Handle no avatar, add delete avatar support

backend/internal/rest/handler_users.go

@@ -20,6 +20,7 @@ type userResponse struct {
 	FullName    *string    `json:"fullName"`
 	Email       *string    `json:"email"`
 	IsAdmin     bool       `json:"isAdmin"`
+	HasAvatar   bool       `json:"hasAvatar"`
 	CreatedAt   time.Time  `json:"createdAt"`
 	UpdatedAt   time.Time  `json:"updatedAt"`
 	ActivatedAt *time.Time `json:"activatedAt"`
@@ -38,7 +39,12 @@ func (h *Handler) listUsers(w http.ResponseWriter, r *http.Request) {
 
 	result := make([]userResponse, 0, len(users))
 	for _, u := range users {
-		result = append(result, newUserResponse(u))
+		hasAvatar, err := h.users.HasAvatar(r.Context(), u)
+		if err != nil {
+			h.fail(w, err)
+			return
+		}
+		result = append(result, newUserResponse(u, hasAvatar))
 	}
 
 	writeJson(w, http.StatusOK, result)
@@ -131,7 +137,18 @@ func (h *Handler) getUserAvatar(w http.ResponseWriter, r *http.Request) {
 
 // avatarURL builds the absolute URL of a user's avatar, preferring the
 // configured PublicBaseURL and falling back to the request's scheme and Host.
+// It returns an empty string when the user has no avatar.
 func (h *Handler) avatarURL(r *http.Request, id int64) string {
+	user, err := h.users.UserById(r.Context(), id)
+	if err != nil {
+		return ""
+	}
+
+	hasAvatar, err := h.users.HasAvatar(r.Context(), user)
+	if err != nil || !hasAvatar {
+		return ""
+	}
+
 	base := h.cfg.PublicBaseURL
 	if base == "" {
 		scheme := "http"
@@ -146,13 +163,25 @@ func (h *Handler) avatarURL(r *http.Request, id int64) string {
 	return fmt.Sprintf("%s/api/users/%d/avatar", base, id)
 }
 
-func newUserResponse(u *user.User) userResponse {
+// respondUser writes a user response that includes whether the user has an
+// avatar stored.
+func (h *Handler) respondUser(w http.ResponseWriter, r *http.Request, u *user.User, status int) {
+	hasAvatar, err := h.users.HasAvatar(r.Context(), u)
+	if err != nil {
+		h.fail(w, err)
+		return
+	}
+	writeJson(w, status, newUserResponse(u, hasAvatar))
+}
+
+func newUserResponse(u *user.User, hasAvatar bool) userResponse {
 	return userResponse{
 		Id:          u.Id,
 		Login:       u.Login,
 		FullName:    u.FullName,
 		Email:       u.Email,
 		IsAdmin:     u.IsAdmin,
+		HasAvatar:   hasAvatar,
 		CreatedAt:   u.CreatedAt,
 		UpdatedAt:   u.UpdatedAt,
 		ActivatedAt: u.ActivatedAt,