feat: share post to other apps

internal/handler/social.go

@@ -59,9 +59,36 @@ func (h *PostHandler) Create(w http.ResponseWriter, r *http.Request) {
 	response.JSON(w, http.StatusCreated, p)
 }
 
+// Reshare records the caller as having reshared the post identified
+// by {id}. Idempotent. Returns 204 on success; conflict for the
+// "reshare your own post" case surfaces as 400 via mapSocialErr's
+// fallthrough (errors.New wrapper in the service).
+func (h *PostHandler) Reshare(w http.ResponseWriter, r *http.Request) {
+	uid := middleware.UserID(r.Context())
+	id := chi.URLParam(r, "id")
+	if err := h.svc.Reshare(r.Context(), id, uid); err != nil {
+		mapSocialErr(w, err)
+		return
+	}
+	w.WriteHeader(http.StatusNoContent)
+}
+
+// Unreshare removes a previously recorded reshare. Idempotent.
+func (h *PostHandler) Unreshare(w http.ResponseWriter, r *http.Request) {
+	uid := middleware.UserID(r.Context())
+	id := chi.URLParam(r, "id")
+	if err := h.svc.Unreshare(r.Context(), id, uid); err != nil {
+		mapSocialErr(w, err)
+		return
+	}
+	w.WriteHeader(http.StatusNoContent)
+}
+
 func (h *PostHandler) Get(w http.ResponseWriter, r *http.Request) {
 	id := chi.URLParam(r, "id")
-	p, err := h.svc.Get(r.Context(), id)
+	// viewerID is "" for anonymous viewers — the service treats that as
+	// "no reshare hydration" so the public-cache shape is unchanged.
+	p, err := h.svc.Get(r.Context(), id, middleware.UserID(r.Context()))
 	if err != nil {
 		mapSocialErr(w, err)
 		return
@@ -420,7 +447,10 @@ func (h *ProfileHandler) Get(w http.ResponseWriter, r *http.Request) {
 }
 
 // Feed returns posts for the public feed. Same payload as ListMine but
-// looked up by handle so it's reachable anonymously.
+// looked up by handle so it's reachable anonymously. When an
+// authenticated viewer hits this route (via OptionalAuth) each post
+// carries `viewer_has_reshared` so the action footer renders the right
+// button. Anonymous viewers get `false` for every post at zero cost.
 func (h *ProfileHandler) Feed(w http.ResponseWriter, r *http.Request) {
 	handle := chi.URLParam(r, "handle")
 	limit, offset := parseLimitOffset(r)
@@ -429,6 +459,29 @@ func (h *ProfileHandler) Feed(w http.ResponseWriter, r *http.Request) {
 		mapSocialErr(w, err)
 		return
 	}
+	viewerID := middleware.UserID(r.Context())
+	if viewerID != "" && len(posts) > 0 {
+		ids := make([]string, 0, len(posts))
+		for i := range posts {
+			// Skip own posts — can't reshare yourself, and the swap
+			// already triggers on isOwner.
+			if posts[i].UserID != viewerID {
+				ids = append(ids, posts[i].ID)
+			}
+		}
+		if len(ids) > 0 {
+			states, err := h.posts.ReshareStatesFor(r.Context(), viewerID, ids)
+			if err != nil {
+				mapSocialErr(w, err)
+				return
+			}
+			for i := range posts {
+				if states[posts[i].ID] {
+					posts[i].ViewerHasReshared = true
+				}
+			}
+		}
+	}
 	response.JSONWithMeta(w, http.StatusOK, posts, paginationMeta(total, limit, offset))
 }