require 'singleton'

module Scrivito
  module Migrations
    class WorkspaceLock
      include Singleton

      def get
        if exists?
          begin
            Workspace.find(workspace_id)
          rescue Scrivito::ResourceNotFound
            create_workspace
          end
        else
          create_workspace
        end
      end

      def remove
        if exists?
          File.delete(filename)
        end
      end

      def exists?
        File.exist?(filename)
      end

      private

      def create_workspace
        Workspace.create(title: 'Migration Working Copy').tap do |workspace|
          write(workspace)
        end
      end

      def write(workspace)
        File.write(filename, workspace.id)
      end

      def workspace_id
        File.read(filename)
      end

      def filename
        File.join(Rails.root, 'tmp/migration_store.lock')
      end
    end
  end
end