Add basic support for GlobalId

hyperclient.gemspec

@@ -19,4 +19,6 @@ Gem::Specification.new do |gem|
   gem.add_dependency 'faraday_hal_middleware'
   gem.add_dependency 'faraday_middleware'
   gem.add_dependency 'net-http-digest_auth'
+
+  gem.add_development_dependency 'globalid'
 end

lib/hyperclient.rb

@@ -7,16 +7,23 @@
 require 'hyperclient/resource'
 require 'hyperclient/resource_collection'
 require 'hyperclient/version'
+require 'hyperclient/railtie' if defined?(Rails)
 
 # Public: Hyperclient namespace.
 #
 module Hyperclient
+  URL_TO_ENDPOINT_MAPPING = { }
+
   # Public: Convenience method to create new EntryPoints.
   #
   # url - A String with the url of the API.
   #
   # Returns a Hyperclient::EntryPoint
   def self.new(url, &block)
-    Hyperclient::EntryPoint.new(url, &block)
+    URL_TO_ENDPOINT_MAPPING[url] = Hyperclient::EntryPoint.new(url, &block)
+  end
+
+  def self.lookup_entry_point(uri)
+    URL_TO_ENDPOINT_MAPPING[uri] || raise(ArgumentError, "Entry point not registered for #{uri}")
   end
 end

lib/hyperclient/global_id.rb

@@ -0,0 +1,56 @@
+# frozen_string_literal: true
+
+require 'delegate'
+require 'globalid'
+
+module Hyperclient
+  module GlobalId
+    class Locator
+      def locate(gid)
+        Hyperclient
+          .lookup_entry_point(gid.params['endpoint'])
+          .public_send(gid.params['key'], gid.params.except('endpoint', 'key'))
+      end
+    end
+
+    class Serializable < SimpleDelegator
+      def id
+        _url
+      end
+    end
+
+    private_constant :Serializable
+
+    def self.app_name
+      "#{GlobalID.app}-hyperclient"
+    end
+
+    def self.setup!
+      ::Hyperclient::Link.include ::GlobalID::Identification
+      ::Hyperclient::Link.prepend ::Hyperclient::GlobalId
+
+      ::GlobalID::Locator.use app_name, ::Hyperclient::GlobalId::Locator.new
+    end
+
+    def to_global_id(options = {})
+      GlobalID.create(Serializable.new(self), default_global_id_options.merge(options))
+    end
+    alias to_gid to_global_id
+
+    def to_signed_global_id(options = {})
+      SignedGlobalID.create(Serializable.new(self), default_global_id_options.merge(options))
+    end
+    alias to_sgid to_signed_global_id
+
+    private
+
+    def default_global_id_options
+      {
+        app: ::Hyperclient::GlobalId.app_name,
+        endpoint: @entry_point._url,
+        key: @key,
+        **@uri_variables || {},
+      }
+    end
+  end
+end

lib/hyperclient/railtie.rb

@@ -0,0 +1,11 @@
+module Hyperclient
+  class Railtie < ::Rails::Railtie #:nodoc:
+    initializer 'hyperclient.client.attach_log_subscriber' do
+      ActiveSupport.on_load(:active_job) do
+        require 'hyperclient/global_id'
+
+        ::Hyperclient::GlobalId.setup!
+      end
+    end
+  end
+end

test/hyperclient/link_test.rb

@@ -1,5 +1,6 @@
 require_relative '../test_helper'
 require 'hyperclient'
+require 'hyperclient/global_id'
 
 module Hyperclient
   describe Link do
@@ -350,5 +351,33 @@ module Hyperclient
         end
       end
     end
+
+    describe 'GlobalId Support' do
+      describe '#to_global_id' do
+        before do
+          Hyperclient::GlobalId.setup!
+          Hyperclient::URL_TO_ENDPOINT_MAPPING[entry_point._url] = entry_point
+        end
+
+        it "serializes the object with entry point, key and uri_variables if present" do
+          link = Link.new('key', { 'href' => "http://api.example.org/key" }, entry_point)
+
+          stub_request(entry_point.connection) do |stub|
+            stub.get('http://api.example.org/') { [200, {}, { '_links' => { 'key' => { 'href' => 'http://api.example.org/key' } } }] }
+          end
+
+          actual = GlobalID.find(link.to_global_id)
+
+          actual._url.must_equal(link._url)
+        end
+
+        it "raises an exception when the hypermedia URL is missing" do
+          link_without_href = Link.new('key', { }, entry_point)
+          message = "Unable to create a Global ID for Hyperclient::GlobalId::Serializable without a model id."
+
+          -> { link_without_href.to_global_id }.must_raise(URI::GID::MissingModelIdError, message)
+        end
+      end
+    end
   end
-end
+end