module Sidekiq
  module Paginator

    def page(key, pageidx=1, page_size=25, opts=nil)
      current_page = pageidx.to_i < 1 ? 1 : pageidx.to_i
      pageidx = current_page - 1
      total_size = 0
      items = []
      starting = pageidx * page_size
      ending = starting + page_size - 1

      Sidekiq.redis do |conn|
        type = conn.type(key)

        case type
        when 'zset'
          rev = opts && opts[:reverse]
          total_size, items = conn.multi do
            conn.zcard(key)
            if rev
              conn.zrevrange(key, starting, ending, :with_scores => true)
            else
              conn.zrange(key, starting, ending, :with_scores => true)
            end
          end
          [current_page, total_size, items]
        when 'list'
          total_size, items = conn.multi do
            conn.llen(key)
            conn.lrange(key, starting, ending)
          end
          [current_page, total_size, items]
        when 'none'
          [1, 0, []]
        else
          raise "can't page a #{type}"
        end
      end
    end

  end
end