//
// 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")
//
// transactions can be read from a file, and saved at end
//
import scala.io.Source
import java.io.PrintWriter
import java.io.File

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

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

if (args.length < 1) {
  println("need command-line argument (name of file, - for none)")
  sys.exit(1)
}
val fileName = args(0)

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

if (fileName != "-") {
  getSavedInfo(fileName)
}

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)

println("name of file to save info?")
if (fileName != "-") {
  println("(blank to reuse " + fileName + ")")
}
val fileName2 = readLine.trim
saveInfo(if (fileName2 == "") fileName else fileName2)


def getTransaction(choice : Char) {
  println("enter amount (integer)")
  try {
    val amount = readLine.trim.toInt
    println("enter description (line of text)")
    val descrip = readLine
    choice match {
      case 'd' => {
        debit(amount, descrip)
      }
      case 'c' => {
        credit(amount, descrip)
      }
      case _ => { } // FIXME should this be an error?
    }
  }
  catch {
    case e:java.lang.NumberFormatException => {
      println("invalid amount")
    }
  }
}

def debit(amt : Int, descrip : String) {
  balance -= amt
  transactions = Transaction(amt, "debit", descrip) :: transactions
}

def credit(amt : Int, descrip : String) {
  balance += amt
  transactions = Transaction(amt, "credit", descrip) :: transactions
}

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

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

def getSavedInfo(fileName : String) {
  try {
    val source = scala.io.Source.fromFile(fileName)
    for (line <- source.getLines) {
      val parts = line.split(",")
      if (parts.length != 3) {
        println("invalid input (not enough fields)")
        sys.exit(1)
      }
      val kind = parts(0)
      val amt = parts(1).trim.toInt
      val descrip = parts(2).trim
      kind match {
        case "debit" => debit(amt, descrip)
        case "credit" => credit(amt, descrip)
        case _ => {
          println("invalid input (not debit/credit)")
          sys.exit(1)
        }
      }
    }
    source.close()
  }
  catch {
    case e:java.io.FileNotFoundException => {
      println("could not open file:  " + e.getMessage)
      sys.exit(1)
    }
    case e:java.io.IOException => {
      println("error reading file:  " + e.getMessage)
      sys.exit(1)
    }
    case e:java.lang.NumberFormatException => {
      println("invalid input (not numeric):  " + e.getMessage)
      sys.exit(1)
    }
  }
}

def saveInfo(fileName : String) {
  try {
    val pw = new PrintWriter(new File(fileName))
    transactions.reverse.foreach(t => 
      {
        pw.println(t.kind + ", " + t.amount + ", " + t.descrip)
      }
    )
    pw.close()
    println("saved to file " + fileName)
  }
  catch {
    case e:java.io.IOException => {
      println("error saving file:  " + e.getMessage)
    }
  }
}