rails 5 datatable

application_datatable.rb

# frozen_string_literal: true

class ApplicationDatatable
  delegate :params, :link_to, :strip_tags, :local_time_ago, :local_date, :current_user, :avatar,
    :avatar_link, :local_time, :admin?, to: :@view

  def initialize view, options={}
    @view = view
    @options = options

    @data_before_filter = total_collection
    @data = @data_before_filter
    apply_search
    apply_status_filter
    @data_after_filter = @data

    prepare_data
  end

  def prepare_data
    @prepared_data ||= collection.
      order(sorting).
      page(page).per(per_page).
      includes([include_associations].flatten).
      map{ |o| yield(o).map{ |o| o.to_s.gsub(/[\n ]+/," ").strip.html_safe } }
  end

  def as_json options={}
    {
      sEcho: params[:sEcho].to_i,
      iTotalRecords: @data_before_filter.count,
      iTotalDisplayRecords: @data_after_filter.count,
      aaData: @prepared_data,
    }
  end

  def include_associations
    []
  end

  def collection
    @data
  end

  def apply_search
    if search.present? && @data.searchable? && !(::Rails.env.stage?)
      @data = @data.where id: @data.search_ids(search)
    end
  end

  def apply_status_filter
    if status_filter.present? && status_filter[0] != "none"
      @data = @data.where(status: status_filter)
    end
  end

  def search
    @search ||= params[:sSearch].to_s.gsub(/\s+/," ").strip[0..8]
  end

  def page
    params[:iDisplayStart].to_i/per_page + 1
  end

  def per_page
    params[:iDisplayLength].to_i > 0 ? params[:iDisplayLength].to_i : 10
  end

  def sorting
    "#{sort_column} #{sort_direction}"
  end

  def sort_column
    return @sort_column if defined? @sort_column

    @sort_column = columns[params[:iSortCol_0].to_i] || columns[0]
    @sort_column = :id if @sort_column == :uuid
    @sort_column
  end

  def self.columns *args
    @columns = args.to_a
  end

  def self._columns
    @columns ||= [:id]
  end

  def columns
    self.class._columns
  end

  def sort_direction
    params[:sSortDir_0] == "asc" ? "ASC" : "DESC"
  end

  def status_filter
    @status_filter ||= params[:sSearch_4].present? ? params[:sSearch_4].to_s.strip.split(",") : []
  end
end