Add link previews

internal/server/pages.go

@@ -22,11 +22,6 @@ func writeJSON(w http.ResponseWriter, status int, v any) {
 	w.Write(append(b, '\n'))
 }
 
-// absBase is the absolute URL of this service, for links and examples.
-//
-// It prefers --public-url. Falling back to the request's Host is display-only:
-// the header is caller-controlled, so it is never used for anything a third
-// party would see.
 func (s *Server) absBase(r *http.Request) string {
 	if s.cfg.PublicURL != "" {
 		return s.cfg.PublicURL + s.cfg.BasePath
@@ -38,11 +33,14 @@ func (s *Server) absBase(r *http.Request) string {
 	return scheme + "://" + r.Host + s.cfg.BasePath
 }
 
-// objectURL builds the download link handed back to an uploader.
 func (s *Server) objectURL(r *http.Request, id string) string {
 	return s.absBase(r) + "d/" + id
 }
 
+func (s *Server) infoURL(r *http.Request, id string) string {
+	return s.absBase(r) + "i/" + id
+}
+
 type indexPage struct {
 	page
 	MaxSize       string
@@ -60,8 +58,6 @@ type indexPage struct {
 }
 
 func (s *Server) handleIndex(w http.ResponseWriter, r *http.Request) {
-	// A remembered token is resolved server-side, so the page can show the real
-	// limits without the cookie ever being readable by a script.
 	lim, err := s.limitsFor(r, s.cookieCredential(r))
 	stale := false
 	switch {
@@ -124,12 +120,19 @@ func (s *Server) handleInfo(w http.ResponseWriter, r *http.Request) {
 // delete attempt, so a mistyped token lands back on the form rather than on a
 // dead end.
 func (s *Server) renderInfo(w http.ResponseWriter, r *http.Request, m *store.Meta, status int, errMsg string) {
+	infoURL := s.infoURL(r, m.ID)
+	head := s.page(r, m.Filename, true)
+	// This is the page people paste at each other, so it is the one that has
+	// to unfurl into something readable.
+	head.Preview = objectPreview(m, infoURL)
+
 	s.render(w, status, "info.html", objectPage{
-		page:      s.page(r, m.Filename, true),
+		page:      head,
 		Meta:      m,
 		Size:      config.FormatSize(m.Size),
 		Expires:   describeExpiry(m.Expires, s.now()),
 		URL:       s.objectURL(r, m.ID),
+		InfoURL:   infoURL,
 		CanDelete: s.mayDelete(r, m, s.credential(r)),
 		Error:     errMsg,
 	})