gistfile1.txt

class TransactionAccount < ActiveRecord::Base
  composed_of :balance, :class_name => "Money", :mapping => [%w(account_balance_cents cents), %w(currency currency) ]

  belongs_to :user
  has_many :sent_transactions,     :class_name => "TransactionItem",
                                  :foreign_key => "transaction_sender_account_id"
  
  has_many :received_transactions, :class_name => "TransactionItem",
                                  :foreign_key => "transaction_receiver_account_id"

  def transactions
      TransactionItem.find(:all, :conditions => ["transaction_sender_account_id = ? OR transaction_receiver_account_id = ?",id,id])
  end

  def update_balance
    calculated_balance = Money.new(0, "USD")
    sent_transactions.each do |transaction|
      calculated_balance += transaction.sender_calculate
    end

    received_transactions.each do |transaction|
      calculated_balance += transaction.receiver_calculate
    end
    self.balance = calculated_balance
    save
  end
end

class TransactionItem < ActiveRecord::Base
  VALID_TRANSACTION_STATUS = ["Pending", "Complete"]


  composed_of :amount, :class_name => "Money", :mapping => [%w(cents cents), %w(currency currency) ]

  belongs_to  :sender,
              :class_name => "TransactionAccount",
              :foreign_key => "transaction_sender_account_id"

  belongs_to  :receiver,
              :class_name => "TransactionAccount",
              :foreign_key => "transaction_receiver_account_id"

  belongs_to  :transaction_object,
              :polymorphic => true

  validates_presence_of :description
  validates_inclusion_of :status, :in => VALID_TRANSACTION_STATUS

  # Used to update a transaction, for example a call that is in progress
  def update

  end

  # Used to finalize a transaction, for example when a call is completed
  def finalize
    
  end

  # Amount the receiver gets
  def receiver_amount
    Money.new(0)
  end

  # Amount the sender gets
  def sender_amount
    Money.new(0)
  end
  # Defines the behaviour of this item when calculating account totals
  def receiver_calculate
    Money.new(0)
  end

  # Defines the behaviour of this item when calculating account totals
  def sender_calculate
    Money.new(0)
  end

  private
    validate :cents_not_zero

    def cents_not_zero
      errors.add("cents", "cannot be zero or less") unless cents > 0
    end 
end

class TransactionItemDeposit < TransactionItem
  validates_presence_of :receiver

  def initialize(account, amount, description)
    super()
    self.receiver = account
    self.amount = Money.new(amount, "USD")
    self.status = "Pending"
    description.nil? ? self.description = "Deposit" : self.description = description
  end

  def receiver_amount
    amount
  end

  def receiver_calculate
    case status
    when "Pending"
      Money.new(0, "USD")
    when "Complete"
      amount
    end
  end
  
  def finalize
    
  end
end