import { describe, expect, it } from "vitest";

/**
 * Mirrors the many-relation grouping fix in prisma-facade queryRelationRows.
 * Keeps the contract local so we don't export private helpers.
 */
function groupRelationRows(
	rows: Array<{ __fk: string; id: number }>,
	mode: "one" | "many",
): Map<string, unknown> {
	const map = new Map<string, unknown>();
	for (const row of rows) {
		const key = String(row.__fk);
		const cleaned = { id: row.id };
		if (mode === "many") {
			const list = map.get(key);
			if (Array.isArray(list)) list.push(cleaned);
			else map.set(key, [cleaned]);
		} else if (!map.has(key)) {
			map.set(key, cleaned);
		}
	}
	return map;
}

describe("prisma-facade relation grouping", () => {
	it("accumulates many rows per parent key", () => {
		const map = groupRelationRows(
			[
				{ __fk: "1", id: 10 },
				{ __fk: "1", id: 11 },
				{ __fk: "2", id: 20 },
			],
			"many",
		);
		expect(map.get("1")).toEqual([{ id: 10 }, { id: 11 }]);
		expect(map.get("2")).toEqual([{ id: 20 }]);
	});

	it("keeps a single row for one relations", () => {
		const map = groupRelationRows(
			[
				{ __fk: "1", id: 10 },
				{ __fk: "1", id: 11 },
			],
			"one",
		);
		expect(map.get("1")).toEqual({ id: 10 });
	});
});