Refactor synth provider and show UI error if not configured

app/models/account/syncable.rb

@@ -8,6 +8,12 @@ def sync_later(start_date = nil)
   def sync(start_date = nil)
     update!(status: "syncing")
 
+    if self.foreign_currency? && !ExchangeRate.exchange_rates_provider.initialized?
+      logger.error("Cancelling sync of foreign account #{id}: No exchange rate provider ready")
+      update!(status: "error")
+      return
+    end
+
     sync_exchange_rates
 
     calc_start_date = start_date - 1.day if start_date.present? && self.balance_on(start_date - 1.day).present?
@@ -21,10 +27,11 @@ def sync(start_date = nil)
     update!(status: "ok", last_sync_date: Date.today, balance: new_balance)
   rescue => e
     update!(status: "error")
-    Rails.logger.error("Failed to sync account #{id}: #{e.message}")
+    logger.error("Failed to sync account #{id}: #{e.message}")
   end
 
   def can_sync?
+    return false if self.foreign_currency? && !ExchangeRate.exchange_rates_provider.initialized?
     # Skip account sync if account is not active or the sync process is already running
     return false unless is_active
     return false if syncing?

app/models/concerns/providable.rb

@@ -7,7 +7,7 @@ module Providable
 
   class_methods do
     def exchange_rates_provider
-      Provider::Synth.new
+      Provider::Synth
     end
 
     def git_repository_provider

app/models/provider/synth.rb

@@ -1,51 +1,62 @@
 class Provider::Synth
-  include Retryable
+  class << self
+    include Retryable
 
-  def initialize(api_key = ENV["SYNTH_API_KEY"])
-    @api_key = api_key || ENV["SYNTH_API_KEY"]
-  end
+    attr_accessor :configuration
 
-  def fetch_exchange_rate(from:, to:, date:)
-    retrying Provider::Base.known_transient_errors do |on_last_attempt|
-      response = Faraday.get("#{base_url}/rates/historical") do |req|
-        req.headers["Authorization"] = "Bearer #{api_key}"
-        req.params["date"] = date.to_s
-        req.params["from"] = from
-        req.params["to"] = to
-      end
+    def initialized?
+      configuration.api_key.present?
+    end
+
+    def configure
+      self.configuration ||= Configuration.new
+      yield(configuration)
+    end
+
+    def fetch_exchange_rate(from:, to:, date:)
+      retrying Provider::Base.known_transient_errors do |on_last_attempt|
+        response = Faraday.get("#{base_url}/rates/historical") do |req|
+          req.headers["Authorization"] = "Bearer #{configuration.api_key}"
+          req.params["date"] = date.to_s
+          req.params["from"] = from
+          req.params["to"] = to
+        end
 
-      if response.success?
-        ExchangeRateResponse.new \
-          rate: JSON.parse(response.body).dig("data", "rates", to),
-          success?: true,
-          raw_response: response
-      else
-        if on_last_attempt
+        if response.success?
           ExchangeRateResponse.new \
-            success?: false,
-            error: build_error(response),
+            rate: JSON.parse(response.body).dig("data", "rates", to),
+            success?: true,
             raw_response: response
         else
-          raise build_error(response)
+          if on_last_attempt
+            ExchangeRateResponse.new \
+              success?: false,
+              error: build_error(response),
+              raw_response: response
+          else
+            raise build_error(response)
+          end
         end
       end
     end
-  end
 
-  private
-    attr_reader :api_key
+    private
+      class Configuration
+        attr_accessor :api_key
+      end
 
-    ExchangeRateResponse = Struct.new :rate, :success?, :error, :raw_response, keyword_init: true
+      ExchangeRateResponse = Struct.new :rate, :success?, :error, :raw_response, keyword_init: true
 
-    def base_url
-      "https://api.synthfinance.com"
-    end
+      def base_url
+        "https://api.synthfinance.com"
+      end
 
-    def build_error(response)
-      Provider::Base::ProviderError.new(<<~ERROR)
-        Failed to fetch exchange rate from #{self.class}
-          Status: #{response.status}
-          Body: #{response.body.inspect}
-      ERROR
-    end
+      def build_error(response)
+        Provider::Base::ProviderError.new(<<~ERROR)
+          Failed to fetch exchange rate from #{self}
+            Status: #{response.status}
+            Body: #{response.body.inspect}
+        ERROR
+      end
+  end
 end

app/views/accounts/show.html.erb

@@ -41,6 +41,9 @@
   <%= turbo_frame_tag "sync_message" do %>
     <%= render partial: "accounts/sync_message", locals: { is_syncing: @account.syncing? } %>
   <% end %>
+  <% if @account.foreign_currency? && !ExchangeRate.exchange_rates_provider.initialized? %>
+    <%= render partial: "shared/alert", locals: { type: "error", content: t(".no_exchange_rate_provider") } %>
+  <% end %>
   <div class="bg-white shadow-xs rounded-xl border border-alpha-black-25 rounded-lg">
     <div class="p-4 flex justify-between">
       <div class="space-y-2">

app/views/shared/_alert.html.erb

@@ -0,0 +1,12 @@
+<%# locals: (type: "error", content: "") -%>
+<% color = type == "error" ? "red" : "blue" %>
+<%= content_tag :div,
+  class: "flex justify-between bg-#{color}-50 rounded-xl p-3",
+  data: {controller: "element-removal" },
+  role: type == "error" ? "alert" : "status" do %>
+  <div class="flex gap-3 text-<%= color %>-500 items-center">
+    <%= lucide_icon("info", class: "w-5 h-5 shrink-0") %>
+    <p class="text-sm"><%= content %></p>
+  </div>
+  <%= content_tag :a, lucide_icon("x", class: "w-5 h-5 shrink-0 text-#{color}-500"), data: { action: "click->element-removal#remove" }, class:"flex gap-1 font-medium items-center text-gray-900 px-3 py-1.5 rounded-lg cursor-pointer" %>
+<% end %>

config/initializers/synth.rb

@@ -0,0 +1,5 @@
+Rails.application.config.to_prepare do
+  Provider::Synth.configure do |config|
+    config.api_key = ENV["SYNTH_API_KEY"]
+  end
+end

config/locales/views/account/en.yml

@@ -35,6 +35,8 @@ en:
         /> <p>After deletion, there is no way you'll be able to restore the account
         information because you'll need to add it as a new account.</p>"
       confirm_title: Delete account?
+      no_exchange_rate_provider: This account cannot be synced at the moment as there
+        is no exchange rate provider configured.
     summary:
       new: New account
     sync:

test/models/provider/synth_test.rb

@@ -4,6 +4,6 @@ class Provider::SynthTest < ActiveSupport::TestCase
   include ExchangeRateProviderInterfaceTest
 
   setup do
-    @subject = Provider::Synth.new
+    @subject = Provider::Synth
   end
 end

test/test_helper.rb

@@ -46,6 +46,10 @@ class TestCase
       end
     end
 
+    Provider::Synth.configure do |config|
+      config.api_key = "api_key"
+    end
+
     # Setup all fixtures in test/fixtures/*.yml for all tests in alphabetical order.
     fixtures :all