// Main Part 3 about Evil Wordle

//===============================

object M2 { 

import io.Source

import scala.util._

// ADD YOUR CODE BELOW

//======================

//(1)

def get_wordle_list(url: String) : List[String] = {

    Try(Source.fromURL(url).getLines.toList).getOrElse(List())

}

// val secrets = get_wordle_list("https://nms.kcl.ac.uk/christian.urban/wordle.txt")

// secrets.length // => 12972

// secrets.filter(_.length != 5) // => Nil

//(2) 

def removeN[A](xs: List[A], elem: A, n: Int) : List[A] = xs match {

    case Nil => Nil

    case x :: tail if x == elem && n > 0 => removeN(tail, elem, n - 1)

    case x :: tail => x :: removeN(tail, elem, n)

}

// removeN(List(1,2,3,2,1), 3, 1)  // => List(1, 2, 2, 1)

// removeN(List(1,2,3,2,1), 2, 1)  // => List(1, 3, 2, 1)

// removeN(List(1,2,3,2,1), 1, 1)  // => List(2, 3, 2, 1)

// removeN(List(1,2,3,2,1), 0, 2)  // => List(1, 2, 3, 2, 1)

// (3)

abstract class Tip

case object Absent extends Tip

case object Present extends Tip

case object Correct extends Tip

def pool(secret: String, word: String) : List[Char] = {

    (for(index <- (0 to word.length-1); if (word(index) != secret(index))) yield secret(index).toChar).toList

}

// t

def aux(secret: List[Char], word: List[Char], pool: List[Char]) : List[Tip] = {

    if (secret.isEmpty) List()

    else {

        if (secret.head == word.head) Correct :: aux(secret.tail, word.tail, pool)

        else if (pool.contains(word.head)) Present :: aux(secret.tail, word.tail, pool.filterNot(_ == word.head))

        else Absent :: aux(secret.tail, word.tail, pool)

    }

}

def score(secret: String, word: String) : List[Tip] = aux(secret.toList, word.toList, pool(secret, word))

// score("chess", "caves") // => List(Correct, Absent, Absent, Present, Correct)

// score("doses", "slide") // => List(Present, Absent, Absent, Present, Present)

// score("chess", "swiss") // => List(Absent, Absent, Absent, Correct, Correct)

// score("chess", "eexss") // => List(Present, Absent, Absent, Correct, Correct)

// (4)

def eval(t: Tip) : Int = t match {

    case Correct => 10

    case Present => 1

    case Absent => 0 

}

def iscore(secret: String, word: String) : Int =  (for(current <- score(secret, word)) yield eval(current)).sum

//iscore("chess", "caves") // => 21

//iscore("chess", "swiss") // => 20

// (5) t

def lowest(secrets: List[String], word: String, current: Int, acc: List[String]) : List[String] = {

    if (secrets.isEmpty) acc

    else {

        val score = iscore(secrets.head, word)

        if (score == current) lowest(secrets.tail, word, current, secrets.head :: acc)

        else if (score < current) lowest(secrets.tail, word, score, List(secrets.head))

        else lowest(secrets.tail, word, current, acc)

    }

}

def evil(secrets: List[String], word: String) = lowest(secrets, word, Int.MaxValue ,List())

//evil(secrets, "stent").length

//evil(secrets, "hexes").length

//evil(secrets, "horse").length

//evil(secrets, "hoise").length

//evil(secrets, "house").length

// (6) t

def frequencies(secrets: List[String]) : Map[Char, Double] = {

    val occurrences = secrets.mkString.groupBy(identity).mapValues(_.length)

    val all_letters = secrets.mkString.length.toDouble

    occurrences.map{ case (c, n) => c -> (1 - n/all_letters) }.toMap

}

// (7) 

def rank(frqs: Map[Char, Double], s: String) : Double = s.map(c => frqs(c)).sum

def ranked_evil(secrets: List[String], word: String): List[String] = {

    val frqs = frequencies(secrets)

    val ranked_secrets = evil(secrets, word).map(s => (s, rank(frqs, s)))

    List((ranked_secrets.sortWith(_._2 > _._2)).map(_._1).head )

}

}

// This template code is subject to copyright 

// by King's College London, 2022. Do not 

// make the template code public in any shape 

// or form, and do not exchange it with other 

// students under any circumstance.