using System;
using System.Windows;
using Serilog.Events;
using XP.Common.Logging.ViewModels;

namespace XP.Common.GeneralForm.Views
{
    /// <summary>
    /// 实时日志查看器窗口，订阅 Serilog 事件并实时显示
    /// Real-time log viewer window, subscribes to Serilog events and displays in real-time
    /// </summary>
    public partial class RealTimeLogViewer : Window
    {
        private readonly RealTimeLogViewerViewModel _viewModel;

        /// <summary>
        /// 构造函数 | Constructor
        /// </summary>
        /// <param name="maxLines">最大行数限制，默认 2000 | Max line count, default 2000</param>
        public RealTimeLogViewer(int maxLines = 2000)
        {
            _viewModel = new RealTimeLogViewerViewModel { MaxLines = maxLines };
            DataContext = _viewModel;

            InitializeComponent();

            // 继承主窗口图标 | Inherit main window icon
            if (Application.Current?.MainWindow != null)
            {
                Icon = Application.Current.MainWindow.Icon;
            }

            // 订阅自动滚动事件 | Subscribe to auto-scroll event
            _viewModel.ScrollToBottomRequested += OnScrollToBottomRequested;

            // 加载缓冲区中的历史日志 | Load buffered history logs
            var history = RealTimeLogSink.Instance.GetBufferedHistory();
            foreach (var logEvent in history)
            {
                _viewModel.AddLogEvent(logEvent);
            }

            // 订阅 Serilog Sink 事件（在历史加载之后，避免重复）| Subscribe after history load
            RealTimeLogSink.Instance.LogEventReceived += OnLogEventReceived;

            Closed += OnWindowClosed;
        }

        /// <summary>
        /// 接收 Serilog 日志事件 | Receive Serilog log event
        /// </summary>
        private void OnLogEventReceived(LogEvent logEvent)
        {
            _viewModel.AddLogEvent(logEvent);
        }

        /// <summary>
        /// 自动滚动到底部 | Auto-scroll to bottom
        /// </summary>
        private void OnScrollToBottomRequested()
        {
            try
            {
                if (LogGridView.Items.Count > 0)
                {
                    var lastItem = LogGridView.Items[LogGridView.Items.Count - 1];
                    LogGridView.ScrollIntoView(lastItem);
                }
            }
            catch
            {
                // 滚动失败时静默处理 | Silently handle scroll failures
            }
        }

        /// <summary>
        /// 窗口关闭时取消订阅，防止内存泄漏 | Unsubscribe on close to prevent memory leaks
        /// </summary>
        private void OnWindowClosed(object? sender, EventArgs e)
        {
            _viewModel.ScrollToBottomRequested -= OnScrollToBottomRequested;
            RealTimeLogSink.Instance.LogEventReceived -= OnLogEventReceived;
        }
    }
}