module ActiveAdmin::ViewHelpers::FormHelper

def active_admin_form_for(resource, options = {}, &block)
  Arbre::Context.new({}, self) do
    active_admin_form_for resource, options, &block
  end.content
end

def fields_for_params(params, options = {})
  namespace = options[:namespace]
  except = options[:except].is_a?(Array) ? options[:except] : [options[:except]]
  params.flat_map do |k, v|
    next if namespace.nil? && %w(controller action commit utf8).include?(k.to_s)
    next if except.map(&:to_s).include?(k.to_s)
    if namespace
      k = "#{namespace}[#{k}]"
    end
    case v
    when String
      { k => v }
    when Symbol
      { k => v.to_s }
    when Hash
      fields_for_params(v, namespace: k)
    when Array
      v.map do |v|
        { "#{k}[]" => v }
      end
    when nil
      { k => '' }
    when TrueClass,FalseClass
      { k => v }
    else
      raise "I don't know what to do with #{v.class} params: #{v.inspect}"
    end
  end.compact
end

def hidden_field_tags_for(params, options={})
  fields_for_params(params, options).map do |kv|
    k, v = kv.first
    hidden_field_tag k, v, id: sanitize_to_id("hidden_active_admin_#{k}")
  end.join("\n").html_safe
end