Resize an image to multiple sizes

multisize.rb

#!/usr/bin/env ruby

require 'optparse'
require 'fileutils'
require 'mini_magick'
require 'pp'

options = {
  output: '.',
  format: '%n%-%s%'
}
OptionParser.new do |opts|
  opts.on('-s', '--sizes a,b,c', Array, 'Set sizes') do |sizes|
    options[:sizes] = sizes.map! { |s| s.split('x') }
    options[:sizes].each { |a| a.push('') if a.size < 2 }
  end

  opts.on('-f', '--input [filename]', String, 'Input file') do |file|
    options[:image] = file
  end

  opts.on('-o', '--output [directory]', String, 'Output directory') do |dir|
    options[:output] = dir
  end

  opts.on('--format "%n%-%s%"', String, 'Format the filename should take') do |format|
    options[:format] = format
  end
end.parse!

if !options[:sizes]
  puts "--sizes flag is required"
  exit
elsif !options[:image]
  puts "an input file is required"
  exit
end

image = MiniMagick::Image.open(options[:image])
ext, name = options[:image].split('/')[-1].split('.').reverse

unless File.directory?(options[:output])
  FileUtils.mkdir_p(options[:output])
end

options[:sizes].sort!
options[:sizes].each do |(width, height)|
  wh = height.empty? ? width.to_s : "#{width}x#{height}"
  new_name = options[:format].gsub('%n%', name)
  new_name = new_name.gsub('%s%', wh)
    .gsub('%w%', width)
    .gsub('%h%', height)

  date_rgx = /%d{(.*)}%/
  if date_match = new_name.match(date_rgx)
    formatted_date = DateTime.now.strftime(date_match[1])
    puts formatted_date.to_s
  end

  new_name = new_name + '.' + ext

  output = File.join(options[:output], new_name)

  image.resize "#{width}x#{height}"
  image.write(output)
end