package dev.kske.chess.pgn;

import java.io.PrintWriter;
import java.util.*;
import java.util.regex.MatchResult;
import java.util.regex.Pattern;

import dev.kske.chess.board.Board;
import dev.kske.chess.board.FENString;
import dev.kske.chess.board.Move;
import dev.kske.chess.board.Piece.Color;

/**
 * Project: <strong>Chess</strong><br>
 * File: <strong>PGNGame.java</strong><br>
 * Created: <strong>22 Sep 2019</strong><br>
 *
 * @since Chess v0.5-alpha
 * @author Kai S. K. Engelbart
 */
public class PGNGame {

	private final Map<String, String> tagPairs = new HashMap<>(7);
	private final Board board;

	/**
	 * Creates an instance of {@link PGNGame}. A new default {@link Board} will
	 * be
	 * created.
	 */
	public PGNGame() {
		board = new Board();
	}

	/**
	 * Creates an instance of {@link PGNGame}.
	 *
	 * @param board the board associated with the game
	 */
	public PGNGame(Board board) {
		this.board = board;
	}

	/**
	 * Parses a game in {@code PGN} format from a {@link Scanner} instance
	 *
	 * @param sc the {@link Scanner} to parse the game from, which is not closed
	 *           after this process
	 * @return the parsed {@link PGNGame}
	 */
	public static PGNGame parse(Scanner sc) {
		PGNGame game = new PGNGame();

		MatchResult matchResult;
		Pattern tagPairPattern = Pattern.compile("\\[(\\w+) \"(.*)\"]"),
			movePattern = Pattern.compile(
				"\\d+\\.\\s+(?:(?:(\\S+)\\s+(\\S+))|(?:O-O-O)|(?:O-O))(?:\\+{0,2}|\\#)"
			),
			nagPattern = Pattern.compile("(\\$\\d{1,3})*"), terminationMarkerPattern = Pattern.compile("1-0|0-1|1\\/2-1\\/2|\\*");

		// Parse tag pairs
		while (sc.findInLine(tagPairPattern) != null) {
			matchResult = sc.match();
			if (matchResult.groupCount() == 2)
				game.setTag(matchResult.group(1), matchResult.group(2));
			else
				break;
			sc.nextLine();
		}
		// Parse movetext
		while (true) {
			// Skip NAG (Numeric Annotation Glyph)
			sc.skip(nagPattern);

			// TODO: Parse RAV (Recursive Annotation Variation)

			if (sc.findWithinHorizon(movePattern, 20) != null) {
				matchResult = sc.match();
				if (matchResult.groupCount() > 0)
					for (int i = 1; i < matchResult.groupCount() + 1; i++) {
						game.board.move(matchResult.group(i));
						System.out.println(
							game.getBoard().getLog().getLast().move.toLAN()
								+ ": " + new FENString(game.board).toString()
						);
					}
				else
					break;
			} else
				break;
		}
		// Parse game termination marker
		if (sc.findWithinHorizon(terminationMarkerPattern, 20) == null)
			System.err.println("Termination marker expected");

		return game;
	}

	/**
	 * Serializes this game to {@code PGN} format.
	 *
	 * @param pw the writer to write the game to
	 */
	public void writePGN(PrintWriter pw) {
		// Set the unknown result tag if no result tag is specified
		tagPairs.putIfAbsent("Result", "*");

		// Write tag pairs
		tagPairs.forEach((k, v) -> pw.printf("[%s \"%s\"]%n", k, v));

		// Insert newline if tags were printed
		if (!tagPairs.isEmpty())
			pw.println();

		if (!board.getLog().isEmpty()) {
			// Collect SAN moves
			Board clone = new Board(board, true);
			List<String> chunks = new ArrayList<>();
			boolean flag = true;
			while (flag) {
				Move move = clone.getLog().getLast().move;
				flag = clone.getLog().hasParent();
				clone.revert();
				String chunk = clone.getLog().getActiveColor() == Color.WHITE
					? String.format(" %d. ", clone.getLog().getFullmoveNumber())
					: " ";
				chunk += move.toSAN(clone);
				chunks.add(chunk);
			}
			Collections.reverse(chunks);

			// Write movetext
			String line = "";
			for (String chunk : chunks)
				if (line.length() + chunk.length() <= 80)
					line += chunk;
				else {
					pw.println(line);
					line = chunk;
				}
			if (!line.isEmpty())
				pw.println(line);
		}
		// Write game termination marker
		pw.print(tagPairs.get("Result"));
	}

	/**
	 * @param tagName the name of a game tag
	 * @return the value of the game tag
	 */
	public String getTag(String tagName) {
		return tagPairs.get(tagName);
	}

	/**
	 * @param tagName the name of a game tag
	 * @return {@code true} if the tag is present
	 */
	public boolean hasTag(String tagName) {
		return tagPairs.containsKey(tagName);
	}

	/**
	 * Sets a game tag.
	 *
	 * @param tagName  the name of the tag
	 * @param tagValue the value of the tag
	 */
	public void setTag(String tagName, String tagValue) {
		tagPairs.put(tagName, tagValue);
	}

	/**
	 * @return the board associated with this game
	 */
	public Board getBoard() { return board; }
}