feat: add post like

internal/service/notification_service.go

@@ -15,6 +15,7 @@ package service
 import (
 	"bytes"
 	"context"
+	"fmt"
 	"html/template"
 	"strings"
 
@@ -29,6 +30,7 @@ import (
 const (
 	NotifFollowRequest  = "follow_request"
 	NotifFollowAccepted = "follow_accepted"
+	NotifPostLike       = "post_like"
 
 	// Reminder kinds are delivered live (email + push + a websocket toast)
 	// but NOT persisted — they're ephemeral nudges, not history.
@@ -96,6 +98,76 @@ func (s *NotificationService) NotifyFollowAccepted(ctx context.Context, recipien
 		"%s accepted your follow request — Prabhupāda Says")
 }
 
+// NotifyPostLike tells the post author that `likerID` liked their post. Sent
+// only when the liker isn't the author (callers also guard). Unlike follows,
+// likes are high-volume, so this delivers a persisted row + realtime nudge +
+// Web Push but NO email. The push is tagged per-post so repeated likes on the
+// same post collapse into one notification rather than stacking.
+func (s *NotificationService) NotifyPostLike(ctx context.Context, postID, authorID, likerID string) {
+	if authorID == "" || likerID == "" || authorID == likerID {
+		return
+	}
+	// Aggregate into the single (author, post) like-notification row, getting
+	// back how many likers it now represents.
+	count, err := s.notifs.UpsertLike(ctx, authorID, likerID, postID)
+	if err != nil {
+		s.logger.Warn("aggregate like notification failed",
+			zap.String("recipient", authorID), zap.Error(err))
+		count = 1
+	}
+
+	actorUser, _ := s.users.FindByID(ctx, likerID)
+	who := "Someone"
+	if actorUser != nil {
+		who = actorDisplay(actorUser)
+	}
+	body := likeMessage(who, count)
+
+	// Realtime nudge — carry actor_count so the toast can read "and N others".
+	if s.rt != nil {
+		payload := map[string]any{"kind": NotifPostLike, "actor_count": count}
+		if actorUser != nil {
+			payload["actor_name"] = actorDisplay(actorUser)
+			payload["actor_handle"] = actorUser.Handle
+			payload["actor_avatar_url"] = actorUser.AvatarURL
+		}
+		if err := s.rt.Trigger(ctx, "notifications."+authorID, "notification", payload); err != nil {
+			s.logger.Warn("realtime like publish failed", zap.String("recipient", authorID), zap.Error(err))
+		}
+	}
+
+	// Web Push — tapping opens the author's own feed anchored to the post.
+	// Tagged per-post so repeated likes collapse into one notification.
+	if s.push == nil {
+		return
+	}
+	url := s.frontendURL + "/notifications"
+	if author, err := s.users.FindByID(ctx, authorID); err == nil && author != nil {
+		url = s.frontendURL + "/u/" + author.Handle + "/posts#post-" + postID
+	}
+	s.push.SendToUser(ctx, authorID, PushPayload{
+		Title: "New Like",
+		Body:  body,
+		URL:   url,
+		Icon:  s.iconURL(),
+		Tag:   NotifPostLike + ":" + postID,
+	})
+}
+
+// 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 {
+	if count <= 1 {
+		return who + " liked your post"
+	}
+	others := count - 1
+	noun := "others"
+	if others == 1 {
+		noun = "other"
+	}
+	return fmt.Sprintf("%s and %d %s liked your post", who, others, noun)
+}
+
 // dispatch persists the notification and sends the matching email. All
 // failures are logged, never propagated.
 func (s *NotificationService) dispatch(ctx context.Context, recipientID, actorID, kind, subjectFmt string) {