mp3years.rb

#!/usr/bin/env ruby

require "rubygems"
require "mp3info"
require "net/http"
require 'cgi'
require 'zlib'
require 'stringio'
require 'rexml/document'

API_KEY = "xxxxxxxxxx"

def get_year(artist, album)
  @@cache ||= {}
  unless @@cache.has_key?([artist, album])
    # Search discogs.com
    search = "\"#{artist}\" \"#{album}\""
    res = Net::HTTP.start("www.discogs.com") do |http|      
      http.get("/search?type=all&q=#{CGI::escape(search)}&f=xml&api_key=#{API_KEY}", "Accept-Encoding" => "gzip")
    end
    body = Zlib::GzipReader.new(StringIO.new(res.body)).read rescue res.body
    # Parse XML to get release ID
    doc = REXML::Document.new(body)
    result = REXML::XPath.first(doc, "//result[@type='release']/uri").text rescue ""
    match = result.match /.*release\/(.*)/
    if match
      release = match[1]
      # Get release and find year
      res = Net::HTTP.start("www.discogs.com") do |http|      
        http.get("/release/#{release}?f=xml&api_key=#{API_KEY}", "Accept-Encoding" => "gzip")
      end
      body = Zlib::GzipReader.new(StringIO.new(res.body)).read
      doc = REXML::Document.new(body)
      year = REXML::XPath.first(doc, "//released").text.to_i
      # Store in file
      @@cache[[artist, album]] = year
    else
      @@cache[[artist, album]] = nil
    end
  end
  @@cache[[artist, album]]
end

# read and display infos & tags
ARGV.each do |file|
  Mp3Info.open(file) do |mp3info|
    unless mp3info.tag.year
      year = get_year(mp3info.tag.artist, mp3info.tag.album)
      if year
        puts "Setting #{mp3info.tag.album} (#{mp3info.tag.artist}) to #{year}"
        mp3info.tag.year = year
      else
        puts "Couldn't find #{mp3info.tag.album} (#{mp3info.tag.artist})"
      end
    end
  end
end