refactor: organize backend by business responsibility

src/modules/investments/instruments/application/instrument-market.ts

@@ -0,0 +1,46 @@
+import { ServiceUnavailableException } from '@nestjs/common';
+import type {
+  TbankCandle,
+  TbankTimestamp,
+} from '../../../../integrations/tbank/tbank.api';
+export function timestamp(value?: TbankTimestamp): string | null {
+  const seconds = Number(value?.seconds);
+  return Number.isFinite(seconds) && seconds > 0
+    ? new Date(seconds * 1000).toISOString()
+    : null;
+}
+export function moscowDay(iso: string): string {
+  return new Date(Date.parse(iso) + 3 * 3_600_000).toISOString().slice(0, 10);
+}
+export function previousClose(
+  candles: TbankCandle[],
+  priceAt: string,
+): TbankCandle | null {
+  return (
+    candles
+      .filter((candle) => {
+        const time = timestamp(candle.time);
+        return (
+          candle.isComplete &&
+          candle.close &&
+          time &&
+          time.slice(0, 10) < moscowDay(priceAt)
+        );
+      })
+      .sort((a, b) => Number(b.time?.seconds) - Number(a.time?.seconds))[0] ??
+    null
+  );
+}
+export async function optional<T>(
+  operation: () => Promise<T>,
+  name: string,
+  unavailable: string[],
+): Promise<T | null> {
+  try {
+    return await operation();
+  } catch (error) {
+    if (!(error instanceof ServiceUnavailableException)) throw error;
+    unavailable.push(name);
+    return null;
+  }
+}