Add contextual fiducial point downloads

Services/CadastralCatalogService.cs

@@ -40,6 +40,14 @@ public sealed class CadastralCatalogService
             .ToArray();
     }
 
+    public async Task<MunicipalityOption?> FindMunicipalityAsync(string municipalityCode)
+    {
+        var code = (municipalityCode ?? string.Empty).Trim();
+        var municipalities = await GetAllMunicipalitiesAsync();
+        return municipalities.FirstOrDefault(item =>
+            string.Equals(item.Code, code, StringComparison.OrdinalIgnoreCase));
+    }
+
     public async Task<IReadOnlyList<string>> GetSheetsAsync(
         MunicipalityOption municipality,
         IProgress<CatalogProgress>? progress = null,

Services/FiducialPointService.cs

@@ -65,7 +65,25 @@ public sealed partial class FiducialPointService
             new Dictionary<string, string> { ["foglio"] = normalizedSheet },
             cancellationToken);
 
-        return DownloadLinkRegex().Matches(html)
+        return ParseFiducialLinks(html);
+    }
+
+    public async Task<IReadOnlyList<FiducialPointEntry>> GetFiducialsAsync(
+        string municipalityCode,
+        string sheet,
+        CancellationToken cancellationToken = default)
+    {
+        var code = NormalizeCode(municipalityCode);
+        var normalizedSheet = NormalizeSheet(sheet);
+        var html = await GetHtmlAsync(
+            $"risultato.php?co={Uri.EscapeDataString(code)}&foglio={Uri.EscapeDataString(normalizedSheet)}",
+            cancellationToken);
+
+        return ParseFiducialLinks(html);
+    }
+
+    private static IReadOnlyList<FiducialPointEntry> ParseFiducialLinks(string html) =>
+        DownloadLinkRegex().Matches(html)
             .Select(match =>
             {
                 var relativeUrl = WebUtility.HtmlDecode(match.Groups["url"].Value);
@@ -77,7 +95,6 @@ public sealed partial class FiducialPointService
             .DistinctBy(item => item.Identifier, StringComparer.OrdinalIgnoreCase)
             .OrderBy(item => item.Identifier, StringComparer.OrdinalIgnoreCase)
             .ToArray();
-    }
 
     public async Task<IReadOnlyList<MappedFiducialPoint>> GetMappedFiducialsAsync(
         string municipalityCode,
@@ -85,7 +102,7 @@ public sealed partial class FiducialPointService
         CancellationToken cancellationToken = default)
     {
         var municipality = NormalizeCode(municipalityCode);
-        if (!int.TryParse(new string(sheet.Where(char.IsDigit).ToArray()), out var sheetNumber))
+        if (!int.TryParse(NormalizeSheet(sheet), out var sheetNumber))
         {
             throw new ArgumentException("Numero di foglio non valido.", nameof(sheet));
         }
@@ -178,6 +195,19 @@ public sealed partial class FiducialPointService
             ? property.ToString().Trim()
             : string.Empty;
 
+    private static string NormalizeSheet(string sheet)
+    {
+        var digits = new string((sheet ?? string.Empty).Where(char.IsDigit).ToArray());
+        if (string.IsNullOrWhiteSpace(digits))
+        {
+            throw new ArgumentException("Numero di foglio non valido.", nameof(sheet));
+        }
+
+        return int.TryParse(digits, out var number)
+            ? number.ToString(System.Globalization.CultureInfo.InvariantCulture)
+            : digits;
+    }
+
     private async Task<string> GetHtmlAsync(string relativeUrl, CancellationToken cancellationToken)
     {
         using var response = await _httpClient.GetAsync(ServiceBaseUrl + relativeUrl, cancellationToken);