Fix #4990: Allow admins to delete uploads.

Allow admins to delete media asset files.

This only deletes the image file itself, not the upload or media asset record. The upload will still
be in the user's upload list, but the image will be gone. The media asset page will still exist, but
it will only show the file's metadata, not the image itself. We don't delete the metadata so we have
a record of what the file's MD5 was and who uploaded it, to prevent the file from being uploaded
again and to take action against the user if necessary.

app/controllers/media_assets_controller.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 class MediaAssetsController < ApplicationController
-  respond_to :html, :json, :xml
+  respond_to :html, :json, :xml, :js
 
   rate_limit :image, rate: 5.0/1.seconds, burst: 50
 
@@ -36,6 +36,13 @@ class MediaAssetsController < ApplicationController
     end
   end
 
+  def destroy
+    @media_asset = authorize MediaAsset.find(params[:id])
+    @media_asset.trash!(CurrentUser.user)
+    flash[:notice] = "File deleted"
+    respond_with(@media_asset)
+  end
+
   def image
     media_asset = authorize MediaAsset.find(params[:media_asset_id])
     variant = media_asset.variant(params[:variant])

app/javascript/src/styles/base/040_colors.scss

@@ -119,6 +119,9 @@ html, body[data-current-user-theme="light"] {
   --success-color: var(--green-5);
   --error-color: var(--red-5);
 
+  --success-hover-color: var(--green-4);
+  --error-hover-color: var(--red-4);
+
   --error-background-color: var(--red-1);
   --success-background-color: var(--green-0);
   --target-background: var(--yellow-0);
@@ -342,8 +345,11 @@ html, body[data-current-user-theme="light"] {
   --link-color: var(--azure-4);
   --link-hover-color: var(--azure-3);
 
-  --success-color: var(--green-3);
-  --error-color: var(--red-3);
+  --success-color: var(--green-4);
+  --error-color: var(--red-4);
+
+  --success-hover-color: var(--green-3);
+  --error-hover-color: var(--red-3);
 
   --default-border-color: var(--grey-7);
 

app/javascript/src/styles/common/utilities.scss

@@ -252,8 +252,13 @@ $spacer: 0.25rem; /* 4px */
 
 .link-color { color: var(--link-color); }
 
-.text-success { color: var(--success-color); }
-.text-error { color: var(--error-color); }
+.text-success { color: var(--success-color) !important; }
+.text-error { color: var(--error-color) !important; }
+.text-danger { color: var(--error-color) !important; }
+
+a.text-success:hover { color: var(--success-hover-color) !important; }
+a.text-error:hover { color: var(--error-hover-color) !important; }
+a.text-danger:hover { color: var(--error-hover-color) !important; }
 
 .transition-opacity {
   transition: opacity 0.15s ease;

app/models/media_asset.rb

@@ -392,17 +392,23 @@ class MediaAsset < ApplicationRecord
       end
     end
 
-    def expunge!
-      delete_files!
-      update!(status: :expunged)
+    def expunge!(current_user, log: true)
+      with_lock do
+        delete_files!
+        update!(status: :expunged)
+        ModAction.log("expunged media asset ##{id} (md5=#{md5})", :media_asset_expunge, subject: self, user: current_user) if log
+      end
     rescue
       update!(status: :failed)
       raise
     end
 
-    def trash!
-      variants.each(&:trash_file!)
-      update!(status: :deleted)
+    def trash!(current_user, log: true)
+      with_lock do
+        variants.each(&:trash_file!)
+        update!(status: :deleted)
+        ModAction.log("deleted media asset ##{id} (md5=#{md5})", :media_asset_delete, subject: self, user: current_user) if log
+      end
     rescue
       update!(status: :failed)
       raise

app/models/mod_action.rb

@@ -42,6 +42,8 @@ class ModAction < ApplicationRecord
     post_vote_undelete: 233,
     pool_delete: 62,
     pool_undelete: 63,
+    media_asset_delete: 72,
+    media_asset_expunge: 76,
     artist_ban: 184,
     artist_unban: 185,
     comment_update: 81,

app/models/post.rb

@@ -780,7 +780,7 @@ class Post < ApplicationRecord
           decrement_tag_post_counts
           remove_from_all_pools
           remove_from_fav_groups
-          media_asset.trash!
+          media_asset.trash!(current_user, log: false)
           destroy
           update_parent_on_destroy
         end

app/policies/media_asset_policy.rb

@@ -5,6 +5,10 @@ class MediaAssetPolicy < ApplicationPolicy
     true
   end
 
+  def destroy?
+    user.is_admin?
+  end
+
   def image?
     can_see_image?
   end

app/views/media_assets/destroy.js.erb

@@ -0,0 +1 @@
+location.reload();

app/views/media_assets/show.html.erb

@@ -73,6 +73,18 @@
                         <%= search_icon %> <%= Danbooru.config.app_name %>
                       <% end %>
                     <% end %>
+
+                    <% if policy(@media_asset).destroy? && @media_asset.post.nil? && !@media_asset.deleted? && !@media_asset.expunged? %>
+                      <% menu.item do %>
+                        <hr class="border">
+                      <% end %>
+
+                      <% menu.item do %>
+                        <%= link_to media_asset_path(@media_asset), class: "text-danger", remote: true, xhr: true, method: :delete, "data-confirm": "This will permanently delete this file. Are you sure?" do %>
+                          <%= delete_icon %> Delete file
+                        <% end %>
+                      <% end %>
+                    <% end %>
                   <% end %>
                 </span>
               </div>