cryptocurrency inflation reporter

coin-calc.rb

# My attempt to understand inflation in the mineable cryptocurrency markets.
#
# Every day mineable coins (e.g., Bitcoin, Ethereum, Litecoin, and
# Bitcoin Cash) add coins to their total market cap. Coins are produced by
# mining, miners have real fiat bills, therefore miners have to convert coins
# to fiat in order to continue mining.
#
# Selling new coins into the existing market means an equivalent amount of fiat
# needs to be added in order to keep the price flat. NOTE: selling new coins
# for fiat also requires real-currency markets to be available for exchange,
# but that's a separate problem.
#
# For the top 4 coins, what's the rough estimate daily inflation?
#
# Block data retrieved from https://bitinfocharts.com Feb 2018
#
# Example run:
#
#   $ RELOAD=1 ruby coin-calc.rb
#
#   LOADING CURRENCY PAIRS FROM GDAX
#
#   Coin          Last Price
#   ------------------------
#   BTC              8124.20
#   ETH               811.51
#   LTC               148.66
#   BCH               994.49
#
#   ========================================
#
#   DAILY NEW COIN VALUE
#
#   Coin             $ value
#   ------------------------
#   BTC          $14,197,631
#   ETH          $15,023,484
#   LTC           $2,140,704
#   BCH           $1,864,668
#   ------------------------
#   Total        $33,226,488
#


require 'net/https'
require 'json'

DAY = 24 * 60 * 60

#        in coins      in seconds            in USD
coins = {
  btc: { reward: 12.5, block_time: 10.3* 60, price: 8221 },
  eth: { reward: 3.0,  block_time: 14,       price: 825 },
  ltc: { reward: 25.0, block_time: 2.5 * 60, price: 150 },
  bch: { reward: 12.5, block_time: 9.6 * 60, price: 1002 },
}

if ENV['RELOAD'] == '1'
  puts
  puts "LOADING CURRENCY PAIRS FROM GDAX"
  puts
  puts "%-8s%16s" % ['Coin', 'Last Price']
  puts "-" * 24
  %w(BTC-USD ETH-USD LTC-USD BCH-USD).each do |pid|
    uri = URI("https://api.gdax.com/products/#{ pid }/stats")
    body = Net::HTTP.get(uri) # => String

    if body
      resp = JSON.parse(body)
      coin = pid.split('-')[0].downcase.to_sym
      coins[coin][:price] = Float(resp['last'])
      puts "%-8s%16s" % [coin.upcase, resp['last'].gsub(/(\d+\.\d{2}).+/, '\1')]
    else
      puts "ERROR!"
    end

    sleep 1
  end
  puts
  puts "=" * 40
  puts
end

def daily_value(coin)
  blocks_per_day = DAY / coin[:block_time]
  block_value = coin[:reward] * coin[:price]
  block_value * blocks_per_day
end

def format(number)
  left, right = number.round(2).to_s.split(".".freeze)

  left.gsub!(/(\d)(?=(\d\d\d)+(?!\d))/) do |digit_to_delimit|
    "#{digit_to_delimit},"
  end

  '$' + left
end

puts "DAILY NEW COIN VALUE"
puts
puts "%-8s%16s" % ['Coin', '$ value']
puts "-" * 24

total = 0

%w(btc eth ltc bch).each do |name|
  label = name.upcase
  coin = coins[name.to_sym]

  dv = daily_value(coin)
  puts "%-8s%16s" % [label, format(dv)]
  total += dv
end


puts "-" * 24
puts "%-8s%16s" % ['Total', format(total)]
puts