module SlackRubyBotServer
  module Api
    module Helpers
      module SortHelpers
        extend ActiveSupport::Concern

        def sort_order(options = {})
          params[:sort] = options[:default_sort_order] unless params[:sort]
          return [] unless params[:sort]
          sort_order = params[:sort].to_s
          unless options[:default_sort_order] == sort_order
            supported_sort_orders = route_sort
            error!("This API doesn't support sorting", 400) if supported_sort_orders.blank?
            unless supported_sort_orders.include?(sort_order)
              error!("Invalid sort order: #{sort_order}, must be#{supported_sort_orders.count == 1 ? '' : ' one of'} '#{supported_sort_orders.join("', '")}'", 400)
            end
          end
          sort_order = sort_order.split(',').map do |sort_entry|
            sort_order = {}
            if sort_entry[0] == '-'
              sort_order[:direction] = :desc
              sort_order[:column] = sort_entry[1..-1]
            else
              sort_order[:direction] = :asc
              sort_order[:column] = sort_entry
            end
            error!("Invalid sort: #{sort_entry}", 400) if sort_order[:column].blank?
            sort_order
          end
          sort_order
        end

        def route_sort
          (env['api.endpoint'].route_setting(:sort) || {})[:sort]
        end

        def sort(coll, options = {})
          sort_order = sort_order(options)
          unless sort_order.empty?
            if coll.respond_to?(:order)
              sort_order.each do |s|
                coll = coll.order(s[:column] => s[:direction])
              end
            elsif coll.respond_to?(:asc) && coll.respond_to?(:desc)
              sort_order.each do |s|
                coll = coll.send(s[:direction], s[:column])
              end
            else
              error!("Cannot sort #{coll.class.name}", 500)
            end
          end
          coll = coll.is_a?(Module) && coll.respond_to?(:all) ? coll.all : coll
        end
      end
    end
  end
end