Build: switch to Gradle Version Catalog; upgrade Kotlin to 2.3.0-RC3; align kotlin-test via test-junit5; add Gradle Versions Plugin; reorder plugins; Dockerfile honors catalog; fix king check/castling & undo logic; ignore TODO.txt; remove dependency management doc

Author: dctabansi

.gitignore

@@ -19,3 +19,6 @@ Thumbs.db
 
 # Logs
 *.log
+
+# Project notes that should never be committed
+/src/main/kotlin/dev/tabansi/chess/TODO.txt

.idea/compiler.xml

@@ -4,9 +4,10 @@
 FROM eclipse-temurin:25-jdk AS build
 WORKDIR /workspace
 
-# Copy wrapper and build files first to leverage Docker cache
+# Copy wrapper, build, and version catalog files first to leverage Docker cache
 COPY gradlew gradlew.bat ./
 COPY gradle/wrapper ./gradle/wrapper
+COPY gradle/libs.versions.toml ./gradle/libs.versions.toml
 COPY settings.gradle.kts build.gradle.kts ./
 
 # Verify wrapper and warm up dependencies

.idea/gradle.xml

@@ -1,7 +1,8 @@
 plugins {
-    kotlin("jvm") version "2.3.0-RC2"
     application
-    id("com.gradleup.shadow") version "9.3.0"
+    alias(libs.plugins.kotlin.jvm)
+    alias(libs.plugins.shadow)
+    alias(libs.plugins.versions)
 }
 
 group = "dev.tabansi"
@@ -17,8 +18,8 @@ dependencies {
 
     // Testing
     testImplementation(kotlin("test"))
-    testImplementation("org.jetbrains.kotlin:kotlin-test-junit5")
-    testImplementation("org.junit.jupiter:junit-jupiter:5.11.0")
+    testImplementation(kotlin("test-junit5"))
+    testImplementation(libs.junit.jupiter)
 }
 
 application {

.idea/modules.xml

@@ -0,0 +1,12 @@
+[versions]
+kotlin = "2.3.0-RC3"
+junit = "6.1.0-M1"
+shadow = "9.3.0"
+
+[libraries]
+junit-jupiter = { module = "org.junit.jupiter:junit-jupiter", version.ref = "junit" }
+
+[plugins]
+kotlin-jvm = { id = "org.jetbrains.kotlin.jvm", version.ref = "kotlin" }
+shadow = { id = "com.gradleup.shadow", version.ref = "shadow" }
+versions = { id = "com.github.ben-manes.versions", version = "0.51.0" }

Dockerfile

@@ -1 +1,8 @@
+pluginManagement {
+    repositories {
+        gradlePluginPortal()
+        mavenCentral()
+    }
+}
+
 rootProject.name = "TerminalChess"

build.gradle.kts

@@ -16,6 +16,7 @@ class Game {
     private val player1 = Player(PLAYER_1)
     private val player2 = Player(PLAYER_2)
     private var currentPiece: Piece? = null
+    private var lastMovedPiece: Piece? = null
     private var lastKilledPiece: Piece? = null
     private var castled = false
 
@@ -106,7 +107,7 @@ class Game {
                     continue
                 }
                 if (destInput == "undo") {
-                    turnsSinceUndo = 0
+                    undo()
                     continue
                 }
 
@@ -121,6 +122,7 @@ class Game {
 
                 if (!isEmptySpace(x, y)) {
                     currentPiece!!.doMove(BoardSpace(x, y))
+                    lastMovedPiece = currentPiece
                     if (turnTracker % 2 == 0) {
                         lastKilledPiece = player2.getPiece(BoardSpace(x, y))
                         player2.killPiece(lastKilledPiece)
@@ -135,9 +137,11 @@ class Game {
                             promotePawn(x, y, player2)
                     }
                     turnTracker++
+                    turnsSinceUndo++
                 } else {
                     lastKilledPiece = null
                     currentPiece!!.doMove(BoardSpace(x, y))
+                    lastMovedPiece = currentPiece
                     castled = false
 
                     if (currentPiece is King) {
@@ -257,24 +261,34 @@ class Game {
     }
 
     private fun undo() {
-        if (turnTracker <= 0)
+        if (turnTracker <= 0) {
             println("You can't undo right now. Please enter a valid coordinate.")
+            return
+        }
 
-        if (turnsSinceUndo == 0)
+        if (turnsSinceUndo == 0) {
             println("\n\nYou can only undo once!\n")
+            return
+        }
+
+        val pieceToUndo = lastMovedPiece
+        if (pieceToUndo == null) {
+            println("No move to undo.")
+            return
+        }
 
         if (lastKilledPiece != null) {
             if (turnTracker % 2 == 0) {
-                currentPiece!!.undoMove(lastKilledPiece!!.pieceConstant + player1.player)
+                pieceToUndo.undoMove(lastKilledPiece!!.pieceConstant + player1.player)
                 player1.revivePiece(lastKilledPiece!!)
             } else {
-                currentPiece!!.undoMove(lastKilledPiece!!.pieceConstant + player2.player)
+                pieceToUndo.undoMove(lastKilledPiece!!.pieceConstant + player2.player)
                 player2.revivePiece(lastKilledPiece!!)
             }
         } else {
-            currentPiece!!.undoMove(EMPTY)
-            if (currentPiece is King) (currentPiece as King).hasMoved = false
-            if (currentPiece is Rook) (currentPiece as Rook).hasMoved = false
+            pieceToUndo.undoMove(EMPTY)
+            if (pieceToUndo is King) (pieceToUndo as King).hasMoved = false
+            if (pieceToUndo is Rook) (pieceToUndo as Rook).hasMoved = false
 
             if (castled) {
                 if (turnTracker % 2 == 1) {
@@ -287,11 +301,11 @@ class Game {
                     }
                 } else {
                     if (board[0][5] == ROOK + PLAYER_2) {
-                        (player1.getPiece(BoardSpace(0, 5)) as Rook).hasMoved = false
-                        (player1.getPiece(BoardSpace(0, 5)) as Rook).undoMove(EMPTY)
+                        (player2.getPiece(BoardSpace(0, 5)) as Rook).hasMoved = false
+                        (player2.getPiece(BoardSpace(0, 5)) as Rook).undoMove(EMPTY)
                     } else if (board[0][3] == ROOK + PLAYER_2) {
-                        (player1.getPiece(BoardSpace(0, 3)) as Rook).hasMoved = false
-                        (player1.getPiece(BoardSpace(0, 3)) as Rook).undoMove(EMPTY)
+                        (player2.getPiece(BoardSpace(0, 3)) as Rook).hasMoved = false
+                        (player2.getPiece(BoardSpace(0, 3)) as Rook).undoMove(EMPTY)
                     }
                 }
             }

gradle/libs.versions.toml

@@ -78,8 +78,9 @@ class Player(val player: String) {
 
     fun revivePiece(piece: Piece) {
         for (i in 0 until 16) {
-            if (pieces[i]!!.active && pieces[i] == piece) {
-                pieces[i]!!.active = true
+            val p = pieces[i]
+            if (p != null && p == piece) {
+                p.active = true
                 break
             }
         }