using System;
using System.Diagnostics;
using System.IO;
using System.Threading;

namespace EveryPublish.Client.Services;

/// <summary>看门狗：spawn agent-core 子进程，5s 心跳检查，失败自动拉起，3 次失败告警</summary>
public class Watchdog : IDisposable
{
    private readonly CoreClient _core;
    private readonly string _dataDir;
    private readonly Action _onFatal;
    private Process? _proc;
    private Timer? _timer;
    private int _failCount;

    public Watchdog(CoreClient core, string dataDir, Action onFatal)
    {
        _core = core;
        _dataDir = dataDir;
        _onFatal = onFatal;
    }

    public void Start()
    {
        Spawn();
        _timer = new Timer(_ => Check(), null, TimeSpan.FromSeconds(5), TimeSpan.FromSeconds(5));
    }

    public void Restart()
    {
        try { _proc?.Kill(); } catch { /* 忽略 */ }
        Spawn();
    }

    private void Spawn()
    {
        var exe = Path.Combine(AppContext.BaseDirectory, "agent-core.exe");
        if (!File.Exists(exe))
        {
            _onFatal();
            return;
        }
        var psi = new ProcessStartInfo
        {
            FileName = exe,
            Arguments = "-dir \"" + _dataDir + "\"",
            WorkingDirectory = Path.GetDirectoryName(exe) ?? AppContext.BaseDirectory,
            CreateNoWindow = true,
            UseShellExecute = false,
        };
        _proc = Process.Start(psi);
    }

    private void Check()
    {
        _core.ReloadLocalJson();
        var healthy = false;
        if (_proc != null && !_proc.HasExited)
        {
            try
            {
                var status = _core.GetStatusAsync().GetAwaiter().GetResult();
                healthy = status != null;
            }
            catch
            {
                healthy = false;
            }
        }
        if (healthy)
        {
            _failCount = 0;
            return;
        }
        _failCount++;
        if (_failCount >= 3)
        {
            _onFatal();
            return;
        }
        Spawn();
    }

    public void Dispose()
    {
        _timer?.Dispose();
        try { _proc?.Kill(); } catch { /* 忽略 */ }
    }
}