using System;
using System.Diagnostics;
using System.Text;
using NLog;
using Prism.Events;
using Prism.Regions;
using RIZO_Application.Core;
using RIZO_Application.Core.Mvvm;

namespace RIZO_Application.Modules.LogModule.ViewModels
{
    public class SystemLogViewModel : RegionViewModelBase
    {
        private readonly IEventAggregator _eventAggregator;
        private SubscriptionToken _token;
        private readonly StringBuilder _logMessageBuilder = new StringBuilder();
        private Logger _logger = LogManager.GetCurrentClassLogger();
        private const int MaxLogLength = 1000; // 假设最大长度为1000，可以根据实际情况调整
        private const string LogFormat = "\n{0}: {1}";

        // 定义一个日志更新事件
        public event EventHandler LogUpdated;

        public string LogMessage
        {
            get { return _logMessageBuilder.ToString(); }
            set
            {
                _logMessageBuilder.Clear();
                _logMessageBuilder.Append(value);
                RaisePropertyChanged(nameof(LogMessage));
            }
        }

        public SystemLogViewModel(
            IRegionManager regionManager,
            IEventAggregator eventAggregator)
            : base(regionManager)
        {
            OnLogReceived("初始化日志系统");
            _eventAggregator = eventAggregator;
            // 订阅事件，使用UI线程处理，保持强引用
            _token = _eventAggregator.GetEvent<SystemLogEvent>().Subscribe(OnLogReceived, ThreadOption.UIThread, true);
        }

        private void OnLogReceived(string message)
        {
            string newLog = string.Format(LogFormat, DateTime.Now, message);
            _logMessageBuilder.Append(newLog);

            if (_logMessageBuilder.Length > MaxLogLength)
            {
                // 计算需要截取的位置，保留最新的日志
                int startIndex = Math.Max(0, _logMessageBuilder.Length - MaxLogLength);
                _logMessageBuilder.Remove(0, startIndex);
            }

            RaisePropertyChanged(nameof(LogMessage));
            _logger.Info(newLog);

            // 触发日志更新事件
            OnLogUpdated();
        }

        protected virtual void OnLogUpdated()
        {
            LogUpdated?.Invoke(this, EventArgs.Empty);
        }

        public void Destroy()
        {
            _token?.Dispose();
        }

        public void AddTestLogMessage()
        {
            // 示例实现，可根据需求修改
            OnLogReceived("测试日志消息");
        }

        public override void OnNavigatedTo(NavigationContext navigationContext)
        {
            //do something
        }
    }
}