use plaintext extracted from markdown in nip23 opengraph text.

go.mod

@@ -13,6 +13,7 @@ require (
 	github.com/go-text/typesetting v0.0.0-20231221124458-48cc05a56658
 	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0
 	github.com/gomarkdown/markdown v0.0.0-20241205020045-f7e15b2f3e62
+	github.com/huantt/plaintext-extractor v1.1.0
 	github.com/kelseyhightower/envconfig v1.4.0
 	github.com/microcosm-cc/bluemonday v1.0.27
 	github.com/nbd-wtf/emoji v0.0.3

go.sum

@@ -124,6 +124,8 @@ github.com/gorilla/css v1.0.1/go.mod h1:BvnYkspnSzMmwRK+b8/xgNPLiIuNZr6vbZBTPQ2A
 github.com/graph-gophers/dataloader/v7 v7.1.0 h1:Wn8HGF/q7MNXcvfaBnLEPEFJttVHR8zuEqP1obys/oc=
 github.com/graph-gophers/dataloader/v7 v7.1.0/go.mod h1:1bKE0Dm6OUcTB/OAuYVOZctgIz7Q3d0XrYtlIzTgg6Q=
 github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
+github.com/huantt/plaintext-extractor v1.1.0 h1:dZkJN0fGZf1o8x9UdR6hHqkZnqIwX94YlGJ/lSXUZ5c=
+github.com/huantt/plaintext-extractor v1.1.0/go.mod h1:zIIbG/hZnsnLgzDbZ2T8fOrA4SLGWCoHWWYZo0Anx9c=
 github.com/ianlancetaylor/demangle v0.0.0-20200824232613-28f6c0f3b639/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=
 github.com/jessevdk/go-flags v0.0.0-20141203071132-1679536dcc89/go.mod h1:4FA24M0QyGHXBuZZK/XkWh8h0e1EYbRYJSGM75WSRxI=
 github.com/jessevdk/go-flags v1.4.0/go.mod h1:4FA24M0QyGHXBuZZK/XkWh8h0e1EYbRYJSGM75WSRxI=

render_event.go

@@ -387,6 +387,10 @@ func renderEvent(w http.ResponseWriter, r *http.Request) {
 			opengraph.SingleTitle = string(INVISIBLE_SPACE)
 		}
 
+		if text, err := markdownExtractor.PlainText(opengraph.Text); err == nil {
+			opengraph.Text = *text
+		}
+
 		params := NotePageParams{
 			BaseEventPageParams: baseEventPageParams,
 			OpenGraphParams:     opengraph,

utils.go

@@ -14,11 +14,11 @@ import (
 	"sync"
 	"time"
 
-	"github.com/puzpuzpuz/xsync/v3"
-	"mvdan.cc/xurls/v2"
-
+	me "github.com/huantt/plaintext-extractor/markdown"
 	"github.com/nbd-wtf/go-nostr"
 	"github.com/nbd-wtf/go-nostr/nip19"
+	"github.com/puzpuzpuz/xsync/v3"
+	"mvdan.cc/xurls/v2"
 )
 
 const (
@@ -43,6 +43,8 @@ var (
 	imageExtensionMatcher = regexp.MustCompile(`.*\.(png|jpg|jpeg|gif|webp|avif)((\?|\#).*)?$`)
 	videoExtensionMatcher = regexp.MustCompile(`.*\.(mp4|ogg|webm|mov)((\?|\#).*)?$`)
 	urlRegex              = xurls.Strict()
+
+	markdownExtractor = me.NewExtractor()
 )
 
 var kindNames = map[int]string{