ANTOOZA-BACKEND/Application/Features/Api/Store/Games/Detail/Handler.cs

using Application.Abstractions.Data;
using Application.Abstractions.Messaging;
using Domain.Entities.Store.ValueObject;
using Microsoft.EntityFrameworkCore;
using SharedKernel.Results;

namespace Application.Features.Api.Store.Games.Detail;

internal sealed class Handler(IAppDbContext db) : IQueryHandler<Query, Result<Response>>
{
    public async Task<Result<Response>> Handle(Query request, CancellationToken ct)
    {
        var now = DateTime.UtcNow;

        var game = await db.Game.AsNoTracking()
            .Where(g => g.ID == request.ID && g.IsActive)
            .Select(g => new
            {
                g.ID,
                g.KorName,
                g.EngName,
                g.Publisher,
                g.Thumbnail,
                g.BigImage,
                g.Description,
                g.Link,
                g.TrailerUrl,
                g.MinSpec,
                g.RecommendedSpec,
                g.CreatedAt,
                g.ReleaseDate
            })
            .FirstOrDefaultAsync(ct);

        if (game is null)
        {
            return Result.Failure<Response>(Error.NotFound("Game.NotFound", "게임을 찾을 수 없습니다."));
        }

        var genres = await db.GameGenreMap.AsNoTracking()
            .Where(m => m.GameID == game.ID && m.GameGenre.IsActive)
            .OrderBy(m => m.GameGenre.Order)
            .Select(m => m.GameGenre.KorName)
            .ToListAsync(ct);

        var categories = await db.GameCategoryMap.AsNoTracking()
            .Where(m => m.GameID == game.ID && m.GameCategory.IsActive)
            .OrderBy(m => m.GameCategory.Order)
            .Select(m => m.GameCategory.KorName)
            .ToListAsync(ct);

        var images = await db.GameImage.AsNoTracking()
            .Where(i => i.GameID == game.ID && !i.IsDisabled)
            .OrderBy(i => i.Order).ThenBy(i => i.ID)
            .Select(i => i.Url)
            .ToListAsync(ct);

        var languages = await db.GameLanguageSupport.AsNoTracking()
            .Where(s => s.GameID == game.ID && s.GameLanguage.IsActive)
            .OrderBy(s => s.GameLanguage.Order).ThenBy(s => s.GameLanguage.KorName)
            .Select(s => new Response.LanguageRow(s.GameLanguage.KorName, s.GameLanguage.EngName, s.Interface, s.FullAudio, s.Subtitles))
            .ToListAsync(ct);

        // 같은 게임 활성 상품 중 무작위 8개 (NEWID 셔플)
        var productsRaw = await db.Product.AsNoTracking()
            .Where(p => p.GameID == game.ID
                && p.IsActive
                && (p.SaleStartAt == null || p.SaleStartAt <= now)
                && (p.SaleEndAt == null || p.SaleEndAt > now))
            .OrderBy(p => Guid.NewGuid())
            .Take(8)
            .Select(p => new
            {
                p.ID,
                p.Name,
                p.Thumbnail,
                p.Price,
                p.DiscountType,
                p.DiscountValue
            })
            .ToListAsync(ct);

        var products = productsRaw.Select(p => new Response.ProductRow(
            p.ID,
            p.Name,
            p.Thumbnail,
            p.Price,
            CalcSalePrice(p.Price, p.DiscountType, p.DiscountValue)
        )).ToList();

        return Result.Success(new Response(
            game.ID,
            game.KorName,
            game.EngName,
            game.Publisher,
            game.Thumbnail,
            game.BigImage,
            game.Description,
            game.Link,
            game.TrailerUrl,
            game.MinSpec,
            game.RecommendedSpec,
            game.CreatedAt,
            game.ReleaseDate,
            genres,
            categories,
            images,
            languages,
            products
        ));
    }

    private static int CalcSalePrice(int price, DiscountType type, int value)
    {
        return type switch
        {
            DiscountType.Percent => Math.Max(0, price - (price * value / 100)),
            DiscountType.Amount  => Math.Max(0, price - value),
            _                    => price
        };
    }
}