feat: add inline mentions in comments

internal/service/comment_service.go

@@ -4,12 +4,41 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"regexp"
 	"strings"
 
 	"github.com/prabhupadasays/spsays-bff/internal/model"
 	"github.com/prabhupadasays/spsays-bff/internal/repository"
 )
 
+// mentionHandleRe matches @handle tokens. The leading boundary (line start or
+// a non-handle character that isn't itself "@") keeps it from firing inside
+// emails (foo@bar) or "@@".
+var mentionHandleRe = regexp.MustCompile(`(^|[^A-Za-z0-9_@])@([A-Za-z0-9_]{1,30})`)
+
+// mentionHandles pulls unique @handles out of a comment body (capped, so a
+// pathological body can't fan out unboundedly).
+func mentionHandles(body string) []string {
+	matches := mentionHandleRe.FindAllStringSubmatch(body, -1)
+	if matches == nil {
+		return nil
+	}
+	seen := map[string]bool{}
+	out := make([]string, 0, len(matches))
+	for _, m := range matches {
+		key := strings.ToLower(m[2])
+		if seen[key] {
+			continue
+		}
+		seen[key] = true
+		out = append(out, m[2])
+		if len(out) >= 20 {
+			break
+		}
+	}
+	return out
+}
+
 // maxCommentLen caps a comment/reply body.
 const maxCommentLen = 2000
 
@@ -87,6 +116,14 @@ func (s *CommentService) Add(ctx context.Context, viewerID, postID string, paren
 			go s.notif.NotifyPostComment(context.Background(), postID, notifyUserID, viewerID)
 		}
 	}
+
+	// Ping anyone @mentioned in the body — skipping the actor and whoever was
+	// already notified above (post/parent author) so they aren't double-pinged.
+	if s.notif != nil {
+		if handles := mentionHandles(body); len(handles) > 0 {
+			go s.notif.NotifyCommentMentions(context.Background(), postID, viewerID, handles, notifyUserID)
+		}
+	}
 	return c, nil
 }
 

internal/service/notification_service.go

@@ -37,6 +37,7 @@ const (
 	NotifPostMention    = "post_mention"
 	NotifPostComment    = "post_comment"
 	NotifCommentReply   = "comment_reply"
+	NotifCommentMention = "comment_mention"
 
 	// Reminder kinds are delivered live (email + push + a websocket toast)
 	// but NOT persisted — they're ephemeral nudges, not history.
@@ -394,8 +395,11 @@ func (s *NotificationService) notifyComment(ctx context.Context, kind, postID, r
 		url = s.frontendURL + "/u/" + h + "/posts#post-" + postID
 	}
 	title, body := "New comment", who+" commented on your post"
-	if kind == NotifCommentReply {
+	switch kind {
+	case NotifCommentReply:
 		title, body = "New reply", who+" replied to your comment"
+	case NotifCommentMention:
+		title, body = "You were mentioned", who+" mentioned you in a comment"
 	}
 	s.push.SendToUser(ctx, recipientID, PushPayload{
 		Title: title,
@@ -406,6 +410,31 @@ func (s *NotificationService) notifyComment(ctx context.Context, kind, postID, r
 	})
 }
 
+// NotifyCommentMentions tells each user named by `handles` that `actorID`
+// mentioned them in a comment on `postID`. Handles are resolved to users,
+// deduped, and the actor plus any `skip` ids (e.g. the post/parent author who
+// already got a comment/reply notification) are excluded so nobody is
+// double-pinged. Reuses the comment notification path (row + realtime + push).
+func (s *NotificationService) NotifyCommentMentions(ctx context.Context, postID, actorID string, handles []string, skip ...string) {
+	if actorID == "" || len(handles) == 0 {
+		return
+	}
+	skipSet := map[string]bool{actorID: true}
+	for _, id := range skip {
+		if id != "" {
+			skipSet[id] = true
+		}
+	}
+	for _, h := range handles {
+		u, err := s.users.FindByHandle(ctx, h)
+		if err != nil || u == nil || skipSet[u.ID] {
+			continue
+		}
+		skipSet[u.ID] = true // dedupe repeats of the same mention
+		s.notifyComment(ctx, NotifCommentMention, postID, u.ID, actorID)
+	}
+}
+
 // likeMessage renders the aggregated like text: "X liked your post" or
 // "X and N others liked your post".
 func likeMessage(who string, count int) string {