require 'grape'
require 'grape/kaminari/version'
require 'grape/kaminari/max_value_validator'
require 'kaminari/grape'

module Grape
  module Kaminari
    module HelperMethods # :nodoc:
      def paginate(collection)
        collection.page(params[:page].to_i)
                  .per(params[:per_page].to_i)
                  .padding(params[:offset].to_i)
                  .tap do |data|
          header 'X-Total',       data.total_count.to_s
          header 'X-Total-Pages', data.total_pages.to_s
          header 'X-Per-Page',    data.limit_value.to_s
          header 'X-Page',        data.current_page.to_s
          header 'X-Next-Page',   data.next_page.to_s
          header 'X-Prev-Page',   data.prev_page.to_s
          header 'X-Offset',      params[:offset].to_s
        end
      end
    end

    module ClassMethods # :nodoc:
      def paginate(**options)
        options.reverse_merge!(
          per_page: ::Kaminari.config.default_per_page || 10,
          max_per_page: ::Kaminari.config.max_per_page,
          offset: 0,
        )
        params do
          optional :page,     type: Integer, default: 1,
                              desc: 'Page offset to fetch.'
          optional :per_page, type: Integer, default: options[:per_page],
                              desc: 'Number of results to return per page.',
                              max_value: options[:max_per_page]
          if  options[:offset].is_a? Numeric
            optional :offset, type: Integer, default: options[:offset],
                              desc: 'Pad a number of results.'
          end
        end
      end
    end

    def self.included(base)
      base.helpers HelperMethods
      base.extend ClassMethods
    end
  end
end