1 files changed, 49 insertions, 0 deletions
diff --git a/services/docker/mail-server/aws-sendmail/util.ts b/services/docker/mail-server/aws-sendmail/util.ts
new file mode 100644
index 0000000..1411840
--- /dev/null
+++ b/services/docker/mail-server/aws-sendmail/util.ts
@@ -0,0 +1,49 @@
+function getZonedDateTime(instant?: Temporal.Instant | Date) {
+  if (instant == null) {
+    instant = Temporal.Now.instant();
+  } else if (instant instanceof Date) {
+    instant = instant.toTemporalInstant();
+  }
+
+  return instant.toZonedDateTimeISO("UTC");
+}
+
+export function generateTimeStringForFileName(
+  instant?: Temporal.Instant | Date,
+  dateOnly: boolean = false,
+): string {
+  const time = getZonedDateTime(instant);
+
+  if (dateOnly) {
+    return time.toPlainDate().toString();
+  } else {
+    return time.toPlainDateTime().toString().replaceAll(/:|\./g, "-");
+  }
+}
+
+export function transformProperties<T extends object, N>(
+  object: T,
+  transformer: (value: T[keyof T], key: keyof T) => N,
+): { [k in keyof T]: N } {
+  return Object.fromEntries(
+    Object.entries(object).map((
+      [k, v],
+    ) => [k, transformer(v, k as keyof T)]),
+  ) as { [k in keyof T]: N };
+}
+
+export function createSingleton<T>(
+  name: string,
+): [() => T, (v: T | null) => void] {
+  let singleton: T | null = null;
+
+  return [
+    () => {
+      if (singleton == null) {
+        throw new Error(`Singleton ${name} is not set now.`);
+      }
+      return singleton;
+    },
+    (newValue: T | null) => singleton = newValue,
+  ];
+}