gobang/lib/models/game_state.dart

import 'package:gobang/models/user_context.dart';

abstract class GameState {
  int step = 0;
  int reg = 0;
  final UserContext userContext;

  GameState(this.userContext);

  bool regretChess();

  bool surrender();

  void play() {
    step++;
  }
}

/// 开局：不可悔棋、不可投降
class StartState extends GameState {
  StartState(super.userContext);

  @override
  bool regretChess() => false;

  @override
  bool surrender() => false;

  @override
  void play() {
    super.play();
    if (step >= 4) {
      userContext.setState(
        MidState(userContext)
          ..step = step
          ..reg = reg,
      );
    }
  }
}

/// 中盘：可悔棋（最多 3 次）、可投降
class MidState extends GameState {
  MidState(super.userContext);

  @override
  bool regretChess() {
    reg++;
    if (reg == 3) {
      userContext.setState(
        EndState(userContext)
          ..step = step
          ..reg = reg,
      );
    }
    return true;
  }

  @override
  bool surrender() => true;
}

/// 终盘：悔棋用尽，仍可投降
class EndState extends GameState {
  EndState(super.userContext);

  @override
  bool regretChess() => false;

  @override
  bool surrender() => true;
}