ANTOOZA-BACKEND/Application/Features/Admin/Store/Coupon/Search/Handler.cs

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

namespace Application.Features.Admin.Store.Coupon.Search;

public sealed class Handler(IAppDbContext db) : IQueryHandler<Query, Response>
{
    public async Task<Response> Handle(Query request, CancellationToken ct)
    {
        var query = db.Coupon.AsNoTracking()
            .Include(c => c.Product)
            .Include(c => c.Game)
            .AsQueryable();

        if (request.GameID.HasValue)
        {
            query = query.Where(c => c.GameID == request.GameID.Value);
        }

        if (request.ProductID.HasValue)
        {
            query = query.Where(c => c.ProductID == request.ProductID.Value);
        }

        if (!string.IsNullOrWhiteSpace(request.Keyword))
        {
            var kw = request.Keyword.Trim();
            query = query.Where(c => c.Name.Contains(kw));
        }

        var total = await query.CountAsync(ct);

        var list = await query
            .OrderByDescending(c => c.ID)
            .Skip((request.Page - 1) * request.PerPage)
            .Take(request.PerPage)
            .Select(c => new
            {
                c.ID,
                c.ProductID,
                ProductName = c.Product!.Name,
                c.GameID,
                GameName = c.Game!.KorName,
                c.Name,
                c.UsagePolicy,
                c.ExpiresAt,
                c.GeneratedCount,
                c.UsedCount,
                AvailableCount = db.CouponCode.Count(cc => cc.CouponID == c.ID && cc.Status == CouponCodeStatus.Available),
                c.LowStockThreshold,
                c.UpdatedAt,
                c.CreatedAt
            })
            .ToListAsync(ct);

        var startNum = total - ((request.Page - 1) * request.PerPage);

        return new Response(
            total,
            [.. list.Select((c, i) => new Response.Row(
                Num: startNum - i,
                c.ID,
                c.ProductID,
                c.ProductName,
                c.GameID,
                c.GameName,
                c.Name,
                c.UsagePolicy,
                c.ExpiresAt,
                c.GeneratedCount,
                c.UsedCount,
                c.AvailableCount,
                c.LowStockThreshold,
                IsLowStock: c.AvailableCount < c.LowStockThreshold,
                c.UpdatedAt,
                c.CreatedAt
            ))]
        );
    }
}