munch-ease-frontend/src/components/shopping/shopping.js

export function groupsToItems(groups) {
  return groups.map((group) => group.shoppingListItems).flat()
}

export function uniqueMeals(shoppingListItems) {
  const mealsWithDuplicates = shoppingListItems.map((item) => item.meal).filter((m) => m)

  const mealsLookup = mealsWithDuplicates.reduce((acc, meal) => {
    acc[meal.id] ??= meal
    return acc
  }, {})

  return Object.values(mealsLookup)
}

export function itemsToGroups(shoppingListItems) {
  const ingredients_by_product_id = {}
  const ingredients_by_name = {}
  for (const item of shoppingListItems) {
    if (item.ingredient.product) {
      let group = ingredients_by_product_id[item.ingredient.product.id]
      if (!group) {
        group = ingredients_by_product_id[item.ingredient.product.id] = {
          product: item.ingredient.product,
          shoppingListItems: [],
        }
      }
      group.shoppingListItems.push(item)
    } else {
      let group = ingredients_by_name[item.ingredient.name]
      if (!group) {
        group = ingredients_by_name[item.ingredient.name] = {
          name: item.ingredient.name,
          shoppingListItems: [],
        }
      }
      group.shoppingListItems.push(item)
    }
  }

  return [...Object.values(ingredients_by_product_id), ...Object.values(ingredients_by_name)]
}