module Sidekiq::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|
    # horrible, think you can make this cleaner?
    type = TYPE_CACHE[key]
    if type
    elsif key.start_with?("queue:")
      type = TYPE_CACHE[key] = "list"
    else
      type = TYPE_CACHE[key] = conn.type(key)
    end
    rev = opts && opts[:reverse]
    case type
    when "zset"
      total_size, items = conn.multi { |transaction|
        transaction.zcard(key)
        if rev
          transaction.zrange(key, starting, ending, "REV", "withscores")
        else
          transaction.zrange(key, starting, ending, "withscores")
        end
      }
      [current_page, total_size, items]
    when "list"
      total_size, items = conn.multi { |transaction|
        transaction.llen(key)
        if rev
          transaction.lrange(key, -ending - 1, -starting - 1)
        else
          transaction.lrange(key, starting, ending)
        end
      }
      items.reverse! if rev
      [current_page, total_size, items]
    when "none"
      [1, 0, []]
    else
      raise "can't page a #{type}"
    end
  end
end

def page_items(items, pageidx = 1, page_size = 25)
  current_page = (pageidx.to_i < 1) ? 1 : pageidx.to_i
  pageidx = current_page - 1
  starting = pageidx * page_size
  items = items.to_a
  [current_page, items.size, items[starting, page_size]]
end