sbt/util/log/src/test/scala/Escapes.scala

package sbt

import org.scalacheck._
import Prop._
import Gen.{ listOf, oneOf }

import ConsoleLogger.{ ESC, hasEscapeSequence, isEscapeTerminator, removeEscapeSequences }

object Escapes extends Properties("Escapes") {
  property("genTerminator only generates terminators") =
    forAllNoShrink(genTerminator) { (c: Char) => isEscapeTerminator(c) }

  property("genWithoutTerminator only generates terminators") =
    forAllNoShrink(genWithoutTerminator) { (s: String) =>
      s.forall { c => !isEscapeTerminator(c) }
    }

  property("hasEscapeSequence is false when no escape character is present") = forAllNoShrink(genWithoutEscape) { (s: String) =>
    !hasEscapeSequence(s)
  }

  property("hasEscapeSequence is true when escape character is present") = forAllNoShrink(genWithRandomEscapes) { (s: String) =>
    hasEscapeSequence(s)
  }

  property("removeEscapeSequences is the identity when no escape character is present") = forAllNoShrink(genWithoutEscape) { (s: String) =>
    val removed: String = removeEscapeSequences(s)
    ("Escape sequence removed: '" + removed + "'") |:
      (removed == s)
  }

  property("No escape characters remain after removeEscapeSequences") = forAll { (s: String) =>
    val removed: String = removeEscapeSequences(s)
    ("Escape sequence removed: '" + removed + "'") |:
      !hasEscapeSequence(removed)
  }

  property("removeEscapeSequences returns string without escape sequences") =
    forAllNoShrink(genWithoutEscape, genEscapePairs) { (start: String, escapes: List[EscapeAndNot]) =>
      val withEscapes: String = start + escapes.map { ean => ean.escape.makeString + ean.notEscape }
      val removed: String = removeEscapeSequences(withEscapes)
      val original = start + escapes.map(_.notEscape)
      ("Input string with escapes: '" + withEscapes + "'") |:
        ("Escapes removed '" + removed + "'") |:
        (original == removed)
    }

  final case class EscapeAndNot(escape: EscapeSequence, notEscape: String)
  final case class EscapeSequence(content: String, terminator: Char) {
    assert(content.forall(c => !isEscapeTerminator(c)), "Escape sequence content contains an escape terminator: '" + content + "'")
    assert(isEscapeTerminator(terminator))
    def makeString: String = ESC + content + terminator
  }
  private[this] def noEscape(s: String): String = s.replace(ESC, ' ')

  lazy val genEscapeSequence: Gen[EscapeSequence] = oneOf(genKnownSequence, genArbitraryEscapeSequence)
  lazy val genEscapePair: Gen[EscapeAndNot] = for (esc <- genEscapeSequence; not <- genWithoutEscape) yield EscapeAndNot(esc, not)
  lazy val genEscapePairs: Gen[List[EscapeAndNot]] = listOf(genEscapePair)

  lazy val genArbitraryEscapeSequence: Gen[EscapeSequence] =
    for (content <- genWithoutTerminator; term <- genTerminator) yield new EscapeSequence(content, term)

  lazy val genKnownSequence: Gen[EscapeSequence] =
    oneOf((misc ++ setGraphicsMode ++ setMode ++ resetMode).map(toEscapeSequence))

  def toEscapeSequence(s: String): EscapeSequence = EscapeSequence(s.init, s.last)

  lazy val misc = Seq("14;23H", "5;3f", "2A", "94B", "19C", "85D", "s", "u", "2J", "K")

  lazy val setGraphicsMode: Seq[String] =
    for (txt <- 0 to 8; fg <- 30 to 37; bg <- 40 to 47) yield txt.toString + ";" + fg.toString + ";" + bg.toString + "m"

  lazy val resetMode = setModeLike('I')
  lazy val setMode = setModeLike('h')
  def setModeLike(term: Char): Seq[String] = (0 to 19).map(i => "=" + i.toString + term)

  lazy val genWithoutTerminator = genRawString.map(_.filter { c => !isEscapeTerminator(c) })

  lazy val genTerminator: Gen[Char] = Gen.choose('@', '~')
  lazy val genWithoutEscape: Gen[String] = genRawString.map(noEscape)

  def genWithRandomEscapes: Gen[String] =
    for (ls <- listOf(genRawString); end <- genRawString) yield ls.mkString("", ESC.toString, ESC.toString + end)

  private def genRawString = Arbitrary.arbString.arbitrary
}