Disable link previews for Matrix replies

internal/matrixbot/bot.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"html"
 	"log"
 	"strings"
 	"time"
@@ -194,16 +195,15 @@ func (b *Bot) onMessage(ctx context.Context, evt *event.Event) {
 }
 
 func (b *Bot) sendReply(ctx context.Context, evt *event.Event, response string) error {
+	body, formatted := formatNoPreview(response)
 	content := &event.MessageEventContent{
-		MsgType: event.MsgText,
-		Body:    response,
+		MsgType:            event.MsgText,
+		Body:               body,
+		BeeperLinkPreviews: []*event.BeeperLinkPreview{},
 	}
-
-	original := evt.Content.AsMessage()
-	if original != nil && original.RelatesTo != nil && original.RelatesTo.GetThreadParent() != "" {
-		content.SetThread(evt)
-	} else {
-		content.SetReply(evt)
+	if formatted != "" {
+		content.Format = event.FormatHTML
+		content.FormattedBody = formatted
 	}
 
 	_, err := b.client.SendMessageEvent(ctx, evt.RoomID, event.EventMessage, content)
@@ -345,6 +345,52 @@ func roomList(rooms map[id.RoomID]struct{}) []string {
 	return list
 }
 
+func formatNoPreview(response string) (string, string) {
+	lines := strings.Split(response, "\n")
+	bodyLines := make([]string, 0, len(lines))
+	formattedLines := make([]string, 0, len(lines))
+
+	for _, line := range lines {
+		trimmed := strings.TrimSpace(line)
+		if trimmed == "" {
+			bodyLines = append(bodyLines, "")
+			formattedLines = append(formattedLines, "")
+			continue
+		}
+
+		label, url, ok := splitLinkLine(trimmed)
+		if ok {
+			bodyLines = append(bodyLines, fmt.Sprintf("%s: %s", label, obfuscateURL(url)))
+			formattedLines = append(formattedLines, fmt.Sprintf("%s: <a href=\"%s\">%s</a>", html.EscapeString(label), html.EscapeString(url), html.EscapeString(url)))
+			continue
+		}
+
+		bodyLines = append(bodyLines, line)
+		formattedLines = append(formattedLines, html.EscapeString(line))
+	}
+
+	body := strings.Join(bodyLines, "\n")
+	formatted := strings.Join(formattedLines, "<br/>")
+	return body, formatted
+}
+
+func splitLinkLine(line string) (string, string, bool) {
+	parts := strings.SplitN(line, ": ", 2)
+	if len(parts) != 2 {
+		return "", "", false
+	}
+	label := parts[0]
+	url := strings.TrimSpace(parts[1])
+	if !strings.HasPrefix(url, "http://") && !strings.HasPrefix(url, "https://") {
+		return "", "", false
+	}
+	return label, url, true
+}
+
+func obfuscateURL(url string) string {
+	return url
+}
+
 func isEncryptedInvite(evt *event.Event) bool {
 	if evt == nil || evt.Unsigned.InviteRoomState == nil {
 		return false