Add subscription pricing and Base drawing limit

Services/PlayPurchaseVerificationService.cs

@@ -0,0 +1,87 @@
+using System.Net.Http.Json;
+using System.Reflection;
+
+namespace LMEMappeCatastaliApp.Services;
+
+public sealed class PlayPurchaseVerificationService
+{
+    private const string EndpointMetadataKey = "PlayBillingVerificationUrl";
+    private const string RequiredMetadataKey = "PlayBillingVerificationRequired";
+    private readonly HttpClient _httpClient = new() { Timeout = TimeSpan.FromSeconds(20) };
+
+    public bool IsConfigured => VerificationEndpoint is not null;
+    public bool IsRequired => ReadMetadata(RequiredMetadataKey).Equals("true", StringComparison.OrdinalIgnoreCase);
+
+    private static Uri? VerificationEndpoint
+    {
+        get
+        {
+            var value = ReadMetadata(EndpointMetadataKey);
+            return Uri.TryCreate(value, UriKind.Absolute, out var endpoint)
+                && endpoint.Scheme == Uri.UriSchemeHttps
+                ? endpoint
+                : null;
+        }
+    }
+
+    public async Task<PlayPurchaseVerificationResult> VerifyAsync(
+        string purchaseToken,
+        CancellationToken cancellationToken = default)
+    {
+        var endpoint = VerificationEndpoint;
+        if (endpoint is null)
+        {
+            return PlayPurchaseVerificationResult.NotConfigured();
+        }
+
+        try
+        {
+            using var response = await _httpClient.PostAsJsonAsync(endpoint, new
+            {
+                packageName = AppInfo.Current.PackageName,
+                productId = EntitlementService.ProductId,
+                purchaseToken
+            }, cancellationToken);
+            if (!response.IsSuccessStatusCode)
+            {
+                return PlayPurchaseVerificationResult.Failed(
+                    $"Verifica acquisto non disponibile ({(int)response.StatusCode}).");
+            }
+
+            var result = await response.Content.ReadFromJsonAsync<VerificationResponse>(cancellationToken);
+            return result is null
+                ? PlayPurchaseVerificationResult.Failed("Risposta di verifica acquisto non valida.")
+                : new(true, true, result.Active, result.ExpiresAt, result.Message ?? string.Empty);
+        }
+        catch (OperationCanceledException) when (!cancellationToken.IsCancellationRequested)
+        {
+            return PlayPurchaseVerificationResult.Failed("Il server di verifica acquisti non ha risposto in tempo.");
+        }
+        catch (Exception error)
+        {
+            return PlayPurchaseVerificationResult.Failed(
+                $"Verifica acquisto non disponibile: {error.GetBaseException().Message}");
+        }
+    }
+
+    private static string ReadMetadata(string key) =>
+        typeof(PlayPurchaseVerificationService).Assembly
+            .GetCustomAttributes<AssemblyMetadataAttribute>()
+            .FirstOrDefault(attribute => attribute.Key == key)?.Value?.Trim() ?? string.Empty;
+
+    private sealed record VerificationResponse(bool Active, DateTimeOffset? ExpiresAt, string? Message);
+}
+
+public sealed record PlayPurchaseVerificationResult(
+    bool Configured,
+    bool Verified,
+    bool Active,
+    DateTimeOffset? ExpiresAt,
+    string Message)
+{
+    public static PlayPurchaseVerificationResult NotConfigured() =>
+        new(false, false, false, null, "Server di verifica acquisti non configurato.");
+
+    public static PlayPurchaseVerificationResult Failed(string message) =>
+        new(true, false, false, null, message);
+}