LMEMappeCatastaliApp/Services/AzureMapsService.cs

using System.Text.Json;

namespace LMEMappeCatastaliApp.Services;

public sealed class AzureMapsService
{
    private const string TilesetEndpoint = "https://atlas.microsoft.com/map/tileset";
    private readonly HttpClient _httpClient = new()
    {
        Timeout = TimeSpan.FromSeconds(20)
    };
    private string? _validatedKey;

    public AzureMapsService()
    {
        _httpClient.DefaultRequestHeaders.UserAgent.ParseAdd("LMEMappeCatastali/0.2.8");
        _httpClient.DefaultRequestHeaders.Accept.ParseAdd("application/json");
    }

    public async Task ValidateKeyAsync(string subscriptionKey, CancellationToken cancellationToken = default)
    {
        var key = subscriptionKey.Trim();
        if (string.IsNullOrWhiteSpace(key))
        {
            throw new ArgumentException("Chiave Azure Maps mancante.", nameof(subscriptionKey));
        }

        if (string.Equals(_validatedKey, key, StringComparison.Ordinal))
        {
            return;
        }

        var url = $"{TilesetEndpoint}?api-version=2024-04-01&tilesetId=microsoft.base.road";
        using var request = new HttpRequestMessage(HttpMethod.Get, url);
        request.Headers.Add("subscription-key", key);
        using var response = await _httpClient.SendAsync(request, cancellationToken);
        if (!response.IsSuccessStatusCode)
        {
            throw new InvalidOperationException(response.StatusCode is System.Net.HttpStatusCode.Unauthorized or System.Net.HttpStatusCode.Forbidden
                ? "Chiave Azure Maps non valida o priva dei permessi Render."
                : $"Azure Maps ha risposto {((int)response.StatusCode)}.");
        }

        await using var content = await response.Content.ReadAsStreamAsync(cancellationToken);
        using var payload = await JsonDocument.ParseAsync(content, cancellationToken: cancellationToken);
        if (!payload.RootElement.TryGetProperty("tiles", out _))
        {
            throw new InvalidDataException("Azure Maps ha restituito una configurazione non valida.");
        }

        _validatedKey = key;
    }
}