inabox/InABox.Avalonia.Platform/Geolocation/DefaultGeolocation.cs

using System.ComponentModel;
using System.Drawing;
using System.Runtime.CompilerServices;
using InABox.Core;

namespace InABox.Avalonia.Platform;

public class DefaultGeolocation : INotifyPropertyChanged, IGeolocation
{
    
    private DateTime _nextCheck = DateTime.MaxValue;
    private TimeSpan _remaining = TimeSpan.Zero;
    
    public bool Scanning
    {
        get => _nextCheck == DateTime.MaxValue;
        set => SetField(ref _nextCheck, value ? DateTime.MinValue : DateTime.MaxValue);
    }

    private GeoPoint? _currentLocation;
    public GeoPoint? CurrentLocation
    {
        get => _currentLocation;
        set
        {
            SetField(ref _currentLocation, value);
            LocationChanged?.Invoke(this, new GeoLocationChangedArgs(value));
        }
    }

    private TimeSpan _frequency = TimeSpan.FromSeconds(10);
    
    public TimeSpan Frequency
    {
        get => _frequency;
        set => SetField(ref _frequency, value);
    }

    public event GeoLocationChangedHandler? LocationChanged;

    public event GeoLocationTimerHandler? TimerChanged;

    public Logger? Logger { get; set; }
    
    public virtual Task<GeoPoint?> GetLocationAsync(CancellationTokenSource cancel)
    {
        return Task.FromResult<GeoPoint?>(new GeoPoint());
    }
    
    private readonly CancellationTokenSource _cancelTokenSource;
    private bool _isCheckingLocation;
    
    public DefaultGeolocation()
    {
        _cancelTokenSource = new CancellationTokenSource();
        try
        {
            _ = Task.Run(async () =>
                {
                    while (!_cancelTokenSource.Token.IsCancellationRequested)
                    {
                        if (!_isCheckingLocation)
                        {
                            if (_nextCheck < DateTime.Now)
                            {
                                try
                                {
                                    _isCheckingLocation = true;
                                    CurrentLocation =
                                        await PlatformTools.Geolocation.GetLocationAsync(_cancelTokenSource);
                                }
                                catch (Exception ex)
                                {
                                    Logger?.Send(LogType.Error, "", $"GPS Location Error: {ex.Message}");
                                    CurrentLocation = null;
                                }

                                _isCheckingLocation = false;
                                _nextCheck = DateTime.Now.Add(_frequency);
                            }
                            else
                            {
                                _remaining = _nextCheck - DateTime.Now;
                                TimerChanged?.Invoke(this, new GeoLocationTimerArgs(_frequency, _remaining));
                                Thread.Sleep(100);
                            }
                        }
                    }
                }
            );
        }
        catch (OperationCanceledException e)
        {
            Logger?.Send(LogType.Error, "", $"GPS Scanning Cancelled: {e.Message}");
        }
        catch (Exception e)
        {
            Logger?.Send(LogType.Error, "", $"GPS Error: {e.Message}");
        }
        
    }
    
    public void Cancel()
    {
        if (_isCheckingLocation && _cancelTokenSource.IsCancellationRequested == false)
            _cancelTokenSource.Cancel();
    }
    
    
    #region INotifyPropertyChanged
    
    public event PropertyChangedEventHandler? PropertyChanged;

    protected virtual void OnPropertyChanged([CallerMemberName] string? propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }

    protected bool SetField<T>(ref T field, T value, [CallerMemberName] string? propertyName = null)
    {
        if (EqualityComparer<T>.Default.Equals(field, value)) return false;
        field = value;
        OnPropertyChanged(propertyName);
        return true;
    }
    
    #endregion
}