using UnityEngine;
using System.Collections;

namespace MyFrameworkPure
{
    //状态机实现
    public class StateMachine<T> where T : class
    {
        /// <summary>
        /// 游戏智能体
        /// </summary>
        private T mAI;

        /// <summary>
        /// 全局状态(可以在任意时间切换至全局状态)
        /// </summary>
        private State<T> mGlobalState;

        /// <summary>
        /// 当前状态
        /// </summary>
        private State<T> mCurrentState;

        /// <summary>
        /// 上一个状态
        /// </summary>
        private State<T> mPreviousState;

        public StateMachine(T ai)
        {
            mAI = ai;
        }

        /// <summary>
        /// 更新状态机
        /// </summary>
        public void UpdateState()
        {
            if (mGlobalState != null)
            {
                mGlobalState.Execute(mAI);
            }

            if (mCurrentState != null)
            {
                mCurrentState.Execute(mAI);
            }
        }

        /// <summary>
        /// 改变状态
        /// </summary>
        /// <param equimpentName="newState">新状态</param>
        public void ChangeState(State<T> newState)
        {
            Debug.Assert(newState != null, "the new state to chanaged is null *** " + newState);
            mPreviousState = mCurrentState;
            mCurrentState.Exit(mAI);
            mCurrentState = newState;
            mCurrentState.Enter(mAI);
        }

        /// <summary>
        /// 反转状态至上一个状态
        /// </summary>
        public void RevertToPreviousState()
        {
            Debug.Assert(mPreviousState != null, "the previous to revert is null *** " + mPreviousState);

            ChangeState(mPreviousState);
        }

        public State<T> GlobalState
        {
            get { return mGlobalState; }
            set { mGlobalState = value; }
        }

        public State<T> CurrentState
        {
            get { return mCurrentState; }
            set { mCurrentState = value; }
        }

        public State<T> PreviousState
        {
            get { return mPreviousState; }
            set { mPreviousState = value; }
        }
    }
}