init

app/lib/display.ts

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+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". */
+export 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";
+}
+
+export 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;
+}
+
+export 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));
+}