/* sbt -- Simple Build Tool
 * Copyright 2009 Mark Harrah
 */
package sbt

object SelectMainClass
{
	// Some(SimpleReader.readLine _)
	def apply(promptIfMultipleChoices: Option[String => Option[String]], mainClasses: Seq[String]): Option[String] =
	{
		mainClasses.toList match
		{
			case Nil => None
			case head :: Nil => Some(head)
			case multiple =>
				promptIfMultipleChoices flatMap { prompt =>
					println("\nMultiple main classes detected, select one to run:\n")
					for( (className, index) <- multiple.zipWithIndex )
						println(" [" + (index+1) + "] " + className)
					val line = trim(prompt("\nEnter number: "))
					println("")
					toInt(line, multiple.length) map multiple.apply
				}
		}
	}
	private def trim(s: Option[String]) = s.getOrElse("")
	private def toInt(s: String, size: Int) =
		try
		{
			val i = s.toInt
			if(i > 0 && i <= size)
				Some(i-1)
			else
			{
				println("Number out of range: was " + i + ", expected number between 1 and " + size)
				None
			}
		}
		catch
		{
			case nfe: NumberFormatException =>
				println("Invalid number: " + nfe.toString)
				None
		}
}