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


/// <summary>
///     状态接口
/// </summary>
public interface IState
{
    /// <summary>
    ///     状态进入状态栈
    /// </summary>
    void OnStateEnter();

    /// <summary>
    ///     状态退出状态栈
    /// </summary>
    void OnStateLeave();

    /// <summary>
    ///     状态由栈顶变成非栈顶
    /// </summary>
    void OnStateOverride();

    /// <summary>
    ///     状态由非栈顶变成栈顶
    /// </summary>
    void OnStateResume();

    string name { get; }
}

public abstract class BaseState : IState
{
    public virtual void OnStateEnter() { }

    public virtual void OnStateLeave() { }

    public virtual void OnStateOverride() { }

    public virtual void OnStateResume() { }

    public virtual string name { get { return GetType().Name; } }
}

/// <summary>
///     状态机
/// </summary>
public class StateMachine
{
    // 状态名-已注册的状态
    private Dictionary<string, IState> _registedState = new Dictionary<string, IState>();

    // 状态堆栈
    private Stack<IState> _stateStack = new Stack<IState>();

    public IState tarState { get; private set; }

    public void RegisterState(string name, IState state)
    {
        if (name == null || state == null)
        {
            return;
        }

        if (_registedState.ContainsKey(name))
        {
            return;
        }

        _registedState.Add(name, state);
    }

    public ClassEnumerator RegisterStateByAttributes<TAttributeType>(Assembly InAssembly, params object[] args)
        where TAttributeType : AutoRegisterAttribute
    {
        var Classes = new ClassEnumerator( 
            typeof(TAttributeType),
            typeof(IState), 
            InAssembly);

        var Iter = Classes.results.GetEnumerator();

        while( Iter.MoveNext() )
        {
            var StateType = Iter.Current;

            IState StateObj = (IState)System.Activator.CreateInstance(StateType, args);

            RegisterState(StateObj, StateObj.name);
        }

        return Classes;
    }

    public ClassEnumerator RegisterStateByAttributes<TAttributeType>(Assembly InAssembly)
        where TAttributeType : AutoRegisterAttribute
    {
        var Classes = new ClassEnumerator(
            typeof(TAttributeType),
            typeof(IState),
            InAssembly);

        var Iter = Classes.results.GetEnumerator();

        while (Iter.MoveNext())
        {
            var StateType = Iter.Current;

            IState StateObj = (IState)System.Activator.CreateInstance(StateType);

            RegisterState(StateObj, StateObj.name);
        }

        return Classes;
    }

    public void RegisterState<TStateImplType>(TStateImplType State, string name)
        where TStateImplType : IState
    {
        RegisterState(name, State);
    }

    /// <summary>
    ///     注销状态
    /// </summary>
    /// <param name="name">状态名</param>
    /// <returns>被注销的状态</returns>
    public IState UnregisterState(string name)
    {
        if (name == null)
        {
            return default(IState);
        }

        IState state;
        if (!_registedState.TryGetValue(name, out state))
        {
            return default(IState);
        }

        _registedState.Remove(name);

        return state;
    }

    /// <summary>
    /// 获取状态
    /// </summary>
    /// <param name="name">状态名</param>
    /// <returns>状态</returns>
    public IState GetState(string name)
    {
        if (null == name)
        {
            return default(IState);
        }

        IState state;
        return _registedState.TryGetValue(name, out state) ? state : default(IState);
    }

    public string GetStateName(IState state)
    {
        if (null == state)
        {
            return null;
        }

        var etr = _registedState.GetEnumerator();
        KeyValuePair<string, IState> pair;
        while (etr.MoveNext())
        {
            pair = etr.Current;

            if (pair.Value == state)
            {
                return pair.Key;
            }
        }

        return null;
    }

    /// <summary>
    ///     压入状态
    /// </summary>
    /// <param name="state">状态</param>
    public void Push(IState state)
    {
        if (state == null)
        {
            return;
        }

        if (_stateStack.Count > 0)
        {
            _stateStack.Peek().OnStateOverride();
        }

        _stateStack.Push(state);

        state.OnStateEnter();
    }

    /// <summary>
    ///     压入状态
    /// </summary>
    /// <param name="name">状态名</param>
    public void Push(string name)
    {
        if (name == null)
        {
            return;
        }

        IState state;
        if (!_registedState.TryGetValue(name, out state))
        {
            return;
        }

        Push(state);
    }

    /// <summary>
    ///     弹出状态
    /// </summary>
    /// <returns>被弹出的状态</returns>
    public IState PopState()
    {
        if (_stateStack.Count <= 0)
        {
            return default(IState);
        }

        IState state = _stateStack.Pop();
        state.OnStateLeave();

        if (_stateStack.Count > 0)
        {
            _stateStack.Peek().OnStateResume();
        }

        return state;
    }

    /// <summary>
    ///     修改栈顶状态
    /// </summary>
    /// <param name="state">新栈顶状态</param>
    /// <returns>原栈顶状态</returns>
    public IState ChangeState(IState state)
    {
        if (state == null)
        {
            return default(IState);
        }

        tarState = state;

        IState oldState = default(IState);
        if (_stateStack.Count > 0)
        {
            oldState = _stateStack.Pop();
            oldState.OnStateLeave();
        }

        _stateStack.Push(state);
        state.OnStateEnter();

        return oldState;
    }

    /// <summary>
    /// 修改栈顶状态
    /// </summary>
    /// <param name="name">新栈顶状态名</param>
    /// <returns>原栈顶状态</returns>
    public IState ChangeState(string name)
    {
        if (name == null)
        {
            DebugHelper.LogWarning("没有状态机类型，使用默认类型：");
            return default(IState);
        }

        IState state;
        if (!_registedState.TryGetValue(name, out state))
        {
            DebugHelper.LogError("找不到状态机类：" + name);
            return default(IState);
        }

        return ChangeState(state);
    }

    /// <summary>
    ///     获取栈顶状态
    /// </summary>
    /// <returns>栈顶状态</returns>
    public IState TopState()
    {
        if (_stateStack.Count <= 0)
        {
            return default(IState);
        }

        return _stateStack.Peek();
    }

    public string TopStateName()
    {
        if (_stateStack.Count <= 0)
        {
            return null;
        }

        IState state = _stateStack.Peek();
        return GetStateName(state);
    }

    /// <summary>
    ///     清空堆栈
    /// </summary>
    public void Clear()
    {
        while (_stateStack.Count > 0)
        {
            _stateStack.Pop().OnStateLeave();
        }
    }

    public int Count { get { return _stateStack.Count; } }
}