# frozen_string_literal: true

module Pragma
  module Decorator
    module Pagination
      module Adapter
        # This adapter provides support for retireving pagination information from collections
        # paginated with {https://github.com/mislav/will_paginate will_paginate}.
        #
        # @api private
        class WillPaginate < Base
          class << self
            # Returns whether this adapter supports the given collection.
            #
            # Esnures that the +WillPaginate+ constant is defined and that the collection responds
            # to +#previous_page+.
            #
            # @return [Boolean] whether the adapter supports the given collection
            #
            # @see Adapter.load_for
            def supports?(collection)
              Object.const_defined?('WillPaginate') && collection.respond_to?(:previous_page)
            end
          end

          # Returns the total number of entries in the collection.
          #
          # @return [Integer] the total number of entries in the collection
          def total_entries
            collection.total_entries
          end

          # Returns the number of entries per page in the collection.
          #
          # @return [Integer] the number of entries per page in the collection
          def per_page
            collection.per_page
          end

          # Returns the total number of pages in the collection.
          #
          # @return [Integer] the total number of pages in the collection
          def total_pages
            collection.total_pages
          end

          # Returns the number of the previous page, if any.
          #
          # @return [Integer|NilClass] the number of the previous page, if any
          def previous_page
            collection.previous_page
          end

          # Returns the number of the current page.
          #
          # @return [Integer] the number of the current page
          def current_page
            collection.current_page
          end

          # Returns the number of the next page, if any.
          #
          # @return [Integer|NilClass] the number of the next page, if any
          def next_page
            collection.next_page
          end
        end
      end
    end
  end
end