using System;
using System.Collections;

namespace AibisDream.Framework
{
    public class StateMachine<T> where T : Enum
    {
        public T CurState => _curState.GetState;
        public event Action<T> OnStateSwitch;

        private IState<T> _curState;
        private readonly Func<T, string, IState<T>> _createState;
        
        public StateMachine(Func<T, string, IState<T>> createState)
        {
            _createState  = createState;
        }

        public IEnumerator Init(T initState)
        {
            return SwitchState(initState);
        }

        public IEnumerator SwitchState(T nextState, string args = "")
        {
            if (_curState != null && CurState.Equals(nextState)) yield break;

            yield return _curState?.Exit();
            _curState = _createState.Invoke(nextState, args);
            OnStateSwitch?.Invoke(nextState);
            yield return _curState.Enter();
        }
        
        public IEnumerator QuitState()
        {
            yield return _curState?.Exit();
            _curState = null;
        }
    }
    
    public interface IState<out T> where T : Enum
    {
        public T GetState { get; }
        public void SetArgs(string args) {}
        public IEnumerator Enter();

        public IEnumerator Exit()
        {
            yield break;
        }
    }
}