refactor: enforce frontend view model boundaries

src/shared/lib/display.ts

@@ -4,6 +4,7 @@ const CENTS_PRECISION = 2;
 type FormatMoneyOptions = {
 	withZeroCents?: boolean;
 };
+
 type Money = { currency: string; value: string };
 
 function formatDate(value: string): string {
@@ -21,23 +22,40 @@ function formatDecimal(value: string): string {
 	const digits = sign ? integer.slice(1) : integer;
 	const groupSize = 3;
 	const groups: string[] = [];
+
 	for (let end = digits.length; end > 0; end -= groupSize) {
 		groups.push(digits.slice(Math.max(0, end - groupSize), end));
 	}
+
 	const grouped = groups.toReversed().join(" ");
 	const suffix = fraction ? `,${fraction}` : "";
+
 	return `${sign}${grouped}${suffix}`;
 }
 
 function formatMoney(
-	money: Money | null | undefined,
+	money: Money
+		| null
+		| undefined,
 	{ withZeroCents = false }: FormatMoneyOptions = {},
 ): string {
 	if (!money) return "—";
-	const [integerPart, fractionPart = ""] = money.value.split(".", DECIMAL_PART_COUNT);
-	const normalizedFraction = withZeroCents ? fractionPart.padEnd(CENTS_PRECISION, "0") : fractionPart;
-	const decimal = normalizedFraction ? `${integerPart}.${normalizedFraction}` : integerPart;
+
+	const [integerPart, fractionPart = ""] = money.value.split(
+		".",
+		DECIMAL_PART_COUNT,
+	);
+
+	const normalizedFraction = withZeroCents
+		? fractionPart.padEnd(CENTS_PRECISION, "0")
+		: fractionPart;
+
+	const decimal = normalizedFraction
+		? `${integerPart}.${normalizedFraction}`
+		: integerPart;
+
 	const currency = money.currency === "RUB" ? "₽" : money.currency;
+
 	return `${formatDecimal(decimal)} ${currency}`;
 }
 
@@ -51,14 +69,22 @@ function formatSnapshotTime(value: string): string {
 
 const logoSize = 160;
 
-function instrumentLogoUrl(logoName: null | string | undefined): null | string {
+function formatChartValue(value: number) {
+	return new Intl.NumberFormat("ru-RU", { maximumFractionDigits: 4 }).format(
+		value,
+	);
+}
+
+function instrumentLogoUrl(logoName?: null | string): null | string {
 	const stem = logoName?.trim().replace(/\.png$/i, "");
+
 	return stem
 		? `https://invest-brands.cdn-tinkoff.ru/${stem}x${logoSize}.png`
-		: /* eslint-disable-line unicorn/no-null -- The existing formatter contract uses null for unavailable data. */ null;
+		: null; // eslint-disable-line unicorn/no-null -- The existing formatter contract uses null for unavailable data.
 }
 
 export {
+	formatChartValue,
 	formatDate,
 	formatDecimal,
 	formatMoney,