barcode-host/Server/HostedService/TimedHostedService.cs

using Barcode.Host.Server.Models;
using Barcode.Host.Shared.DataModels;
using Barcode.Host.Shared.KeyboardMouse;
using Barcode.Host.Shared.Models.Stateless;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Serilog.Context;

namespace Barcode.Host.Server.HostedService;

public class TimedHostedService : IHostedService, IAggregateInputReader, IDisposable
{

    public event InputReader.RaiseKeyPress? OnKeyPress;

    private readonly int _ExecutionCount;
    private readonly AppSettings _AppSettings;
    private readonly ISerialService _SerialService;
    private readonly ILastScanService _LastScanService;
    private readonly ILogger<TimedHostedService> _Logger;
    private readonly ILinuxGroupManager _LinuxGroupManager;
    private readonly Dictionary<string, InputReader> _Readers;
    private readonly Dictionary<EventCode, char> _CharToEventCodes;
    private readonly List<(string MethodName, Timer Timer)> _Timers;

    public TimedHostedService(ILogger<TimedHostedService> logger, AppSettings appSettings, ILinuxGroupManager linuxGroupManager, ILastScanService lastScanService, ISerialService serialService)
    {
        _Readers = new();
        _Logger = logger;
        _ExecutionCount = 0;
        _CharToEventCodes = new();
        _AppSettings = appSettings;
        _SerialService = serialService;
        _LastScanService = lastScanService;
        _LinuxGroupManager = linuxGroupManager;
        Timer writeTimer = new(Write, null, Timeout.Infinite, Timeout.Infinite);
        Timer scanForNewInputsTimer = new(ScanForNewInputs, null, Timeout.Infinite, Timeout.Infinite);
        _Timers = new List<(string, Timer)>() { (nameof(Write), writeTimer), (nameof(ScanForNewInputs), scanForNewInputsTimer) };
    }

    public Task StartAsync(CancellationToken stoppingToken)
    {
        string? methodName = IMethodName.GetActualAsyncMethodName();
        using (LogContext.PushProperty("MethodName", methodName))
        {
            _Logger.LogInformation($"Timed Hosted Service: {_AppSettings.GitCommitSeven}:{Environment.ProcessId} running.");
            _SerialService.Open();
            if (!_LinuxGroupManager.IsInInputGroup().WaitAsync(stoppingToken).Result)
            {
                if (string.IsNullOrEmpty(_AppSettings.RootPassword))
                    throw new Exception($"Please check appsettings file(s) for <{nameof(_AppSettings.RootPassword)}>!");
                _ = _LinuxGroupManager.AddUserToInputGroup(_AppSettings.RootPassword);
                _ = _LinuxGroupManager.RebootSystem(_AppSettings.RootPassword);
            }
            List<(EventCode, char)> collection = _LastScanService.IncludeEventCodes();
            foreach ((EventCode eventCode, char @char) in collection)
                _CharToEventCodes.Add(eventCode, @char);
            int dueTime = 0;
            foreach ((string _, Timer timer) in _Timers)
            {
                dueTime += 300;
                _ = timer.Change(dueTime, Timeout.Infinite);
            }
        }
        return Task.CompletedTask;
    }

    public Task StopAsync(CancellationToken stoppingToken)
    {
        string? methodName = IMethodName.GetActualAsyncMethodName();
        using (LogContext.PushProperty("MethodName", methodName))
        {
            _Logger.LogInformation($"Timed Hosted Service: {_AppSettings.GitCommitSeven}:{Environment.ProcessId} is stopping.");
            for (short i = 0; i < short.MaxValue; i++)
            {
                Thread.Sleep(500);
                if (_ExecutionCount == 0)
                    break;
            }
        }
        return Task.CompletedTask;
    }

    public void Dispose()
    {
        foreach ((string _, Timer timer) in _Timers)
            timer.Dispose();
        foreach (InputReader inputReader in _Readers.Values)
        {
            inputReader.OnKeyPress -= ReaderOnOnKeyPress;
            inputReader.Dispose();
        }
        _Readers.Clear();
        _SerialService.Close();
        GC.SuppressFinalize(this);
    }

    private void ReaderOnOnKeyPress(KeyPressEvent e)
    {
        OnKeyPress?.Invoke(e);
        if (e.TimeSpan.TotalMilliseconds > _AppSettings.ClearLastScanServiceAfter)
            _LastScanService.Clear();
        if (e.KeyState == KeyState.KeyUp && _CharToEventCodes.TryGetValue(e.EventCode, out char @char))
            _LastScanService.Add(e.EventCode, @char);
    }

    private Timer? GetTimer(string methodName)
    {
        (string MethodName, Timer Timer)[] results = _Timers.Where(l => l.MethodName == methodName).ToArray();
        return !results.Any() ? null : results.First().Timer;
    }

    private void ScanForNewInputs()
    {
        string fileName;
        IEnumerable<LinuxDevice>? devices = null;
        string[] files = Directory.GetFiles("/dev/input/", "event*");
        foreach (string file in files)
        {
            if (_Readers is null || _Readers.ContainsKey(file))
                continue;
            devices ??= DeviceReader.Get(_AppSettings.LinuxDevicePath);
            fileName = Path.GetFileName(file);
            InputReader reader = new(file, _Logger);
            if (devices.Any(l => !string.IsNullOrEmpty(l.Name) && l.Name.EndsWith(_AppSettings.DeviceNameEndsWith) && l.Handlers.Any(m => m == fileName)))
                reader.OnKeyPress += ReaderOnOnKeyPress;
            _Readers?.Add(file, reader);
        }
        IEnumerable<InputReader>? deadReaders = _Readers?.Values.Where(r => r.Faulted);
        if (deadReaders is not null)
        {
            foreach (InputReader? inputReader in deadReaders)
            {
                _ = _Readers?.Remove(inputReader.Path);
                inputReader.OnKeyPress -= ReaderOnOnKeyPress;
                inputReader.Dispose();
            }
        }
    }

    private void ScanForNewInputs(object? sender)
    {
        try
        { ScanForNewInputs(); }
        catch (Exception ex) { _Logger.LogError(ex, nameof(ScanForNewInputs)); }
        try
        {
            Timer? timer = GetTimer(nameof(ScanForNewInputs));
            if (timer is not null)
            {
                TimeSpan timeSpan = new(DateTime.Now.AddSeconds(30).Ticks - DateTime.Now.Ticks);
                _ = timer.Change((int)timeSpan.TotalMilliseconds, Timeout.Infinite);
            }
        }
        catch (Exception ex) { _Logger.LogError(ex, $"{nameof(ScanForNewInputs)}-{nameof(Timer)}.{nameof(Timer.Change)}"); }
    }

    private void Write()
    {
        int count = _LastScanService.GetCount();
        if (count > 0)
        {
            Result<string> result = _LastScanService.GetScan();
            if (!string.IsNullOrEmpty(result.Results))
                _SerialService.SerialPortWrite(count, result.Results);
        }
    }

    private void Write(object? sender)
    {
        try
        { Write(); }
        catch (Exception ex) { _Logger.LogError(ex, nameof(Write)); }
        try
        {
            Timer? timer = GetTimer(nameof(Write));
            if (timer is not null)
            {
                TimeSpan timeSpan = new(DateTime.Now.AddMilliseconds(_AppSettings.WriteToSerialEvery).Ticks - DateTime.Now.Ticks);
                _ = timer.Change((int)timeSpan.TotalMilliseconds, Timeout.Infinite);
            }
        }
        catch (Exception ex) { _Logger.LogError(ex, $"{nameof(Write)}-{nameof(Timer)}.{nameof(Timer.Change)}"); }
    }

}