multitag search for last.fm (cached)

lastfm_multitag.rb

require 'lastfm'

api_key ||= 'xxx'
api_secret ||= 'xxx'
$lastfm ||= Lastfm.new(api_key, api_secret)
# token = lastfm.auth.get_token
# lastfm.session = lastfm.auth.get_session(:token => token)['key']
$cache ||= {}

def multitag *tags
  artists = tags.map do |tag|
    print '.'
    results = $cache[tag] ||= $lastfm.tag.get_top_artists(:tag => tag, :limit => 9999)
    Hash[tag, results]
  end.compact.inject(&:merge)
  print '.'
  matches = artists.map { |_, a| a.map { |x| x['name'] } }.inject(&:&)
  puts '.'
  matches = matches.map do |a|
    [a, artists.map { |tag, as| [tag, as.find { |x| x['name'] == a }['rank']] } ]
  end.sort { |x| x.map{|y|y[1].map{|z|z[1].to_i}.inject(&:+)}.inject(&:<=>) }
  matches.empty? ? raise : matches
rescue
  puts 'No matches'
end