Merge pull request 'Add report logos and configurable folder scan depth' (#2) from feat/report-logos-and-scan-depth into main

Reviewed-on: #2

Services/Export/ReportMergeHelper.cs

@@ -0,0 +1,116 @@
+using System.IO;
+using System.IO.Compression;
+using System.Text;
+
+namespace SharepointToolbox.Web.Services.Export;
+
+/// <summary>How a multi-site report is bundled for download.</summary>
+public enum ReportMergeMode
+{
+    /// <summary>One document containing all sites, no per-site separation.</summary>
+    SingleMerged,
+    /// <summary>One HTML document with one tab per site (CSV falls back to merged).</summary>
+    SingleTabbed,
+    /// <summary>One file per site, delivered as a single ZIP.</summary>
+    MultipleFiles
+}
+
+/// <summary>Output format of a report.</summary>
+public enum ReportFormat
+{
+    Csv,
+    Html
+}
+
+/// <summary>A ready-to-download artifact: bytes plus filename and MIME type.</summary>
+public sealed record MergeOutput(string FileName, byte[] Bytes, string Mime);
+
+/// <summary>
+/// Bundles per-site report content into a single downloadable artifact
+/// according to a <see cref="ReportMergeMode"/>. Format-agnostic: the caller
+/// supplies a <c>buildDoc</c> delegate that renders one site's results to a
+/// document string; this helper handles flattening, tabbing, and zipping.
+/// </summary>
+public static class ReportMergeHelper
+{
+    /// <summary>
+    /// Builds the download artifact.
+    /// </summary>
+    /// <param name="sites">Per-site results (label + result list).</param>
+    /// <param name="mode">How to bundle the output.</param>
+    /// <param name="baseName">File stem, e.g. "permissions".</param>
+    /// <param name="timestamp">Stamp appended to single-file names, e.g. "20260602_101500".</param>
+    /// <param name="format">CSV or HTML.</param>
+    /// <param name="buildDoc">Renders one result list to a complete document.</param>
+    public static MergeOutput Build<T>(
+        IReadOnlyList<(string Label, IReadOnlyList<T> Results)> sites,
+        ReportMergeMode mode,
+        string baseName,
+        string timestamp,
+        ReportFormat format,
+        Func<IReadOnlyList<T>, string> buildDoc)
+    {
+        var ext = format == ReportFormat.Csv ? "csv" : "html";
+        var mime = format == ReportFormat.Csv ? "text/csv;charset=utf-8" : "text/html;charset=utf-8";
+        // CSV is BOM-prefixed for Excel; HTML is not.
+        var enc = new UTF8Encoding(encoderShouldEmitUTF8Identifier: format == ReportFormat.Csv);
+
+        // Tabs are an HTML-only concept — degrade to a single merged CSV.
+        if (mode == ReportMergeMode.SingleTabbed && format == ReportFormat.Csv)
+            mode = ReportMergeMode.SingleMerged;
+
+        switch (mode)
+        {
+            case ReportMergeMode.SingleTabbed:
+            {
+                var parts = sites
+                    .Select(s => (s.Label, buildDoc(s.Results)))
+                    .ToList();
+                var html = ReportSplitHelper.BuildTabbedHtml(parts, baseName);
+                return new MergeOutput($"{baseName}_{timestamp}.html", enc.GetBytes(html), mime);
+            }
+
+            case ReportMergeMode.MultipleFiles:
+            {
+                using var ms = new MemoryStream();
+                using (var zip = new ZipArchive(ms, ZipArchiveMode.Create, leaveOpen: true))
+                {
+                    var used = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+                    foreach (var s in sites)
+                    {
+                        var name = UniqueName(used, $"{baseName}_{ReportSplitHelper.SanitizeFileName(s.Label)}.{ext}");
+                        var entry = zip.CreateEntry(name, CompressionLevel.Optimal);
+                        using var es = entry.Open();
+                        var bytes = enc.GetBytes(buildDoc(s.Results));
+                        es.Write(bytes, 0, bytes.Length);
+                    }
+                }
+                return new MergeOutput($"{baseName}_{timestamp}.zip", ms.ToArray(), "application/zip");
+            }
+
+            case ReportMergeMode.SingleMerged:
+            default:
+            {
+                var flat = sites.SelectMany(s => s.Results).ToList();
+                var bytes = enc.GetBytes(buildDoc(flat));
+                return new MergeOutput($"{baseName}_{timestamp}.{ext}", bytes, mime);
+            }
+        }
+    }
+
+    /// <summary>
+    /// Returns <paramref name="candidate"/> or, if already taken, a suffixed
+    /// variant ("name_2.ext", "name_3.ext", …) so ZIP entries never collide.
+    /// </summary>
+    private static string UniqueName(HashSet<string> used, string candidate)
+    {
+        if (used.Add(candidate)) return candidate;
+        var stem = Path.GetFileNameWithoutExtension(candidate);
+        var ext = Path.GetExtension(candidate);
+        for (int i = 2; ; i++)
+        {
+            var next = $"{stem}_{i}{ext}";
+            if (used.Add(next)) return next;
+        }
+    }
+}

Services/Export/WebExportService.cs

@@ -25,4 +25,13 @@ public class WebExportService
         var bytes = new UTF8Encoding(encoderShouldEmitUTF8Identifier: false).GetBytes(content);
         await _js.InvokeVoidAsync("sptb.downloadFile", fileName, "text/html;charset=utf-8", Convert.ToBase64String(bytes));
     }
+
+    /// <summary>
+    /// Downloads pre-encoded bytes (e.g. a ZIP or a merged report produced by
+    /// <see cref="ReportMergeHelper"/>) with an explicit MIME type.
+    /// </summary>
+    public async Task DownloadBytesAsync(byte[] content, string fileName, string mime)
+    {
+        await _js.InvokeVoidAsync("sptb.downloadFile", fileName, mime, Convert.ToBase64String(content));
+    }
 }