Simple Paginate

paginated.rb

#= Paginated
#
#  Usage:
#
#    customers = store.customers.extend Paginated
#    customers.per_page(5) # defaults to 25
#    customers.page(0)     # returns an array
#
# count
# where.limit
# where.skip

module Paginated
  @@default_per_page = 25

  InvalidPageNumError = Class.new(StandardError)

  class << self
    def default_per_page=(num)
      @@default_per_page = num
    end
  end

  class Pagination
    attr_reader :total_pages, :current_page, :skip_items

    def initialize(total_items, per_page, current_page)
      @per_page     = per_page
      @current_page = current_page
      @skip_items   = current_page * per_page
      @total_pages  = (total_items / per_page).ceil

      raise InvalidPageNumError, 'page asked for exceeds max page number' \
        if @current_page > @total_pages - 1
    end
  end

  def pagination
    @pagination
  end

  def page(page_num)
    per_page = @per_page || @@default_per_page

    @pagination = Pagination.new(where.count, per_page, page_num)
    where.limit(per_page).skip(@pagination.skip_items)
  end

  def per_page(num)
    @per_page = num
  end
end

class Customers
  def where
    Where.new
  end
end

class Where < Hash
  def count
    1000
  end

  def limit(num)
    self[:limit] = num
    self
  end

  def skip(num)
    self[:skip] = num
    self
  end
end

Paginated.default_per_page = 22

customers = Customers.new
customers.extend Paginated
p customers.page(1)
p customers.pagination