module Bashly
  # A helper class, used by the `Array#indent` extension.
  # It will return the array of strings with all strings prefixed by `indentation`
  # unless the line is within a heredoc block.
  class IndentationHelper
    attr_reader :marker, :indentation

    def initialize(indentation)
      @indentation = indentation
      @marker = nil
    end

    def indent(line)
      if inside_heredoc?
        reset_marker if heredoc_closed?(line)
        line
      else
        set_heredoc_state(line)
        "#{indentation}#{line}"
      end
    end

  private

    def reset_marker
      @marker = nil
    end

    def inside_heredoc?
      !!marker
    end

    def set_heredoc_state(line)
      @marker = extract_heredoc_marker(line)
    end

    def extract_heredoc_marker(line)
      line =~ /<<-?\s*['"]?(\w+)['"]?/ ? $1 : nil
    end

    def heredoc_closed?(line)
      inside_heredoc? && /^#{marker}\n?$/.match?(line)
    end
  end
end