Demo Taler flow without validating payment yet

app/controllers/payment_gateways/taler_controller.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+module PaymentGateways
+  class TalerController < BaseController
+    include OrderCompletion
+
+    # The Taler merchant backend has taken the payment.
+    # Now we just need to confirm that and update our local database
+    # before finalising the order.
+    def confirm
+      payment = Spree::Payment.find(params[:payment_id])
+      @order = payment.order
+      process_payment_completion!
+    end
+  end
+end

app/models/spree/payment_method/taler.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require "taler"
+
 module Spree
   class PaymentMethod
     # GNU Taler is a distributed, open source payment system.
@@ -32,15 +34,46 @@ module Spree
       # https://backend.demo.taler.net/instances/blog/orders/2026..?token=S8Y..&session_id=b0b..
       def external_payment_url(options)
         order = options.fetch(:order)
-        total_amount = order&.total || 5
-        taler_amount = "KUDOS:#{total_amount}"
-        new_order = client.create_order(taler_amount, "OFN Order", "https://ofn.example.net")
-        order = client.fetch_order(new_order["order_id"])
-        order["order_status_url"]
+        payment = load_payment(order)
+
+        payment.source ||= self
+        payment.response_code ||= create_taler_order(payment)
+        payment.redirect_auth_url ||= fetch_order_url(payment)
+        payment.save! if payment.changed?
+
+        payment.redirect_auth_url
+      end
+
+      def purchase(_money, _creditcard, _gateway_options)
+        # TODO: implement
+        ActiveMerchant::Billing::Response.new(true, "test")
       end
 
       private
 
+      def load_payment(order)
+        order.payments.checkout.where(payment_method: self).last
+      end
+
+      def create_taler_order(payment)
+        # We are ignoring currency for now so that we can test with the
+        # current demo backend only working with the KUDOS currency.
+        taler_amount = "KUDOS:#{payment.amount}"
+        urls = Rails.application.routes.url_helpers
+        new_order = client.create_order(
+          taler_amount,
+          I18n.t("payment_method_taler.order_summary"),
+          urls.payment_gateways_confirm_taler_url(payment_id: payment.id),
+        )
+
+        new_order["order_id"]
+      end
+
+      def fetch_order_url(payment)
+        order = client.fetch_order(payment.response_code)
+        order["order_status_url"]
+      end
+
       def client
         @client ||= ::Taler::Client.new(preferred_backend_url, preferred_api_key)
       end

config/locales/en.yml

@@ -3502,6 +3502,8 @@ en:
   payment_processing_failed: "Payment could not be processed, please check the details you entered"
   payment_method_not_supported: "That payment method is unsupported. Please choose another one."
   payment_updated: "Payment Updated"
+  payment_method_taler:
+    order_summary: "Open Food Network order"
   cannot_perform_operation: "Could not update the payment"
   action_required: "Action required"
   tag_rules: "Tag Rules"

config/routes.rb

@@ -82,6 +82,8 @@ Openfoodnetwork::Application.routes.draw do
 
     get "/stripe/confirm", to: "stripe#confirm", as: :confirm_stripe
     get "/stripe/authorize/:order_number", to: "stripe#authorize", as: :authorize_stripe
+
+    get "/taler/:payment_id", to: "taler#confirm", as: :confirm_taler
   end
 
   get '/checkout', to: 'checkout#edit'

spec/models/spree/payment_method/taler_spec.rb

@@ -11,9 +11,14 @@ RSpec.describe Spree::PaymentMethod::Taler do
   }
 
   describe "external_payment_url", vcr: true do
-    it "retrieves a URL to pay at" do
-      url = subject.external_payment_url(order: nil)
+    it "retrieves a URL to pay at and stores it on the payment record" do
+      order = create(:order_ready_for_confirmation, payment_method: taler)
+      url = subject.external_payment_url(order:)
       expect(url).to match %r{\Ahttps://backend.demo.taler.net/instances/sandb}
+
+      payment = order.payments.last.reload
+      expect(payment.response_code).to match "2026.022-0284X4GE8WKMJ"
+      expect(payment.redirect_auth_url).to eq url
     end
   end
 end

spec/requests/payment_gateways/taler_spec.rb

@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe "/payment_gateways/taler/:id" do
+  it "completes the order" do
+    shop = create(:distributor_enterprise)
+    taler = Spree::PaymentMethod::Taler.create!(
+      name: "Taler",
+      environment: "test",
+      distributors: [shop],
+    )
+    order = create(:order_ready_for_confirmation, payment_method: taler)
+    payment = Spree::Payment.last
+    payment.update!(
+      payment_method: taler,
+      response_code: "taler-order-id:12345",
+      redirect_auth_url: "https://merchant.backend.where-we-paid.com",
+    )
+
+    get payment_gateways_confirm_taler_path(payment_id: payment.id)
+    expect(response).to redirect_to(order_path(order, order_token: order.token))
+
+    payment.reload
+    expect(payment.state).to eq "completed"
+  end
+end