Reworking media scanning to handle multiple artists/albums. Untested.

core/src/main/groovy/com/jdbernard/wdiwtlt/MediaLibrary.groovy

@@ -63,29 +63,29 @@ public class MediaLibrary {
 
         mf.name = fileTag?.getFirst(TITLE)?.trim() ?: f.name
         mf.filePath = relPath
-        mf.comment = fileTag?.getFirst(COMMENT)?.trim()
+        mf.comment = fileTag?.getAll(COMMENT)?.collect { it.trim() }.join('\n\n')
         mf.trackNumber = safeToInteger(fileTag?.getFirst(TRACK))
 
         def folderParts = mf.filePath.split("[\\\\/]")[1..<-1] as LinkedList
 
         // Find artist and album names (if any)
-        def artistName = fileTag?.getFirst(ARTIST)?.trim()
-        def albumName = fileTag?.getFirst(ALBUM)?.trim()
+        def artistNames = fileTag?.getAll(ARTIST)?.collect { it.trim() }
+        def albumNames = fileTag?.getAll(ALBUM)?.collect { it.trim() }
 
-        if (!artistName) {
+        if (!artistNames) {
             mf.metaInfoSource = MediaFile.FILE_LOCATION
-            artistName = folderParts.size() >= 2 ?  folderParts[0] : null }
+            artistNames = folderParts.size() >= 2 ?  [folderParts[0]] : [] }
 
-        if (!albumName) {
+        if (!albumNames) {
             mf.metaInfoSource = MediaFile.FILE_LOCATION
-            albumName = folderParts.peekLast() }
+            albumNames = [folderParts.peekLast()] }
 
         // Hash the file
         mf.fileHash = f.withInputStream { DigestUtils.md5Hex(it) }
 
         orm.withTransaction {
             orm.create(mf)
-            associateWithArtistAndAlbum(mf, artistName, albumName, fileTag)
+            associateWithArtistsAndAlbums(mf, artistNames, albumNames, fileTag)
         }
     }
 
@@ -98,42 +98,65 @@ public class MediaLibrary {
         return match }
 
     public List<Artist> getArtistsByName(String name) {
-        return orm.getArtistByName(name) ?: orm.getArtistsLikeName(name) }
+        return [orm.getArtistByName(name)] ?: orm.getArtistsLikeName(name) }
 
     public List<Album> getAlbumsByName(String name) {
-        return orm.getAlbumByName(name) ?: orm.getAlbumsLikeName(name) }
+        return orm.getAlbumsByName(name) ?: orm.getAlbumsLikeName(name) }
 
-    private void associateWithArtistAndAlbum(MediaFile mf, String artistName,
-    String albumName, JATag fileTag) {
-        Artist artist = null
-        Album album = null
-        boolean newAlbumOrArtist = false
+    private void associateWithArtistsAndAlbums(MediaFile mf, String artistNames,
+    String albumNames, Integer albumYear) {
 
-        if (artistName) {
-            artist = orm.getArtistByName(artistName)
-            if (!artist) {
-                newAlbumOrArtist = true
-                artist = new Artist(name: artistName)
-                orm.create(artist) } }
+        def albums = []
 
-        if (albumName) {
-            album = orm.getAlbumByName(albumName)
+        // Find or create artists.
+        def artists = artistNames.collect { artistName ->
+            Artist artist = orm.getArtistByName(artistName)
+            if (!artist) artist = orm.create(new Artist(name: artistName))
+            return artist }
+
+        // Associate file with artists.
+        artists.each { orm.associate(artist, mf) }
+
+        // Find or create albums
+        def albums = albumNames.collect { albumName ->
+            Album album
+
+            // If we know what year the album was released we can use that to
+            // narrow down the list of matching albums.
+            if (albumYear != null) {
+                // Look first to see if we already know about this album
+                // associated with one of the artists for this piece.
+                album = artists.inject(null, { foundAlbum, artist ->
+                    if (foundAlbum) return foundAlbum
+                    return orm.getAlbumByNameAndYearAndArtistId(albumName,
+                        albumYear, artist.id) }
+                // If we don't have it with one of the artists, see if we have
+                // one that matches the name and year.
+                if (!album)
+                    album = orm.getAlbumByNameAndYear(albumName, albumYear) }
+
+            else {
+                album = artists.inject(null, { foundAlbum, artist ->
+                    if (foundAlbum) return foundAlbum
+                    return orm.getAlbumByNameAndArtistId(albumName, artist.id) }
                 if (!album) {
-                newAlbumOrArtist = true
-                try {
-                    album = new Album(name: albumName,
-                        year: safeToInteger(fileTag?.getFirst(YEAR)),
-                        trackTotal: safeToInteger(fileTag?.getFirst(TRACK_TOTAL))) }
-                catch (UnsupportedOperationException use) {
-                    album = new Album(name: albumName,
-                        year: safeToInteger(fileTag?.getFirst(YEAR))) }
-                orm.create(album) } }
+                    def foundAlbums = org.getAlbumsByName(albumName)
+                    album = foundAlbums ? foundAlbums[0] : 0 } }
 
-        if (artist && album && newAlbumOrArtist)
-            orm.addAlbumArtist(album.id, artist.id)
+            // We still can't find the album at all. We'll need to create it
+            if (!album)
+                album = orm.create(new Album(name: albumName, albumYear))
 
-        if (artist) orm.associateMediaFileWithArtist(mf.id, artist.id)
-        if (album) orm.associateMediaFileWithAlbum(mf.id, album.id)
+            return album }
+
+        // Associate file with albums
+        albums.each { orm.associate(album, mf) }
+
+        // Make sure we have association between all of the artists and albums.
+        artists.each { artist ->
+            def albumsForArtist = orm.getAlbumsByArtistId(artist.id)
+            def albumsMissing = albums - albumsForArtist
+            albumsMissing.each { album -> orm.associate(artist, album) } }
     }
 
     /** #### `getRelativePath`