Add API resource instance methods to StripeClient

This change introduces a proof-of-concept to add convenience methods to
access API resources through a StripeClient for per-client
configuration. This first iteration only allows for the `api_key` to be
configured but can be extended to allow other options such as
`stripe_version`, which should solve stripe#872.

The primary workhorse for this feature is a new module called
`Stripe::ClientAPIOperations` that defines instance methods on
`StripeClient` when it is included. A `ClientProxy` is used to send any
method calls to an API resource with the instantiated client injected.
There are a few noteworthy aspects of this approach:

- Many resources are namespaced, which introduces a unique challenge
  when it comes to method chaining calls (e.g.
  client.issuing.authorizations).  In order to handle those cases, we
  create a `ClientProxy` object for the root namespace (e.g., "issuing")
  and define all resource methods (e.g. "authorizations") at once to
  avoid re-defining the proxy object when there are multiple resources
  per namespace.

- Sigma deviates from other namespaced API resources and does not have
  an `OBJECT_NAME` separated by a period. We account for that nuance
  directly.

- `method_missing` is substantially slower than direct calls. Therefore,
  methods are defined where possible but `method_missing` is still used
  at the last step when delegating resource methods to the actual
  resource.

lib/stripe.rb

@@ -31,7 +31,6 @@
 require "stripe/util"
 require "stripe/connection_manager"
 require "stripe/multipart_encoder"
-require "stripe/stripe_client"
 require "stripe/stripe_object"
 require "stripe/stripe_response"
 require "stripe/list_object"
@@ -40,10 +39,15 @@
 require "stripe/singleton_api_resource"
 require "stripe/webhook"
 require "stripe/stripe_configuration"
+require "stripe/client_api_operations"
 
 # Named API resources
 require "stripe/resources"
 
+# StripeClient requires API Resources to be loaded
+# due to dynamic methods defined by ClientAPIOperations
+require "stripe/stripe_client"
+
 # OAuth
 require "stripe/oauth"
 
@@ -62,6 +66,8 @@ module Stripe
   class << self
     extend Forwardable
 
+    attr_reader :configuration
+
     # User configurable options
     def_delegators :@configuration, :api_key, :api_key=
     def_delegators :@configuration, :api_version, :api_version=

lib/stripe/client_api_operations.rb

@@ -0,0 +1,89 @@
+# frozen_string_literal: true
+
+module Stripe
+  # Define instance methods on the including class (i.e. StripeClient)
+  # to access API resources.
+  module ClientAPIOperations
+    # Proxy object to inject the client into API resources. When included,
+    # all resources are defined as singleton methods on the client in the
+    # plural form (e.g. Stripe::Account => client.accounts).
+    class ClientProxy
+      def initialize(client:, resource: nil)
+        @client = client
+        @resource = resource
+      end
+
+      attr_reader :client
+
+      def with_client(client)
+        @client = client
+        self
+      end
+
+      # Used to either send a method to the API resource or the nested
+      # ClientProxy when a resource is namespaced. Since the method signature
+      # differs when operating on a collection versus a singular resource, it's
+      # required to perform introspection on the parameters to respect any
+      # passed in options or overrides.
+      def method_missing(method, *args)
+        super unless @resource
+        opts_pos = @resource.method(method).parameters.index(%i[opt opts])
+        args[opts_pos] = { client: @client }.merge(args[opts_pos] || {})
+
+        @resource.public_send(method, *args) || super
+      end
+
+      def respond_to_missing?(symbol, include_private = false)
+        super unless @resource
+        @resource.respond_to?(symbol) || super
+      end
+    end
+
+    def self.included(base)
+      base.class_eval do
+        # Sigma, unlike other namespaced API objects, is not separated by a
+        # period so we modify the object name to follow the expected convention.
+        api_resources = Stripe::Util.api_object_classes
+        sigma_class = api_resources.delete("scheduled_query_run")
+        api_resources["sigma.scheduled_query_run"] = sigma_class
+
+        # Group namespaces that have mutiple resourses
+        grouped_resources = api_resources.group_by do |key, _|
+          key.include?(".") ? key.split(".").first : key
+        end
+
+        grouped_resources.each do |resource_namespace, resources|
+          # Namespace resource names are separated with a period by convention.
+          if resources[0][0].include?(".")
+
+            # Defines the methods required for chaining calls for resources that
+            # are namespaced. A proxy object is created so that all resource
+            # methods can be defined at once.
+            #
+            # NOTE: At some point, a smarter pluralization scheme may be
+            # necessary for resource names with complex pluralization rules.
+            proxy = ClientProxy.new(client: nil)
+            resources.each do |resource_name, resource_class|
+              method_name = resource_name.split(".").last
+              proxy.define_singleton_method("#{method_name}s") do
+                ClientProxy.new(client: proxy.client, resource: resource_class)
+              end
+            end
+
+            # Defines the first method for resources that are namespaced. By
+            # convention these methods are singular. A proxy object is returned
+            # so that the client can be injected along the method chain.
+            define_method(resource_namespace) do
+              proxy.with_client(self)
+            end
+          else
+            # Defines plural methods for non-namespaced resources
+            define_method("#{resource_namespace}s".to_sym) do
+              ClientProxy.new(client: self, resource: resources[0][1])
+            end
+          end
+        end
+      end
+    end
+  end
+end

lib/stripe/connection_manager.rb

@@ -16,7 +16,8 @@ class ConnectionManager
     # garbage collected or not.
     attr_reader :last_used
 
-    def initialize
+    def initialize(config = Stripe.configuration)
+      @config = config
       @active_connections = {}
       @last_used = Util.monotonic_time
 
@@ -117,14 +118,14 @@ def execute_request(method, uri, body: nil, headers: nil, query: nil)
       # reused Go's default for `DefaultTransport`.
       connection.keep_alive_timeout = 30
 
-      connection.open_timeout = Stripe.open_timeout
-      connection.read_timeout = Stripe.read_timeout
+      connection.open_timeout = @config.open_timeout
+      connection.read_timeout = @config.read_timeout
 
       connection.use_ssl = uri.scheme == "https"
 
-      if Stripe.verify_ssl_certs
+      if @config.verify_ssl_certs
         connection.verify_mode = OpenSSL::SSL::VERIFY_PEER
-        connection.cert_store = Stripe.ca_store
+        connection.cert_store = @config.ca_store
       else
         connection.verify_mode = OpenSSL::SSL::VERIFY_NONE
         warn_ssl_verify_none
@@ -138,10 +139,10 @@ def execute_request(method, uri, body: nil, headers: nil, query: nil)
     # out those pieces to make passing them into a new connection a little less
     # ugly.
     private def proxy_parts
-      if Stripe.proxy.nil?
+      if @config.proxy.nil?
         [nil, nil, nil, nil]
       else
-        u = URI.parse(Stripe.proxy)
+        u = URI.parse(@config.proxy)
         [u.host, u.port, u.user, u.password]
       end
     end

lib/stripe/oauth.rb

@@ -7,9 +7,10 @@ module OAuthOperations
 
       def self.execute_resource_request(method, url, params, opts)
         opts = Util.normalize_opts(opts)
-        opts[:client] ||= StripeClient.active_client
-        opts[:api_base] ||= Stripe.connect_base
+        opts[:client] ||= params[:client] || StripeClient.active_client
+        opts[:api_base] ||= opts[:client].config.connect_base
 
+        params.delete(:client)
         super(method, url, params, opts)
       end
     end
@@ -29,7 +30,8 @@ def self.get_client_id(params = {})
     end
 
     def self.authorize_url(params = {}, opts = {})
-      base = opts[:connect_base] || Stripe.connect_base
+      client = params[:client] || StripeClient.active_client
+      base = opts[:connect_base] || client.config.connect_base
 
       path = "/oauth/authorize"
       path = "/express" + path if opts[:express]

lib/stripe/object_types.rb

@@ -1,15 +1,17 @@
 # frozen_string_literal: true
 
 # rubocop:disable Metrics/MethodLength
-
 module Stripe
   module ObjectTypes
     def self.object_names_to_classes
       {
         # data structures
         ListObject::OBJECT_NAME => ListObject,
+      }.merge(api_object_names_to_classes)
+    end
 
-        # business objects
+    def self.api_object_names_to_classes
+      {
         Account::OBJECT_NAME => Account,
         AccountLink::OBJECT_NAME => AccountLink,
         AlipayAccount::OBJECT_NAME => AlipayAccount,
@@ -96,5 +98,4 @@ def self.object_names_to_classes
     end
   end
 end
-
 # rubocop:enable Metrics/MethodLength

lib/stripe/resources/account.rb

@@ -136,6 +136,7 @@ def deauthorize(client_id = nil, opts = {})
         client_id: client_id,
         stripe_user_id: id,
       }
+      opts = @opts.merge(Util.normalize_opts(opts))
       OAuth.deauthorize(params, opts)
     end
 

lib/stripe/resources/file.rb

@@ -25,8 +25,9 @@ def self.create(params = {}, opts = {})
         end
       end
 
+      config = opts[:client]&.config || Stripe.configuration
       opts = {
-        api_base: Stripe.uploads_base,
+        api_base: config.uploads_base,
         content_type: MultipartEncoder::MULTIPART_FORM_DATA,
       }.merge(Util.normalize_opts(opts))
       super