import java.util.*

/*
* Algorithm:
*   1. last jew in line (first to guess):
*       a. count number of white hats
*       b. if number of white hats is even:
*          i. return "WHITE"
*       c. else:
*          i. return "BLACK"
*   2. for each thereafter:
*       a. count number of white hats visible
*       b. if the number is even:
*           i. if number of jews to answer "WHITE" before me is even, guess="BLACK"
*           ii. else guess="WHITE"
*       c. else:
*           i. if number of jews to answer "BLACK" before me is even, guess="WHITE"
*           ii. else guess="BLACK"
*       d. if first jew to guess, guessed "WHITE":
*           i. return $guess
*       e. else:
*           i. return opposite color of $guess
*/

fun Int.isEven() = this%2 == 0

class Line(private val numJewsInLine: Int) {
    private var line : Array<Jew>

    init {
        line = Array(numJewsInLine) { i -> Jew(i) }
    }

    fun getNumWhiteHatsVisibleToIndex(index: Int): Int {
        var count = 1
        for (i in 0..(index-1)) {
            if (line[i].hat.color == Hat.HatColors.WHITE) {
                count++
            }
        }
        return count
    }

    fun getFirstJewGuess(): Hat.HatColors {
        return if (getNumWhiteHatsVisibleToIndex(numJewsInLine-1).isEven()) {
            Hat.HatColors.WHITE
        } else {
            Hat.HatColors.BLACK
        }
    }

    fun guess(): Pair<Double, String> {
        val guessOutput = StringBuilder() // holds log of guesses
        var numJewsGuessedWhite = 0
        var correctGuesses = 0

        var guess = getFirstJewGuess()
        guessOutput.append("Jew number $numJewsInLine guess: $guess. actual color: ${line[numJewsInLine-1].hat.color} - ${if (guess == line[numJewsInLine-1].hat.color) "CORRECT" else "WRONG"}\n")
        if (guess == line[numJewsInLine-1].hat.color) correctGuesses++

        for (i in numJewsInLine-2 downTo 0) {
            guess = line[i].guessHatColor(this, numJewsGuessedWhite)
            if (guess == line[i].hat.color) correctGuesses++
            guessOutput.append("Jew number ${i+1} guess: $guess. actual color: ${line[i].hat.color} - ${if (guess == line[i].hat.color) "CORRECT" else "WRONG"}\n")
            if (guess == Hat.HatColors.WHITE) numJewsGuessedWhite++
        }
        return Pair(correctGuesses.toDouble()/numJewsInLine, guessOutput.toString())
    }

}

class Jew (val hat: Hat, private val indexInLine: Int) {
    fun guessHatColor(line: Line, numJewsGuessedWhiteBeforeMe: Int): Hat.HatColors {
        val numWhiteHatsVisibleToMe = line.getNumWhiteHatsVisibleToIndex(indexInLine)
        val guessColor =
                if (numWhiteHatsVisibleToMe.isEven()) {
                    if (numJewsGuessedWhiteBeforeMe.isEven()) Hat.HatColors.BLACK else Hat.HatColors.WHITE
                } else {
                    if (numJewsGuessedWhiteBeforeMe.isEven()) Hat.HatColors.WHITE else Hat.HatColors.BLACK
                }

        return if (line.getFirstJewGuess() == Hat.HatColors.WHITE) guessColor else Hat().getOppositeColor(guessColor)
    }

    constructor(indexInLine : Int) : this(Hat(), indexInLine)
}

class Hat (var color : HatColors){
    enum class HatColors {
        WHITE,
        BLACK
    }

    fun getOppositeColor(color: HatColors): HatColors = if (color == HatColors.WHITE) HatColors.BLACK else HatColors.WHITE

    constructor() : this((if (Random().nextBoolean()) HatColors.WHITE else HatColors.BLACK))
}

fun main(args : Array<String>) {
    val line = Line(10)
    val (stats, log) = line.guess()

    println("Percentage of jews who guess correctly: ${(stats * 100)}%\n$log")
}