import type { Recipe, RecipeIngredient } from "@/app/types";
import { CATALOG_BY_ID } from "./catalog";

// ---------------------------------------------------------------------------
// Human-friendly ingredient lines, scaled to a serving count.
//
//   ing("white_rice", 1.5, "cup") for 4 → shown for 2 as "¾ cup  Long Grain White Rice"
//   ing("black_beans", 1, "each")       → "1 ×  Black Beans, canned (15 oz can)"
// ---------------------------------------------------------------------------

const FRACTIONS: [number, string][] = [
  [0, ""],
  [1 / 8, "⅛"],
  [1 / 4, "¼"],
  [1 / 3, "⅓"],
  [1 / 2, "½"],
  [2 / 3, "⅔"],
  [3 / 4, "¾"],
  [1, ""],
];

/** 0.75 → "¾", 1.5 → "1½", 2.33 → "2⅓", 13.2 → "13". */
function formatQuantity(value: number): string {
  if (value >= 10) return String(Math.round(value));
  const whole = Math.floor(value);
  const fraction = value - whole;
  const [nearest, glyph] = FRACTIONS.reduce((best, f) => (Math.abs(f[0] - fraction) < Math.abs(best[0] - fraction) ? f : best));
  const total = whole + (nearest === 1 ? 1 : 0);
  if (total === 0 && glyph === "") return "⅛"; // never show "0" for a real ingredient
  return `${total > 0 ? total : ""}${glyph}` || "0";
}

interface IngredientLine {
  quantity: string;
  /** e.g. "cup", "lb", or "×" for counted items. */
  unit: string;
  name: string;
  /** Package hint for counted items, e.g. "15 oz can". */
  detail?: string;
}

function ingredientLine(ingredient: RecipeIngredient, scale: number): IngredientLine {
  const item = CATALOG_BY_ID.get(ingredient.itemId);
  const name = item?.name ?? ingredient.itemId;
  const quantity = formatQuantity(ingredient.amount * scale);

  if (ingredient.unit === "each") {
    // Single-unit packages (a can, a jar) read better with the package size.
    const detail = item && item.packageSize === 1 && item.packageLabel !== "each" ? item.packageLabel : undefined;
    return { quantity, unit: "×", name, detail };
  }
  return { quantity, unit: ingredient.unit, name };
}

export function ingredientLines(recipe: Recipe, servings: number): IngredientLine[] {
  const scale = servings / recipe.servings;
  return recipe.ingredients.map((i) => ingredientLine(i, scale));
}