service_store.rb in umlaut-3.1.0.pre1

- old
+ new
@@ -1,63 +1,132 @@
-# Loads Service definitions from Rails.root/config/umlaut_services.yml
-# instantiates services from definitions, by id.
+# A ServiceStore is a collection of umlaut service definitions, with identifiers. 
 #
-# It's terrible we need to do this globally like this, but
-# too hard to back out of legacy design now. 
+# There is one default global one that is typically used; originally this
+# was all neccesarily global state, but we refactored to be an actual object,
+# although there's still a default global one used, with class methods
+# that delegate to it, for backwards compat and convenience. 
+#
+# By default, a ServiceStore loads service definitions from 
+# Rails.root/config/umlaut_services.yml . Although in testing,
+# or for future architectural expansion, services can be manually supplied
+# instead. 
+#
+# A ServiceStore instantiates services from definitions, by id, 
+# ServiceStore.instantiate_service!("our_sfx")
+#
+# A ServiceStore's cached service definitions can be reset, useful in
+# testing:  ServiceStore.reset!
+#
+# They'll then be lazily reloaded on next access, unless manually set. 
 class ServiceStore
-  
+  @@global_service_store = ServiceStore.new
+  def self.global_service_store
+    @@global_service_store
+  end
+
+  # certain class methods all default to global default ServiceStore,
+  # for global ServiceStore.  For convenience, and backwards-compat. 
+  [ :config, :"config=", :service_definitions, :service_definition_for, 
+    :'instantiate_service!', :'reset!' ].each do |method|
+    self.define_singleton_method(method) do |*args|      
+      global_service_store.send(method, *args)
+    end
+  end
+
+
   # Returns complete hash loaded from services.yml
-  def self.config
-    # cache hash loaded from YAML, ensure it has the keys we expect. 
-    unless defined? @@services_config_list
+  def config
+    # cache hash loaded from YAML, ensure it has the keys we expect.
+    unless defined? @services_config_list
       yaml_path = File.expand_path("config/umlaut_services.yml", Rails.root)
-      if File.exists? yaml_path
-        @@services_config_list = YAML::load(File.open( yaml_path ))        
-      else
-        @@services_config_list = {}
-      end
-      @@services_config_list["default"] ||= {}
-      @@services_config_list["default"]["services"] ||= {}
+      @services_config_list = (File.exists? yaml_path) ? YAML::load(File.open(yaml_path)) : {}
+      @services_config_list["default"] ||= {}
+      @services_config_list["default"]["services"] ||= {}
     end
-    return @@services_config_list
+    return @services_config_list
   end
-  
+
+  # Manually set a config hash, as would normally be found serialized
+  # in config/umlaut_services.yml.  Useful in testing. All keys
+  # should be strings!! 
+  #
+  # Needs to have the somewhat cumbersome expected structure:
+  # ["default"]["services"] => { "service_id" => definition_hash }  
+  def config=(hash)
+    reset!
+    @services_config_list = hash
+  end
+
   # Returns hash keyed by unique service name, value service definition
-  # hash. 
-  def self.service_definitions
-    unless defined? @@service_definitions
-      @@service_definitions = {}
+  # hash.
+  def service_definitions
+    unless defined? @service_definitions
+      @service_definitions = {}
       config.each_pair do |group_name, group|
-        @@service_definitions.merge!(  group["services"]  ) if group["services"]
+        if group["services"]
+          # Add the group name to each service
+          # in the group
+          group["services"].each_pair do |service_id, service|
+            service["group"] = group_name
+          end
+          # Merge the group's services into the service definitions.
+          @service_definitions.merge!(  group["services"]  )
+        end
       end
       # set service_id key in each based on hash key
-      @@service_definitions.each_pair do |key, hash|
+      @service_definitions.each_pair do |key, hash|
         hash["service_id"] =  key
       end
     end
-    return @@service_definitions
+    return @service_definitions
   end
-  
-  def self.service_definition_for(service_id)
+
+  # Reset cached service definitions. They'll be lazily loaded when asked for, 
+  # typically by being looked up from disk again. Typically used for testing. 
+  def reset!
+    remove_instance_variable "@service_definitions"   if defined? @service_definitions
+    remove_instance_variable "@services_config_list"  if defined? @services_config_list
+  end
+
+  def service_definition_for(service_id)
     return service_definitions[service_id]
   end
-  
-  # pass in string unique key OR a service definition hash, 
+
+  # pass in array of service group ids. eg. ["group1", "-group2"]
+  #
+  # Returns a list of service definition hashes.
+  #
+  # Start with default group(s). Remove any that are mentioned with "-group_id" in
+  # the group list, add in any that are mentioned with "group_id"
+  def determine_services(specified_groups = [])    
+    services = {}
+
+    activated_service_groups = self.config.select do |group_id, group_definition|
+      ((group_id == "default" || group_definition["default"] == true)  ||
+      specified_groups.include?(group_id)) &&
+      ! specified_groups.include?("-#{group_id}")
+    end
+
+    activated_service_groups.each_pair do |group_id, group_definition|
+      services.merge! (group_definition["services"] || {})
+    end
+
+    # Remove any disabled services
+    services.reject! {|service_id, hash| hash && hash["disabled"] == true}
+
+    return services
+  end
+
+
+  # pass in string unique key OR a service definition hash,
   # and a current UmlautRequest.
-  # get back instantiated Service object. 
-  def self.instantiate_service!(service, request)
+  # get back instantiated Service object.
+  def instantiate_service!(service, request)
     definition = service.kind_of?(Hash) ? service : service_definition_for(service.to_s)
-        
-    if definition.nil?
-      raise "Service '#{service}'' does not exist in umlaut-services.yml"
-    end
-    
+    raise "Service '#{service}'' does not exist in umlaut-services.yml" if definition.nil?
     className = definition["type"] || definition["service_id"]
     classConst = Kernel.const_get(className)
     service = classConst.new(definition)
     service.request = request
-
-    return service    
+    return service
   end
-  
-  
 end