module ActiveAdmin::FormHelper

def active_admin_filters_form_for(search, filters, options = {})
  defaults = { builder: ActiveAdmin::Filters::FormBuilder, url: collection_path, html: { class: "filters-form" } }
  required = { html: { method: :get }, as: :q }
  options = defaults.deep_merge(options).deep_merge(required)
  form_for search, options do |f|
    f.template.concat hidden_field_tags_for(params, except: except_hidden_fields)
    filters.each do |attribute, opts|
      next if opts.key?(:if) && !call_method_or_proc_on(self, opts[:if])
      next if opts.key?(:unless) && call_method_or_proc_on(self, opts[:unless])
      filter_opts = opts.except(:if, :unless)
      filter_opts[:input_html] = instance_exec(&filter_opts[:input_html]) if filter_opts[:input_html].is_a?(Proc)
      f.filter attribute, filter_opts
    end
    buttons = content_tag :div, class: "filters-form-buttons" do
      f.submit(I18n.t("active_admin.filters.buttons.filter"), class: "filters-form-submit") +
        link_to(I18n.t("active_admin.filters.buttons.clear"), collection_path, class: "filters-form-clear")
    end
    f.template.concat buttons
  end
end

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

def except_hidden_fields
  [:q, :page]
end

def fields_for_params(params, options = {})
  namespace = options[:namespace]
  except = Array.wrap(options[:except]).map &:to_s
  params.flat_map do |k, v|
    next if namespace.nil? && RESERVED_PARAMS.include?(k.to_s)
    next if except.include?(k.to_s)
    if namespace
      k = "#{namespace}[#{k}]"
    end
    case v
    when String, TrueClass, FalseClass
      { 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 => "" }
    else
      raise TypeError, "Cannot convert #{v.class} value: #{v.inspect}"
    end
  end.compact
end

def hidden_field_tags_for(params, options = {})
  fields_for_params(params.to_unsafe_hash, 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