class Byebug::SourceFileFormatter

def amend(line, ceiling)
  [ceiling, [1, line].max].min
end

def amend_final(line)
  amend(line, max_line)
end

def amend_initial(line)
  amend(line, max_initial_line)
end

def initialize(file, annotator)
  @file = file
  @annotator = annotator
end

def lines(min, max)
  File.foreach(file).with_index.map do |line, lineno|
    next unless (min..max).cover?(lineno + 1)
    format(
      "%<annotation>s %<lineno>#{max.to_s.size}d: %<source>s",
      annotation: annotator.call(lineno + 1),
      lineno: lineno + 1,
      source: line
    )
  end
end

def lines_around(center)
  lines(*range_around(center))
end

def max_initial_line
  max_line - size + 1
end

def max_line
  @max_line ||= n_lines(file)
end

def range_around(center)
  range_from(center - size / 2)
end

def range_from(min)
  first = amend_initial(min)
  [first, first + size - 1]
end

def size
  [Setting[:listsize], max_line].min
end