class Reline::LineEditor

def delete_text(start = nil, length = nil)
  if start.nil? and length.nil?
    if @is_multiline
      if @buffer_of_lines.size == 1
        @line&.clear
        @byte_pointer = 0
        @cursor = 0
        @cursor_max = 0
      elsif @line_index == (@buffer_of_lines.size - 1) and @line_index > 0
        @buffer_of_lines.pop
        @line_index -= 1
        @line = @buffer_of_lines[@line_index]
        @byte_pointer = 0
        @cursor = 0
        @cursor_max = calculate_width(@line)
      elsif @line_index < (@buffer_of_lines.size - 1)
        @buffer_of_lines.delete_at(@line_index)
        @line = @buffer_of_lines[@line_index]
        @byte_pointer = 0
        @cursor = 0
        @cursor_max = calculate_width(@line)
      end
    else
      @line&.clear
      @byte_pointer = 0
      @cursor = 0
      @cursor_max = 0
    end
  elsif not start.nil? and not length.nil?
    if @line
      before = @line.byteslice(0, start)
      after = @line.byteslice(start + length, @line.bytesize)
      @line = before + after
      @byte_pointer = @line.bytesize if @byte_pointer > @line.bytesize
      str = @line.byteslice(0, @byte_pointer)
      @cursor = calculate_width(str)
      @cursor_max = calculate_width(@line)
    end
  elsif start.is_a?(Range)
    range = start
    first = range.first
    last = range.last
    last = @line.bytesize - 1 if last > @line.bytesize
    last += @line.bytesize if last < 0
    first += @line.bytesize if first < 0
    range = range.exclude_end? ? first...last : first..last
    @line = @line.bytes.reject.with_index{ |c, i| range.include?(i) }.map{ |c| c.chr(Encoding::ASCII_8BIT) }.join.force_encoding(@encoding)
    @byte_pointer = @line.bytesize if @byte_pointer > @line.bytesize
    str = @line.byteslice(0, @byte_pointer)
    @cursor = calculate_width(str)
    @cursor_max = calculate_width(@line)
  else
    @line = @line.byteslice(0, start)
    @byte_pointer = @line.bytesize if @byte_pointer > @line.bytesize
    str = @line.byteslice(0, @byte_pointer)
    @cursor = calculate_width(str)
    @cursor_max = calculate_width(@line)
  end
end