MM-38081: Fix for disappearing permalink previews (#18400)

* MM-38081: Fix for disappearing previews.

* MM-38081: Update method signature in tests.

* MM-38081: Adds test replicating bug.

app/post_metadata.go

@@ -218,7 +218,7 @@ func (a *App) getEmbedForPost(post *model.Post, firstLink string, isNewPost bool
 		return nil, nil
 	}
 
-	og, image, permalink, err := a.getLinkMetadata(firstLink, post.CreateAt, isNewPost)
+	og, image, permalink, err := a.getLinkMetadata(firstLink, post.CreateAt, isNewPost, post.GetPreviewedPostProp())
 	if err != nil {
 		return nil, err
 	}
@@ -289,7 +289,7 @@ func (a *App) getImagesForPost(post *model.Post, imageURLs []string, isNewPost b
 	}
 
 	for _, imageURL := range imageURLs {
-		if _, image, _, err := a.getLinkMetadata(imageURL, post.CreateAt, isNewPost); err != nil {
+		if _, image, _, err := a.getLinkMetadata(imageURL, post.CreateAt, isNewPost, post.GetPreviewedPostProp()); err != nil {
 			mlog.Debug("Failed to get dimensions of an image in a post",
 				mlog.String("post_id", post.Id), mlog.String("image_url", imageURL), mlog.Err(err))
 		} else if image != nil {
@@ -453,7 +453,7 @@ func looksLikeAPermalink(url, siteURL string) bool {
 	return matched
 }
 
-func (a *App) getLinkMetadata(requestURL string, timestamp int64, isNewPost bool) (*opengraph.OpenGraph, *model.PostImage, *model.Permalink, error) {
+func (a *App) getLinkMetadata(requestURL string, timestamp int64, isNewPost bool, previewedPostPropVal string) (*opengraph.OpenGraph, *model.PostImage, *model.Permalink, error) {
 	requestURL = resolveMetadataURL(requestURL, a.GetSiteURL())
 
 	timestamp = model.FloorToNearestHour(timestamp)
@@ -464,14 +464,14 @@ func (a *App) getLinkMetadata(requestURL string, timestamp int64, isNewPost bool
 		permalink = nil
 	}
 
-	if ok {
+	if ok && previewedPostPropVal == "" {
 		return og, image, permalink, nil
 	}
 
 	// Check the database if this isn't a new post. If it is a new post and the data is cached, it should be in memory.
 	if !isNewPost {
 		og, image, ok = a.getLinkMetadataFromDatabase(requestURL, timestamp)
-		if ok {
+		if ok && previewedPostPropVal == "" {
 			cacheLinkMetadata(requestURL, timestamp, og, image, nil)
 			return og, image, nil, nil
 		}