown,
+  fallback = "操作失敗，請稍後再試。",
+): string {
+  const body = getApiErrorBody(error);
+  if (body?.message) {
+    return body.message;
+  }
+
+  const firstFieldError = Object.values(body?.errors ?? {})[0]?.[0];
+  if (firstFieldError) {
+    return firstFieldError;
+  }
+
+  return error instanceof Error ? error.message : fallback;
+}
+
+export function isUnregisteredPhoneError(error: unknown): boolean {
+  return (
+    getApiErrorStatus(error) === 401 &&
+    getApiErrorBody(error)?.message === "手機門號不存在或尚未註冊"
+  );
+}