feat: post reshare enhancements

internal/service/social_service.go

@@ -75,39 +75,33 @@ func (s *PostService) Get(ctx context.Context, id, viewerID string) (*model.Post
 	return p, nil
 }
 
-// Reshare records that the caller has reshared the given post. Idempotent
-// — calling it twice with the same (post, user) is a no-op. Resharing
-// your own post is rejected: there's nothing to bring onto an account
-// that already authored the post.
-func (s *PostService) Reshare(ctx context.Context, postID, callerID string) error {
-	p, err := s.posts.FindByID(ctx, postID)
-	if err != nil {
-		return err
-	}
-	if p.UserID == callerID {
-		return errors.New("cannot reshare your own post")
-	}
-	return s.posts.AddReshare(ctx, postID, callerID)
+// Reshare materialises a reshare as a brand-new posts row owned by the
+// caller, with reshared_from_post_id pointing to the canonical original.
+// Idempotent — calling it twice returns the same reshare row. Resharing
+// one's own post (canonical or chained) is rejected at the repo layer.
+//
+// Returns the new post so the frontend can drop it into local state
+// without a round-trip.
+func (s *PostService) Reshare(ctx context.Context, postID, callerID string) (*model.Post, error) {
+	return s.posts.Reshare(ctx, postID, callerID)
 }
 
-// Unreshare removes a previously recorded reshare. Idempotent — no-ops
-// when no row exists.
+// Unreshare removes the caller's reshare of a canonical post by deleting
+// their own reshare posts row. Idempotent — no-ops when nothing to delete.
 func (s *PostService) Unreshare(ctx context.Context, postID, callerID string) error {
-	return s.posts.RemoveReshare(ctx, postID, callerID)
+	return s.posts.Unreshare(ctx, postID, callerID)
 }
 
 // hydrateReshareStates fills in ViewerHasReshared on each post via one
-// batched lookup against post_reshares. Skips the query when the viewer
-// is anonymous (`viewerID == ""`) since the answer is uniformly false.
-// Also fast-paths posts authored by the viewer — they can't be reshared
-// by themselves, so we leave the flag at its zero value.
+// batched lookup. Skips the query when the viewer is anonymous (the
+// answer is uniformly false) or the slice is empty.
 func (s *PostService) hydrateReshareStates(ctx context.Context, viewerID string, posts []*model.Post) error {
 	if viewerID == "" || len(posts) == 0 {
 		return nil
 	}
 	ids := make([]string, 0, len(posts))
 	for _, p := range posts {
-		if p == nil || p.UserID == viewerID {
+		if p == nil {
 			continue
 		}
 		ids = append(ids, p.ID)
@@ -150,9 +144,9 @@ func (s *PostService) Delete(ctx context.Context, postID, callerID string) error
 	return s.posts.Delete(ctx, postID, callerID)
 }
 
-// ReplaceImages swaps the image set on a post. The caller must own the
-// post. Returns the fresh post payload so the client can reconcile its
-// local state without a separate fetch.
+// ReplaceImages swaps the image set on a post. Owner-only — every
+// reshare is its own posts row, owned by the resharer, so this works
+// uniformly for canonical posts and reshares.
 func (s *PostService) ReplaceImages(ctx context.Context, postID, callerID string, imageURLs []string) (*model.Post, error) {
 	if err := s.posts.ReplaceImages(ctx, postID, callerID, imageURLs); err != nil {
 		return nil, err
@@ -180,12 +174,11 @@ func (s *PostService) ListByHandle(ctx context.Context, handle, viewerID string,
 	return posts, total, nil
 }
 
-// ListMine is the owner's view of their own profile feed — authored
-// posts plus reshares (the repo's ListByUser unions the two). The
-// viewer here is by construction the feed owner, so every reshared
-// row is one the viewer themselves reshared — we flip
-// ViewerHasReshared inline rather than spending a hydration round-trip
-// to learn what we already know.
+// ListMine is the owner's view of their own profile feed. Every post
+// they own — authored or reshared — comes from posts.user_id, so the
+// viewer is by construction the owner. ViewerHasReshared is true for
+// reshare rows (the user IS the resharer) and false for canonical
+// rows (you don't "reshare your own post").
 func (s *PostService) ListMine(ctx context.Context, userID string, limit, offset int) ([]model.Post, int, error) {
 	if limit <= 0 || limit > 50 {
 		limit = 20
@@ -198,7 +191,7 @@ func (s *PostService) ListMine(ctx context.Context, userID string, limit, offset
 		return nil, 0, err
 	}
 	for i := range posts {
-		if posts[i].ResharedAt != nil {
+		if posts[i].ResharedFromPostID != nil {
 			posts[i].ViewerHasReshared = true
 		}
 	}