feat: orphan songs not present in the media directory

Tools/LibraryWatcher.cs

@@ -1,3 +1,4 @@
+using Microsoft.EntityFrameworkCore;
 using Shadow.Data;
 using Shadow.Entities;
 using System;
@@ -65,27 +66,79 @@ public class LibraryWatcher(string watchPath, string[] excludedPaths, Applicatio
 	{
 		Console.WriteLine("Performing full library scan...");
 
-		List<string> multimedia = await GetAllMultimediaAsync();
-		foreach (string filepath in multimedia)
+		// Current library state as present in database
+		List<Song> currentLibraryMedia = await db.Songs
+			.Where(s => s.State == 0)
+			.ToListAsync();
+
+		// Updated library state
+		List<Song> updatedSongList = [];
+		List<string> newMultimediaPathNames = await GetAllMultimediaAsync();
+		foreach (string filepath in newMultimediaPathNames)
 		{
 			Console.WriteLine(filepath);
 			Dictionary<string, string> fileInfo = await MetadataExtractor.ExtractAsync(filepath);
 
 			// Pretend we are doing parsing here...
 			Console.WriteLine(GeneralUseHelpers.DictAsJson(fileInfo));
-			MediaParser.CreateSong(db, fileInfo);
+			Song? songInDb = db.Songs
+				.Include(s => s.Album)
+				.FirstOrDefault(s => s.Uri == fileInfo["_shadow:fileHash"]);
+			if (songInDb != null)
+			{
+				// Don't parse the song
+				Console.WriteLine("Skipping song as it already exists in database...");
+
+				// But update it's location in case it has been moved
+				songInDb.Filepath = filepath;
+
+				// And state in case it has been reinstated
+				songInDb.State = 0;       // Set non-orphaned state
+				songInDb.Album.State = 0; // -||-
+				db.Update(songInDb); // Is this necessary?
+				await db.SaveChangesAsync();
+
+				// Afterwards include it in the updated song list
+				updatedSongList.Add(songInDb);
+			}
+			else
+			{
+				// A new song? Parse it and add to DB
+				Song? newSong = MediaParser.CreateSong(db, fileInfo);
+
+				// Sanity check
+				if (newSong != null)
+					updatedSongList.Add(newSong);
+			}
 		}
 
-		Console.WriteLine($"Full scan complete! Processed {multimedia.Count} files.");
+		Console.WriteLine($"Full scan complete! Processed {newMultimediaPathNames.Count} files.");
+
+		List<Song> orphanedSongs = currentLibraryMedia
+			.Except(updatedSongList)
+			.ToList();
+
+		Console.WriteLine($"Detected {orphanedSongs.Count} new orphaned songs");
+		foreach (Song s in orphanedSongs)
+		{
+			Song dbSong = db.Songs
+				.Include(d => d.Artist)
+				.First(d => d.Id == s.Id);
+			Console.WriteLine($"- {dbSong.Title} by {dbSong.Artist.Name} (previous path: {dbSong.Filepath})");
+			dbSong.State = 1;
+			await db.SaveChangesAsync();
+		}
+
+		Console.WriteLine();
 
 		// Update state inside of DB
-		string currentLibraryState = MetadataExtractor.GetStringMD5(string.Join("\n", multimedia));
+		string updatedLibraryState = MetadataExtractor.GetStringMD5(string.Join("\n", newMultimediaPathNames));
 		Global lastLibraryState = db.Globals.FirstOrDefault(g => g.Key == "libraryState")
 			?? new() { Key = "libraryState"};
-		lastLibraryState.Value = currentLibraryState;
+		lastLibraryState.Value = updatedLibraryState;
 		db.Update(lastLibraryState);
 		await db.SaveChangesAsync();
 
-		return multimedia;
+		return newMultimediaPathNames;
 	}
 }