From de6d8c54ae50c4f9fc9f73c15df54411185523d5 Mon Sep 17 00:00:00 2001
From: Thorsten Eckel <te@znuny.com>
Date: Wed, 20 Dec 2017 16:08:37 +0100
Subject: [PATCH] Introduced new simple provider structure to DRY up Units and
 enforce sanitized naming.

---
 .../unit/common/fallback_provider.rb          | 29 ---------------
 .../unit/common/provider/attribute.rb         | 36 +++++++++++++++++++
 .../unit/common/provider/fallback.rb          | 16 +++++++++
 lib/sequencer/unit/exchange/connection.rb     |  4 +--
 .../exchange/folder_contacts/folder_ids.rb    |  4 +--
 lib/sequencer/unit/ldap/config.rb             |  5 +--
 lib/sequencer/unit/ldap/connection.rb         |  5 +--
 7 files changed, 62 insertions(+), 37 deletions(-)
 delete mode 100644 lib/sequencer/unit/common/fallback_provider.rb
 create mode 100644 lib/sequencer/unit/common/provider/attribute.rb
 create mode 100644 lib/sequencer/unit/common/provider/fallback.rb

diff --git a/lib/sequencer/unit/common/fallback_provider.rb b/lib/sequencer/unit/common/fallback_provider.rb
deleted file mode 100644
index 5ea564ce2..000000000
--- a/lib/sequencer/unit/common/fallback_provider.rb
+++ /dev/null
@@ -1,29 +0,0 @@
-class Sequencer
-  class Unit
-    module Common
-      class FallbackProvider < Sequencer::Unit::Base
-
-        def process
-          provides = self.class.provides
-          raise 'Only one provide attribute possible' if provides.size != 1
-
-          attribute = provides.first
-          return if state.provided?(attribute)
-
-          result = fallback
-
-          # don't store nil values which are default anyway
-          return if result.nil?
-
-          state.provide(attribute, result)
-        end
-
-        private
-
-        def fallback
-          raise 'Missing implementation of fallback method'
-        end
-      end
-    end
-  end
-end
diff --git a/lib/sequencer/unit/common/provider/attribute.rb b/lib/sequencer/unit/common/provider/attribute.rb
new file mode 100644
index 000000000..115af7466
--- /dev/null
+++ b/lib/sequencer/unit/common/provider/attribute.rb
@@ -0,0 +1,36 @@
+class Sequencer
+  class Unit
+    module Common
+      module Provider
+        class Attribute < Sequencer::Unit::Base
+
+          def process
+            return if ignore?
+            state.provide(attribute, value)
+          end
+
+          private
+
+          def attribute
+            @attribute ||= provides
+          end
+
+          def provides
+            provides_list = self.class.provides
+            raise "Only single provide attribute possible for class #{self.class.name}" if provides_list.size != 1
+            provides_list.first
+          end
+
+          def value
+            @value ||= send(attribute)
+          end
+
+          def ignore?
+            # don't store nil values which are default anyway
+            value.nil?
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/sequencer/unit/common/provider/fallback.rb b/lib/sequencer/unit/common/provider/fallback.rb
new file mode 100644
index 000000000..a5b6b6288
--- /dev/null
+++ b/lib/sequencer/unit/common/provider/fallback.rb
@@ -0,0 +1,16 @@
+class Sequencer
+  class Unit
+    module Common
+      module Provider
+        class Fallback < Sequencer::Unit::Common::Provider::Attribute
+
+          private
+
+          def ignore?
+            state.provided?(attribute) || super
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/sequencer/unit/exchange/connection.rb b/lib/sequencer/unit/exchange/connection.rb
index 2c8f2234c..da71593b8 100644
--- a/lib/sequencer/unit/exchange/connection.rb
+++ b/lib/sequencer/unit/exchange/connection.rb
@@ -1,14 +1,14 @@
 class Sequencer
   class Unit
     module Exchange
-      class Connection < Sequencer::Unit::Common::FallbackProvider
+      class Connection < Sequencer::Unit::Common::Provider::Fallback
 
         uses :ews_config
         provides :ews_connection
 
         private
 
-        def fallback
+        def ews_connection
           Viewpoint::EWSClient.new(
             config[:endpoint],
             config[:user],
diff --git a/lib/sequencer/unit/import/exchange/folder_contacts/folder_ids.rb b/lib/sequencer/unit/import/exchange/folder_contacts/folder_ids.rb
index 49ef21099..0618cbda7 100644
--- a/lib/sequencer/unit/import/exchange/folder_contacts/folder_ids.rb
+++ b/lib/sequencer/unit/import/exchange/folder_contacts/folder_ids.rb
@@ -3,13 +3,13 @@ class Sequencer
     module Import
       module Exchange
         module FolderContacts
-          class FolderIds < Sequencer::Unit::Common::FallbackProvider
+          class FolderIds < Sequencer::Unit::Common::Provider::Fallback
 
             provides :ews_folder_ids
 
             private
 
-            def fallback
+            def ews_folder_ids
               ::Import::Exchange.config[:folders]
             end
           end
diff --git a/lib/sequencer/unit/ldap/config.rb b/lib/sequencer/unit/ldap/config.rb
index 77d242753..3425c4f5c 100644
--- a/lib/sequencer/unit/ldap/config.rb
+++ b/lib/sequencer/unit/ldap/config.rb
@@ -3,12 +3,13 @@ require 'import/ldap'
 class Sequencer
   class Unit
     module Ldap
-      class Config < Sequencer::Unit::Common::FallbackProvider
+      class Config < Sequencer::Unit::Common::Provider::Fallback
+
         provides :ldap_config
 
         private
 
-        def fallback
+        def ldap_config
           ::Import::Ldap.config
         end
       end
diff --git a/lib/sequencer/unit/ldap/connection.rb b/lib/sequencer/unit/ldap/connection.rb
index 7d03da751..4276d95dd 100644
--- a/lib/sequencer/unit/ldap/connection.rb
+++ b/lib/sequencer/unit/ldap/connection.rb
@@ -3,13 +3,14 @@ require 'ldap'
 class Sequencer
   class Unit
     module Ldap
-      class Connection < Sequencer::Unit::Common::FallbackProvider
+      class Connection < Sequencer::Unit::Common::Provider::Fallback
+
         uses :ldap_config
         provides :ldap_connection
 
         private
 
-        def fallback
+        def ldap_connection
           ::Ldap.new(ldap_config)
         end
       end