using System;
using System.Collections.Generic;
using System.Linq;

namespace IOTContainer.MvvmBase
{
    /// <summary>
    /// 消息基础类
    /// </summary>
    public class MessageBase
    {
        #region 静态函数
        private static MessageBase _defult;
        /// <summary>
        /// 默认消息体
        /// </summary>
        public static MessageBase Defult
        {
            get
            {
                if (_defult == null)
                    _defult = new MessageBase();

                return _defult;
            }
        }
        #endregion

        #region 构造函数
        /// <summary>
        /// 初始化插件消息器
        /// </summary>
        public MessageBase()
        {
            this._messages = new List<MessageItem>();
        }
        #endregion

        #region 字段属性
        /// <summary>
        /// 消息列表
        /// </summary>
        private List<MessageItem> _messages;
        #endregion

        #region 对外方法
        /// <summary>
        /// 注册消息
        /// </summary>
        /// <param name="recipient">接收者</param>
        /// <param name="token">消息令牌</param>
        /// <param name="handler">消息操作事件</param>
        public void Register(object recipient, string token, MessageHandler handler)
        {
            if (recipient == null)
                throw new Exception("Recipient Is Null!");
            if (string.IsNullOrWhiteSpace(token))
                throw new Exception("Toke Is Null Or WhiteSpace!");
            if (handler == null)
                throw new Exception("Handler Is Null!");

            this._messages.Add(new MessageItem(recipient, token, handler));
        }

        /// <summary>
        /// 广播消息
        /// </summary>
        /// <param name="sender">发送者</param>
        /// <param name="token">消息令牌</param>
        /// <param name="args">消息信息</param>
        public void Send(object sender, string token, MessageArgs args)
        {
            if (string.IsNullOrWhiteSpace(token))
                throw new Exception("Toke Is Null Or WhiteSpace!");

            var messages = this._messages.Where(x => x.Token == token);

            foreach (var item in messages)
            {
                item.Do(sender, args);
            }
        }

        /// <summary>
        /// 发送消息
        /// </summary>
        /// <param name="sender">发送者</param>
        /// <param name="recipient">接收者</param>
        /// <param name="token">消息令牌</param>
        /// <param name="args">消息信息</param>
        public void Send(object sender, object recipient, string token, MessageArgs args)
        {
            if (recipient == null)
                throw new Exception("Recipient Is Null!");
            if (string.IsNullOrWhiteSpace(token))
                throw new Exception("Toke Is Null Or WhiteSpace!");

            var messages = this._messages.Where(x => x.Recipient == recipient && x.Token == token);

            foreach (var item in messages)
            {
                item.Do(sender, args);
            }
        }

        /// <summary>
        /// 取消注册,移除所有包含recipient的消息
        /// </summary>
        /// <param name="recipient">接收者</param>
        public void Unregister(object recipient)
        {
            if (recipient == null)
                throw new Exception("Recipient Is Null!");

            this._messages.RemoveAll(x => x.Recipient == recipient);
        }

        /// <summary>
        /// 取消注册,移除所有包含recipient,token的消息
        /// </summary>
        /// <param name="recipient">接收者</param>
        /// <param name="token">消息令牌</param>
        public void Unregister(object recipient, string token)
        {
            if (recipient == null)
                throw new Exception("Recipient Is Null!");
            if (string.IsNullOrWhiteSpace(token))
                throw new Exception("Toke Is Null Or WhiteSpace!");

            this._messages.RemoveAll(x => x.Recipient == recipient && x.Token == token);
        }
        #endregion

        #region 消息子项
        /// <summary>
        /// 消息子项
        /// </summary>
        private class MessageItem : IDisposable
        {
            public MessageItem(object recipient, string token, MessageHandler handler)
            {
                this.Recipient = recipient;
                this.Token = token;
                this._handler = handler;
            }

            /// <summary>
            /// 注册者
            /// </summary>
            public object Recipient { get; private set; }

            /// <summary>
            /// 令牌
            /// </summary>
            public string Token { get; private set; }

            /// <summary>
            /// 操作事件
            /// </summary>
            private event MessageHandler _handler;

            /// <summary>
            /// 执行发送消息事件
            /// </summary>
            /// <param name="sender">发送者</param>
            /// <param name="args">消息</param>
            public void Do(object sender, MessageArgs args)
            {
                this._handler?.Invoke(sender, args);
            }

            /// <summary>
            /// 销毁程序
            /// </summary>
            public void Dispose()
            {
                this.Recipient = null;
                this.Token = null;
                this._handler = null;
            }
        }
        #endregion
    }

    #region 消息委托
    /// <summary>
    /// 消息传递委托定义
    /// </summary>
    /// <param name="sender">发送者</param>
    /// <param name="e">消息</param>
    public delegate void MessageHandler(object sender, MessageArgs e);

    /// <summary>
    /// 消息回调委托定义
    /// </summary>
    /// <param name="sender">发送者</param>
    /// <param name="e">消息</param>
    public delegate void MessageCallBack(object sender, object message);
    #endregion

    #region 消息体定义
    /// <summary>
    /// 消息体
    /// </summary>
    public sealed class MessageArgs
    {
        public static readonly MessageArgs Empty = new MessageArgs();

        /// <summary>
        /// 无参构造函数
        /// </summary>
        public MessageArgs()
        {
            this.Message = null;
        }

        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="message">消息</param>
        public MessageArgs(object message)
        {
            this.Message = message;
            this._callback = null;
        }

        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="message">消息</param>
        /// <param name="callback">回调函数</param>
        public MessageArgs(object message, MessageCallBack callback)
        {
            this.Message = message;
            this._callback = callback;
        }

        /// <summary>
        /// 消息
        /// </summary>
        public object Message { get; }

        /// <summary>
        /// 操作事件
        /// </summary>
        private event MessageCallBack _callback;

        /// <summary>
        /// 执行回调事件
        /// </summary>
        /// <param name="sender">发送者</param>
        /// <param name="message">消息</param>
        public void Callback(object sender, object message)
        {
            this._callback?.Invoke(sender, message);
        }
    }
    #endregion
}