/* sbt -- Simple Build Tool
 * Copyright 2010  Mark Harrah
 */
package sbt
package complete

import History.number

final class History private(lines: IndexedSeq[String], error: String => Unit) extends NotNull
{
	private def reversed = lines.reverse

	def all: Seq[String] = lines
	def size = lines.length
	def !! : Option[String] = !- (1)
	def apply(i: Int): Option[String] = if(0 <= i && i < size) Some( lines(i) ) else { error("Invalid history index: " + i); None }
	def !(i: Int): Option[String] = apply(i)

	def !(s: String): Option[String] =
		number(s) match
		{
			case Some(n) => if(n < 0) !- (-n) else apply(n)
			case None => nonEmpty(s) { reversed.find(_.startsWith(s)) }
		}
	def !- (n: Int): Option[String] = apply(size - n - 1)

	def !?(s: String): Option[String] = nonEmpty(s) { reversed.drop(1).find(_.contains(s)) }

	private def nonEmpty[T](s: String)(act: => Option[T]): Option[T] =
		if(s.isEmpty)
		{
			error("No action specified to history command")
			None
		}
		else
			act

	def list(historySize: Int, show: Int): Seq[String] =
		lines.toList.drop((lines.size - historySize) max 0).zipWithIndex.map { case (line, number) => "   " + number + "  " + line }.takeRight(show max 1)
}

object History
{
	def apply(lines: Seq[String], error: String => Unit): History = new History(lines.toIndexedSeq, error)

	def number(s: String): Option[Int] =
		try { Some(s.toInt) }
		catch { case e: NumberFormatException => None }
}