Group

group.rb

class Group
  include DataMapper::Resource

  property :id, Serial

  property :title, String, unique: true, length: 1..20
  property :rules, String

  SUPPORT_MODELS = %w[account offering city country]
  SUPPORT_ACTIONS = %w[read create destroy edit]

  def can? action, model
    action = action.to_s.downcase
    if model.is_a? String or model.is_a? Symbol
      model = model.to_s.downcase
    else
      if model.respond_to? :name and model.is_a? Class
        model = model.name.to_s.downcase
      else
        model = model.class.name.to_s.downcase
      end
    end

    return false unless SUPPORT_MODELS.include?(model)
    return false unless SUPPORT_ACTIONS.include?(action)

    rules_hash[model] ? rules_hash[model].include?(action) : false
  end

  def method_missing name, *args
    if name =~ /^role_([a-z]+)_([a-z]+)(?:(\=))?$/
      if SUPPORT_MODELS.include?($1) and SUPPORT_ACTIONS.include?($2)
        _hash = rules_hash

        if $3.nil?
          return false if _hash[$1].nil?

          _hash[$1].include?($2)
        else
          if args.first
            _hash[$1] ||= []
            _hash[$1] << $2 unless _hash[$1].include?($2)
          else
            _hash[$1].delete $2
          end

          self.rules_hash = _hash
        end
      else
        super
      end
    else
      super
    end
  end

  private

  def rules_hash
    if self.rules
      JSON::parse(self.rules)
    else
      {}
    end
  end

  def rules_hash= hash
    self.rules = hash.to_json
  end
end