require "bancor/version"

module Bancor
  attr_accessor :total_supply, :price

  ETH = 300000.freeze        # 300000(ETH)
  CRR = 0.2.freeze           # CRR = 20%
  RATE = 1.freeze            # Rate 1ETH = 1BNT

  def initialize
    @total_supply = ETH
    @reserved_token = ETH * 0.2 # ETH 20% to reserve. CRR = 20%
    @price = @reserved_token / (@total_supply * CRR)
  end

  def buying(quantity)
    token = @total_supply * (((1 + (quantity / @reserved_token)) ** CRR) - 1)
    @reserved_token = @reserved_token + quantity
    @total_supply = @total_supply + token
    @price = @reserved_token / (@total_supply * CRR)
  end

  def selling(quantity)
    token = @reserved_token * (1 - ((1 - (quantity / @total_supply)) ** (1/CRR)))
    @reserved_token = @reserved_token - token
    @total_supply = @total_supply - quantity
    @price = @reserved_token / (@total_supply * CRR)
  end
end