feat: implementation of step 5 of the plan - still not fully done

lib/bds/media.ex

@@ -262,6 +262,87 @@ defmodule BDS.Media do
     end
   end
 
+  def list_media_translations(media_id) when is_binary(media_id) do
+    Repo.all(
+      from translation in Translation,
+        where: translation.translation_for == ^media_id,
+        order_by: [asc: translation.language]
+    )
+  end
+
+  def list_linked_posts(media_id) when is_binary(media_id) do
+    Repo.all(
+      from post in BDS.Posts.Post,
+        join: post_media in "post_media",
+        on: post_media.post_id == post.id,
+        where: post_media.media_id == ^media_id,
+        order_by: [asc: post_media.sort_order, asc: post.updated_at],
+        select: %{
+          post_id: post.id,
+          title: fragment("COALESCE(?, ?, ?)", post.title, post.slug, post.id),
+          sort_order: post_media.sort_order
+        }
+    )
+  end
+
+  def link_media_to_post(media_id, post_id) when is_binary(media_id) and is_binary(post_id) do
+    case {Repo.get(Media, media_id), Repo.get(BDS.Posts.Post, post_id)} do
+      {nil, _post} ->
+        {:error, :not_found}
+
+      {_media, nil} ->
+        {:error, :not_found}
+
+      {%Media{} = media, %BDS.Posts.Post{} = post} ->
+        project = Projects.get_project!(media.project_id)
+
+        Repo.transaction(fn ->
+          case Repo.query("SELECT 1 FROM post_media WHERE post_id = ? AND media_id = ? LIMIT 1", [post.id, media.id]) do
+            {:ok, %{rows: [[1]]}} ->
+              :already_linked
+
+            _other ->
+              sort_order = next_sort_order(media.id)
+
+              {:ok, _result} =
+                Repo.query(
+                  "INSERT INTO post_media (id, project_id, post_id, media_id, sort_order, created_at) VALUES (?, ?, ?, ?, ?, ?)",
+                  [Ecto.UUID.generate(), media.project_id, post.id, media.id, sort_order, Persistence.now_ms()]
+                )
+
+              :linked
+          end
+
+          :ok = write_sidecar(project, media)
+          :ok
+        end)
+        |> case do
+          {:ok, :ok} -> {:ok, :linked}
+          {:error, reason} -> {:error, reason}
+        end
+    end
+  end
+
+  def unlink_media_from_post(media_id, post_id) when is_binary(media_id) and is_binary(post_id) do
+    case Repo.get(Media, media_id) do
+      nil ->
+        {:error, :not_found}
+
+      %Media{} = media ->
+        project = Projects.get_project!(media.project_id)
+
+        Repo.transaction(fn ->
+          {:ok, _result} = Repo.query("DELETE FROM post_media WHERE media_id = ? AND post_id = ?", [media.id, post_id])
+          :ok = write_sidecar(project, media)
+          :ok
+        end)
+        |> case do
+          {:ok, :ok} -> {:ok, :unlinked}
+          {:error, reason} -> {:error, reason}
+        end
+    end
+  end
+
   def thumbnail_paths(%Media{id: id}) do
     prefix = String.slice(id, 0, 2)
 
@@ -675,6 +756,13 @@ defmodule BDS.Media do
     end
   end
 
+  defp next_sort_order(media_id) do
+    case Repo.query("SELECT COALESCE(MAX(sort_order), -1) FROM post_media WHERE media_id = ?", [media_id]) do
+      {:ok, %{rows: [[value]]}} when is_integer(value) -> value + 1
+      _other -> 0
+    end
+  end
+
   defp blank_to_nil(nil), do: nil
   defp blank_to_nil(""), do: nil
   defp blank_to_nil(value), do: value