Port of http://www.reddit.com/r/woweconomy/comments/2d0og2/my_java_source_code_for_how_i_found_the_cheapest/ to ruby2

auction_search.rb

# Run as: ruby auction_search.rb <item_id>
# Requires ruby 2.0 or higher, has no other dependencies.
# Will make its own temp file in the current directory for storing auction data,
# to make repeat queries faster. Delete the folder to force download fresh data.

# Sample output:
#   Arthas (  high) |
#                   | 450000.0 horde-Auromus

require 'fileutils'
require 'json'
require 'ostruct'
require 'open-uri'
require 'pp'

def servers
  # Returns array of structs, relevant fields would be name, slug, population, status
  json = JSON.parse(open("http://us.battle.net/api/wow/realm/status").read)
  json["realms"].map{|r| OpenStruct.new(r) }
end

def auction_file(slug)
  FileUtils.mkdir_p("tmp")
  filename = "tmp/#{slug}.json"

  if !File.exist?(filename)
    index_url = "http://us.battle.net/api/wow/auction/data/#{slug}"
    url = JSON.parse(open(index_url).read)["files"].first["url"]
    `curl -so #{filename} #{url}`
  end
  File.read(filename)
end

def auctions(slug)
  json = JSON.parse(auction_file(slug))
  %w(alliance horde neutral).each do |faction|
    json[faction]["auctions"].each do |auc|
      yield OpenStruct.new(auc.merge(faction: faction))
    end
  end
rescue JSON::ParserError
  FileUtils.rm("tmp/#{slug}.json")
  puts "Error processing file for #{slug}, re-run script to redownload"
end

COPPER_TO_GOLD = 1_00_00
item_id = ARGV.pop.to_i
servers.each do |server|
  next unless server.population == "high"
  puts "%20s (%6s) |" % [server.name, server.population]
  auctions(server.slug) do |auction|
    next unless auction.item == item_id

    buyout = auction.buyout.to_f / auction.quantity / COPPER_TO_GOLD
    puts "%20s  %6s  | %6.1f %s-%s" % ["", "", buyout, auction.faction, auction.owner]
  end
end