Free shipping above a total, excluding a collection

api_version = "2026-10"

[[extensions]]
name = "Free shipping above a total, excluding a collection"
handle = "free-shipping-excluding-collection"
type = "function"

  [[extensions.targeting]]
  target = "cart.delivery-options.discounts.generate.run"
  input_query = "src/cart_delivery_options_discounts_generate_run.graphql"
  input_variables = { namespace = "$app", key = "function-configuration" }
  export = "cart-delivery-options-discounts-generate-run"

  [extensions.build]
  command = ""
  path = "dist/function.wasm"

query CartDeliveryOptionsDiscountsGenerateRunInput($excludedCollectionIds: [ID!]) {
  cart {
    lines {
      cost {
        subtotalAmount {
          amount
        }
      }
      merchandise {
        __typename
        ... on ProductVariant {
          product {
            inAnyCollection(ids: $excludedCollectionIds)
          }
        }
      }
    }
    deliveryGroups {
      id
    }
  }
  presentmentCurrencyRate
  discount {
    discountClasses
    metafield(namespace: "$app", key: "function-configuration") {
      jsonValue
    }
  }
}

// @ts-check

/**
 * @typedef {import("../generated/api").CartDeliveryOptionsDiscountsGenerateRunInput} CartDeliveryOptionsDiscountsGenerateRunInput
 * @typedef {import("../generated/api").CartDeliveryOptionsDiscountsGenerateRunResult} CartDeliveryOptionsDiscountsGenerateRunResult
 */

/**
 * Settings stored as JSON in the discount's metafield. The same metafield
 * feeds the query's $excludedCollectionIds variable (see input_variables in
 * shopify.extension.toml), so Shopify checks collection membership.
 */
const DEFAULT_CONFIG = {
  // In the store's currency; converted to the customer's currency below.
  minimumAmount: 1000,
  message: "Free shipping",
};

/** @type {CartDeliveryOptionsDiscountsGenerateRunResult} */
const NO_DISCOUNT = { operations: [] };

/**
 * @param {CartDeliveryOptionsDiscountsGenerateRunInput} input
 * @returns {CartDeliveryOptionsDiscountsGenerateRunResult}
 */
export function cartDeliveryOptionsDiscountsGenerateRun(input) {
  // A Function may only return operations for the classes the discount was created with.
  if (!input.discount.discountClasses.includes("SHIPPING")) return NO_DISCOUNT;
  const config = { ...DEFAULT_CONFIG, ...input.discount.metafield?.jsonValue };

  // Products in an excluded collection (gift cards, sale items, oversized goods)
  // don't count towards the threshold.
  const qualifyingSubtotal = input.cart.lines
    .filter((line) => !(line.merchandise.__typename === "ProductVariant" && line.merchandise.product.inAnyCollection))
    .reduce((sum, line) => sum + Number(line.cost.subtotalAmount.amount), 0);
  const minimum = config.minimumAmount * Number(input.presentmentCurrencyRate);
  if (qualifyingSubtotal < minimum || input.cart.deliveryGroups.length === 0) return NO_DISCOUNT;

  return {
    operations: [
      {
        deliveryDiscountsAdd: {
          candidates: [
            {
              message: config.message,
              targets: input.cart.deliveryGroups.map((group) => ({ deliveryGroup: { id: group.id } })),
              value: { percentage: { value: "100" } },
            },
          ],
          selectionStrategy: "ALL",
        },
      },
    ],
  };
}