#!/usr/bin/env ruby -w

require 'json'

def main
  while dir = ARGV.shift
    unless File.directory? dir
      puts "[warn] Skipping non-directory: #{dir}"
      next
    end

    all_images = Dir[File.join(dir, '*@[23]x.png')].map { |f| File.basename f }
    image3x = File.basename Dir[File.join(dir, '*@3x.png')].first
    image2x = File.basename  Dir[File.join(dir, '*@2x.png')].first
    image1x = (all_images - [image2x, image3x]).first
    unless [2, 3].include?(all_images.size) && image2x && image3x
      puts "[warn] Skipping #{dir} because 2x and 3x images are required. 1x image is optional. Max 3 images."
      next
    end

    images = [image1x, image2x, image3x]
    scale = 0
    imageset_images = images
      .map { |filename|
        scale += 1
        filename && {
          idiom: 'universal',
          filename: filename,
          scale: "#{scale}x"
        }
      }
      .compact
    imageset = {
      images: imageset_images,
      info: {
        version: 1,
        author: 'generate-xcode-imageset'
      }
    }
    json = JSON.pretty_generate(imageset)
    path = File.join(dir, 'Contents.json')
    File.write(path, json)
    images_written = images.compact
    puts "* Wrote #{images_written.size} images to #{path}: #{images_written.join(', ')}"
  end
end

main if $0 == __FILE__