refactor: update import statements to use api.io for GameContextExport and GameContextImport

modules/io/src/main/scala/de/nowchess/io/GameContextExport.scala

@@ -1,3 +0,0 @@
-package de.nowchess.io
-
-type GameContextExport = de.nowchess.api.io.GameContextExport

modules/io/src/main/scala/de/nowchess/io/GameContextImport.scala

@@ -1,3 +0,0 @@
-package de.nowchess.io
-
-type GameContextImport = de.nowchess.api.io.GameContextImport

modules/io/src/main/scala/de/nowchess/io/GameFileService.scala

@@ -1,6 +1,8 @@
 package de.nowchess.io
 
 import de.nowchess.api.game.GameContext
+import de.nowchess.api.io.{GameContextExport, GameContextImport}
+
 import java.nio.file.{Files, Path}
 import java.nio.charset.StandardCharsets
 import scala.util.Try

modules/io/src/main/scala/de/nowchess/io/fen/FenExporter.scala

@@ -2,25 +2,17 @@ package de.nowchess.io.fen
 
 import de.nowchess.api.board.*
 import de.nowchess.api.game.GameContext
-import de.nowchess.io.GameContextExport
+import de.nowchess.api.io.GameContextExport
 
 object FenExporter extends GameContextExport:
 
+  /** Convert a Board to FEN piece-placement string (rank 8 to rank 1, separated by '/'). */
   def boardToFen(board: Board): String =
     Rank.values.reverse
       .map(rank => buildRankString(board, rank))
       .mkString("/")
 
-  def gameContextToFen(context: GameContext): String =
-    val piecePlacement = boardToFen(context.board)
-    val activeColor    = if context.turn == Color.White then "w" else "b"
-    val castling       = castlingString(context.castlingRights)
-    val enPassant      = context.enPassantSquare.map(_.toString).getOrElse("-")
-    val fullMoveNumber = 1 + (context.moves.length / 2)
-    s"$piecePlacement $activeColor $castling $enPassant ${context.halfMoveClock} $fullMoveNumber"
-
-  def exportGameContext(context: GameContext): String = gameContextToFen(context)
-
+  /** Build the FEN representation for a single rank. */
   private def buildRankString(board: Board, rank: Rank): String =
     val rankSquares = File.values.map(file => Square(file, rank))
     val (result, emptyCount) = rankSquares.foldLeft(("", 0)):
@@ -33,6 +25,18 @@ object FenExporter extends GameContextExport:
             (acc, empty + 1)
     if emptyCount > 0 then result + emptyCount.toString else result
 
+  /** Convert a GameContext to a complete FEN string. */
+  def gameContextToFen(context: GameContext): String =
+    val piecePlacement = boardToFen(context.board)
+    val activeColor    = if context.turn == Color.White then "w" else "b"
+    val castling       = castlingString(context.castlingRights)
+    val enPassant      = context.enPassantSquare.map(_.toString).getOrElse("-")
+    val fullMoveNumber = 1 + (context.moves.length / 2)
+    s"$piecePlacement $activeColor $castling $enPassant ${context.halfMoveClock} $fullMoveNumber"
+
+  def exportGameContext(context: GameContext): String = gameContextToFen(context)
+
+  /** Convert castling rights to FEN notation. */
   private def castlingString(rights: CastlingRights): String =
     val wk     = if rights.whiteKingSide then "K" else ""
     val wq     = if rights.whiteQueenSide then "Q" else ""
@@ -41,6 +45,7 @@ object FenExporter extends GameContextExport:
     val result = s"$wk$wq$bk$bq"
     if result.isEmpty then "-" else result
 
+  /** Convert a Piece to its FEN character (uppercase = White, lowercase = Black). */
   private def pieceToFenChar(piece: Piece): Char =
     val base = piece.pieceType match
       case PieceType.Pawn   => 'p'

modules/io/src/main/scala/de/nowchess/io/fen/FenParser.scala

@@ -2,7 +2,7 @@ package de.nowchess.io.fen
 
 import de.nowchess.api.board.*
 import de.nowchess.api.game.GameContext
-import de.nowchess.io.GameContextImport
+import de.nowchess.api.io.GameContextImport
 
 object FenParser extends GameContextImport:
 

modules/io/src/main/scala/de/nowchess/io/fen/FenParserCombinators.scala

@@ -2,9 +2,10 @@ package de.nowchess.io.fen
 
 import de.nowchess.api.board.*
 import de.nowchess.api.game.GameContext
-import de.nowchess.io.GameContextImport
+
 import scala.util.parsing.combinator.RegexParsers
 import FenParserSupport.*
+import de.nowchess.api.io.GameContextImport
 
 object FenParserCombinators extends RegexParsers with GameContextImport:
 

modules/io/src/main/scala/de/nowchess/io/fen/FenParserFastParse.scala

@@ -4,8 +4,8 @@ import fastparse.*
 import fastparse.NoWhitespace.*
 import de.nowchess.api.board.*
 import de.nowchess.api.game.GameContext
-import de.nowchess.io.GameContextImport
 import FenParserSupport.*
+import de.nowchess.api.io.GameContextImport
 
 object FenParserFastParse extends GameContextImport:
 

modules/io/src/main/scala/de/nowchess/io/json/JsonExporter.scala

@@ -6,8 +6,9 @@ import com.fasterxml.jackson.module.scala.DefaultScalaModule
 import de.nowchess.api.board.*
 import de.nowchess.api.move.{Move, MoveType, PromotionPiece}
 import de.nowchess.api.game.GameContext
-import de.nowchess.io.GameContextExport
+import de.nowchess.api.io.GameContextExport
 import de.nowchess.io.pgn.PgnExporter
+
 import java.time.{LocalDate, ZoneId, ZonedDateTime}
 
 /** Exports a GameContext to a comprehensive JSON format using Jackson.

modules/io/src/main/scala/de/nowchess/io/json/JsonParser.scala

@@ -5,7 +5,8 @@ import com.fasterxml.jackson.module.scala.DefaultScalaModule
 import de.nowchess.api.board.*
 import de.nowchess.api.move.{Move, MoveType, PromotionPiece}
 import de.nowchess.api.game.GameContext
-import de.nowchess.io.GameContextImport
+import de.nowchess.api.io.GameContextImport
+
 import scala.util.Try
 
 /** Imports a GameContext from JSON format using Jackson.

modules/io/src/main/scala/de/nowchess/io/pgn/PgnExporter.scala

@@ -1,56 +1,75 @@
 package de.nowchess.io.pgn
 
-import de.nowchess.api.board.{Board, PieceType}
+import de.nowchess.api.board.*
+import de.nowchess.api.move.{Move, MoveType, PromotionPiece}
 import de.nowchess.api.game.GameContext
 import de.nowchess.api.io.GameContextExport
-import de.nowchess.api.move.{Move, MoveType, PromotionPiece}
 import de.nowchess.rules.sets.DefaultRules
 
 object PgnExporter extends GameContextExport:
 
+  /** Export a GameContext to PGN format. */
   def exportGameContext(context: GameContext): String =
-    exportGame(
-      Map("Event" -> "?", "White" -> "?", "Black" -> "?", "Result" -> "*"),
-      context.moves,
+    val headers = Map(
+      "Event"  -> "?",
+      "White"  -> "?",
+      "Black"  -> "?",
+      "Result" -> "*",
     )
 
+    exportGame(headers, context.moves)
+
+  /** Export a game with headers and moves to PGN format. */
   def exportGame(headers: Map[String, String], moves: List[Move]): String =
-    val headerLines = headers.map { case (k, v) => s"""[$k "$v"]""" }.mkString("\n")
-    val moveText    = if moves.isEmpty then "" else buildMoveText(headers, moves)
+    val headerLines = headers
+      .map { case (key, value) =>
+        s"""[$key "$value"]"""
+      }
+      .mkString("\n")
+
+    val moveText =
+      if moves.isEmpty then ""
+      else
+        val contexts = moves.scanLeft(GameContext.initial)((ctx, move) => DefaultRules.applyMove(ctx)(move))
+        val sanMoves = moves.zip(contexts).map { case (move, ctx) => moveToAlgebraic(move, ctx.board) }
+
+        val groupedMoves = sanMoves.zipWithIndex.groupBy(_._2 / 2)
+        val moveLines = for (moveNumber, movePairs) <- groupedMoves.toList.sortBy(_._1) yield
+          val moveNum      = moveNumber + 1
+          val whiteMoveStr = movePairs.find(_._2 % 2 == 0).map(_._1).getOrElse("")
+          val blackMoveStr = movePairs.find(_._2 % 2 == 1).map(_._1).getOrElse("")
+          if blackMoveStr.isEmpty then s"$moveNum. $whiteMoveStr"
+          else s"$moveNum. $whiteMoveStr $blackMoveStr"
+
+        val termination = headers.getOrElse("Result", "*")
+        moveLines.mkString(" ") + s" $termination"
+
     if headerLines.isEmpty then moveText
     else if moveText.isEmpty then headerLines
     else s"$headerLines\n\n$moveText"
 
-  private def buildMoveText(headers: Map[String, String], moves: List[Move]): String =
-    val contexts = moves.scanLeft(GameContext.initial)((ctx, move) => DefaultRules.applyMove(ctx)(move))
-    val sanMoves = moves.zip(contexts).map { case (move, ctx) => moveToAlgebraic(move, ctx.board) }
-    val grouped  = sanMoves.zipWithIndex.groupBy(_._2 / 2)
-    val moveLines = grouped.toList.sortBy(_._1).map { case (n, pairs) =>
-      val w = pairs.find(_._2 % 2 == 0).map(_._1).getOrElse("")
-      val b = pairs.find(_._2 % 2 == 1).map(_._1).getOrElse("")
-      if b.isEmpty then s"${n + 1}. $w" else s"${n + 1}. $w $b"
-    }
-    moveLines.mkString(" ") + s" ${headers.getOrElse("Result", "*")}"
-
+  /** Convert a Move to Standard Algebraic Notation using the board state before the move. */
   private def moveToAlgebraic(move: Move, boardBefore: Board): String =
     move.moveType match
       case MoveType.CastleKingside  => "O-O"
       case MoveType.CastleQueenside => "O-O-O"
       case MoveType.EnPassant       => s"${move.from.file.toString.toLowerCase}x${move.to}"
       case MoveType.Promotion(pp) =>
-        val suffix = pp match
+        val promSuffix = pp match
           case PromotionPiece.Queen  => "=Q"
           case PromotionPiece.Rook   => "=R"
           case PromotionPiece.Bishop => "=B"
           case PromotionPiece.Knight => "=N"
         val isCapture = boardBefore.pieceAt(move.to).isDefined
-        if isCapture then s"${move.from.file.toString.toLowerCase}x${move.to}$suffix"
-        else s"${move.to}$suffix"
+        if isCapture then s"${move.from.file.toString.toLowerCase}x${move.to}$promSuffix"
+        else s"${move.to}$promSuffix"
       case MoveType.Normal(isCapture) =>
         val dest   = move.to.toString
         val capStr = if isCapture then "x" else ""
         boardBefore.pieceAt(move.from).map(_.pieceType).getOrElse(PieceType.Pawn) match
-          case PieceType.Pawn   => if isCapture then s"${move.from.file.toString.toLowerCase}x$dest" else dest
+          case PieceType.Pawn =>
+            if isCapture then s"${move.from.file.toString.toLowerCase}x$dest"
+            else dest
           case PieceType.Knight => s"N$capStr$dest"
           case PieceType.Bishop => s"B$capStr$dest"
           case PieceType.Rook   => s"R$capStr$dest"

modules/io/src/main/scala/de/nowchess/io/pgn/PgnParser.scala

@@ -3,7 +3,7 @@ package de.nowchess.io.pgn
 import de.nowchess.api.board.*
 import de.nowchess.api.move.{Move, MoveType, PromotionPiece}
 import de.nowchess.api.game.GameContext
-import de.nowchess.io.GameContextImport
+import de.nowchess.api.io.GameContextImport
 import de.nowchess.rules.sets.DefaultRules
 
 /** A parsed PGN game containing headers and the resolved move list. */