From bb6ce632da81d515d4270e893e83708dedf55ec3 Mon Sep 17 00:00:00 2001
From: Sergey Kucher <s.e.kucher@gmail.com>
Date: Thu, 22 Oct 2015 15:40:49 +0500
Subject: [PATCH] add field 'single' and  processor 'counter' pc4-15459

---
 lib/treasury/fields/single.rb      | 16 +++++++++++++
 lib/treasury/processors/counter.rb | 37 ++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+)
 create mode 100644 lib/treasury/fields/single.rb
 create mode 100644 lib/treasury/processors/counter.rb

diff --git a/lib/treasury/fields/single.rb b/lib/treasury/fields/single.rb
new file mode 100644
index 0000000..760b7ea
--- /dev/null
+++ b/lib/treasury/fields/single.rb
@@ -0,0 +1,16 @@
+module Treasury
+  module Fields
+    module Single
+      extend ActiveSupport::Concern
+
+      module ClassMethods
+        protected
+
+        def init_accessor(params)
+          @accessing_object = extract_object(params)
+          @accessing_field  = nil
+        end
+      end
+    end
+  end
+end
diff --git a/lib/treasury/processors/counter.rb b/lib/treasury/processors/counter.rb
new file mode 100644
index 0000000..07ab12e
--- /dev/null
+++ b/lib/treasury/processors/counter.rb
@@ -0,0 +1,37 @@
+module Treasury
+  module Processors
+    module Counter
+      include Single
+
+      protected
+
+      def process_insert
+        increment_current_value if satisfied?
+      end
+
+      def process_update
+        if satisfied?
+          increment_current_value unless was_counted?
+        else
+          decrement_current_value if was_counted?
+        end
+      end
+
+      def process_delete
+        decrement_current_value if was_counted?
+      end
+
+      def satisfied?
+        condition? @event.raw_data
+      end
+
+      def was_counted?
+        condition? @event.raw_prev_data
+      end
+
+      def condition?(data)
+        raise NotImplemenedError
+      end
+    end
+  end
+end
\ No newline at end of file