# frozen_string_literal: true

module Rpl
  module Lang
    class Dictionary
      attr_reader :vars,
                  :local_vars_layers

      def initialize
        @words = {}
        @vars = {}
        @local_vars_layers = []
      end

      def add( name, implementation )
        @words[ name ] = implementation
      end

      def add_var( name, implementation )
        @vars[ name ] = implementation
      end

      def remove_vars( names )
        names.each do |name|
          @vars.delete( name )
        end
      end

      def remove_var( name )
        remove_vars( [name] )
      end

      def remove_all_vars
        @vars = {}
      end

      def add_local_vars_layer
        @local_vars_layers << {}
      end

      def add_local_var( name, implementation )
        @local_vars_layers.last[ name ] = implementation
      end

      def remove_local_vars( names )
        names.each do |name|
          @local_vars_layers.last.delete( name )
        end
      end

      def remove_local_var( name )
        remove_local_vars( [name] )
      end

      def remove_local_vars_layer
        @local_vars_layers.pop
      end

      def lookup( name )
        # look in local variables from the deepest layer up
        local_vars_layer = @local_vars_layers.reverse.find { |layer| layer[ name ] }
        word = local_vars_layer.nil? ? nil : local_vars_layer[ name ]

        # otherwise look in (global) variables
        word ||= @vars[ name ]

        # or is it a core word
        word ||= @words[ name ]

        word
      end
    end
  end
end