For this exercise you will complete the PaginationHelper class, which is a utility class helpful for querying paging information related to an array.

pagination_helper.rb

# 
# I have to admit this is my first time using ruby and I find the syntax very easy and appealing.
# 
# A simple PaginationHelper utility class
# 
# Gerard Lee <[email protected]>
# Oct 1, 2018

class PaginationHelper

  # declare global variable here that holds collection array and item per page
  $collection = Array.new # im not sure if this is necessary in ruby, 
                          # in java you have to declare before anything else
  $items_per_page = 0

  # The constructor takes in an array of items and a integer indicating how many
  # items fit within a single page
  def initialize(collection, items_per_page)
    # assign collection and item per page to the global variable
    $collection = collection
    $items_per_page = items_per_page
  end

  # returns the number of items within the entire collection
  def item_count
    # return is not necessary, but being explicit about it is good
    return $collection.length
  end

  # returns the number of pages
  def page_count
    # by dividing collections.lenth over the items per page, we get the page count
    # round up to the nearest whole number
    return ($collection.length / $items_per_page.to_f).ceil
  end

  # returns the number of items on the current page. page_index is zero based.
  # this method should return -1 for page_index values that are out of range
  def page_item_count(page_index)
    if ((page_index < 0) || (page_index >= page_count()))
      return -1
    end

    if (page_index < page_count() - 1)
      return $items_per_page
    end

    last_page_count = ($collection.length % $items_per_page)
    return last_page_count
  end

  # determines what page an item is on. Zero based indexes.
  # this method should return -1 for item_index values that are out of range
  def page_index(item_index)
    # if item_index is in out of scope, then return -1
    if ((item_index < 0) || (item_index >= item_count()))
      return -1
    end

    # item_index will be therefore in scope, just divide by items_per_page and get the floor
    return (item_index / $items_per_page.to_f).floor
  end

end