add irreversible admin-only action to permanently delete an image file

lib/philomena/images.ex

@@ -138,6 +138,20 @@ defmodule Philomena.Images do
     |> Repo.isolated_transaction(:serializable)
   end
 
+  def destroy_image(%Image{} = image) do
+    changeset = Image.remove_image_changeset(image)
+
+    Multi.new()
+    |> Multi.update(:image, changeset)
+    |> Multi.run(:remove_file, fn _repo, %{image: image} ->
+      Uploader.unpersist_old_upload(image)
+      Hider.destroy_thumbnails(image)
+
+      {:ok, nil}
+    end)
+    |> Repo.isolated_transaction(:serializable)
+  end
+
   def lock_comments(%Image{} = image, locked) do
     image
     |> Image.lock_comments_changeset(locked)

lib/philomena/images/hider.ex

@@ -21,6 +21,14 @@ defmodule Philomena.Images.Hider do
     File.rename(source, target)
   end
 
+  def destroy_thumbnails(image) do
+    hidden = image_thumb_dir(image, image.hidden_image_key)
+    normal = image_thumb_dir(image)
+
+    File.rm_rf(hidden)
+    File.rm_rf(normal)
+  end
+
   # fixme: these are copied from the thumbnailer
   defp image_thumb_dir(%Image{created_at: created_at, id: id}),
     do: Path.join([image_thumbnail_root(), time_identifier(created_at), to_string(id)])

lib/philomena/images/image.ex

@@ -166,6 +166,12 @@ defmodule Philomena.Images.Image do
     |> unsafe_validate_unique([:image_orig_sha512_hash], Repo)
   end
 
+  def remove_image_changeset(image) do
+    image
+    |> change(removed_image: image.image)
+    |> change(image: nil)
+  end
+
   def source_changeset(image, attrs) do
     image
     |> cast(attrs, [:source_url])

lib/philomena/users/ability.ex

@@ -45,6 +45,7 @@ defimpl Canada.Can, for: [Atom, Philomena.Users.User] do
   def can?(%User{role: "moderator"}, :show, %Filter{}), do: true
 
   # Manage images
+  def can?(%User{role: "moderator"}, :destroy, %Image{}), do: false
   def can?(%User{role: "moderator"}, _action, Image), do: true
   def can?(%User{role: "moderator"}, _action, %Image{}), do: true
 

lib/philomena_web/controllers/image/destroy_controller.ex

@@ -0,0 +1,39 @@
+defmodule PhilomenaWeb.Image.DestroyController do
+  use PhilomenaWeb, :controller
+
+  alias Philomena.Images.Image
+  alias Philomena.Images
+
+  plug PhilomenaWeb.CanaryMapPlug, create: :destroy
+  plug :load_and_authorize_resource, model: Image, id_name: "image_id", persisted: true
+  plug :verify_deleted when action in [:create]
+
+  def create(conn, _params) do
+    image = conn.assigns.image
+
+    case Images.destroy_image(image) do
+      {:ok, %{image: image}} ->
+        conn
+        |> put_flash(:info, "Image contents destroyed.")
+        |> redirect(to: Routes.image_path(conn, :show, image))
+
+      _error ->
+        conn
+        |> put_flash(:error, "Failed to destroy image.")
+        |> redirect(to: Routes.image_path(conn, :show, image))
+    end
+  end
+
+  defp verify_deleted(conn, _opts) do
+    case conn.assigns.image.hidden_from_users do
+      true ->
+        conn
+
+      _false ->
+        conn
+        |> put_flash(:error, "Cannot destroy a non-hidden image!")
+        |> redirect(to: Routes.image_path(conn, :show, conn.assigns.image))
+        |> halt()
+    end
+  end
+end

lib/philomena_web/router.ex

@@ -201,6 +201,7 @@ defmodule PhilomenaWeb.Router do
       resources "/scratchpad", Image.ScratchpadController, only: [:edit, :update], singleton: true
       resources "/uploader", Image.UploaderController, only: [:update], singleton: true
       resources "/anonymous", Image.AnonymousController, only: [:create, :delete], singleton: true
+      resources "/destroy", Image.DestroyController, only: [:create], singleton: true
 
       resources "/comment_lock", Image.CommentLockController,
         only: [:create, :delete],

lib/philomena_web/templates/image/_options.html.slime

@@ -141,3 +141,8 @@
           = button_to "Lock tag editing", Routes.image_tag_lock_path(@conn, :create, @image), method: "post", class: "button"
         - else
           = button_to "Unlock tag editing", Routes.image_tag_lock_path(@conn, :delete, @image), method: "delete", class: "button"
+
+      = if @image.hidden_from_users and can?(@conn, :destroy, @image) do
+        br
+        .flex.flex--spaced-out
+          = button_to "Destroy image", Routes.image_destroy_path(@conn, :create, @image), method: "post", class: "button button--state-danger", data: [confirm: "This action is IRREVERSIBLE. Are you sure?"]