module example-jukebox {
  namespace "http://example.com/ns/example-jukebox";
  prefix "jbox";

  organization "Example, Inc.";
  contact "support at example.com";
  description "Example Jukebox Data Model Module.";
  revision "2016-08-15" {
    description "Initial version.";
    reference "example.com document 1-4673.";
  }

  identity genre {
    description
      "Base for all genre types.";
  }

  // abbreviated list of genre classifications
  identity alternative {
    base genre;
    description
      "Alternative music.";
  }
  identity blues {
    base genre;
    description
      "Blues music.";
  }
  identity country {
    base genre;
    description
      "Country music.";
  }
  identity jazz {
    base genre;
    description
      "Jazz music.";
  }
  identity pop {
    base genre;
    description
      "Pop music.";
  }
  identity rock {
    base genre;
    description
      "Rock music.";
  }

  container jukebox {
    presence
      "An empty container indicates that the jukebox
       service is available.";

    description
      "Represents a 'jukebox' resource, with a library, playlists,
       and a 'play' operation.";

    container library {

      description
        "Represents the 'jukebox' library resource.";

      list artist {
        key name;
        description
          "Represents one 'artist' resource within the
           'jukebox' library resource.";

        leaf name {
          type string {
            length "1 .. max";
          }
          description
            "The name of the artist.";
        }

        list album {
          key name;
          description
            "Represents one 'album' resource within one
             'artist' resource, within the jukebox library.";

          leaf name {
            type string {
              length "1 .. max";
            }
            description
              "The name of the album.";
          }
          
          leaf genre {
            type identityref { base genre; }
            description
              "The genre identifying the type of music on
               the album.";
          }

          leaf year {
            type uint16 {
              range "1900 .. max";
            }
            description
              "The year the album was released.";
          }

          container admin {
            description
              "Administrative information for the album.";

            leaf label {
              type string;
              description
                "The label that released the album.";
            }
            leaf catalogue-number {
              type string;
              description
                "The album's catalogue number.";
            }
          }

          list song {
            key name;
            description
              "Represents one 'song' resource within one
               'album' resource, within the jukebox library.";

            leaf name {
              type string {
                 length "1 .. max";
              }
              description
                "The name of the song.";
            }
            leaf location {
              type string;
              mandatory true;
              description
                "The file location string of the
                 media file for the song.";
            }
            leaf format {
              type string;
              description
                "An identifier string for the media type
                 for the file associated with the
                 'location' leaf for this entry.";
            }
            leaf length {
              type uint32;
              units "seconds";
              description
                "The duration of this song in seconds.";
            }
          }   // end list 'song'
        }   // end list 'album'
      }  // end list 'artist'

      leaf artist-count {
         type uint32;
         units "artists";
         config false;
         description
           "Number of artists in the library.";
      }
      leaf album-count {
         type uint32;
         units "albums";
         config false;
         description
           "Number of albums in the library.";
      }
      leaf song-count {
         type uint32;
         units "songs";
         config false;
         description
           "Number of songs in the library.";
      }
    }  // end library

    list playlist {
      key name;
      description
        "Example configuration data resource.";

      leaf name {
        type string;
        description
          "The name of the playlist.";
      }
      leaf description {
        type string;
        description
          "A comment describing the playlist.";
      }
      list song {
        key index;
        ordered-by user;

        description
          "Example nested configuration data resource.";

        leaf index {    // not really needed
          type uint32;
          description
            "An arbitrary integer index for this playlist song.";
        }
        leaf id {
          type instance-identifier;
          mandatory true;
          description
            "Song identifier.  Must identify an instance of
             /jukebox/library/artist/album/song/name.";
        }
      }
    }

    container player {
      description
        "Represents the jukebox player resource.";

      leaf gap {
        type decimal64 {
          fraction-digits 1;
          range "0.0 .. 2.0";
        }
        units "tenths of seconds";
        description
          "Time gap between each song.";
      }
    }
  }

  rpc play {
    description
      "Control function for the jukebox player.";
    input {
      leaf playlist {
        type string;
        mandatory true;
        description
          "The playlist name.";
      }
      leaf song-number {
        type uint32;
        mandatory true;
        description
          "Song number in playlist to play.";
      }
    }
  }
}