From 48522ba27d7fa7ba2a55684126743af66feb1883 Mon Sep 17 00:00:00 2001
From: John Long <patimen@yahoo.com>
Date: Sun, 2 Jan 2022 16:26:25 -0800
Subject: [PATCH] Add Kotlin version of Animal

Animal fascinated me as a kid. I wrote a version in Modula-2 for a Junior High School project. Didn't realize at the time I was studying binary trees.
---
 03_Animal/kotlin/Animal.kt | 119 +++++++++++++++++++++++++++++++++++++
 03_Animal/kotlin/README.md |   3 +
 2 files changed, 122 insertions(+)
 create mode 100644 03_Animal/kotlin/Animal.kt
 create mode 100644 03_Animal/kotlin/README.md

diff --git a/03_Animal/kotlin/Animal.kt b/03_Animal/kotlin/Animal.kt
new file mode 100644
index 00000000..bac9af08
--- /dev/null
+++ b/03_Animal/kotlin/Animal.kt
@@ -0,0 +1,119 @@
+/**
+ * ANIMAL
+ *
+ *
+ * Converted from BASIC to Kotlin by John Long (@patimen)
+ *
+ * Animal is basically a perfect example of a binary tree. Implement it
+ * as such, with the QuestionNode either having an answer if it is a terminal node
+ * or a Question
+ */
+
+fun main() {
+    printIntro()
+    val rootQuestionNode =
+        QuestionOrAnswer(question = Question("DOES IT SWIM", QuestionOrAnswer("FISH"), QuestionOrAnswer("BIRD")))
+    while (true) {
+        val choice = ask("ARE YOU THINKING OF AN ANIMAL")
+        when {
+            choice == "LIST" -> printKnownAnimals(rootQuestionNode)
+            choice.startsWith("Q") -> return
+            choice.startsWith("Y") -> {
+                // A wrong answer means it's a new animal!
+                val wrongAnswer = rootQuestionNode.getWrongAnswer()
+                if (wrongAnswer == null) {
+                    // The computer got the right answer!
+                    println("WHY NOT TRY ANOTHER ANIMAL?")
+                } else {
+                    // Get a new question to ask next time
+                    wrongAnswer.askForInformationAndSave()
+                }
+            }
+        }
+    }
+}
+
+// Takes care of asking a question (on the same line) and getting
+// an answer or a blank string
+fun ask(question: String): String {
+    print("$question? ")
+    return readLine()?.uppercase() ?: ""
+}
+
+// Special case for a "yes or no" question, returns true of yes
+fun askYesOrNo(question: String): Boolean {
+    return generateSequence {
+        print("$question? ")
+        readLine()
+    }.firstNotNullOf { yesOrNo(it) }
+}
+
+// If neither Y (true) or N (false), return null, so the above sequence
+// will just keep executing until it gets the answer
+private fun yesOrNo(string: String): Boolean? =
+    when (string.uppercase().firstOrNull()) {
+        'Y' -> true
+        'N' -> false
+        else -> null
+    }
+
+private fun printKnownAnimals(question: QuestionOrAnswer) {
+    println("\nANIMALS I ALREADY KNOW ARE:")
+    val animals = question.getAnswers().chunked(4)
+    animals.forEach { line ->
+        // The '*' in front of line.toTypedArray() "spreads" the array as a list of parameters instead
+        System.out.printf("%-15s".repeat(line.size), *line.toTypedArray())
+        println()
+    }
+}
+
+private fun printIntro() {
+    println("                                ANIMAL")
+    println("              CREATIVE COMPUTING  MORRISTOWN, NEW JERSEY")
+    println("\n\n")
+    println("PLAY 'GUESS THE ANIMAL'")
+    println("\n")
+    println("THINK OF AN ANIMAL AND THE COMPUTER WILL TRY TO GUESS IT.")
+}
+
+class QuestionOrAnswer(private var answer: String? = null, var question: Question? = null) {
+    fun getAnswers(): List<String> = answer?.let { listOf(it) } ?: question!!.getAnswers()
+    fun getWrongAnswer(): QuestionOrAnswer? {
+        if (answer != null) {
+            // "takeUnless" will return null if the answer is "yes". In this case
+            // we will return the "wrong answer", aka the terminal answer that was incorrect
+            return this.takeUnless { askYesOrNo("IS IT A $answer") }
+        }
+        return question?.getWrongAnswer()
+    }
+
+    fun askForInformationAndSave() {
+        //Failed to get it right and ran out of questions
+        //Let's ask the user for the new information
+        val newAnimal = ask("THE ANIMAL YOU WERE THINKING OF WAS A")
+        val newQuestion = ask("PLEASE TYPE IN A QUESTION THAT WOULD DISTINGUISH A \n$newAnimal FROM A $answer\n")
+        val newAnswer = askYesOrNo("FOR A $newAnimal THE ANSWER WOULD BE")
+
+        val trueAnswer = if (newAnswer) newAnimal else answer
+        val falseAnswer = if (newAnswer) answer else newAnimal
+        // Replace our answer with null  and set the question with the data we just got
+        // This makes it a question instead of an answer
+        this.answer = null
+        this.question = Question(newQuestion, QuestionOrAnswer(trueAnswer), QuestionOrAnswer(falseAnswer))
+    }
+}
+
+class Question(
+    private val question: String,
+    private val trueAnswer: QuestionOrAnswer,
+    private val falseAnswer: QuestionOrAnswer
+) {
+    fun getAnswers(): List<String> = trueAnswer.getAnswers() + falseAnswer.getAnswers()
+
+    fun getWrongAnswer(): QuestionOrAnswer? =
+        if (askYesOrNo(question)) {
+            trueAnswer.getWrongAnswer()
+        } else {
+            falseAnswer.getWrongAnswer()
+        }
+}
diff --git a/03_Animal/kotlin/README.md b/03_Animal/kotlin/README.md
new file mode 100644
index 00000000..f43a5b70
--- /dev/null
+++ b/03_Animal/kotlin/README.md
@@ -0,0 +1,3 @@
+Original source downloaded [from Vintage Basic](http://www.vintage-basic.net/games.html)
+
+Conversion to [Kotlin](https://kotlinlang.org/)