Git pre-commit hook for image optimization.

pre-commit

#!/usr/bin/env ruby

require 'image_optim'

staged_files =  `git diff --cached --name-only --diff-filter=ACM`.split("\n")
staged_files.select! { |f| f =~ %r{/images/} }

if staged_files.any?
  image_optim = ImageOptim.new(pngout: false)

  begin
    optimized_images =
      image_optim.optimize_images!(staged_files) do |filename, was_optimized|
        filename if was_optimized
      end

    optimized_images.compact!

  rescue ImageOptim::BinNotFoundError => e
    puts "#{e.message}.
      This binary is a dependency of image_optim.
      See https://github.com/toy/image_optim for more info.".gsub(/\s+/, " ")
    exit 1
  end

  if optimized_images.any?
    puts "Optimized #{optimized_images.map(&:to_s).inspect}.
      Please add them to your commit.".gsub(/\s+/, " ")
    exit 1
  end
end