using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using System;

namespace OnePixelFramework
{
	public class StateMachine : MonoBehaviour
	{
		private Dictionary<int, State> stateDict = new Dictionary<int, State>();

         // 當前狀態
		public State curState 
		{
			private set;
			get;
		}

        // 前一個狀態
		public State preState 
		{
			private set;
			get;
		}

        // T 必須是Enum型別
		public T GetCurStateId<T>() where T : struct, IConvertible
		{
			return GetStateId<T>(this.curState);
		}

        // T 必須是Enum型別
        public T GetPreStateId<T>() where T : struct, IConvertible
		{
			return GetStateId<T>(this.preState);
		}

        // 獲取State的狀態id
        private static T GetStateId<T>(State state)
		{
			Type enumType = typeof(T);

			if (!enumType.IsEnum) 
			{
				throw new ArgumentException("T must be an enumerated type");
			}

			int value;

			if (state != null)
			{
				value = Convert.ToInt32(state.id);
			}
			else
			{
				value = -1;
			}

			return (T) Enum.ToObject(enumType, value);
		}

        // 根據自定義Enum建立State
		public State CreateState(Enum stateId)
		{
			State state        = new State();
			state.id           = stateId;
			state.stateMachine = this;
			this.stateDict.Add(Convert.ToInt32(stateId), state);

			return state;
		}

        // 狀態切換
		public State SetState(Enum stateId)
		{
			if (this.curState != null)
			{
				if (this.curState.OnExit != null)
				{
					this.curState.OnExit();
				}
			}

			this.preState = this.curState;
			this.curState = this.stateDict[Convert.ToInt32(stateId)];

			if (this.curState.OnEnter != null)
			{
				this.curState.OnEnter();
			}

			return this.curState;
		}

        // 狀態執行
        public virtual void Update()
		{
			if (this.curState != null)
			{
				if (this.curState.Update != null)
				{
					this.curState.Update();
				}
			}
		}

        // 狀態物件
		public class State
		{
			public Enum         id;
			public object       userData;
			public StateMachine stateMachine;
			public Action       OnEnter;
			public Action       OnExit ;
			public Action       Update ;

			public State SetId(Enum id)
			{
				this.id = id;
				return this;
			}

			public State SetUserData(object userData)
			{
				this.userData = userData;
				return this;
			}

			public State SetOnEnter(Action OnEnter)
			{
				this.OnExit = OnEnter;
				return this;
			}

			public State SetOnExit(Action OnExit)
			{
				this.OnExit = OnExit;
				return this;
			}

			public State SetUpdate(Action Update)
			{
				this.Update = Update;
				return this;
			}
		}
	}
}