Refactor If()-Macro to use Nested::Decider

lib/trailblazer/macro/if.rb

@@ -5,19 +5,42 @@ def self.If(condition, name: :default, id: Macro.id_for(condition, macro: :If, h
         raise ArgumentError, "If() requires a block"
       end
 
-      option = Trailblazer::Option(condition)
-      wrap = ->((ctx, flow_options), **circuit_args, &block) {
-        ctx[:"result.condition.#{name}"] = result =
-          option.call(ctx, keyword_arguments: ctx.to_hash, **circuit_args)
+      block_activity, outputs = Macro.block_activity_for(nil, &block)
+      success_output = outputs.find { |output| output.semantic == :success }
+      state = Declarative::State(
+        block_activity:   [block_activity, {copy: Trailblazer::Declarative::State.method(:subclass)}],
+        name:             [name, {}],
+        success_signal:   [success_output.signal, {}]
+      )
 
-        if result
-          block.call
-        else
-          [Trailblazer::Activity::Right, [ctx, flow_options]]
-        end
-      }
+      task = Class.new(If) do
+        extend Macro::Strategy::State
+        initialize!(state)
+      end
+
+      merge = [
+        [Nested::Decider.new(condition), id: "If.compute_condition", prepend: "task_wrap.call_task"],
+      ]
+
+      task_wrap_extension = Activity::TaskWrap::Extension::WrapStatic.new(extension: Activity::TaskWrap::Extension(*merge))
+
+      Activity::Railway.Subprocess(task).merge(
+        id:         id,
+        extensions: [task_wrap_extension],
+      )
+    end
+  end
 
-      Wrap(wrap, id: id, &block)
+  class If < Macro::Strategy
+    def self.call((ctx, flow_options), **circuit_options)
+      name = @state.get(:name)
+      ctx[:"result.condition.#{name}"] = flow_options[:decision]
+
+      if flow_options[:decision]
+        Activity::Circuit::Runner.(block_activity, [ctx, flow_options], **circuit_options)
+      else
+        [@state.get(:success_signal), [ctx, flow_options]]
+      end
     end
   end
 end