refactor: clarify frontend model ownership

src/pages/account/model/positions.ts

@@ -0,0 +1,177 @@
+import { formatShare, type Portfolio } from "@/entities/portfolio";
+import { formatMoney, instrumentLogoUrl } from "@/shared/lib";
+
+type AccountPagePosition = Portfolio["positions"][number] & {
+	instrumentTo?: string;
+	logoSrc: null | string;
+	returnText: null | string;
+	returnTone?: AccountPageReturnTone;
+	shareText: null | string;
+};
+
+type AccountPagePositionGroup = {
+	key: string;
+	positions: AccountPagePosition[];
+};
+
+type AccountPagePositionSection = {
+	groups: AccountPagePositionGroup[];
+	kind: PositionSectionKind;
+};
+
+type AccountPageReturnTone = "negative" | "positive";
+
+type PositionSectionKind = "bonds"
+	| "other"
+	| "stocks";
+
+function groupPositions(
+	positions: AccountPagePosition[],
+): AccountPagePositionGroup[] {
+	const groups = new Map<string, AccountPagePositionGroup>();
+
+	for (const [index, position] of positions.entries()) {
+		const identity = positionIdentity(position);
+		const rowKey = JSON.stringify(["row", position.account?.id, index]);
+
+		const key
+			= identity && position.account
+				? JSON.stringify([position.type, ...identity])
+				: rowKey;
+
+		const group = groups.get(key);
+
+		if (
+			group
+			&& group.positions.every(
+				item => item.account?.id !== position.account?.id,
+			)
+		) {
+			group.positions.push(position);
+		}
+		else {
+			const uniqueKey = group ? rowKey : key;
+			groups.set(uniqueKey, { key: uniqueKey, positions: [position] });
+		}
+	}
+
+	// eslint-disable-next-line unicorn/prefer-iterator-to-array -- Production targets ES2023; Iterator helpers require a newer browser baseline.
+	return [...groups.values()];
+}
+
+function positionIdentity(position: AccountPagePosition) {
+	if (position.instrumentUid?.trim())
+		return ["uid", position.instrumentUid.trim()];
+	if (position.figi?.trim()) return ["figi", position.figi.trim()];
+
+	return position.isin?.trim() ? ["isin", position.isin.trim()] : undefined;
+}
+
+function toAccountPagePositionSections(
+	portfolio: Portfolio,
+	instrumentDetails: Map<string, undefined
+	| { slug: string }> = new Map(),
+): AccountPagePositionSection[] {
+	const denominators = new Map<string, number>();
+
+	for (const position of portfolio.positions) {
+		if (!position.currentValue) continue;
+		const currency = position.currentValue.currency;
+		denominators.set(
+			currency,
+			(denominators.get(currency) ?? 0) + Number(position.currentValue.value),
+		);
+	}
+
+	const stocks = toSection(
+		"stocks",
+		portfolio,
+		denominators,
+		instrumentDetails,
+	);
+
+	const bonds = toSection("bonds", portfolio, denominators, instrumentDetails);
+	const other = toSection("other", portfolio, denominators, instrumentDetails);
+
+	return [stocks, bonds, other].filter(section => section.groups.length > 0);
+}
+
+function toPosition(
+	position: Portfolio["positions"][number],
+	denominators: Map<string, number>,
+	kind: PositionSectionKind,
+	instrumentSlug?: string,
+): AccountPagePosition {
+	const isExpanded = kind !== "other";
+
+	const returnValue = position.absoluteReturn
+		? Number(position.absoluteReturn.value)
+		: null;
+
+	let returnTone: AccountPageReturnTone | undefined;
+	if (returnValue !== null && returnValue !== 0)
+		returnTone = returnValue > 0 ? "positive" : "negative";
+
+	const returnPrefix
+		= isExpanded && returnValue !== null && returnValue > 0 ? "+" : "";
+
+	return {
+		...position,
+		instrumentTo:
+			(kind === "stocks" || kind === "bonds") && position.instrumentUid
+				? `/${kind}/${encodeURIComponent(instrumentSlug ?? position.instrumentUid)}`
+				: undefined,
+		logoSrc: isExpanded
+			? instrumentLogoUrl(position.logoName)
+			: null,
+		returnText: position.absoluteReturn
+			? `${returnPrefix}${formatMoney(position.absoluteReturn)}`
+			: null,
+		returnTone,
+		shareText: position.currentValue?.currency
+			? formatShare(position.currentValue, {
+					currency: position.currentValue.currency,
+					value: String(denominators.get(position.currentValue.currency) ?? 0),
+				})
+			: null,
+	};
+}
+
+function toSection(
+	kind: PositionSectionKind,
+	portfolio: Portfolio,
+	denominators: Map<string, number>,
+	instrumentDetails: Map<string, undefined
+	| { slug: string }>,
+): AccountPagePositionSection {
+	return {
+		groups: groupPositions(
+			portfolio.positions
+				.filter((position) => {
+					if (kind === "stocks") return position.type === "STOCK";
+
+					return kind === "bonds"
+						? position.type === "BOND"
+						: position.type !== "STOCK"
+							&& position.type !== "BOND"
+							&& position.type !== "CURRENCY";
+				})
+				.map(position =>
+					toPosition(
+						position,
+						denominators,
+						kind,
+						instrumentDetails.get(position.instrumentUid ?? "")?.slug,
+					),
+				),
+		),
+		kind,
+	};
+}
+
+export {
+	type AccountPagePosition,
+	type AccountPagePositionGroup,
+	type AccountPagePositionSection,
+	toAccountPagePositionSections,
+};