//
// program to simulate checkbook, sort of -- maintain list of transactions
// (debits and credits) and current balance, allow some simple queries of
// transactions
//
// each transaction will consist of an amount, "debit" or "credit",
// and a line of text to identify it (e.g., "paycheck" or "rent")
//

case class Transaction(amount : Int, kind : String, descrip : String)

var balance = 0
var transactions = List[Transaction]()

val Prompt = """enter one of:
    d for debit
    c for credit
    h for transaction history
    s to search transactions
    q to quit"""

println("starting balance (integer):")
balance = readInt

var choice = ' '

do {
  println("\ncurrent balance $" + balance)
  println(Prompt)
  choice = readChar

  choice match {
    case 'd' | 'c' => {
      getTransaction(choice)
    }
    case 'h' => {
      println(transactions.length + " transactions available")
      println("how many to display?")
      val count = readInt
      transactions.take(count).foreach(elem => printTransaction(elem))
    }
    case 's' => {
      println("text to search for:")
      val s = readLine
      transactions.filter(trans => descrMatch(trans, s)).
        foreach(elem => printTransaction(elem))
    }
    case 'q' => { }
    case _ => {
      println("invalid choice")
    }
  }
} while (choice != 'q')
println("ending balance $" + balance)

def getTransaction(choice : Char) {
  println("enter amount (integer)")
  val amount= readInt
  println("enter description (line of text)")
  val descrip = readLine
  choice match {
    case 'd' => {
      balance -= amount
      transactions = Transaction(amount, "debit", descrip) :: transactions
    }
    case 'c' => {
      balance += amount
      transactions = Transaction(amount, "credit", descrip) :: transactions
    }
    case _ => { } // FIXME should this be an error?
  }
}

def printTransaction(t : Transaction) {
  println(t.kind + " $" + t.amount + " (" + t.descrip + ")")
}

def descrMatch(trans : Transaction, searchText : String) : Boolean = {
  trans.descrip.contains(searchText)
}