feat(catalog): implement production-grade LTD raffle system

- Added weighted selection based on badges, account age, achievement score, friend count, room count, and furniture count
- Implemented 20s buffer window with automatic drawing logic
- Added support for both randomized and sequential serial numbers
- Implemented Landing View countdown timer (Header 2178)
- Added 'One-Per-Customer' anti-hoarding policy
- Refactored to lean, high-performance C# 12 patterns (Primary Constructors, Collection Expressions)

Author: Diddyy

.config/dotnet-tools.json

@@ -8,6 +8,13 @@
         "csharpier"
       ],
       "rollForward": false
+    },
+    "dotnet-ef": {
+      "version": "9.0.8",
+      "commands": [
+        "dotnet-ef"
+      ],
+      "rollForward": false
     }
   }
-}
+}

Turbo.Catalog/CatalogService.cs

@@ -1,5 +1,10 @@
 using System;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Logging;
+using Turbo.Database.Context;
 using Turbo.Primitives.Catalog;
 using Turbo.Primitives.Catalog.Enums;
 using Turbo.Primitives.Catalog.Providers;
@@ -10,12 +15,14 @@ namespace Turbo.Catalog;
 
 public sealed class CatalogService(
     ILogger<ICatalogService> logger,
-    ICatalogSnapshotProvider<NormalCatalog> normalCatalogProvider
+    ICatalogSnapshotProvider<NormalCatalog> normalCatalogProvider,
+    IDbContextFactory<TurboDbContext> dbCtxFactory
 ) : ICatalogService
 {
     private readonly ILogger<ICatalogService> _logger = logger;
     private readonly ICatalogSnapshotProvider<NormalCatalog> _normalCatalogProvider =
         normalCatalogProvider;
+    private readonly IDbContextFactory<TurboDbContext> _dbCtxFactory = dbCtxFactory;
 
     public CatalogSnapshot GetCatalogSnapshot(CatalogType catalogType)
     {
@@ -28,4 +35,40 @@ public CatalogSnapshot GetCatalogSnapshot(CatalogType catalogType)
             _ => throw new NotSupportedException($"Catalog type {catalogType} is not supported."),
         };
     }
+
+    public async Task<UpcomingLtdSnapshot?> GetUpcomingLtdAsync(CancellationToken ct)
+    {
+        await using var dbCtx = await _dbCtxFactory.CreateDbContextAsync(ct);
+
+        // Find the nearest upcoming active LTD drop
+        var now = DateTime.UtcNow;
+        var nextSeries = await dbCtx
+            .LtdSeries.AsNoTracking()
+            .Where(s => s.IsActive && s.StartsAt > now)
+            .OrderBy(s => s.StartsAt)
+            .FirstOrDefaultAsync(ct);
+
+        if (nextSeries == null)
+            return null;
+
+        var catalogSnap = GetCatalogSnapshot(CatalogType.Normal);
+        var product = catalogSnap.ProductsById.Values.FirstOrDefault(p =>
+            p.LtdSeriesId == nextSeries.Id
+        );
+
+        if (product == null)
+            return null;
+
+        // Resolve PageId from Offer
+        if (!catalogSnap.OffersById.TryGetValue(product.OfferId, out var offer))
+            return null;
+
+        return new UpcomingLtdSnapshot
+        {
+            SecondsUntil = (int)(nextSeries.StartsAt!.Value - now).TotalSeconds,
+            PageId = offer.PageId,
+            OfferId = offer.Id,
+            ClassName = product.ClassName,
+        };
+    }
 }

Turbo.Catalog/Configuration/CatalogConfig.cs

@@ -1,6 +1,158 @@
+using System;
+
 namespace Turbo.Catalog.Configuration;
 
 public class CatalogConfig
 {
     public const string SECTION_NAME = "Turbo:Catalog";
+
+    /// <summary>
+    /// Configuration for LTD raffle weighting criteria.
+    /// </summary>
+    public LtdRaffleWeightConfig LtdRaffle { get; set; } = new();
+}
+
+/// <summary>
+/// Configuration for LTD raffle weighting criteria.
+/// Hotel owners can tune these values to define their own fairness criteria.
+/// </summary>
+public class LtdRaffleWeightConfig
+{
+    /// <summary>
+    /// Base weight given to all participants (ensures everyone has a chance).
+    /// </summary>
+    public double BaseWeight { get; set; } = 1.0;
+
+    /// <summary>
+    /// Default buffer window in seconds.
+    /// </summary>
+    public int DefaultBufferSeconds { get; set; } = 20;
+
+    /// <summary>
+    /// If true, uses pure random selection (equal chance for all).
+    /// Set to true to disable all weighting.
+    /// </summary>
+    public bool UsePureRandom { get; set; } = false;
+
+    /// <summary>
+    /// If true, serial numbers are assigned randomly (Habbo style).
+    /// If false, they are assigned sequentially (1, 2, 3...).
+    /// </summary>
+    public bool RandomizeSerials { get; set; } = true;
+
+    /// <summary>
+    /// If true, each player can only win one item per LTD series.
+    /// If false, players can buy as many as they want (if stock permits).
+    /// </summary>
+    public bool LimitOnePerCustomer { get; set; } = true;
+
+    /// <summary>
+    /// Badge count weighting configuration.
+    /// </summary>
+    public WeightCriterion BadgeCount { get; set; } =
+        new()
+        {
+            Enabled = true,
+            BonusPerUnit = 0.02,
+            MaxBonus = 1.0,
+        };
+
+    /// <summary>
+    /// Account age (days) weighting configuration.
+    /// </summary>
+    public WeightCriterion AccountAgeDays { get; set; } =
+        new()
+        {
+            Enabled = true,
+            BonusPerUnit = 0.00137, // ~0.5 per year
+            MaxBonus = 0.5,
+        };
+
+    /// <summary>
+    /// Online time (minutes) weighting configuration.
+    /// Note: Requires online time tracking to be implemented.
+    /// </summary>
+    public WeightCriterion OnlineTimeMinutes { get; set; } =
+        new()
+        {
+            Enabled = false,
+            BonusPerUnit = 0.00005,
+            MaxBonus = 0.5,
+        };
+
+    /// <summary>
+    /// Room count weighting configuration.
+    /// </summary>
+    public WeightCriterion RoomCount { get; set; } =
+        new()
+        {
+            Enabled = false,
+            BonusPerUnit = 0.05,
+            MaxBonus = 0.5,
+        };
+
+    /// <summary>
+    /// Furniture count weighting configuration.
+    /// </summary>
+    public WeightCriterion FurnitureCount { get; set; } =
+        new()
+        {
+            Enabled = false,
+            BonusPerUnit = 0.001,
+            MaxBonus = 0.5,
+        };
+
+    /// <summary>
+    /// Friend count weighting configuration.
+    /// </summary>
+    public WeightCriterion FriendCount { get; set; } =
+        new()
+        {
+            Enabled = false,
+            BonusPerUnit = 0.01,
+            MaxBonus = 0.5,
+        };
+
+    /// <summary>
+    /// Respects earned (from other users) weighting configuration.
+    /// </summary>
+    public WeightCriterion RespectsReceived { get; set; } =
+        new()
+        {
+            Enabled = false,
+            BonusPerUnit = 0.005,
+            MaxBonus = 0.5,
+        };
+
+    /// <summary>
+    /// Achievement score weighting configuration.
+    /// </summary>
+    public WeightCriterion AchievementScore { get; set; } =
+        new()
+        {
+            Enabled = false,
+            BonusPerUnit = 0.0001,
+            MaxBonus = 0.5,
+        };
+}
+
+/// <summary>
+/// Configuration for a single weighting criterion.
+/// </summary>
+public class WeightCriterion
+{
+    /// <summary>
+    /// Whether this criterion is used in weight calculation.
+    /// </summary>
+    public bool Enabled { get; set; }
+
+    /// <summary>
+    /// Bonus weight added per unit of this criterion.
+    /// </summary>
+    public double BonusPerUnit { get; set; }
+
+    /// <summary>
+    /// Maximum bonus that can be gained from this criterion.
+    /// </summary>
+    public double MaxBonus { get; set; }
 }