package dev.kske.chess.uci;

import java.io.*;
import java.util.ArrayList;
import java.util.List;

import dev.kske.chess.board.Move;

/**
 * Project: <strong>Chess</strong><br>
 * File: <strong>UCIReceiver.java</strong><br>
 * Created: <strong>19.07.2019</strong><br>
 *
 * @since Chess v0.3-alpha
 * @author Kai S. K. Engelbart
 */
public class UCIReceiver implements Runnable {

	private final BufferedReader in;

	private List<UCIListener> listeners;

	/**
	 * Creates an instance of {@link UCIReceiver}.
	 *
	 * @param in the input stream to parse for commands generated by the engine
	 */
	public UCIReceiver(InputStream in) {
		this.in = new BufferedReader(new InputStreamReader(in));
		listeners = new ArrayList<>();
	}

	/**
	 * Starts listening for UCI commands passed through the input stream.
	 */
	@Override
	public void run() {
		String line;
		while (!Thread.currentThread().isInterrupted())
			try {
				if ((line = in.readLine()) != null && !line.isEmpty())
					parse(line);
			} catch (IndexOutOfBoundsException ex) {
				System.err.println("Too few arguments were provided!");
				ex.printStackTrace();
			} catch (IOException ex) {
				ex.printStackTrace();
			}
	}

	private void parse(String line) {
		int spaceIndex = line.indexOf(' ');
		String command
			= spaceIndex == -1 ? line : line.substring(0, spaceIndex);
		switch (command) {
			case "id":
				parseId(line.substring(command.length() + 1));
				break;
			case "uciok":
				listeners.forEach(UCIListener::onUCIOk);
				break;
			case "readyok":
				listeners.forEach(UCIListener::onReadyOk);
				break;
			case "bestmove":
				parseBestMove(line.substring(command.length() + 1));
				break;
			case "copyprotection":
				parseCopyProtection(line.substring(command.length() + 1));
				break;
			case "registration":
				parseRegistration(line.substring(command.length() + 1));
				break;
			case "info":
				parseInfo(line.substring(command.length() + 1));
				break;
			case "option":
				parseOption(line.substring(command.length() + 1));
				break;
			default:
				System.err.printf("Unknown command '%s' found!%n", command);
		}
	}

	private void parseId(String line) {
		String param = line.substring(0, line.indexOf(' '));
		String arg = line.substring(param.length() + 1);
		switch (param) {
			case "name":
				listeners.forEach(l -> l.onIdName(arg));
				break;
			case "author":
				listeners.forEach(l -> l.onIdAuthor(arg));
				break;
			default:
				System.err.printf(
					"Unknown parameter '%s' for command 'id' found!%n",
					param
				);
		}
	}

	private void parseBestMove(String line) {
		String[] tokens = line.split(" ");
		String move = tokens[0];

		// Ponder move
		if (tokens.length == 3)
			listeners.forEach(l -> l.onBestMove(move, Move.fromLAN(tokens[2])));
		else
			listeners.forEach(l -> l.onBestMove(move));
	}

	private void parseCopyProtection(String line) {
		switch (line) {
			case "checking":
				listeners.forEach(UCIListener::onCopyProtectionChecking);
				break;
			case "ok":
				listeners.forEach(UCIListener::onCopyProtectionOk);
				break;
			case "error":
				listeners.forEach(UCIListener::onCopyProtectionError);
				break;
			default:
				System.err.printf(
					"Unknown parameter '%s' for command 'copyprotection' found!%n",
					line
				);
		}
	}

	private void parseRegistration(String line) {
		switch (line) {
			case "checking":
				listeners.forEach(UCIListener::onRegistrationChecking);
				break;
			case "ok":
				listeners.forEach(UCIListener::onRegistrationOk);
				break;
			case "error":
				listeners.forEach(UCIListener::onRegistrationError);
				break;
			default:
				System.err.printf(
					"Unknown parameter '%s' for command 'registration' found!%n",
					line
				);
		}
	}

	private void parseInfo(String line) {
		listeners.forEach(l -> l.onInfo(new UCIInfo(line)));
	}

	private void parseOption(String line) {
		listeners.forEach(l -> l.onOption(new UCIOption(line)));
	}

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