ame.rb

require 'open-uri'
require 'RMagick'

if ARGV.length != 2
  puts 'Usage: ./ame.rb latitude longtitude'
  exit
end

url = 'http://tokyo-ame.jwa.or.jp/mesh/100/%s.gif' %
  Time.at((Time.now - 30).to_i / 300 * 300).strftime('%Y%m%d%H%M')
x = (ARGV[1].to_f - 138.4) / 2.14
y = (36.23 - ARGV[0].to_f) / 1.13

if [x, y].all? {|n| (0...1).include? n }
  image = Magick::Image.read(open(url).to_path).first
  x = (x * image.columns).to_i
  y = (y * image.rows).to_i
  pixel = image.pixel_color(x, y)
  pixel = image.pixel_color(x-1, y-1) if pixel.to_color == 'black'

  if pixel.opacity == 0
    pixel = (pixel.red & 0xff) << 16 | (pixel.green & 0xff) << 8 | pixel.blue & 0xff
    intensity = [0xccffff, 0x6699ff, 0x33ffff, 0x00ff00,
      0xffff00, 0xff9900, 0xff00ff, 0xff0000].index(pixel) + 1
  else
    intensity = 0
  end

  puts "intensity: #{intensity}"
else
  puts 'outside the area'
end