import "dart:async";
import "dart:collection";
import "dart:convert";
import "dart:io";

import "package:omnichess/classes/best_move_searcher.dart";
import "package:omnichess/classes/position.dart";
import "package:omnichess/constants/piece.dart";

class Omnichess {

  BestMoveSearcher bestMoveSearcher = BestMoveSearcher();
  String positionCommand = "startpos";
  String? bestMove;

  bool debug = false;

  Omnichess();

  void _positionCommand(Queue<String> inputComponents) {
    positionCommand = inputComponents.join(" ");
  }

  Future<void> _goCommand(Queue<String> inputComponents) async {
    int? moveTime;
    while (inputComponents.isNotEmpty) {
      final String inputComponent = inputComponents.removeFirst();
      if ("movetime" == inputComponent) {
        moveTime = int.tryParse(inputComponents.firstOrNull ?? "");
      }
    }
    final Position position = Position.fromPositionCommand(positionCommand);
    final String? bestMove = await bestMoveSearcher.search(position, moveTime);
    print("bestmove ${bestMove ?? "(none)"}");
  }

  Future<void> _stopCommand() async {
    await bestMoveSearcher.stop();
  }

  Future<bool> elaborate(String line) async {
    final Queue<String> inputComponents = Queue.from(line.split(" "));
    final String command = inputComponents.removeFirst();
    if (command == "uci") {
      print("id name Omnichess");
      print("id author Dany Thach");
      print("uciok");
      return true;
    }
    if (command == "debug") {
      debug = "on" == inputComponents.first;
      return true;
    }
    if (command == "isready") {
      print("readyok");
      return true;
    }
    if (command == "ucinewgame") {
      positionCommand = "startpos";
      return true;
    }
    if (command == "position") {
      _positionCommand(inputComponents);
      return true;
    }
    if (command == "go") {
      await _goCommand(inputComponents);
      return true;
    }
    if (command == "stop") {
      await _stopCommand();
      return true;
    }
    if (command == "quit") {
      return false;
    }
    return true;
  }

  void debugPrintPosition() {
    final Position position = Position.fromPositionCommand(positionCommand);
    for (int i = 0; i < position.board.length; i++) {
      if (i % 8 == 0) {
        stdout.write("info string ");
      }
      stdout.write(Piece.fenCharacterByPiece[position.board[i]]);
      if (i % 8 == 7) {
        stdout.writeln();
      }
    }
    print(position.isWhiteTurn ? "info string white to move" : "info string black to move");
    if (position.canWhiteCastleKingside) {
      print("info string white can castle kingside");
    }
    if (position.canWhiteCastleQueenside) {
      print("info string white can castle queenside");
    }
    if (position.canBlackCastleKingside) {
      print("info string black can castle kingside");
    }
    if (position.canBlackCastleQueenside) {
      print("info string black can castle queenside");
    }
    if (null != position.enPassantTargetSquare) {
      print("info string en passant possible on ${position.enPassantTargetSquareAlgebraic}");
    }
    print("info string halfmove clock ${position.halfmoveClock}");
    print("info string fullmove number ${position.fullmoveNumber}");
    print("info string position fen ${position.fen}");
  }

  void loop() async {
    // final DateTime now = DateTime.now();
    // final String logName = "${now.year}"
    //   "${now.month.toString().padLeft(2, "0")}"
    //   "${now.day.toString().padLeft(2, "0")}"
    //   "-"
    //   "${now.hour.toString().padLeft(2, "0")}"
    //   "${now.minute.toString().padLeft(2, "0")}"
    //   "${now.second.toString().padLeft(2, "0")}"
    //   "${now.millisecond.toString().padLeft(3, "0")}"
    //   ".log";
    // final File log = File("logs/$logName");
    // if (!log.existsSync()) {
    //   log.createSync();
    // }
    late StreamSubscription<String> inputSubscription;
    inputSubscription = stdin
      .transform(utf8.decoder)
      .transform(LineSplitter())
      .listen((String line) async {
        // log.writeAsStringSync("$line\n", mode: FileMode.append);
        final String input = line.trim();
        final bool keepGoing = await elaborate(input);
        if (!keepGoing) {
          await inputSubscription.cancel();
        }
        if (debug) {
          debugPrintPosition();
        }
      });
    await inputSubscription.asFuture();
  }

}