[backend/masto-client] Fix notification pagination (ISH-204)

Iceshrimp.Backend/Controllers/Mastodon/NotificationController.cs

@@ -50,7 +50,7 @@ public class NotificationController(DatabaseContext db, NotificationRenderer not
 		                  .EnsureNoteVisibilityFor(p => p.Note, user)
 		                  .FilterBlocked(p => p.Notifier, user)
 		                  .FilterBlocked(p => p.Note, user)
-		                  .Paginate(query, ControllerContext)
+		                  .Paginate(p => p.MastoId, query, ControllerContext)
 		                  .PrecomputeNoteVisibilities(user)
 		                  .RenderAllForMastodonAsync(notificationRenderer, user);
 

Iceshrimp.Backend/Core/Database/Migrations/20240326191000_AddNotificationMastoIdIndex.cs

@@ -0,0 +1,27 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Iceshrimp.Backend.Core.Database.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddNotificationMastoIdIndex : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateIndex(
+                name: "IX_notification_masto_id",
+                table: "notification",
+                column: "masto_id");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "IX_notification_masto_id",
+                table: "notification");
+        }
+    }
+}

Iceshrimp.Backend/Core/Database/Migrations/DatabaseContextModelSnapshot.cs

@@ -2926,6 +2926,8 @@ namespace Iceshrimp.Backend.Core.Database.Migrations
 
                     b.HasIndex("IsRead");
 
+                    b.HasIndex("MastoId");
+
                     b.HasIndex("NoteId");
 
                     b.HasIndex("NotifieeId");

Iceshrimp.Backend/Core/Database/Tables/Notification.cs

@@ -12,6 +12,7 @@ namespace Iceshrimp.Backend.Core.Database.Tables;
 [Index("NotifieeId")]
 [Index("CreatedAt")]
 [Index("AppAccessTokenId")]
+[Index("MastoId")]
 public class Notification : IEntity
 {
 	[PgName("notification_type_enum")]

Iceshrimp.Backend/Core/Extensions/QueryableExtensions.cs

@@ -85,6 +85,60 @@ public static class QueryableExtensions
 		return query.Take(Math.Min(pq.Limit ?? defaultLimit, maxLimit));
 	}
 
+	public static IQueryable<T> Paginate<T>(
+		this IQueryable<T> query,
+		Expression<Func<T, long>> predicate,
+		MastodonPaginationQuery pq,
+		int defaultLimit,
+		int maxLimit
+	) where T : IEntity
+	{
+		if (pq.Limit is < 1)
+			throw GracefulException.BadRequest("Limit cannot be less than 1");
+
+		if (pq is { SinceId: not null, MinId: not null })
+			throw GracefulException.BadRequest("Can't use sinceId and minId params simultaneously");
+
+		long? sinceId = null;
+		long? minId   = null;
+		long? maxId   = null;
+
+		if (pq.SinceId != null)
+		{
+			if (!long.TryParse(pq.SinceId, out var res))
+				throw GracefulException.BadRequest("sinceId must be an integer");
+			sinceId = res;
+		}
+
+		if (pq.MinId != null)
+		{
+			if (!long.TryParse(pq.MinId, out var res))
+				throw GracefulException.BadRequest("minId must be an integer");
+			minId = res;
+		}
+
+		if (pq.MaxId != null)
+		{
+			if (!long.TryParse(pq.MaxId, out var res))
+				throw GracefulException.BadRequest("maxId must be an integer");
+			maxId = res;
+		}
+
+		query = pq switch
+		{
+			{ SinceId: not null, MaxId: not null } => query.Where(predicate.Compose(id => id > sinceId && id < maxId))
+			                                               .OrderByDescending(predicate),
+			{ MinId: not null, MaxId: not null } => query.Where(predicate.Compose(id => id > minId && id < maxId))
+			                                             .OrderBy(predicate),
+			{ SinceId: not null } => query.Where(predicate.Compose(id => id > sinceId)).OrderByDescending(predicate),
+			{ MinId: not null }   => query.Where(predicate.Compose(id => id > minId)).OrderBy(predicate),
+			{ MaxId: not null }   => query.Where(predicate.Compose(id => id < maxId)).OrderByDescending(predicate),
+			_                     => query.OrderByDescending(predicate)
+		};
+
+		return query.Take(Math.Min(pq.Limit ?? defaultLimit, maxLimit));
+	}
+
 	public static IQueryable<T> Paginate<T>(
 		this IQueryable<T> query,
 		PaginationQuery pq,
@@ -140,6 +194,22 @@ public static class QueryableExtensions
 		return Paginate(query, predicate, pq, filter.DefaultLimit, filter.MaxLimit);
 	}
 
+	public static IQueryable<T> Paginate<T>(
+		this IQueryable<T> query,
+		Expression<Func<T, long>> predicate,
+		MastodonPaginationQuery pq,
+		ControllerContext context
+	) where T : IEntity
+	{
+		var filter = context.ActionDescriptor.FilterDescriptors.Select(p => p.Filter)
+		                    .OfType<LinkPaginationAttribute>()
+		                    .FirstOrDefault();
+		if (filter == null)
+			throw new GracefulException("Route doesn't have a LinkPaginationAttribute");
+
+		return Paginate(query, predicate, pq, filter.DefaultLimit, filter.MaxLimit);
+	}
+
 	public static IQueryable<T> Paginate<T>(
 		this IQueryable<T> query,
 		PaginationQuery pq,