sneak/Shared/FSM.cs

using System;
using System.Collections.Generic;

namespace SemiColinGames {
  public interface IState {
    public void Enter();
    public string? Update(NPC npc, float modelTime, AABB[] collisionTargets);
  }

  public class FSM {
    float timeInState = 0f;
    Dictionary<string, IState> states;
    IState state;

    public FSM(Dictionary<string, IState> states, string initial) {
      this.states = states;
      StateName = initial;
      Transition(StateName);
    }

    public string StateName { get; private set; }

    public void Update(NPC npc, float modelTime, AABB[] collisionTargets) {
      timeInState += modelTime;
      string? newState = state.Update(npc, modelTime, collisionTargets);
      if (newState != null) {
        Transition(newState);
      }
    }

    void Transition(string state) {
      Debug.WriteLine("{0} -> {1} @ {2}", StateName, state, timeInState);
      timeInState = 0f;
      StateName = state;
      IState newState = states[state];
      this.state = newState;
      this.state.Enter();
    }
  }
}