require "whitelist_scope/version"

module WhitelistScope
  attr_reader :whitelist

  def whitelist_scope(name, body)
    @whitelist ||= []
    name = name.to_sym

    if respond_to?(name)
      raise ArgumentError, "Could not create scope, There is an existing method with this name."
    end

    scope name, body
    @whitelist << name
  end

  def call_whitelisted_scope(*scope_names)
    existing_scope = nil

    scope_names.flatten.each do |scope_name|
      existing_scope = call_scope_by_name(existing_scope, scope_name)
    end
    existing_scope
  end

  private

  def call_scope_by_name(existing_scope, scope_name)
    scope_name = scope_name.to_sym unless scope_name.nil?

    if @whitelist.include? scope_name
      if existing_scope
        existing_scope.send(scope_name)
      else
        send(scope_name)
      end
    else
      raise NoMethodError, "The scope you provided, '#{scope_name}', does not exist."
    end
  end
end