lib/graphql/relay/array_connection.rb


# frozen_string_literal: true
module GraphQL
  module Relay
    class ArrayConnection < BaseConnection
      def cursor_from_node(item)
        idx = (after ? index_from_cursor(after) : 0) + sliced_nodes.find_index(item) + 1
        encode(idx.to_s)
      end

      def has_next_page
        if first
          # There are more items after these items
          sliced_nodes.count > first
        elsif GraphQL::Relay::ConnectionType.bidirectional_pagination && before
          # The original array is longer than the `before` index
          index_from_cursor(before) < nodes.length + 1
        else
          false
        end
      end

      def has_previous_page
        if last
          # There are items preceding the ones in this result
          sliced_nodes.count > last
        elsif GraphQL::Relay::ConnectionType.bidirectional_pagination && after
          # We've paginated into the Array a bit, there are some behind us
          index_from_cursor(after) > 0
        else
          false
        end
      end

      def first
        @first ||= begin
          capped = limit_pagination_argument(arguments[:first], max_page_size)
          if capped.nil? && last.nil?
            capped = max_page_size
          end
          capped
        end
      end

      def last
        @last ||= limit_pagination_argument(arguments[:last], max_page_size)
      end

      private

      # apply first / last limit results
      def paged_nodes
        @paged_nodes ||= begin
          items = sliced_nodes

          items = items.first(first) if first
          items = items.last(last) if last
          items = items.first(max_page_size) if max_page_size && !first && !last

          items
        end
      end

      # Apply cursors to edges
      def sliced_nodes
        @sliced_nodes ||= if before && after
          nodes[index_from_cursor(after)..index_from_cursor(before)-1] || []
        elsif before
          nodes[0..index_from_cursor(before)-2] || []
        elsif after
          nodes[index_from_cursor(after)..-1] || []
        else
          nodes
        end
      end

      def index_from_cursor(cursor)
        decode(cursor).to_i
      end
    end

    BaseConnection.register_connection_implementation(Array, ArrayConnection)
  end
end