#! /usr/bin/env ruby

if ARGV.length != 1
        abort("Incorrect arguments - needs input file")
elsif not File.exist? (ARGV[0])
	abort("File #{ARGV[0]} did not exist")
end

file = ARGV[0]

OPEN_SPACE = "."
GALAXY = "#"

input_space = File.open(file, "r").each_line(chomp: true).map(&:each_char).map(&:to_a)

first, *rest = input_space
open_columns = first.zip(*rest).map {|col| col.all? {|cell| cell == OPEN_SPACE}}

expanded_space = input_space.flat_map do |row|
	new_row = row.zip(open_columns).flat_map {|cell, is_open| is_open ? [cell, cell] : [cell]}
	if row.all? {|cell| cell == OPEN_SPACE} then [new_row, new_row] else [new_row] end
end

galaxies = expanded_space.each_with_index.flat_map {|row, y| row.each_with_index.map {|cell, x| [x, y] if cell == GALAXY}}.compact
galactic_distances = galaxies.combination(2).map {|a, b| (a[0] - b[0]).abs + (a[1] - b[1]).abs}
puts galactic_distances.sum