Automatic-Parking/Source/ProofOfConcept/Services/ZoneDeterminatorService.cs

using System.Diagnostics;
using Microsoft.Extensions.Options;
using NetTopologySuite.Features;
using NetTopologySuite.Geometries;
using NetTopologySuite.IO;
using SzakatsA.Result;

namespace ProofOfConcept.Services;

public class ZoneDeterminatorService
{
    private readonly ILogger<ZoneDeterminatorService> logger;
    private ZoneDeterminatorServiceConfiguration configuration;

    private FeatureCollection parkingZones;
    private bool initialized;
    
    public ZoneDeterminatorService(ILogger<ZoneDeterminatorService> logger, IOptions<ZoneDeterminatorServiceConfiguration> options)
    {
        this.logger = logger;
        this.configuration = options.Value;
        
        this.parkingZones = new FeatureCollection();
        this.initialized = false;
    }
    
    public async Task<Result<string>> DetermineZoneCodeAsync(double latitude, double longitude, CancellationToken cancellationToken = default(CancellationToken))
    {
        this.logger.LogTrace("Determinating parking zone code for coordinates: {Latitude}, {Longitude}...", latitude, longitude);

        if (!this.initialized)
            await InitializeAsync(cancellationToken);
        
        Point point = new Point(longitude, latitude);
        IFeature? zone = this.parkingZones.FirstOrDefault(f => f.Geometry.Contains(point));

        if (zone is null)
            return Result.Success(String.Empty);
        else if (!zone.Attributes.Exists("zoneid"))
            return Result.Fail(new MissingFieldException("Zone ID not found for parking zone"));
        else if (zone.Attributes["zoneid"] is null)
            return Result.Fail(new NullReferenceException("Zone ID null for parking zone"));
        else if (zone.Attributes["zoneid"].ToString() is null)
            return Result.Fail(new InvalidCastException($"Zone ID is of type {zone.Attributes["zoneID"].GetType().FullName}"));
        else
            return Result.Success(zone.Attributes["zoneid"].ToString()!);
    }

    public async Task InitializeAsync(CancellationToken cancellationToken = default(CancellationToken))
    {
        this.logger.LogTrace("Initializing...");
        Stopwatch sw = Stopwatch.StartNew();

        this.logger.LogTrace("Reading file...");
        string geojson = await File.ReadAllTextAsync(this.configuration.ZoneFilePath, cancellationToken);
        this.logger.LogTrace("File read in {Elapsed} ms", sw.ElapsedMilliseconds);
        
        this.logger.LogTrace("Parsing geojson...");
        GeoJsonReader reader = new GeoJsonReader();
        this.parkingZones = reader.Read<FeatureCollection>(geojson);
        this.logger.LogTrace("Geojson parsed in {Elapsed} ms: {FeatureCount} features", sw.ElapsedMilliseconds, this.parkingZones.Count);
        
        this.initialized = true;
        this.logger.LogInformation("Initialized");
    }
}

public class ZoneDeterminatorServiceConfiguration
{
    public string ZoneFilePath { get; set; } = "Resources/zones.geojson";
}