add submitter fields autocomplete

app/controllers/api/submitters_autocomplete_controller.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+module Api
+  class SubmittersAutocompleteController < ApiBaseController
+    load_and_authorize_resource :submitter, parent: false
+
+    SELECT_COLUMNS = %w[email phone name].freeze
+    LIMIT = 100
+
+    def index
+      submitters = search_submitters(@submitters)
+
+      values = submitters.limit(LIMIT).group(SELECT_COLUMNS.join(', ')).pluck(SELECT_COLUMNS.join(', '))
+
+      attrs = values.map { |row| SELECT_COLUMNS.zip(row).to_h }
+      attrs = attrs.uniq { |e| e[params[:field]] } if params[:field].present?
+
+      render json: attrs
+    end
+
+    private
+
+    def search_submitters(submitters)
+      if SELECT_COLUMNS.include?(params[:field])
+        column = Submitter.arel_table[params[:field].to_sym]
+
+        term = "%#{params[:q].downcase}%"
+
+        submitters.where(column.lower.matches(term))
+      else
+        Submitters.search(submitters, params[:q])
+      end
+    end
+  end
+end