// Document lines carry no UOM of their own: every quantity in the system is a count of the
// item's base UOM (FR-MD-02/03). Screens that used to render a per-line UOM picker now show
// the unit as a derived, read-only label — the user still needs to know that "12" means
// 12 bottles, they just cannot change it.

import { ItemListItem, Uom } from "@/types/master-data"

/** Minimal shapes so this works with both `Item` and `ItemListItem`. */
type ItemLike = Pick<ItemListItem, "itemId" | "baseUomId">

/**
 * Display name of an item's base UOM, e.g. "BOTTLE". Returns an em dash when no item is
 * selected yet, and falls back to the raw id if the UOM list has not loaded.
 */
export function baseUomLabel(
  items: readonly ItemLike[],
  uoms: readonly Uom[],
  itemId: number | null | undefined,
): string {
  if (!itemId) return "—"
  const item = items.find((candidate) => candidate.itemId === itemId)
  if (!item) return "—"
  return uoms.find((u) => u.uomId === item.baseUomId)?.name ?? `#${item.baseUomId}`
}

/**
 * Display name for a UOM id that may be absent — an intermediate production output's WIP
 * label, which is null on any output that references a real item.
 */
export function uomLabel(uoms: readonly Uom[], uomId: number | null | undefined): string {
  if (!uomId) return "—"
  return uoms.find((u) => u.uomId === uomId)?.name ?? `#${uomId}`
}

/**
 * The unit an item's content is measured in — "ml" or "g" — or null when the item has no
 * content size. Used to label a production input entered in content units.
 */
export function contentUnitLabel(
  items: readonly Pick<ItemListItem, "itemId" | "contentBaseUnit">[],
  itemId: number | null | undefined,
): string | null {
  if (!itemId) return null
  const unit = items.find((candidate) => candidate.itemId === itemId)?.contentBaseUnit
  return unit ? unit.toLowerCase() : null
}