Parse Ruby gems

parser.rb

require "prism"

class Parser
  def initialize(list, rubygems_client: RubyGems::Client.new)
    @list = list
    @rubygems_client = rubygems_client
  end

  def parse
    return parse_gemfile_format if gemfile_format?

    parse_single_line_format
  end

  private

    attr_reader :list, :rubygems_client

    def gemfile_format? = lines.any? { gem_method_call?(_1) }

    def parse_gemfile_format
      ast = Prism.parse(list)
      root_node = ast.value

      parsed_gems = []

      root_node.statements.body.each do |call_node|
        case call_node.name
        when :gem
          name = gem_name_from_call_node(call_node)
          parsed_gems << name
        when :group
          names = gem_names_from_group(call_node)
          parsed_gems.concat(names) if names.present?
        end
      end

      parsed_gems.compact_blank.map { rubygems_client.info(_1) }
    end

    def parse_single_line_format
      lines.filter_map do |line|
        gem_name = line.strip
        gem_info = rubygems_client.info(gem_name) unless gem_name.empty?
        gem_info
      end.compact_blank
    end

    def gem_names_from_group(call_node)
      statements_node = call_node&.block&.body
      statements_node.body.map { gem_name_from_call_node(_1) }
    end

    def gem_name_from_call_node(call_node) = call_node&.arguments&.arguments&.first&.unescaped

    def gem_method_call?(line) = line.strip.include?("gem ")

    def lines = list.lines
end