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
 }