Sketch out a BulletTrain::FormBuilder

app/helpers/application_helper.rb

@@ -1,7 +1,39 @@
+class BulletTrain::FormBuilder < ActionView::Helpers::FormBuilder
+  attr_accessor :onchange
+  delegate :render, :tag, to: :@template
+
+  # <%= bullet_train_form_with model: [:account, Post.new], autosubmit: true do |form| %>
+  def initialize(*, options)
+    @onchange = "this.form.requestSubmit()" if options.delete(:autosubmit)
+    super
+  end
+
+  # <%= form.buttons :post_at_shortcuts, %w[now this_week next_week].index_with(&:titleize) %>
+  def buttons(method, button_field_options, onchange: @onchange, **)
+    render "shared/fields/buttons", form: self, method:, button_field_options:, options: {onchange:, **}
+  end
+
+  # <%= form.date_field :post_at %>
+  def date_field(method, onchange: @onchange, **)
+    render "shared/fields/date_field", form: self, method:, options: {onchange:, **}
+  end
+
+  # <%= form.super_select :status, Post.statuses.keys.index_by(&:titleize) %>
+  def super_select(method, choices = nil, html_options: {}, multiple: false, **options)
+    html_options[:onchange] = onchange if onchange
+    html_options[:multiple] = multiple if multiple
+    render "shared/fields/super_select", form: self, method:, choices:, options:, html_options:
+  end
+end
+
 module ApplicationHelper
   include Helpers::Base
 
   def current_theme
     :light
   end
+
+  def bullet_train_form_with(*, **, &)
+    form_with(*, **, builder: BulletTrain::FormBuilder, &)
+  end
 end