type DiffIngredient = { rawName: string; quantity?: string | number | null; unit?: string | null };
type DiffStep = { instruction: string };

const norm = (s: string) => s.trim().toLowerCase();

/** True if an AI-adapted/varied recipe is functionally identical to its
 * source — same servings, same ingredients (name/quantity/unit, in order),
 * same steps. Used to skip persisting a "variation" that changed nothing,
 * which otherwise clutters recipe history with no-op duplicates. */
export function isRecipeUnchanged(
  original: { baseServings: number; ingredients: DiffIngredient[]; steps: DiffStep[] },
  candidate: { baseServings: number; ingredients: DiffIngredient[]; steps: DiffStep[] }
): boolean {
  if (original.baseServings !== candidate.baseServings) return false;
  if (original.ingredients.length !== candidate.ingredients.length) return false;
  if (original.steps.length !== candidate.steps.length) return false;

  for (let i = 0; i < original.ingredients.length; i++) {
    const o = original.ingredients[i]!;
    const c = candidate.ingredients[i]!;
    if (norm(o.rawName) !== norm(c.rawName)) return false;
    if (String(o.quantity ?? "") !== String(c.quantity ?? "")) return false;
    if (norm(o.unit ?? "") !== norm(c.unit ?? "")) return false;
  }

  for (let i = 0; i < original.steps.length; i++) {
    if (norm(original.steps[i]!.instruction) !== norm(candidate.steps[i]!.instruction)) return false;
  }

  return true;
}