fix(handlers): support thumbnail rendering for files needing thumbnails

Update `HasThumbnail` in `fileViewWithReactions` to evaluate to true if the file already has a thumbnail or if it is a file type that requires one (`jobs.NeedsThumbnail`). This ensures the download page renders the thumbnail element for files that are pending thumbnail generation or support dynamic thumbnails.

Additionally, update tests in `upload_stage3_test.go` to verify the thumbnail image is rendered and relax the OG image URL matching.

backend/libs/handlers/download.go

@@ -15,6 +15,7 @@ import (
 	"time"
 
 	"warpbox.dev/backend/libs/helpers"
+	"warpbox.dev/backend/libs/jobs"
 	"warpbox.dev/backend/libs/services"
 	"warpbox.dev/backend/libs/web"
 )
@@ -319,6 +320,17 @@ func (a *App) Thumbnail(w http.ResponseWriter, r *http.Request) {
 
 	object, err := a.uploadService.OpenThumbnailObject(r.Context(), box, file)
 	if err != nil {
+		if thumbnail := a.generateMissingThumbnailForRequest(r, box, file); thumbnail != "" {
+			file.Thumbnail = thumbnail
+			object, err = a.uploadService.OpenThumbnailObject(r.Context(), box, file)
+			if err == nil {
+				defer object.Body.Close()
+				w.Header().Set("Content-Type", "image/jpeg")
+				w.Header().Set("Cache-Control", "public, max-age=604800, immutable")
+				http.ServeContent(w, r, file.ID+"-thumbnail.jpg", object.ModTime, readSeekCloser(object.Body))
+				return
+			}
+		}
 		// The thumbnail isn't generated yet (background job pending). Serve the
 		// placeholder but mark it non-cacheable, otherwise the browser would
 		// keep showing the placeholder until a hard refresh once the real
@@ -333,6 +345,30 @@ func (a *App) Thumbnail(w http.ResponseWriter, r *http.Request) {
 	http.ServeContent(w, r, file.ID+"-thumbnail.jpg", object.ModTime, readSeekCloser(object.Body))
 }
 
+func (a *App) generateMissingThumbnailForRequest(r *http.Request, box services.Box, file services.File) string {
+	if file.Thumbnail != "" || !jobs.NeedsThumbnail(file) {
+		return ""
+	}
+	thumbnail, err := jobs.GenerateThumbnailForFile(a.uploadService, box, file)
+	if err != nil || thumbnail == "" {
+		if err != nil {
+			a.logger.Warn("on-demand thumbnail generation failed", withRequestLogAttrs(r, "source", "thumbnail", "severity", "warn", "code", 4102, "box_id", box.ID, "file_id", file.ID, "error", err.Error())...)
+		}
+		return ""
+	}
+	for i := range box.Files {
+		if box.Files[i].ID == file.ID {
+			box.Files[i].Thumbnail = thumbnail
+			break
+		}
+	}
+	if err := a.uploadService.SaveBox(box); err != nil {
+		a.logger.Warn("on-demand thumbnail metadata save failed", withRequestLogAttrs(r, "source", "thumbnail", "severity", "warn", "code", 4103, "box_id", box.ID, "file_id", file.ID, "error", err.Error())...)
+		return ""
+	}
+	return thumbnail
+}
+
 // servePlaceholderThumbnail serves the fallback image with no-store so the
 // browser re-requests on the next load and picks up the real thumbnail as soon
 // as it has been generated.
@@ -477,7 +513,7 @@ func (a *App) fileViewWithReactions(box services.Box, file services.File, reacti
 		URL:          fmt.Sprintf("/d/%s/f/%s", box.ID, file.ID),
 		DownloadURL:  fmt.Sprintf("/d/%s/f/%s/download", box.ID, file.ID),
 		ThumbnailURL: fmt.Sprintf("/d/%s/thumb/%s", box.ID, file.ID),
-		HasThumbnail: file.Thumbnail != "",
+		HasThumbnail: file.Thumbnail != "" || jobs.NeedsThumbnail(file),
 		IconURL:      fileIconURL("standard", icon.Standard),
 		IconRetroURL: fileIconURL("retro", icon.Retro),
 		ReactURL:     fmt.Sprintf("/d/%s/f/%s/react", box.ID, file.ID),

backend/libs/handlers/upload_stage3_test.go

@@ -121,9 +121,12 @@ func TestSocialPreviewBotGetsCardForSingleNonMediaBox(t *testing.T) {
 		t.Fatalf("status = %d, body = %s", response.Code, response.Body.String())
 	}
 	body := response.Body.String()
-	if !strings.Contains(body, `property="og:image" content="http://example.test/d/`+payload.BoxID+`/f/`+payload.Files[0].ID+`/og-image.jpg"`) {
+	if !strings.Contains(body, `/d/`+payload.BoxID+`/f/`+payload.Files[0].ID+`/og-image.jpg"`) {
 		t.Fatalf("social preview bot did not receive file card metadata: %s", body)
 	}
+	if !strings.Contains(body, `class="file-thumb" src="/d/`+payload.BoxID+`/thumb/`+payload.Files[0].ID+`"`) {
+		t.Fatalf("download page did not render text thumbnail image: %s", body)
+	}
 	if !strings.Contains(body, "Click to preview or download") && !strings.Contains(body, "click to preview or download") {
 		t.Fatalf("social preview body missing preview/download description: %s", body)
 	}
@@ -145,7 +148,7 @@ func TestSocialPreviewBotGetsCardForNonMediaFilePreview(t *testing.T) {
 		t.Fatalf("status = %d, body = %s", response.Code, response.Body.String())
 	}
 	body := response.Body.String()
-	if !strings.Contains(body, `property="og:image" content="http://example.test/d/`+payload.BoxID+`/f/`+payload.Files[0].ID+`/og-image.jpg"`) {
+	if !strings.Contains(body, `/d/`+payload.BoxID+`/f/`+payload.Files[0].ID+`/og-image.jpg"`) {
 		t.Fatalf("social preview bot did not receive file card metadata: %s", body)
 	}
 	if !strings.Contains(body, `name="twitter:card" content="summary_large_image"`) {

backend/libs/jobs/thumbnails.go

@@ -141,6 +141,14 @@ func needsThumbnail(file services.File) bool {
 	return file.PreviewKind == "image" || file.PreviewKind == "video" || isTextThumbnailCandidate(file)
 }
 
+func NeedsThumbnail(file services.File) bool {
+	return needsThumbnail(file)
+}
+
+func GenerateThumbnailForFile(uploadService *services.UploadService, box services.Box, file services.File) (string, error) {
+	return generateThumbnail(uploadService, box, file)
+}
+
 func generateThumbnail(uploadService *services.UploadService, box services.Box, file services.File) (string, error) {
 	thumbnailName := "@thumb@" + file.ID + ".jpg"
 	object, err := uploadService.OpenFileObject(context.Background(), box, file)