Refacor Mastermind and implement functional style

src/assignment/week2/mastermind/Common.kt

@@ -0,0 +1,3 @@
+package assignment.week2.mastermind
+
+data class Evaluation(val rightPosition: Int, val wrongPosition: Int)

src/assignment/week2/mastermind/evaluateGuess.kt

@@ -1,6 +1,4 @@
-package mastermind
-
-data class Evaluation(val rightPosition: Int, val wrongPosition: Int)
+package assignment.week2.mastermind
 
 enum class Match {
     RIGHT_POSITION,
@@ -13,31 +11,57 @@ fun evaluateGuess(secret: String, guess: String): Evaluation {
     val secretMatches = createMatches(secret)
 
     for ((index, guessChar) in guess.withIndex()) {
-        if (secretMatches[index].char == guessChar) {
-            if (secretMatches[index].match == Match.WRONG_POSITION) {
-                for ((index, secretChar) in secret.drop(index + 1).withIndex()) {
-                    if (secretChar == guessChar) {
-                        secretMatches[index].match = Match.WRONG_POSITION
-                        break
-                    }
-                }
-            }
-            secretMatches[index].match = Match.RIGHT_POSITION
+        val secretMatch = secretMatches[index]
+        if (secretMatch.char == guessChar) {
+            handleMatch(secretMatches, index)
             continue
         }
-        for ((index, secretChar) in secret.withIndex()) {
-            if (secretMatches[index].match == null && secretChar == guessChar) {
-                secretMatches[index].match = Match.WRONG_POSITION
-                break
-            }
-        }
+        handleNotMatch(secretMatches, guessChar)
     }
 
     return Evaluation(
-        secretMatches.filter { it.match == Match.RIGHT_POSITION }.size,
-        secretMatches.filter { it.match == Match.WRONG_POSITION }.size
+        secretMatches.countMatch(Match.RIGHT_POSITION),
+        secretMatches.countMatch(Match.WRONG_POSITION)
     )
 }
 
-fun createMatches(secret: String): List<CharMatch> = secret.map { CharMatch(it, null) }
+private fun handleNotMatch(
+    secretMatches: List<CharMatch>,
+    guessChar: Char
+) {
+    for (secretMatch in secretMatches) {
+        if (secretMatch.match == null && secretMatch.char == guessChar) {
+            secretMatch.match = Match.WRONG_POSITION
+            return
+        }
+    }
+}
 
+private fun handleMatch(secretMatches: List<CharMatch>, index: Int) {
+    val secretMatch = secretMatches[index]
+    if (secretMatch.match == Match.WRONG_POSITION) {
+        moveWrongPosition(
+            secretMatches.drop(index + 1).map { it.char },
+            secretMatch.char,
+            secretMatches
+        )
+    }
+    secretMatch.match = Match.RIGHT_POSITION
+}
+
+private fun List<CharMatch>.countMatch(match: Match): Int = filter { it.match == match }.size
+
+private fun moveWrongPosition(
+    chars: List<Char>,
+    guessChar: Char,
+    secretMatches: List<CharMatch>
+) {
+    for ((index, secretChar) in chars.withIndex()) {
+        if (secretChar == guessChar) {
+            secretMatches[index].match = Match.WRONG_POSITION
+            return
+        }
+    }
+}
+
+fun createMatches(secret: String): List<CharMatch> = secret.map { CharMatch(it, null) }

src/assignment/week2/mastermind/evaluateGuessFunctional.kt

@@ -0,0 +1,22 @@
+package assignment.week2.mastermind
+
+fun evaluateGuessFunctional(secret: String, guess: String): Evaluation {
+    val rightPositions = secret.zip(guess).count { (sChar, gChar) -> sChar == gChar }
+
+    val commonLetters = "ABCDEF".sumOf { ch ->
+        secret.count { it == ch }.coerceAtMost(guess.count { it == ch })
+    }
+    return Evaluation(rightPositions, commonLetters - rightPositions)
+}
+
+fun main() {
+    val result = Evaluation(rightPosition = 1, wrongPosition = 1)
+    evaluateGuessFunctional("BCDF", "ACEB") eq result
+    evaluateGuessFunctional("AAAF", "ABCA") eq result
+    evaluateGuessFunctional("ABCA", "AAAF") eq result
+}
+
+private infix fun <T> T.eq(other: T) {
+    if (this != other) throw AssertionError("Expected $this to equal $other")
+    println("OK")
+}

src/assignment/week2/mastermind/playMastermind.kt

@@ -1,4 +1,4 @@
-package mastermind
+package assignment.week2.mastermind
 
 import kotlin.random.Random
 
@@ -11,8 +11,8 @@ fun main() {
 }
 
 fun playMastermind(
-        differentLetters: Boolean,
-        secret: String = generateSecret(differentLetters)
+    differentLetters: Boolean,
+    secret: String = generateSecret(differentLetters)
 ) {
     var evaluation: Evaluation
 
@@ -20,17 +20,21 @@ fun playMastermind(
         print("Your guess: ")
         var guess = readLine()!!
         while (hasErrorsInInput(guess)) {
-            println("Incorrect input: $guess. " +
-                    "It should consist of $CODE_LENGTH characters from $ALPHABET. " +
-                    "Please try again.")
+            println(
+                "Incorrect input: $guess. " +
+                        "It should consist of $CODE_LENGTH characters from $ALPHABET. " +
+                        "Please try again."
+            )
             guess = readLine()!!
         }
         evaluation = evaluateGuess(secret, guess)
         if (evaluation.isComplete()) {
             println("The guess is correct!")
         } else {
-            println("Right positions: ${evaluation.rightPosition}; " +
-                    "wrong positions: ${evaluation.wrongPosition}.")
+            println(
+                "Right positions: ${evaluation.rightPosition}; " +
+                        "wrong positions: ${evaluation.wrongPosition}."
+            )
         }
 
     } while (!evaluation.isComplete())