Include expanded urls in social cards (#2427)

* include expanded urls in social cards (#2427)

* break expandPostLinks into its own function, add bounds checking

1 files changed, 46 insertions, 0 deletions

diff --git a/bskyweb/cmd/bskyweb/server.go b/bskyweb/cmd/bskyweb/server.go
index e391b8b03..7571e536e 100644
--- a/bskyweb/cmd/bskyweb/server.go
+++ b/bskyweb/cmd/bskyweb/server.go
@@ -10,6 +10,7 @@ import (
 	"net/http"
 	"os"
 	"os/signal"
+	"slices"
 	"strings"
 	"syscall"
 	"time"
@@ -351,9 +352,54 @@ func (srv *Server) WebPost(c echo.Context) error {
 			data["imgThumbUrls"] = thumbUrls
 		}
 	}
+
+	data["postText"] = expandPostLinks(postView)
+
 	return c.Render(http.StatusOK, "post.html", data)
 }
 
+// function to expand shortened links in rich text back to full urls, replacing shortened urls in
+// social card meta tags and the noscript output. this essentially reverses the effect
+// of shortenLinks() in src/lib/strings/rich-text-manip.ts
+func expandPostLinks(postView *appbsky.FeedDefs_PostView) string {
+	if postView.Record != nil {
+		rec := postView.Record.Val.(*appbsky.FeedPost)
+		postText := rec.Text
+		var charsAdded int64 = 0
+		// iterate over facets, check if they're link facets, and if found, grab the uri
+		for _, facet := range rec.Facets {
+			linkUri := ""
+			if slices.ContainsFunc(facet.Features, func(feat *appbsky.RichtextFacet_Features_Elem) bool {
+				if feat.RichtextFacet_Link != nil && feat.RichtextFacet_Link.LexiconTypeID == "app.bsky.richtext.facet#link" {
+					linkUri = feat.RichtextFacet_Link.Uri
+					// only expand uris that have been shortened (as opposed to those with non-uri anchor text)
+					if int64(len(postText)) >= facet.Index.ByteEnd+charsAdded &&
+						strings.HasSuffix(postText[facet.Index.ByteStart+charsAdded:facet.Index.ByteEnd+charsAdded], "...") &&
+						strings.Contains(linkUri, postText[facet.Index.ByteStart+charsAdded:(facet.Index.ByteEnd+charsAdded)-3]) {
+						return true
+					}
+				}
+				return false
+			}) {
+				// replace the shortened uri with the full length one from the facet using utf8 byte offsets
+				if int64(len(postText)) >= facet.Index.ByteEnd+charsAdded {
+					postText = postText[0:facet.Index.ByteStart+charsAdded] + linkUri + postText[facet.Index.ByteEnd+charsAdded:]
+					charsAdded += int64(len(linkUri)) - (facet.Index.ByteEnd - facet.Index.ByteStart)
+				}
+			}
+		}
+		// if the post has an embeded link and its url doesn't already appear in postText, append it to
+		// the end to avoid social cards with missing links
+		if postView.Embed != nil &&
+			postView.Embed.EmbedExternal_View != nil &&
+			!strings.Contains(postText, postView.Embed.EmbedExternal_View.External.Uri) {
+			postText = fmt.Sprintf("%s\n%s", postText, postView.Embed.EmbedExternal_View.External.Uri)
+		}
+		return postText
+	}
+	return ""
+}
+
 func (srv *Server) WebProfile(c echo.Context) error {
 	ctx := c.Request().Context()
 	data := pongo2.Context{}