public Task Invoke(IDictionary<string, object> env) { var request = new OwinRequest(env); var response = new OwinResponse(env); var requestPath = Uri.UnescapeDataString(request.Path); var backgrounds = DataManager.ActualBackgroundStorage; if (requestPath.StartsWith("/backgrounds/")) { if (request.Method != "GET") return response.RespondMethodNotAllowed(); var query = requestPath.Substring("/backgrounds".Length); if (query.EndsWith("/list")) { string path = query.Substring(0, query.Length - "list".Length); var dir = backgrounds.GetDirectory(path); try { StringBuilder sb = new StringBuilder(); ListBackgroundEntries(dir, sb); return response.RespondString(sb.ToString()); } catch (FileNotFoundException) { return response.RespondNotFound(); } } else if (query == "/listall") { StringBuilder sb = new StringBuilder(); ListBackgroundEntries(backgrounds.Root, sb, true); return response.RespondString(sb.ToString()); } else { bool preview = false; if (query.EndsWith("/preview")) { preview = true; query = query.Substring(0, query.Length - "/preview".Length); } try { var file = backgrounds.GetFile(query); var contentType = file.MimeType; if (!String.IsNullOrEmpty(contentType)) { response.SetHeader("Content-Type", contentType); } return response.RespondDownloaded(preview ? file.PreviewUri : file.Uri); } catch (FileNotFoundException) { return response.RespondNotFound(); } } } else { return next(env); } }