class Utils

  RECORDING_SRC_PREFIX = 'rec_'
  RECORDING_SOURCES = ["#{RECORDING_SRC_PREFIX}youtube", "#{RECORDING_SRC_PREFIX}soundcloud"]
  USERNAME_SITES = %W{youtube facebook soundcloud bandcamp fandalism twitter reverbnation}
  SITE_TYPES = ['url'].concat(USERNAME_SITES).concat(RECORDING_SOURCES)

  USER_AGENT = "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2227.1 Safari/537.36"


  def self.recording_source?(site)
    RECORDING_SOURCES.include?(site)
  end

  def self.extract_recording_id(site, recording_url)
    recording_url.strip!
    case site
    when 'rec_youtube'
      #  regex derived from:  https://gist.github.com/afeld/1254889
      if recording_url =~ /(youtu.be\/|youtube.com\/(watch\?(.*&)?v=|(embed|v)\/))([^\?&\"\'>]+)/
        return $5
      end
    when 'rec_soundcloud'
      if recording_url =~ /^https?:\/\/.*soundcloud.com\/.+/
        tmpfile = Tempfile.new(site)
        tmpfile.close
        curl_args = "-A '#{USER_AGENT}' -L --output #{tmpfile.path} --fail --show-error "
        `curl #{curl_args} '#{recording_url}' 2>&1`
        result = File.read(tmpfile.path)
        File.delete(tmpfile.path)
        if result =~ /"soundcloud:\/\/sounds:(\d+)"/
          return $1 
        end
      end
    end
    nil
  end

  def self.username_url(username, site)
    case site
    when 'youtube'
      "https://www.youtube.com/c/#{username}"
    when 'facebook'
      "https://www.facebook.com/#{username}"
    when 'soundcloud'
      "https://soundcloud.com/#{username}"
    when 'bandcamp'
      "http://#{username}.bandcamp.com"
    when 'bandcamp-fan'
      "http://bandcamp.com/#{username}"
    when 'fandalism'
      "http://fandalism.com/#{username}"
    when 'twitter'
      "https://twitter.com/#{username}"
    when 'reverbnation'
      "http://www.reverbnation.com/#{username}"
    else
      nil
    end
  end

  def self.site_validator(url, site=nil)
    curl_args = "-A '#{USER_AGENT}' --silent --head --fail --show-error "
    case site
    when 'bandcamp'
      cmd = "curl #{curl_args} '#{url}' 2>&1"
      result = `#{cmd}`.chomp
      if $?.success?
        if /^HTTP\/\d+\.\d+ 2\d\d OK/ =~ result.lines[0]
          return nil
        else
          if /http:\/\/(.*)\.bandcamp.com/ =~ url
            return self.site_validator(self.username_url($1, 'bandcamp-fan'), 'bandcamp-fan')
          end
          return "Unrecognized url (#{url})"
        end
      else
        result =~ /curl: \(\d+\) (.*)/
        return "#{$1} (#{url})"
      end
    else
      curl_args << "-L --output /dev/null "
      cmd = "curl #{curl_args} '#{url}' 2>&1"
      result = `#{cmd}`.chomp
    end
    if $?.success?
      return nil
    else
      result =~ /curl: \(\d+\) (.*)/
      return "#{$1} (#{url})"
    end
  end

end