using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading;

public class FileTimestampAndSizeWatcher
{
    private readonly string _filePath;
    private DateTime _lastModifiedTime;
    private long _lastFileSize;
    public static long _lastReadPosition;
    private Timer _pollingTimer;
    private FileSystemWatcher _watcher;

    public event Action<string> OnFileUpdated;

    private readonly ConcurrentQueue<string> _logQueue = new ConcurrentQueue<string>();
    private readonly AutoResetEvent _logEvent = new AutoResetEvent(false);
    private bool _isConsuming = false;
    private readonly int _maxQueueSize = 1000000;  // 璁剧疆鏈€澶ч槦鍒楀ぇ灏?
    private readonly int _maxRetries = 5; // 鏈€澶ч噸璇曟鏁?
    private readonly int _retryDelay = 1000; // 閲嶈瘯闂撮殧锛屽崟浣嶏細姣

    public FileTimestampAndSizeWatcher(string filePath)
    {
        _filePath = filePath;
        _lastModifiedTime = File.GetLastWriteTime(_filePath);
        _lastFileSize = new FileInfo(_filePath).Length;

        // 鍚姩鏃朵粠澶村紑濮嬭鍙?
        _lastReadPosition = 0;

    }


    public void Start()
    {
        // 鍚姩鏃跺垱寤哄垵濮嬬殑 FileSystemWatcher
        CreateWatcher();

        //鍚敤鏃ュ織娑堣垂
        StartLogConsumer();

        // 鍒濆璇诲彇鏂囦欢鎵€鏈夊唴瀹?
        string initialContent = ReadFileContent();
        ProcessLogContent(initialContent);

        // 璁剧疆瀹氭椂鍣紝姣忓垎閽熷埛鏂颁竴娆?FileSystemWatcher
        _pollingTimer = new Timer(RefreshWatcher, null, TimeSpan.Zero, TimeSpan.FromMinutes(1));
    }

    private void CreateWatcher()
    {
        // 鍒涘缓鏂扮殑 FileSystemWatcher 瀹炰緥
        _watcher = new FileSystemWatcher(Path.GetDirectoryName(_filePath))
        {
            Filter = Path.GetFileName(_filePath),
            NotifyFilter = NotifyFilters.LastWrite | NotifyFilters.Size
        };

        // 娉ㄥ唽浜嬩欢澶勭悊绋嬪簭
        _watcher.Changed += OnChanged;

        // 鍚姩鐩戝惉
        _watcher.EnableRaisingEvents = true;
    }

    private void RefreshWatcher(object state)
    {
        try
        {
            // 绂佺敤鐜版湁鐨?FileSystemWatcher锛堝彧鏄仠姝㈣Е鍙戜簨浠讹紝瀹炰緥渚濈劧瀛樺湪锛?
            _watcher.EnableRaisingEvents = false;

            // 閲婃斁鐜版湁鐨?FileSystemWatcher 瀹炰緥
            _watcher.Dispose();

            // 閲嶆柊鍒涘缓 FileSystemWatcher锛屽苟閲嶆柊娉ㄥ唽浜嬩欢澶勭悊绋嬪簭
            CreateWatcher();
        }
        catch (Exception ex)
        {
            RainOpsMini.Helpers.RainOpsLog.Log($"鍒锋柊 FileSystemWatcher 鏃跺彂鐢熷紓甯? {ex.Message}");
        }
    }

    private string ReadFileContent()
    {
        string newContent = string.Empty;

        for (int retries = 0; retries < _maxRetries; retries++)
        {
            try
            {
                // 浣跨敤 FileStream 浠ュ彧璇诲拰鍏变韩璇诲彇鍐欏叆鐨勬ā寮忔墦寮€鏂囦欢
                using (var stream = new FileStream(_filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
                {
                    stream.Seek(_lastReadPosition, SeekOrigin.Begin);

                    using (var reader = new StreamReader(stream))
                    {
                        newContent = reader.ReadToEnd();
                        _lastReadPosition = stream.Position; // 鏇存柊璇诲彇浣嶇疆
                    }
                }

                break; // 鎴愬姛璇诲彇鏂囦欢鍚庤烦鍑洪噸璇?
            }
            catch (IOException ex)
            {
                // 璁板綍姣忔閲嶈瘯澶辫触鐨勪俊鎭?
                if (retries == _maxRetries - 1)
                {
                    throw; // 濡傛灉閲嶈瘯瓒呰繃鏈€澶ф鏁帮紝鎶涘嚭寮傚父
                }
                Thread.Sleep(_retryDelay); // 绛夊緟涓€娈垫椂闂村悗閲嶈瘯
            }
        }

        return newContent;
    }

    private void OnChanged(object sender, FileSystemEventArgs e)
    {
        try
        {
            DateTime currentModifiedTime = File.GetLastWriteTime(_filePath);
            long currentFileSize = new FileInfo(_filePath).Length;

            if (currentFileSize < _lastReadPosition)
            {
                _lastReadPosition = 0;
            }

            if (currentModifiedTime != _lastModifiedTime || currentFileSize != _lastFileSize)
            {
                _lastModifiedTime = currentModifiedTime;
                _lastFileSize = currentFileSize;

                string newContent = ReadFileContent(); // 璋冪敤鏂扮殑鏂囦欢璇诲彇鏂规硶
                ProcessLogContent(newContent);
            }
        }
        catch (IOException ex)
        {
        }
    }

    private void ProcessLogContent(string content)
    {
        if (!string.IsNullOrWhiteSpace(content))
        {
            var logs = content
                .Split(new[] { "\r\n", "\n" }, StringSplitOptions.RemoveEmptyEntries)
                .ToList();

            foreach (var log in logs)
            {
                if (_logQueue.Count >= _maxQueueSize)
                {
                    // 涓㈠純鏈€鑰佺殑鏃ュ織
                    _logQueue.TryDequeue(out _);
                }
                _logQueue.Enqueue(log);
            }

            _logEvent.Set(); // 閫氱煡娑堣垂鑰呮湁鏂版暟鎹?
        }
    }

    private void StartLogConsumer()
    {
        if (_isConsuming) return;
        _isConsuming = true;

        Thread consumerThread = new Thread(() =>
        {
            while (_isConsuming)
            {
                while (_logQueue.TryDequeue(out var log))
                {
                    try
                    {
                        // 浣跨敤绾跨▼姹犳潵澶勭悊鍥炶皟锛岀‘淇濆洖璋冪殑澶氱嚎绋嬪鐞?
                        ThreadPool.QueueUserWorkItem(state =>
                        {
                            try
                            {
                                OnFileUpdated?.Invoke(log);
                            }
                            catch (Exception ex)
                            {
                            }
                        });
                    }
                    catch (Exception ex)
                    {
                    }
                }

                // 鎵归噺澶勭悊鏃ュ織锛岄伩鍏嶉绻佸敜閱?
                _logEvent.WaitOne();
            }
        });

        consumerThread.IsBackground = true;
        consumerThread.Start();
    }

    public void Stop()
    {
        _watcher?.Dispose();
        _pollingTimer?.Dispose();

        _isConsuming = false;
        _logEvent.Set(); // 閫€鍑虹嚎绋嬮樆濉?
    }
}