export const buildInventoryTimeline = (
	weeklyDemand: Array<{
		MaterialHumanReadableId: string;
		WeekStart: string;
		WeeklyDemand: number;
	}>,
	opening: Record<string, number>,
) => {
	// group weekly demand by material
	const grouped: Record<
		string,
		Array<{ WeekStart: string; Demand: number }>
	> = {};

	for (const d of weeklyDemand) {
		const mat = d.MaterialHumanReadableId;
		grouped[mat] ??= [];
		grouped[mat].push({
			WeekStart: d.WeekStart,
			Demand: Number(d.WeeklyDemand),
		});
	}

	// sort weeks chronologically per material
	for (const mat of Object.keys(grouped)) {
		grouped[mat].sort(
			(a, b) =>
				new Date(a.WeekStart).getTime() - new Date(b.WeekStart).getTime(),
		);
	}

	const result: Array<{
		MaterialHumanReadableId: string;
		WeekStart: string;
		OpeningInventory: number;
		Consumption: number;
		ClosingInventory: number;
	}> = [];

	for (const [mat, weeks] of Object.entries(grouped)) {
		// get starting inventory from the ERP result
		let inv = opening[mat] ?? 0;

		for (const w of weeks) {
			const week = w.WeekStart;
			const demand = Number(w.Demand);

			const openingInv = inv;
			const closingInv = openingInv - demand;

			result.push({
				MaterialHumanReadableId: mat,
				WeekStart: week,
				OpeningInventory: Number(openingInv.toFixed(2)),
				Consumption: Number(demand.toFixed(2)),
				ClosingInventory: Number(closingInv.toFixed(2)),
			});

			inv = closingInv;
		}
	}

	return result;
};