package dev.kske.chess.io;

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

import dev.kske.chess.uci.UCIHandle;
import dev.kske.chess.uci.UCIListener;

/**
 * Project: <strong>Chess</strong><br>
 * File: <strong>EngineUtil.java</strong><br>
 * Created: <strong>23.07.2019</strong><br>
 *
 * @since Chess v0.2-alpha
 * @author Kai S. K. Engelbart
 * @author Leon Hofmeister
 */
public class EngineUtil {

	private static volatile List<EngineInfo> engineInfos;

	private static final String engineInfoFile = "engine_infos.ser";

	static {
		loadEngineInfos();
	}

	private EngineUtil() {}

	/**
	 * Stores information about an engine while checking its availability.
	 *
	 * @param enginePath the path to the executable of the engine
	 */
	public static void addEngine(String enginePath) {
		try {
			EngineInfo info = new EngineInfo(enginePath);
			UCIHandle handle = new UCIHandle(enginePath);
			handle.registerListener(new UCIListener() {

				@Override
				public void onIdName(String name) {
					info.name = name;
				}

				@Override
				public void onIdAuthor(String author) {
					info.author = author;
				}

				@Override
				public void onUCIOk() {
					engineInfos.add(info);
					handle.quit();
					saveEngineInfos();
				}
			});
			handle.start();
		} catch (IOException ex) {
			ex.printStackTrace();
		}
	}

	@SuppressWarnings("unchecked")
	private static void loadEngineInfos() {
		try (
			ObjectInputStream in
				= new ObjectInputStream(new FileInputStream(engineInfoFile))
		) {
			Object obj = in.readObject();
			if (obj instanceof ArrayList<?>)
				engineInfos = (ArrayList<EngineInfo>) obj;
			else
				throw new IOException("Serialized object has the wrong class.");
		} catch (ClassNotFoundException | IOException ex) {
			engineInfos = new ArrayList<>();
		}
	}

	private static void saveEngineInfos() {
		try (
			ObjectOutputStream out
				= new ObjectOutputStream(new FileOutputStream(engineInfoFile))
		) {
			out.writeObject(engineInfos);
		} catch (IOException ex) {
			ex.printStackTrace();
		}
	}

	/**
	 * Stores the name and author of an engine, as well as a path to its
	 * executable.<br>
	 * <br>
	 * Project: <strong>Chess</strong><br>
	 * File: <strong>EngineUtil.java</strong><br>
	 * Created: <strong>23.07.2019</strong><br>
	 *
	 * @since Chess v0.2-alpha
	 * @author Kai S. K. Engelbart
	 */
	public static class EngineInfo implements Serializable {

		private static final long serialVersionUID = -474177108900833005L;

		/**
		 * The path to the executable of the engine
		 */
		public String path;

		/**
		 * The name of the engine
		 */
		public String name;

		/**
		 * The author of the engine
		 */
		public String author;

		/**
		 * Creates an instance of {@link EngineInfo}.
		 *
		 * @param path the path of the engine executable
		 */
		public EngineInfo(String path) {
			this.path = path;
		}

		@Override
		public String toString() {
			return name + " by " + author + " at " + path;
		}
	}

	/**
	 * @return a list of all stored engine infos
	 */
	public static List<EngineInfo> getEngineInfos() { return engineInfos; }
}