class Account
  attr_reader :account_id, :balance

  def initialize(account_id)
    @account_id = account_id
    @balance = 0
  end

  def withdraw(amount)
    raise "Insufficient funds" if amount < 0
    @balance -= amount
  end

  def deposit(amount)
    @balance += amount
  end

  def update_log(msg, date, amount)
    puts "Account: #{inspect}, #{msg}, #{date.to_s}, #{amount}"
  end

  def self.find(account_id)
    @@store ||= Hash.new
    return @@store[account_id] if @@store.has_key? account_id

    if :savings == account_id
      account = SavingsAccount.new(account_id)
      account.deposit(100000)
    elsif :checking == account_id
      account = CheckingAccount.new(account_id)
    else
      account = Account.new(account_id)
    end
    @@store[account_id] = account
    account
  end
end

module MoneySource
  include Rdci::Role

  def transfer_out
    raise "Insufficient funds" if balance < Amount
    withdraw Amount
    DestinationAccount.deposit Amount
    update_log "Transfer Out", Time.now, Amount
    DestinationAccount.update_log "Transfer In", Time.now, Amount
  end

end

class TransferMoneyContext
  include Rdci::Context

  attr_reader :source_account, :destination_account, :amount

  def self.execute(amt, source_account_id, destination_account_id)
    TransferMoneyContext.new(amt, source_account_id, destination_account_id).execute
  end

  def initialize(amt, source_account_id, destination_account_id)
    @source_account = Account.find(source_account_id)
    @source_account.mixin MoneySource

    @destination_account = Account.find(destination_account_id)
    @amount = amt
  end

  def execute
    in_context do
      source_account.transfer_out
    end
    @source_account.unmix MoneySource
  end

end

class SavingsAccount < Account
end

class CheckingAccount < Account
end

TransferMoneyContext.execute(300, :savings, :checking)

puts "Savings: #{Account.find(:savings).balance}, Checking: #{Account.find(:checking).balance}"