using System.IO;
using CYQ.Data.Tool;

namespace CYQ.Data.Cache
{
    /// <summary>
    /// 用于监控分布式缓存的配置列表，实际高可用，动态加载，而不需要关停运行的服务。
    /// </summary>
    internal class HostConfigWatch
    {
        //用于验证权限的委托事件。
        internal delegate void OnConfigChangedDelegate(string configValue);
        public event OnConfigChangedDelegate OnConfigChangedEvent;

        public HostConfigWatch(string configValue)
        {
            StartWatch(configValue);
            CompareHostListByConfig(configValue);
        }

        private void StartWatch(string configValue)
        {
            if (string.IsNullOrEmpty(configValue)) { return; }
            if (configValue.EndsWith(".txt") || configValue.EndsWith(".ini"))
            {
                string path = AppConfig.RunPath + configValue;
                if (File.Exists(path))
                {
                    IOWatch.On(path, delegate (FileSystemEventArgs e)
                    {
                        if (OnConfigChangedEvent != null)
                        {
                            OnConfigChangedEvent(IOHelper.ReadAllText(path));
                        }
                    });
                }
            }
        }


        /// <summary>
        /// 存档配置文件对应的原始主机列表。
        /// </summary>
        public MList<string> HostList = new MList<string>();
        /// <summary>
        /// 变化后要追加的主机。
        /// </summary>
        public MList<string> HostAddList = new MList<string>();
        /// <summary>
        /// 变化后要移除的主机。
        /// </summary>
        public MList<string> HostRemoveList = new MList<string>();

        /// <summary>
        /// 和旧配置相比较，找出变化后的主机信息
        /// </summary>
        /// <param name="configValue">新的配置值</param>
        public void CompareHostListByConfig(string configValue)
        {
            lock (this)
            {
                if (string.IsNullOrEmpty(configValue)) { return; }
                string[] hostItems = configValue.Trim().Split(',');
                if (hostItems == null || hostItems.Length == 0) { return; }

                HostAddList.Clear();
                HostRemoveList.Clear();
                //开始比较主机配置版本差异
                if (HostList.Count == 0)
                {
                    foreach (string host in hostItems)
                    {
                        string item = host.Trim();
                        if (string.IsNullOrEmpty(item) || item.StartsWith("#"))
                        {
                            continue;
                        }
                        if (!HostAddList.Contains(item))
                        {
                            HostAddList.Add(item);
                            HostList.Add(item);
                        }
                    }
                }
                else
                {
                    foreach (string host in hostItems)
                    {
                        string item = host.Trim();
                        if (string.IsNullOrEmpty(item) || item.StartsWith("#"))
                        {
                            continue;
                        }
                        if (HostList.Contains(item))
                        {
                            HostList.Remove(item);
                        }
                        else if (!HostAddList.Contains(item))
                        {
                            HostAddList.Add(item);
                        }
                    }
                    //剩下的就是要移除的。
                    foreach (string host in HostList.List)
                    {
                        HostRemoveList.Add(host);
                    }
                    HostList.Clear();
                    //把项添加到HostList项。
                    foreach (string host in hostItems)
                    {
                        string item = host.Trim();
                        if (string.IsNullOrEmpty(item) || item.StartsWith("#"))
                        {
                            continue;
                        }
                        if (!HostList.Contains(item))
                        {
                            HostList.Add(item);
                        }
                    }
                }
            }
        }
    }
}