chore: import MusifyBackend into monorepo (preserving history)

git-subtree-dir: MusifyBackend
git-subtree-mainline: 6829e769ed
git-subtree-split: ed7b00c2cc

MusifyBackend/Application/PlayLists/Handlers/GetPlayListsByUserIdQueryHandler.cs

@@ -0,0 +1,37 @@
+using Ardalis.Result;
+using Microsoft.EntityFrameworkCore;
+using Musify.Application.Pagination;
+using Musify.Application.PlayLists.Responses;
+using Musify.Application.PlayLists.Queries;
+using X.PagedList.EF;
+using Mediator;
+using Musify.Application.Contracts;
+
+namespace Musify.Application.PlayLists.Handlers
+{
+    public class GetPlayListsByUserIdQueryHandler(IDatabase database)
+        : IQueryHandler<GetPlayListsByUserIdQuery, Result<PaginatedResponse<PlayListApplicationResponse> > >
+    {
+        public async ValueTask<Result<PaginatedResponse<PlayListApplicationResponse> >> Handle(GetPlayListsByUserIdQuery request, CancellationToken cancellationToken)
+        {
+            var playListsQuery = database.PlayLists
+                .AsNoTracking()
+                .Where(p => p.UserId == request.UserId);
+
+            if (request.Name is not null)
+            {
+                var normalizedName = request.Name.Trim().ToUpperInvariant();
+                playListsQuery = playListsQuery.Where(p => p.NormalizedName.Contains(normalizedName));
+            }
+
+            var totalCount = await playListsQuery.CountAsync(cancellationToken);
+
+            var pagedPlayLists = await playListsQuery
+                .OrderBy(p => p.CreatedAt)
+                .Select(p => PlayListApplicationResponse.FromEntity(p))
+                .ToPagedListAsync(request.PageNumber, request.PageSize, totalCount, cancellationToken);
+
+            return Result.Success(PaginatedResponse<PlayListApplicationResponse>.FromPagedList(pagedPlayLists));
+        }
+    }
+}