class RubyXL::Reference

def self.ind2ref(row = 0, col = 0)
  str = ''
  loop do
    x = col % 26
    str = ('A'.ord + x).chr + str
    col = (col / 26).floor - 1
    break if col < 0
  end
  str += (row + 1).to_s
end

def self.ref2ind(str)
  return [ -1, -1 ] unless str =~ /\A([A-Z]+)(\d+)\Z/
  col = 0
  $1.each_byte { |chr| col = col * 26 + (chr - 64) }
  [ $2.to_i - 1, col - 1 ]
end

def ==(other)
  !other.nil? && (@row_range == other.row_range) && (@col_range == other.col_range)
end

def cover?(other)
  !other.nil? && (@row_range.cover?(other.row_range.begin) && @row_range.cover?(other.row_range.end) &&
                  @col_range.cover?(other.col_range.begin) && @col_range.cover?(other.col_range.end))
end

def first_col
  @col_range.begin
end

def first_row
  @row_range.begin
end

def initialize(*params)
  row_from = row_to = col_from = col_to = nil
  case params.size
  when 4 then row_from, row_to, col_from, col_to = params
  when 2 then row_from, col_from = params
  when 1 then
    raise ArgumentError.new("invalid value for #{self.class}: #{params[0].inspect}") unless params[0].is_a?(String)
    from, to = params[0].split(':')
    row_from, col_from = self.class.ref2ind(from)
    row_to, col_to = self.class.ref2ind(to) unless to.nil?
  end
  @row_range = Range.new(row_from || 0, row_to || row_from || ROW_MAX)
  @col_range = Range.new(col_from || 0, col_to || col_from || COL_MAX)
end

def inspect
  if single_cell? then
    "#<#{self.class} @row=#{@row_range.begin} @col=#{@col_range.begin}>"
  else
    "#<#{self.class} @row_range=#{@row_range} @col_range=#{@col_range}>"
  end
end

def last_col
  @col_range.end
end

def last_row
  @row_range.end
end

def single_cell?
  (@row_range.begin == @row_range.end) && (@col_range.begin == @col_range.end)
end

def to_s
  if single_cell? then
    self.class.ind2ref(@row_range.begin, @col_range.begin)
  else
    self.class.ind2ref(@row_range.begin, @col_range.begin) + ':' + self.class.ind2ref(@row_range.end, @col_range.end)
  end
end