Reverses a text file with unicode support. Flips ascii art (naively).

reverse_lines.rb

#!/usr/bin/env ruby

# Usage: ruby reverse_lines.rb input.txt output.txt
# This script reads each line from the input file,
# reverses the order of the characters,
# and writes the result to the output file.
# It supports ASCII and Unicode charaters (utf-8).
# The primary use-case is for manipulating ascii art, to flip the other direction.
# A more robust version would replace commonly used characters with its complement
# (E.g. the braille character ⠦ becomes ⠴ ).
# Creating such a library is out-of-scope of this project, for now.

if ARGV.length != 2
  puts "Usage: ruby #{__FILE__} <input_file> <output_file>"
  exit 1
end

input_file = ARGV[0]
output_file = ARGV[1]

# Ensure UTF-8 encoding for Unicode support
File.open(output_file, 'w:UTF-8') do |out|
  File.foreach(input_file, encoding: 'UTF-8') do |line|
    reversed_line = line.chomp.reverse + "\n"  # Reverse chars, preserve trailing newline
    out.write(reversed_line)
  end
end

puts "Reversed lines written to #{output_file}"