Basic coin control for Bitcoin/Altcoin wallets in Ruby

wallet.rb

require 'rpcjson'
require 'bigdecimal'
require 'bigdecimal/util'

class Wallet

	class InsufficientFundsError < StandardError; end

	def initialize(user, pass, host = '127.0.0.1:22555', fee = '0.1'.to_d)
		@rpc = RPC::JSON::Client.new "http://#{user}:#{pass}@#{host}", 1.1
		@fee = fee
	end

	def address_balance(address, confs = 0)
		unspent_outputs = list_unspent confs, 9999999, [address]
		unspent_outputs.inject(0){|sum,o| sum + o['amount']}
	end

	def send_from_address(from, to, amount)
		total_amount = (amount + @fee).round(8)
		unspent_outputs = list_unspent 0, 9999999, [from]
		amount_to_spend = BigDecimal('0')
		txs_to_spend = []
		unspent_outputs.each do |o|
			break if amount_to_spend >= total_amount
			amount_to_spend += o['amount'].to_s.to_d
			txs_to_spend << {'txid' => o['txid'], 'vout' => o['vout']}
		end
		raise InsufficientFundsError if amount_to_spend < total_amount
		new_outputs = {}		
		new_outputs[to] = amount.round(8).to_f
		new_outputs[from] = (amount_to_spend - send_amount - @fee).round(8).to_f
		raw_tx = create_raw_transaction txs_to_spend, new_outputs
		signed_tx = sign_raw_transaction raw_tx
		send_raw_transaction signed_tx['hex']
	end

	def method_missing(method, *args)
		@rpc.send method.to_s.gsub('_','').to_sym, *args
	end

end