annotations/Azaion.Common/Services/GpsMatcher/GPSMatcherService.cs

using System.IO;
using Azaion.Common.DTO;
using Azaion.Common.DTO.Config;
using Azaion.Common.Extensions;
using MediatR;
using Microsoft.Extensions.Options;

namespace Azaion.Common.Services;

public interface IGpsMatcherService
{
    Task RunGpsMatching(string userRouteDir, GeoPoint geoPoint, CancellationToken detectToken = default);
    void StopGpsMatching();
    Task SetGpsResult(GPSMatcherResultEvent result, CancellationToken detectToken = default);
    Task FinishGPS(GPSMatcherFinishedEvent notification, CancellationToken cancellationToken);
}

public class GpsMatcherService(IGpsMatcherClient gpsMatcherClient,
    ISatelliteDownloader satelliteTileDownloader,
    IOptions<DirectoriesConfig> dirConfig,
    IOptions<GpsDeniedConfig> gpsDeniedConfig,
    IMediator mediator) : IGpsMatcherService
{
    private readonly DirectoriesConfig _dirConfig = dirConfig.Value;
    private const int ZOOM_LEVEL = 18;
    private const int POINTS_COUNT = 10;
    private const int DISTANCE_BETWEEN_POINTS_M = 140;
    private const double SATELLITE_RADIUS_M = DISTANCE_BETWEEN_POINTS_M * (POINTS_COUNT + 1);
    private const int MAX_AVG_POINTS = 2;

    private string _routeDir = "";
    private string _userRouteDir = "";
    private List<string> _allRouteImages = new();
    private Dictionary<string, int> _currentRouteImages = new();
    private GeoPoint _lastGeoPoint = new();
    private CancellationToken _detectToken;
    private int _currentIndex;
    private readonly Queue<Direction> _directions = new();


    public async Task RunGpsMatching(string userRouteDir, GeoPoint initGeoPoint, CancellationToken detectToken = default)
    {
        _routeDir = Path.Combine(Constants.EXTERNAL_GPS_DENIED_FOLDER, _dirConfig.GpsRouteDirectory);
        _userRouteDir = userRouteDir;

        _allRouteImages = Directory.GetFiles(userRouteDir)
            .OrderBy(x => x).ToList();
        _lastGeoPoint = initGeoPoint;
        _detectToken = detectToken;
        await StartMatchingRound(0);
    }

    private async Task StartMatchingRound(int startIndex)
    {
        //empty route dir
        if (Directory.Exists(_routeDir))
            Directory.Delete(_routeDir, true);
        Directory.CreateDirectory(_routeDir);

        _currentRouteImages = _allRouteImages
            .Skip(startIndex)
            .Take(POINTS_COUNT)
            .Select((fullName, index) =>
            {
                var filename = Path.GetFileName(fullName);
                File.Copy(Path.Combine(_userRouteDir, filename), Path.Combine(_routeDir, filename));
                return new { Filename = Path.GetFileNameWithoutExtension(fullName), Index = startIndex + index };
            })
            .ToDictionary(x => x.Filename, x => x.Index);

        await satelliteTileDownloader.GetTiles(_lastGeoPoint, SATELLITE_RADIUS_M, ZOOM_LEVEL, _detectToken);
        await gpsMatcherClient.StartMatching(new StartMatchingEvent
        {
            ImagesCount = POINTS_COUNT,
            GeoPoint = _lastGeoPoint,
            SatelliteImagesDir = _dirConfig.GpsSatDirectory,
            RouteDir = _dirConfig.GpsRouteDirectory
        });
    }

    public void StopGpsMatching()
    {
        gpsMatcherClient.Stop();
    }

    public async Task SetGpsResult(GPSMatcherResultEvent result, CancellationToken detectToken = default)
    {
        _currentIndex = _currentRouteImages[result.Image];
        _currentRouteImages.Remove(result.Image);

        if (result.KeyPoints >= gpsDeniedConfig.Value.MinKeyPoints)
        {
            var direction = _lastGeoPoint.DirectionTo(result.GeoPoint);
            _directions.Enqueue(direction);
            if (_directions.Count > MAX_AVG_POINTS)
                _directions.Dequeue();
            _lastGeoPoint = result.GeoPoint;
        }
        else
        {
            var direction = new Direction(_directions.Average(x => x.Distance), _directions.Average(x => x.Azimuth));
            _lastGeoPoint = _lastGeoPoint.GoDirection(direction);
        }
        await mediator.Publish(new GPSMatcherResultProcessedEvent(result, _lastGeoPoint), detectToken);
    }

    public async Task FinishGPS(GPSMatcherFinishedEvent notification, CancellationToken cancellationToken)
    {
        if (_currentRouteImages.Count == 0 && _currentIndex < _allRouteImages.Count)
            await StartMatchingRound(_currentIndex);
    }
}