package dev.kske.chess.uci;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
import java.util.StringJoiner;

import dev.kske.chess.board.Move;

/**
 * Project: <strong>Chess</strong><br>
 * File: <strong>UCIHandle.java</strong><br>
 * Created: <strong>18.07.2019</strong><br>
 *
 * @since Chess v0.3-alpha
 * @author Kai S. K. Engelbart
 */
public class UCIHandle {

	private final Process process;
	private final PrintWriter out;
	private final UCIReceiver receiver;

	/**
	 * Creates an instance of {@link UCIHandle}. The engine process is started
	 * and
	 * passed to a new {@link UCIReceiver}.
	 *
	 * @param enginePath the path to the engine executable
	 * @throws IOException if the engine process could not be started
	 */
	public UCIHandle(String enginePath) throws IOException {
		process = new ProcessBuilder(enginePath).start();
		out = new PrintWriter(process.getOutputStream(), true);
		receiver = new UCIReceiver(process.getInputStream());
	}

	/**
	 * Starts the {@link UCIReceiver} used to gather engine output.
	 */
	public void start() {
		new Thread(receiver, "UCI Receiver").start();
		uci();
	}

	/**
	 * Tells the engine to use UCI.
	 */
	public void uci() {
		out.println("uci");
	}

	/**
	 * Switches the debug mode of the engine on or off.
	 *
	 * @param debug Enables debugging if set to {@code true}, disables it
	 *              otherwise
	 */
	public void debug(boolean debug) {
		out.println("debug " + (debug ? "on" : "off"));
	}

	/**
	 * Synchronized the engine with the GUI
	 */
	public void isready() {
		out.println("isready");
	}

	/**
	 * Signifies a button press to the engine.
	 *
	 * @param name The name of the button
	 */
	public void setOption(String name) {
		out.println("setoption name " + name);
	}

	/**
	 * Changes an internal parameter of the engine.
	 *
	 * @param name  The name of the parameter
	 * @param value The value of the parameter
	 */
	public void setOption(String name, String value) {
		out.printf("setoption name %s value %s%n", name, value);
	}

	/**
	 * Registers the engine
	 *
	 * @param name The name the engine should be registered with
	 * @param code The code the engine should be registered with
	 */
	public void register(String name, String code) {
		out.printf("register %s %s%n", name, code);
	}

	/**
	 * Tells the engine to postpone the registration.
	 */
	public void registerLater() {
		out.println("register later");
	}

	/**
	 * Tells the engine that the next search will be from a different game.
	 */
	public void uciNewGame() {
		out.println("ucinewgame");
	}

	/**
	 * Sets up the position in its initial state.
	 */
	public void positionStartpos() {
		out.println("position startpos");
	}

	/**
	 * Sets up the position described in the FEN string.
	 *
	 * @param fen FEN representation of the current board
	 */
	public void positionFEN(String fen) {
		out.println("position fen " + fen);
	}

	/**
	 * Sets up the position described by a list of moves.
	 *
	 * @param moves the moves to execute from the starting position to reach the
	 *              desired position
	 */
	public void positionMoves(List<Move> moves) {
		StringJoiner joiner = new StringJoiner(" ");
		moves.forEach(m -> joiner.add(m.toLAN()));
		out.println("position moves " + joiner);
	}

	/**
	 * Starts calculating on the current position.
	 */
	public void go() {
		out.println("go");
	}

	/**
	 * Starts calculating on the current position.
	 * This command has multiple optional parameters which will only be included
	 * in
	 * the call if they are not {@code null}, greater than zero or {@code true}
	 * for
	 * {@code searchMoves}, all integer parameters and all boolean parameters
	 * respectively.
	 *
	 * @param searchMoves restrict the search to these moves only
	 * @param ponder      start the search in ponder mode
	 * @param wTime       the amount of milliseconds left on white's clock
	 * @param bTime       the amount of milliseconds left on black's clocks
	 * @param wInc        white's increment per move in milliseconds
	 * @param bInc        black's increment per move in milliseconds
	 * @param movesToGo   the number of moves left until the next time control
	 * @param depth       the maximal amount of plies to search
	 * @param nodes       the maximal amount of nodes to search
	 * @param mate        the amount of moves in which to search for a mate
	 * @param moveTime    the exact search time
	 * @param infinite    search until the {@code stop} command
	 */
	public void go(
		List<Move> searchMoves, boolean ponder, int wTime, int bTime, int wInc,
		int bInc, int movesToGo, int depth, int nodes, int mate,
		int moveTime, boolean infinite
	) {
		StringJoiner joiner = new StringJoiner(" ");
		joiner.add("go");

		if (searchMoves != null && !searchMoves.isEmpty()) {
			joiner.add("searchmoves");
			searchMoves.forEach(m -> joiner.add(m.toLAN()));
		}
		if (ponder)
			joiner.add("ponder");
		if (wTime > 0) {
			joiner.add("wtime");
			joiner.add(String.valueOf(wTime));
		}
		if (bTime > 0) {
			joiner.add("btime");
			joiner.add(String.valueOf(bTime));
		}
		if (wInc > 0) {
			joiner.add("winc");
			joiner.add(String.valueOf(wInc));
		}
		if (bInc > 0) {
			joiner.add("bind");
			joiner.add(String.valueOf(bInc));
		}
		if (movesToGo > 0) {
			joiner.add("movestogo");
			joiner.add(String.valueOf(movesToGo));
		}
		if (depth > 0) {
			joiner.add("depth");
			joiner.add(String.valueOf(depth));
		}
		if (nodes > 0) {
			joiner.add("nodes");
			joiner.add(String.valueOf(nodes));
		}
		if (mate > 0) {
			joiner.add("mate");
			joiner.add(String.valueOf(mate));
		}
		if (moveTime > 0) {
			joiner.add("movetime");
			joiner.add(String.valueOf(moveTime));
		}
		if (infinite)
			joiner.add("infinite");
		out.println(joiner);
	}

	/**
	 * Stops calculation as soon as possible.
	 */
	public void stop() {
		out.println("stop");
	}

	/**
	 * Tells the engine that the user has played the expected move.
	 */
	public void ponderHit() {
		out.println("ponderhit");
	}

	/**
	 * Quits the engine process as soon as possible.
	 */
	public void quit() {
		out.println("quit");
	}

	/**
	 * Registers a UCI listener.
	 *
	 * @param listener the UCI listener to register
	 */
	public void registerListener(UCIListener listener) {
		receiver.registerListener(listener);
	}
}