feat: add kept downloads section to admin UI

- List all downloaded files with artist/album/file info
- Download button to save files locally
- Delete button with live row removal
- Shows total file count and size
- Auto-refreshes every 30 seconds
- Security: path validation to prevent directory traversal

allstarr/Controllers/AdminController.cs

@@ -3302,3 +3302,187 @@ public class LinkPlaylistRequest
     public string Name { get; set; } = string.Empty;
     public string SpotifyPlaylistId { get; set; } = string.Empty;
 }
+
+    
+    /// <summary>
+    /// GET /api/admin/downloads
+    /// Lists all downloaded files in the downloads directory
+    /// </summary>
+    [HttpGet("downloads")]
+    public IActionResult GetDownloads()
+    {
+        try
+        {
+            var downloadPath = _configuration["Library:DownloadPath"] ?? "./downloads";
+            
+            if (!Directory.Exists(downloadPath))
+            {
+                return Ok(new { files = new List<object>(), totalSize = 0 });
+            }
+            
+            var files = new List<object>();
+            long totalSize = 0;
+            
+            // Recursively get all audio files
+            var audioExtensions = new[] { ".flac", ".mp3", ".m4a", ".opus" };
+            var allFiles = Directory.GetFiles(downloadPath, "*.*", SearchOption.AllDirectories)
+                .Where(f => audioExtensions.Contains(Path.GetExtension(f).ToLowerInvariant()))
+                .ToList();
+            
+            foreach (var filePath in allFiles)
+            {
+                var fileInfo = new FileInfo(filePath);
+                var relativePath = Path.GetRelativePath(downloadPath, filePath);
+                
+                // Parse artist/album/track from path structure
+                var parts = relativePath.Split(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar);
+                var artist = parts.Length > 0 ? parts[0] : "";
+                var album = parts.Length > 1 ? parts[1] : "";
+                var fileName = parts.Length > 2 ? parts[^1] : Path.GetFileName(filePath);
+                
+                files.Add(new
+                {
+                    path = relativePath,
+                    fullPath = filePath,
+                    artist,
+                    album,
+                    fileName,
+                    size = fileInfo.Length,
+                    sizeFormatted = FormatFileSize(fileInfo.Length),
+                    lastModified = fileInfo.LastWriteTimeUtc,
+                    extension = fileInfo.Extension
+                });
+                
+                totalSize += fileInfo.Length;
+            }
+            
+            return Ok(new
+            {
+                files = files.OrderBy(f => ((dynamic)f).artist).ThenBy(f => ((dynamic)f).album).ThenBy(f => ((dynamic)f).fileName),
+                totalSize,
+                totalSizeFormatted = FormatFileSize(totalSize),
+                count = files.Count
+            });
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to list downloads");
+            return StatusCode(500, new { error = "Failed to list downloads" });
+        }
+    }
+    
+    /// <summary>
+    /// DELETE /api/admin/downloads
+    /// Deletes a specific downloaded file
+    /// </summary>
+    [HttpDelete("downloads")]
+    public IActionResult DeleteDownload([FromQuery] string path)
+    {
+        try
+        {
+            if (string.IsNullOrEmpty(path))
+            {
+                return BadRequest(new { error = "Path is required" });
+            }
+            
+            var downloadPath = _configuration["Library:DownloadPath"] ?? "./downloads";
+            var fullPath = Path.Combine(downloadPath, path);
+            
+            // Security: Ensure the path is within the download directory
+            var normalizedFullPath = Path.GetFullPath(fullPath);
+            var normalizedDownloadPath = Path.GetFullPath(downloadPath);
+            
+            if (!normalizedFullPath.StartsWith(normalizedDownloadPath))
+            {
+                return BadRequest(new { error = "Invalid path" });
+            }
+            
+            if (!System.IO.File.Exists(fullPath))
+            {
+                return NotFound(new { error = "File not found" });
+            }
+            
+            System.IO.File.Delete(fullPath);
+            _logger.LogInformation("Deleted download: {Path}", path);
+            
+            // Clean up empty directories
+            var directory = Path.GetDirectoryName(fullPath);
+            while (directory != null && directory != downloadPath)
+            {
+                if (Directory.Exists(directory) && !Directory.EnumerateFileSystemEntries(directory).Any())
+                {
+                    Directory.Delete(directory);
+                    _logger.LogDebug("Deleted empty directory: {Dir}", directory);
+                }
+                else
+                {
+                    break;
+                }
+                directory = Path.GetDirectoryName(directory);
+            }
+            
+            return Ok(new { success = true, message = "File deleted successfully" });
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to delete download: {Path}", path);
+            return StatusCode(500, new { error = "Failed to delete file" });
+        }
+    }
+    
+    /// <summary>
+    /// GET /api/admin/downloads/file
+    /// Downloads a specific file
+    /// </summary>
+    [HttpGet("downloads/file")]
+    public IActionResult DownloadFile([FromQuery] string path)
+    {
+        try
+        {
+            if (string.IsNullOrEmpty(path))
+            {
+                return BadRequest(new { error = "Path is required" });
+            }
+            
+            var downloadPath = _configuration["Library:DownloadPath"] ?? "./downloads";
+            var fullPath = Path.Combine(downloadPath, path);
+            
+            // Security: Ensure the path is within the download directory
+            var normalizedFullPath = Path.GetFullPath(fullPath);
+            var normalizedDownloadPath = Path.GetFullPath(downloadPath);
+            
+            if (!normalizedFullPath.StartsWith(normalizedDownloadPath))
+            {
+                return BadRequest(new { error = "Invalid path" });
+            }
+            
+            if (!System.IO.File.Exists(fullPath))
+            {
+                return NotFound(new { error = "File not found" });
+            }
+            
+            var fileName = Path.GetFileName(fullPath);
+            var fileStream = System.IO.File.OpenRead(fullPath);
+            
+            return File(fileStream, "application/octet-stream", fileName);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to download file: {Path}", path);
+            return StatusCode(500, new { error = "Failed to download file" });
+        }
+    }
+    
+    private static string FormatFileSize(long bytes)
+    {
+        string[] sizes = { "B", "KB", "MB", "GB", "TB" };
+        double len = bytes;
+        int order = 0;
+        while (len >= 1024 && order < sizes.Length - 1)
+        {
+            order++;
+            len = len / 1024;
+        }
+        return $"{len:0.##} {sizes[order]}";
+    }
+}