using System;
using System.Collections.Generic;

namespace TyphoonUI
{
    /// <summary>
    /// UI活动代理
    /// </summary>
    public struct UIOperationHandler
    {
        public long Id;

        public UIOperationHandler(long id)
        {
            Id = id;
        }

        /// <summary>
        /// 获取当前状态
        /// </summary>
        public OperationStatus GetStatus() => UIOperation._GetOperationStatus(Id);

        /// <summary>
        /// 是否有效
        /// </summary>
        /// <returns></returns>
        public bool IsValid() => UIOperation._IsValid(Id);

        /// <summary>
        /// 切换到完成状态
        /// </summary>
        public void ToFinishStatus()
        {
            //活动执行完毕
            UIOperation._ChangeOperationStatus(Id, OperationStatus.Finish);
        }

        /// <summary>
        /// 切换到运行中状态
        /// </summary>
        public void ToRunningStatus()
        {
            //等待活动执行中
            UIOperation._ChangeOperationStatus(Id, OperationStatus.Running);
        }

        /// <summary>
        /// 执行行为
        /// </summary>
        internal void Run()
        {
            UIOperation._RunOperation(Id);
        }


        /// <summary>
        /// 释放
        /// </summary>
        internal void Release()
        {
            UIOperation._Release(Id);
        }
    }


    /// <summary>
    /// UI活动
    /// </summary>
    internal class UIOperation
    {
        private static readonly Dictionary<long, UIOperation> Operations = new Dictionary<long, UIOperation>();
        private static long _idCounter;
        public static event Action<long> OnStateChanged;

        /// <summary>
        /// 获取状态
        /// </summary>
        internal static OperationStatus _GetOperationStatus(long id)
        {
            if (Operations.TryGetValue(id, out var match))
            {
                return match.Status;
            }

            return OperationStatus.Finish;
        }

        /// <summary>
        /// 切换状态
        /// </summary>
        internal static void _ChangeOperationStatus(long id, OperationStatus status)
        {
            if (Operations.TryGetValue(id, out var match))
            {
                match.ChangeStatus(status);
            }
        }

        /// <summary>
        /// 执行行为
        /// </summary>
        internal static void _RunOperation(long id)
        {
            if (Operations.TryGetValue(id, out var match))
            {
                match.Run();
            }
        }

        /// <summary>
        /// 是否有效
        /// </summary>
        internal static bool _IsValid(long id)
        {
            if (Operations.TryGetValue(id, out var match))
            {
                return match.IsValid;
            }

            return false;
        }

        /// <summary>
        /// 释放
        /// </summary>
        internal static void _Release(long id)
        {
            if (Operations.TryGetValue(id, out var match))
            {
                match.Release();
            }
        }


        internal static UIOperationHandler Create(Action<UIOperationHandler> handler)
        {
            var operation = new UIOperation
            {
                Handler = handler
            };
            return new UIOperationHandler(operation.OperationId);
        }

        private UIOperation()
        {
            OperationId = _idCounter += 1;
            Operations.Add(OperationId, this);
        }

        /// <summary>
        /// 当前状态
        /// </summary>
        internal OperationStatus Status { private set; get; } = OperationStatus.Ready;

        /// <summary>
        /// ID
        /// </summary>
        internal long OperationId { get; }

        /// <summary>
        /// 是否有效
        /// </summary>
        internal bool IsValid { private set; get; } = true;

        /// <summary>
        /// 逻辑代理
        /// </summary>
        internal Action<UIOperationHandler> Handler { private set; get; }

        //切换状态
        internal void ChangeStatus(OperationStatus status)
        {
            //状态一致，不处理
            if (Equals(Status, status))
            {
                return;
            }

            //切换状态，触发状态变化
            Status = status;
            //通知队列,状态发生变化
            OnStateChanged?.Invoke(OperationId);
        }

        //开始执行
        internal void Run()
        {
            Status = OperationStatus.Running;
            //执行活动逻辑
            Handler?.Invoke(new UIOperationHandler(OperationId));
        }

        internal void Release()
        {
            IsValid = false;
            Operations.Remove(OperationId);
            Handler = null;
        }
    }
}