3DChess/app/src/main/java/chess/pgn/PgnExport.java

package chess.pgn;

import java.util.List;

import chess.controller.CommandExecutor;
import chess.controller.PlayerCommand;
import chess.controller.Command.CommandResult;
import chess.controller.commands.CastlingCommand;
import chess.controller.commands.GetPieceAtCommand;
import chess.controller.commands.GetPlayerMovesCommand;
import chess.controller.commands.MoveCommand;
import chess.controller.commands.NewGameCommand;
import chess.controller.commands.PromoteCommand;
import chess.controller.event.EmptyGameDispatcher;
import chess.model.Color;
import chess.model.Coordinate;
import chess.model.Game;
import chess.model.Move;
import chess.model.Piece;
import chess.model.pieces.Pawn;

/**
 * Export a game to PGN format.
 */

public class PgnExport {

	private static final PiecePgnName piecePgnName = new PiecePgnName();

	private static Piece pieceAt(CommandExecutor commandExecutor, Coordinate coordinate) {
		GetPieceAtCommand cmd = new GetPieceAtCommand(coordinate);
		commandExecutor.executeCommand(cmd);
		return cmd.getPiece();
	}

	private static List<Move> playerMoves(CommandExecutor commandExecutor) {
		GetPlayerMovesCommand cmd = new GetPlayerMovesCommand();
		commandExecutor.executeCommand(cmd);
		return cmd.getMoves();
	}

	private static String gameEnd(Game game) {
		switch (game.checkGameStatus(game.getPlayerTurn())) {
			case Draw:
			case Pat:
				return "1/2-1/2";

			case CheckMate:
				if (game.getPlayerTurn() == Color.White)
					return "0-1";
				return "1-0";

			default:
				return "";
		}
	}

	/**
	 * Resolve PGN ambiguity in the case of two pieces of the same type able to move on the same square.
	 * @param cmdExec the command executor attached to the game
	 * @param pieceMove move of the piece
	 * @return the character that solves the eventual ambiguity, empty if no ambiguity to start with
	 */
	private static String resolveAmbiguity(CommandExecutor cmdExec, Move pieceMove) {
		Piece movingPiece = pieceAt(cmdExec, pieceMove.getStart());

		assert movingPiece != null;

		if (movingPiece instanceof Pawn)
			return "";

		List<Move> moves = playerMoves(cmdExec);

		for (Move move : moves) {
			if (move.equals(pieceMove) || !move.getFinish().equals(pieceMove.getFinish()))
				continue;

			Piece otherPiece = pieceAt(cmdExec, move.getStart());

			// checking type of piece
			if (!otherPiece.getClass().equals(movingPiece.getClass()))
				continue;

			String startPos = toString(pieceMove.getStart());

			if (move.getStart().getX() != pieceMove.getStart().getX())
				// not on the same column
				return Character.toString(startPos.charAt(0));
			else
				return Character.toString(startPos.charAt(1));

		}

		return "";
	}

	/**
	 * From a move, get the capture-part of the associated PGN string.
	 * @param move the move
	 * @param movingPiece the piece that is moving
	 * @return the capture string of the PGN move
	 */
	private static String capture(MoveCommand move, Piece movingPiece) {
		String result = "";
		if (move.getDeadPiece() != null) {
			if (movingPiece instanceof Pawn) {
				result += toString(move.getMove().getStart()).charAt(0);
			}
			result += "x";
		}
		return result;
	}

	private static String promote(PlayerCommand nextCommand) {
		if (nextCommand != null && nextCommand instanceof PromoteCommand promoteCommand) {
			String result = "=";
			result += switch (promoteCommand.getPromoteType()) {
				case Bishop -> "B";
				case Knight -> "N";
				case Queen -> "Q";
				case Rook -> "R";
			};
			return result;
		}
		return "";
	}

	private static String castling(CastlingCommand castlingCommand) {
		String result = "O-O";
		if (castlingCommand.isBigCastling())
			result += "-O";
		return result;
	}

	private static String checkCheckMate(Game game) {
		switch (game.checkGameStatus(game.getPlayerTurn())) {
			case CheckMate:
				return "#";

			case Check:
				return "+";

			default:
				return "";
		}
	}

	private record MoveResult(String move, CommandResult commandResult) {
	}

	private static MoveResult printMove(PlayerCommand cmd, PlayerCommand nextCommand, Game virtualGame,
			CommandExecutor executor) {
		String result = "";
		if (cmd instanceof MoveCommand move) {

			Piece movingPiece = virtualGame.getBoard().pieceAt(move.getMove().getStart());

			assert movingPiece != null;

			// piece name
			result += piecePgnName.visit(movingPiece);

			// ambiguious start
			result += resolveAmbiguity(executor, move.getMove());

			// capture
			result += capture(move, movingPiece);

			// end cell
			result += toString(move.getMove().getFinish());

			// promote
			result += promote(nextCommand);

		} else if (cmd instanceof CastlingCommand castlingCommand) {
			result += castling(castlingCommand);
		}

		CommandResult commandResult = executor.executeCommand(cmd);

		// check or checkmate
		result += checkCheckMate(virtualGame);

		result += " ";

		return new MoveResult(result, commandResult);
	}

	public static String exportGame(Game game) {

		Game virtualGame = new Game();

		CommandExecutor executor = new CommandExecutor(virtualGame, new EmptyGameDispatcher());
		executor.executeCommand(new NewGameCommand());

		List<PlayerCommand> commands = game.getMoves();
		String result = "";

		int tour = 1;

		String lastMove = null;

		for (int i = 0; i < commands.size(); i++) {
			PlayerCommand cmd = commands.get(i);
			PlayerCommand nextCommand = null;

			if (i != commands.size() - 1) {
				nextCommand = commands.get(i + 1);
			}
			MoveResult moveResult = printMove(cmd, nextCommand, virtualGame, executor);
			if (moveResult.commandResult() == CommandResult.Moved && virtualGame.getPlayerTurn() == Color.Black) {
				result += tour + ".";
				tour++;
			}
			
			if (moveResult.commandResult() == CommandResult.ActionNeeded) {
				lastMove = moveResult.move();
				continue;
			}
			
			if (lastMove != null && moveResult.commandResult() == CommandResult.Moved){
				result += lastMove;
				lastMove = null;
				continue;
			}
			result += moveResult.move();

		}
		return result + " " + gameEnd(virtualGame);
	}

	public static String toString(Coordinate coordinate) {
		String letters = "abcdefgh";
		String numbers = "87654321";
		return Character.toString(letters.charAt(coordinate.getX())) + numbers.charAt(coordinate.getY());
	}
}