add shipping costs with live exchange rates and country detection

Shipping rates fetched from Printify during product sync, converted to
GBP at sync time using frankfurter.app ECB exchange rates with 5%
buffer. Cached in shipping_rates table per blueprint/provider/country.

Cart page shows shipping estimate with country selector (detected from
Accept-Language header, persisted in cookie). Stripe Checkout includes
shipping_options for UK domestic and international delivery. Order
shipping_cost extracted from Stripe on payment.

ScheduledSyncWorker runs every 6 hours via Oban cron to keep rates
and exchange rates fresh. REST_OF_THE_WORLD fallback covers unlisted
countries. 780 tests, 0 failures.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

test/simpleshop_theme/shipping_test.exs

@@ -0,0 +1,310 @@
+defmodule SimpleshopTheme.ShippingTest do
+  use SimpleshopTheme.DataCase, async: false
+
+  alias SimpleshopTheme.Shipping
+  alias SimpleshopTheme.Shipping.ShippingRate
+
+  import SimpleshopTheme.ProductsFixtures
+
+  describe "upsert_rates/2" do
+    test "inserts new rates" do
+      conn = provider_connection_fixture()
+
+      rates = [
+        %{
+          blueprint_id: 100,
+          print_provider_id: 200,
+          country_code: "GB",
+          first_item_cost: 450,
+          additional_item_cost: 100,
+          currency: "GBP"
+        },
+        %{
+          blueprint_id: 100,
+          print_provider_id: 200,
+          country_code: "US",
+          first_item_cost: 650,
+          additional_item_cost: 150,
+          currency: "USD"
+        }
+      ]
+
+      assert {:ok, 2} = Shipping.upsert_rates(conn.id, rates)
+      assert Repo.aggregate(ShippingRate, :count) == 2
+    end
+
+    test "replaces existing rates on conflict" do
+      conn = provider_connection_fixture()
+
+      rates = [
+        %{
+          blueprint_id: 100,
+          print_provider_id: 200,
+          country_code: "GB",
+          first_item_cost: 450,
+          additional_item_cost: 100,
+          currency: "GBP"
+        }
+      ]
+
+      {:ok, 1} = Shipping.upsert_rates(conn.id, rates)
+
+      updated_rates = [
+        %{
+          blueprint_id: 100,
+          print_provider_id: 200,
+          country_code: "GB",
+          first_item_cost: 550,
+          additional_item_cost: 200,
+          currency: "GBP"
+        }
+      ]
+
+      {:ok, 1} = Shipping.upsert_rates(conn.id, updated_rates)
+
+      assert Repo.aggregate(ShippingRate, :count) == 1
+      rate = Repo.one(ShippingRate)
+      assert rate.first_item_cost == 550
+      assert rate.additional_item_cost == 200
+    end
+  end
+
+  describe "get_rate/3" do
+    test "returns rate when it exists" do
+      conn = provider_connection_fixture()
+
+      {:ok, _} =
+        Shipping.upsert_rates(conn.id, [
+          %{
+            blueprint_id: 100,
+            print_provider_id: 200,
+            country_code: "GB",
+            first_item_cost: 450,
+            additional_item_cost: 100,
+            currency: "GBP"
+          }
+        ])
+
+      rate = Shipping.get_rate(100, 200, "GB")
+      assert rate.first_item_cost == 450
+      assert rate.country_code == "GB"
+    end
+
+    test "returns nil when no rate exists" do
+      assert Shipping.get_rate(999, 999, "XX") == nil
+    end
+  end
+
+  describe "calculate_for_cart/2" do
+    test "returns {:ok, 0} for empty cart" do
+      assert {:ok, 0} = Shipping.calculate_for_cart([], "GB")
+    end
+
+    test "calculates shipping for single item" do
+      conn = provider_connection_fixture()
+
+      product =
+        product_fixture(%{
+          provider_connection: conn,
+          provider_data: %{"blueprint_id" => 100, "print_provider_id" => 200}
+        })
+
+      variant = product_variant_fixture(%{product: product})
+
+      {:ok, _} =
+        Shipping.upsert_rates(conn.id, [
+          %{
+            blueprint_id: 100,
+            print_provider_id: 200,
+            country_code: "GB",
+            first_item_cost: 450,
+            additional_item_cost: 100,
+            currency: "GBP"
+          }
+        ])
+
+      cart_items = [%{variant_id: variant.id, quantity: 1}]
+      assert {:ok, 450} = Shipping.calculate_for_cart(cart_items, "GB")
+    end
+
+    test "calculates shipping for multiple quantities" do
+      conn = provider_connection_fixture()
+
+      product =
+        product_fixture(%{
+          provider_connection: conn,
+          provider_data: %{"blueprint_id" => 100, "print_provider_id" => 200}
+        })
+
+      variant = product_variant_fixture(%{product: product})
+
+      {:ok, _} =
+        Shipping.upsert_rates(conn.id, [
+          %{
+            blueprint_id: 100,
+            print_provider_id: 200,
+            country_code: "GB",
+            first_item_cost: 450,
+            additional_item_cost: 100,
+            currency: "GBP"
+          }
+        ])
+
+      cart_items = [%{variant_id: variant.id, quantity: 3}]
+      # first_item_cost + 2 * additional_item_cost = 450 + 200 = 650
+      assert {:ok, 650} = Shipping.calculate_for_cart(cart_items, "GB")
+    end
+
+    test "returns error when no rates found" do
+      conn = provider_connection_fixture()
+
+      product =
+        product_fixture(%{
+          provider_connection: conn,
+          provider_data: %{"blueprint_id" => 100, "print_provider_id" => 200}
+        })
+
+      variant = product_variant_fixture(%{product: product})
+
+      cart_items = [%{variant_id: variant.id, quantity: 1}]
+      assert {:error, :rates_not_found} = Shipping.calculate_for_cart(cart_items, "XX")
+    end
+
+    test "groups items by print provider" do
+      conn = provider_connection_fixture()
+
+      product1 =
+        product_fixture(%{
+          provider_connection: conn,
+          provider_data: %{"blueprint_id" => 100, "print_provider_id" => 200}
+        })
+
+      product2 =
+        product_fixture(%{
+          provider_connection: conn,
+          provider_data: %{"blueprint_id" => 101, "print_provider_id" => 200}
+        })
+
+      variant1 = product_variant_fixture(%{product: product1})
+      variant2 = product_variant_fixture(%{product: product2})
+
+      {:ok, _} =
+        Shipping.upsert_rates(conn.id, [
+          %{
+            blueprint_id: 100,
+            print_provider_id: 200,
+            country_code: "GB",
+            first_item_cost: 450,
+            additional_item_cost: 100,
+            currency: "GBP"
+          },
+          %{
+            blueprint_id: 101,
+            print_provider_id: 200,
+            country_code: "GB",
+            first_item_cost: 500,
+            additional_item_cost: 150,
+            currency: "GBP"
+          }
+        ])
+
+      cart_items = [
+        %{variant_id: variant1.id, quantity: 1},
+        %{variant_id: variant2.id, quantity: 1}
+      ]
+
+      # Same provider: highest first_item_cost (500) + 1 additional item cost
+      assert {:ok, cost} = Shipping.calculate_for_cart(cart_items, "GB")
+      # 500 (highest first item) + one additional item cost (100 or 150)
+      assert cost in [600, 650]
+    end
+  end
+
+  describe "upsert_rates/3 with exchange rates" do
+    test "converts rates to GBP at sync time with buffer" do
+      conn = provider_connection_fixture()
+      exchange_rates = %{"USD" => 0.80}
+
+      rates = [
+        %{
+          blueprint_id: 100,
+          print_provider_id: 1,
+          country_code: "US",
+          first_item_cost: 1000,
+          additional_item_cost: 500,
+          currency: "USD"
+        }
+      ]
+
+      {:ok, 1} = Shipping.upsert_rates(conn.id, rates, exchange_rates)
+
+      rate = Shipping.get_rate(100, 1, "US")
+      assert rate.currency == "GBP"
+      # 1000 USD cents * 0.80 rate * 1.05 buffer, ceil'd
+      assert rate.first_item_cost == 841
+      assert rate.additional_item_cost == 421
+    end
+
+    test "leaves GBP rates unconverted" do
+      conn = provider_connection_fixture()
+      exchange_rates = %{"USD" => 0.80}
+
+      rates = [
+        %{
+          blueprint_id: 100,
+          print_provider_id: 1,
+          country_code: "GB",
+          first_item_cost: 500,
+          additional_item_cost: 200,
+          currency: "GBP"
+        }
+      ]
+
+      {:ok, 1} = Shipping.upsert_rates(conn.id, rates, exchange_rates)
+
+      rate = Shipping.get_rate(100, 1, "GB")
+      assert rate.currency == "GBP"
+      assert rate.first_item_cost == 500
+      assert rate.additional_item_cost == 200
+    end
+  end
+
+  describe "list_available_countries/0" do
+    test "returns distinct country codes" do
+      conn = provider_connection_fixture()
+
+      {:ok, _} =
+        Shipping.upsert_rates(conn.id, [
+          %{
+            blueprint_id: 100,
+            print_provider_id: 200,
+            country_code: "GB",
+            first_item_cost: 450,
+            additional_item_cost: 100,
+            currency: "GBP"
+          },
+          %{
+            blueprint_id: 100,
+            print_provider_id: 200,
+            country_code: "US",
+            first_item_cost: 650,
+            additional_item_cost: 150,
+            currency: "USD"
+          },
+          %{
+            blueprint_id: 101,
+            print_provider_id: 200,
+            country_code: "GB",
+            first_item_cost: 500,
+            additional_item_cost: 100,
+            currency: "GBP"
+          }
+        ])
+
+      countries = Shipping.list_available_countries()
+      assert "GB" in countries
+      assert "US" in countries
+      assert length(countries) == 2
+    end
+  end
+end

test/simpleshop_theme/sync/scheduled_sync_worker_test.exs

@@ -0,0 +1,40 @@
+defmodule SimpleshopTheme.Sync.ScheduledSyncWorkerTest do
+  use SimpleshopTheme.DataCase, async: false
+  use Oban.Testing, repo: SimpleshopTheme.Repo
+
+  alias SimpleshopTheme.Sync.ScheduledSyncWorker
+  alias SimpleshopTheme.Sync.ProductSyncWorker
+
+  import SimpleshopTheme.ProductsFixtures
+
+  describe "perform/1" do
+    test "enqueues sync for enabled connections" do
+      conn = provider_connection_fixture(%{enabled: true})
+
+      Oban.Testing.with_testing_mode(:manual, fn ->
+        assert :ok = perform_job(ScheduledSyncWorker, %{})
+
+        assert_enqueued(
+          worker: ProductSyncWorker,
+          args: %{provider_connection_id: conn.id}
+        )
+      end)
+    end
+
+    test "skips disabled connections" do
+      _conn = provider_connection_fixture(%{enabled: false})
+
+      Oban.Testing.with_testing_mode(:manual, fn ->
+        assert :ok = perform_job(ScheduledSyncWorker, %{})
+        refute_enqueued(worker: ProductSyncWorker)
+      end)
+    end
+
+    test "handles no connections gracefully" do
+      Oban.Testing.with_testing_mode(:manual, fn ->
+        assert :ok = perform_job(ScheduledSyncWorker, %{})
+        refute_enqueued(worker: ProductSyncWorker)
+      end)
+    end
+  end
+end

test/simpleshop_theme_web/plugs/country_detect_test.exs

@@ -0,0 +1,99 @@
+defmodule SimpleshopThemeWeb.Plugs.CountryDetectTest do
+  use SimpleshopThemeWeb.ConnCase, async: true
+
+  alias SimpleshopThemeWeb.Plugs.CountryDetect
+
+  defp with_cookies(conn) do
+    Plug.Conn.fetch_cookies(conn)
+  end
+
+  describe "call/2" do
+    test "detects GB from en-GB header", %{conn: conn} do
+      conn =
+        conn
+        |> init_test_session(%{})
+        |> with_cookies()
+        |> put_req_header("accept-language", "en-GB,en;q=0.9")
+        |> CountryDetect.call([])
+
+      assert get_session(conn, "country_code") == "GB"
+    end
+
+    test "detects DE from de-DE header", %{conn: conn} do
+      conn =
+        conn
+        |> init_test_session(%{})
+        |> with_cookies()
+        |> put_req_header("accept-language", "de-DE,de;q=0.9,en;q=0.8")
+        |> CountryDetect.call([])
+
+      assert get_session(conn, "country_code") == "DE"
+    end
+
+    test "detects FR from fr-FR header", %{conn: conn} do
+      conn =
+        conn
+        |> init_test_session(%{})
+        |> with_cookies()
+        |> put_req_header("accept-language", "fr-FR,fr;q=0.9")
+        |> CountryDetect.call([])
+
+      assert get_session(conn, "country_code") == "FR"
+    end
+
+    test "defaults to GB when no country in header", %{conn: conn} do
+      conn =
+        conn
+        |> init_test_session(%{})
+        |> with_cookies()
+        |> put_req_header("accept-language", "en;q=0.9")
+        |> CountryDetect.call([])
+
+      assert get_session(conn, "country_code") == "GB"
+    end
+
+    test "defaults to GB when no Accept-Language header", %{conn: conn} do
+      conn =
+        conn
+        |> init_test_session(%{})
+        |> with_cookies()
+        |> CountryDetect.call([])
+
+      assert get_session(conn, "country_code") == "GB"
+    end
+
+    test "does not overwrite existing country_code in session", %{conn: conn} do
+      conn =
+        conn
+        |> init_test_session(%{"country_code" => "US"})
+        |> with_cookies()
+        |> put_req_header("accept-language", "en-GB,en;q=0.9")
+        |> CountryDetect.call([])
+
+      assert get_session(conn, "country_code") == "US"
+    end
+
+    test "cookie overrides session country", %{conn: conn} do
+      conn =
+        conn
+        |> init_test_session(%{"country_code" => "GB"})
+        |> put_req_cookie("shipping_country", "DE")
+        |> with_cookies()
+        |> CountryDetect.call([])
+
+      assert get_session(conn, "country_code") == "DE"
+    end
+
+    test "cookie overrides Accept-Language detection", %{conn: conn} do
+      conn =
+        conn
+        |> init_test_session(%{})
+        |> put_req_cookie("shipping_country", "US")
+        |> with_cookies()
+        |> put_req_header("accept-language", "en-GB,en;q=0.9")
+        |> CountryDetect.call([])
+
+      assert get_session(conn, "country_code") == "US"
+    end
+  end
+end