fixes #77: restore cross-page gallery organization

lib/philomena_web/controllers/gallery_controller.ex

@@ -57,22 +57,32 @@ defmodule PhilomenaWeb.GalleryController do
     {:ok, {images, _tags}} =
       ImageLoader.search_string(conn, query, queries: sort.queries, sorts: sort.sorts)
 
-    interactions = Interactions.user_interactions(images, user)
+    {gallery_prev, gallery_next} = prev_next_page_images(conn, query, sort)
+
+    interactions = Interactions.user_interactions([images, gallery_prev, gallery_next], user)
 
     watching = Galleries.subscribed?(gallery, user)
-    gallery_images = Jason.encode!(Enum.map(images, & &1.id))
+
+    prev_image = if gallery_prev, do: [gallery_prev], else: []
+    next_image = if gallery_next, do: [gallery_next], else: []
+
+    gallery_images = prev_image ++ Enum.to_list(images) ++ next_image
+    gallery_json = Jason.encode!(Enum.map(gallery_images, & &1.id))
 
     Galleries.clear_notification(gallery, user)
 
     conn
     |> NotificationCountPlug.call([])
     |> Map.put(:params, params)
-    |> assign(:clientside_data, gallery_images: gallery_images)
+    |> assign(:clientside_data, gallery_images: gallery_json)
     |> render("show.html",
       title: "Showing Gallery",
       layout_class: "layout--wide",
       watching: watching,
       gallery: gallery,
+      gallery_prev: gallery_prev,
+      gallery_next: gallery_next,
+      gallery_images: gallery_images,
       images: images,
       interactions: interactions
     )
@@ -135,6 +145,39 @@ defmodule PhilomenaWeb.GalleryController do
     |> redirect(to: Routes.gallery_path(conn, :index))
   end
 
+  defp prev_next_page_images(conn, query, sort) do
+    limit = conn.assigns.image_pagination.page_size
+    offset = (conn.assigns.image_pagination.page_number - 1) * limit
+
+    # Inconsistency: Elasticsearch doesn't allow requesting offsets which are less than 0,
+    # but it does allow requesting offsets which are beyond the total number of results.
+
+    prev_image = gallery_image(offset - 1, conn, query, sort)
+    next_image = gallery_image(offset + limit, conn, query, sort)
+
+    {prev_image, next_image}
+  end
+
+  defp gallery_image(offset, _conn, _query, _sorts) when offset < 0, do: nil
+
+  defp gallery_image(offset, conn, query, sort) do
+    pagination_params = %{page_number: offset + 1, page_size: 1}
+
+    {:ok, {image, _tags}} =
+      ImageLoader.search_string(
+        conn,
+        query,
+        pagination: pagination_params,
+        queries: sort.queries,
+        sorts: sort.sorts
+      )
+
+    case Enum.to_list(image) do
+      [image] -> image
+      [] -> nil
+    end
+  end
+
   defp parse_search(%{"gallery" => gallery_params}) do
     parse_title(gallery_params) ++
       parse_creator(gallery_params) ++

lib/philomena_web/templates/gallery/show.html.slime

@@ -5,7 +5,7 @@ elixir:
   pagination = render PhilomenaWeb.PaginationView, "_pagination.html", page: @images, route: route, params: scope
   info = render PhilomenaWeb.PaginationView, "_pagination_info.html", page: @images
 
-#sortable
+#sortable class=sortable_classes(@conn)
   .block#imagelist-container
     section.block__header.flex
       span.block__header__title.hide-mobile
@@ -72,7 +72,7 @@ elixir:
         strong Note that you may have to wait a couple of seconds before the order is applied.
 
     .block__content.js-resizable-media-container
-      = for image <- @images do
+      = for image <- @gallery_images do
         = render PhilomenaWeb.ImageView, "_image_box.html", image: image, link: image_url.(image), size: :thumb, conn: @conn
 
     .block__header.block__header--light.flex

lib/philomena_web/views/gallery_view.ex

@@ -5,6 +5,19 @@ defmodule PhilomenaWeb.GalleryView do
 
   def scope(conn), do: ImageScope.scope(conn)
 
+  def sortable_classes(%{assigns: %{gallery_prev: prev, gallery_next: next}}) do
+    []
+    |> sortable_prev(prev)
+    |> sortable_next(next)
+    |> Enum.join(" ")
+  end
+
+  def sortable_prev(list, nil), do: list
+  def sortable_prev(list, _), do: ["js-sortable-has-prev" | list]
+
+  def sortable_next(list, nil), do: list
+  def sortable_next(list, _), do: ["js-sortable-has-next" | list]
+
   def show_subscription_link?(%{id: id}, %{id: id}), do: false
   def show_subscription_link?(_user1, _user2), do: true
 end