using System;
using System.Collections.Generic;

namespace MazeGen
{
    /// <summary>
    /// Tracks one agent's progress through the maze: current room, ordered path history
    /// (for visualization/backtracking), and O(1) sets for "have I been here" / "have I
    /// used this exit" checks. Plain C# class - no MonoBehaviour/scene dependency, so it's
    /// cheap to run many of these (e.g. for future autonomous multi-agent scenarios).
    /// </summary>
    public class MazeAgent
    {
        public readonly string Name;
        public Room CurrentRoom { get; private set; }
        public int NewRoomsVisited { get; private set; }

        private readonly List<Room> _path = new List<Room>();
        private readonly HashSet<int> _visitedRoomIds = new HashSet<int>();
        private readonly HashSet<int> _usedExitIds = new HashSet<int>();

        public IReadOnlyList<Room> PathHistory => _path;

        public event Action<Room> RoomEntered;
        public event Action<Room> ReachedExitRoom;

        public MazeAgent(string name, Room startRoom)
        {
            Name = name;
            EnterRoom(startRoom, null);
        }

        public bool HasVisited(int roomId) => _visitedRoomIds.Contains(roomId);
        public bool HasUsedExit(Exit exit) => _usedExitIds.Contains(exit.Id);

        public void EnterRoom(Room room, Exit viaExit)
        {
            if (viaExit != null)
                _usedExitIds.Add(viaExit.Id);

            if (_visitedRoomIds.Add(room.Id))
                NewRoomsVisited++;

            CurrentRoom = room;
            _path.Add(room);

            RoomEntered?.Invoke(room);
            if (room.Kind == RoomKind.Exit)
                ReachedExitRoom?.Invoke(room);
        }
    }
}