module Furnace::AST
  class Node
    attr_reader :type, :children

    def initialize(type, children=[], properties={})
      @type, @children = type.to_sym, children.to_a
      properties.each do |name, value|
        instance_variable_set :"@#{name}", value
      end
      freeze
    end

    def update(type=nil, children=nil, properties={})
      new_type     = type     || @type
      new_children = children || @children

      if @type == new_type &&
          @children == new_children &&
          properties.empty?
        self
      else
        dup.send :initialize, new_type, new_children, properties
      end
    end

    def ==(other)
      if equal?(other)
        true
      elsif other.respond_to? :to_ast
        other = other.to_ast
        other.type == self.type &&
          other.children == self.children
      else
        false
      end
    end

    def to_s
      "(#{fancy_type} ...)"
    end

    def to_sexp(indent=0)
      str = "#{"  " * indent}(#{fancy_type}"

      children.each do |child|
        if (!children[0].is_a?(Node) && child.is_a?(Node)) ||
            (children[0].is_a?(Node) && child.is_a?(Node) &&
              child.children.any? { |c| c.is_a?(Node) || c.is_a?(Array) })
          str << "\n#{child.to_sexp(indent + 1)}"
        else
          str << " #{child.inspect}"
        end
      end

      str << ")"

      str
    end
    alias :inspect :to_sexp

    def to_ast
      self
    end

    protected

    def fancy_type
      @type.to_s.gsub('_', '-')
    end
  end
end