/** Keys used to pick one inventory row when an item has multiple stock-UOM buckets. */
export type InventoryBucketPick = {
  itemId?: number | null;
  itemCode?: string | null;
  itemName?: string | null;
  uomId?: number | null;
  stockUomId?: number | null;
  uom?: string | null;
  shortUom?: string | null;
  stockUom?: string | null;
};

export type InventoryBucketRow = {
  itemId?: number | null;
  itemCode?: string | null;
  itemName?: string | null;
  stockUomId?: number | null;
  uomCode?: string | null;
  uomUdfudesc?: string | null;
  uomShortDesc?: string | null;
  availableQty?: number | null;
  onHandQty?: number | null;
  unavailableQty?: number | null;
};

const norm = (s?: string | null) => (s ?? "").trim().toLowerCase();

/** Available = onHand − unavailable. Do not treat 0 as missing (`||` is wrong). */
export function inventoryAvailableQty(inv: InventoryBucketRow): number {
  if (inv.availableQty != null && !Number.isNaN(Number(inv.availableQty))) {
    return Number(inv.availableQty);
  }
  return Number(inv.onHandQty ?? 0) - Number(inv.unavailableQty ?? 0);
}

function itemMatches(inv: InventoryBucketRow, pick: InventoryBucketPick): boolean {
  if (pick.itemId != null && inv.itemId != null) {
    return Number(inv.itemId) === Number(pick.itemId);
  }
  if (pick.itemCode && inv.itemCode) {
    return inv.itemCode === pick.itemCode;
  }
  if (pick.itemName && inv.itemName) {
    return inv.itemName === pick.itemName;
  }
  return false;
}

function uomMatches(inv: InventoryBucketRow, pick: InventoryBucketPick): boolean {
  const pickUomId = pick.stockUomId ?? pick.uomId;
  if (pickUomId != null && inv.stockUomId != null) {
    return Number(inv.stockUomId) === Number(pickUomId);
  }
  const labels = [pick.uom, pick.shortUom, pick.stockUom].map(norm).filter(Boolean);
  if (labels.length === 0) return true;
  const invLabels = [inv.uomUdfudesc, inv.uomShortDesc, inv.uomCode].map(norm);
  return labels.some((l) => invLabels.includes(l));
}

export function matchInventoryBucket(
  inventories: InventoryBucketRow[],
  pick: InventoryBucketPick,
): InventoryBucketRow | undefined {
  const itemHits = inventories.filter((inv) => itemMatches(inv, pick));
  if (itemHits.length === 0) return undefined;
  const hasUomPick =
    pick.stockUomId != null ||
    pick.uomId != null ||
    [pick.uom, pick.shortUom, pick.stockUom].some((s) => Boolean(norm(s)));
  if (hasUomPick) {
    return itemHits.find((inv) => uomMatches(inv, pick));
  }
  return itemHits[0];
}

export function getStockAvailableFromInventories(
  inventories: InventoryBucketRow[],
  pick: InventoryBucketPick,
): number {
  const inv = matchInventoryBucket(inventories, pick);
  return inv ? inventoryAvailableQty(inv) : 0;
}