social-snippet/social-snippet

class SocialSnippet::Inserter

  attr_reader :src_index
  attr_reader :dest_index
  attr_reader :src
  attr_reader :dest

  # Constructor
  #
  # @param src [Array<String>] The source code
  def initialize(src)
    @src_index = 0
    @dest_index = -1
    @src = src.clone.freeze
    @dest = []
  end

  # Set index
  #
  # @param new_index [Number] The next index
  def set_index(new_index)
    if new_index > src.length
      raise "invalid index"
    end
    if new_index > src_index
      last_index = [new_index - 1, src.length - 1].min
      insert src[src_index .. last_index]
      @src_index = new_index
    end
  end

  # Set index to last
  def set_index_last
    set_index src.length
  end

  # Ignore current line
  def ignore
    @src_index += 1
  end

  # Insert text
  #
  # @param line_or_lines [String or Array<String>] The inserted text
  def insert(line_or_lines)
    if line_or_lines.is_a?(Array)
      lines = line_or_lines
      dest.insert dest_index + 1, *lines
      @dest_index += lines.length
    else
      line = line_or_lines
      dest.insert dest_index + 1, line
      @dest_index += 1
    end
  end

  # Get text
  #
  # @return [String]
  def to_s
    dest.join($/)
  end

end