using foodmarket.Application.Common.Tenancy;
using foodmarket.Application.Inventory;
using foodmarket.Domain.Inventory;
using foodmarket.Infrastructure.Persistence;
using Microsoft.EntityFrameworkCore;

namespace foodmarket.Infrastructure.Inventory;

/// <summary>Создаёт/закрывает <see cref="NegativeStockAlert"/> при изменении остатка.
/// Сущности только трекаются в текущем <c>DbContext</c> — SaveChanges делает
/// вызывающий документ (атомарно с проводкой).</summary>
public sealed class NegativeStockAlertService : INegativeStockAlertService
{
    private readonly AppDbContext _db;
    private readonly ITenantContext _tenant;

    public NegativeStockAlertService(AppDbContext db, ITenantContext tenant)
    {
        _db = db;
        _tenant = tenant;
    }

    public async Task OnStockLevelAsync(
        Guid storeId, Guid productId, decimal newQty,
        string? causeDocType, Guid? causeDocId, string? causeDocNumber,
        Guid? causeUserId, DateTime? causeAt,
        CancellationToken ct = default)
    {
        var orgId = _tenant.OrganizationId;
        if (orgId is null) return;
        var now = DateTime.UtcNow;

        // Ищем открытый алерт по (store, product). Учитываем и ещё не сохранённые
        // (Local) — на случай нескольких движений одного товара в одном документе.
        var open = _db.NegativeStockAlerts.Local
                       .FirstOrDefault(a => a.StoreId == storeId && a.ProductId == productId && a.ResolvedAt == null)
                   ?? await _db.NegativeStockAlerts
                       .FirstOrDefaultAsync(a => a.StoreId == storeId && a.ProductId == productId && a.ResolvedAt == null, ct);

        if (newQty < 0)
        {
            if (open is null)
            {
                _db.NegativeStockAlerts.Add(new NegativeStockAlert
                {
                    OrganizationId = orgId.Value,
                    StoreId = storeId,
                    ProductId = productId,
                    Quantity = newQty,
                    CauseDocType = causeDocType,
                    CauseDocId = causeDocId,
                    CauseDocNumber = causeDocNumber,
                    CauseUserId = causeUserId,
                    CauseAt = causeAt ?? now,
                    FirstDetectedAt = now,
                    LastUpdatedAt = now,
                });
            }
            else
            {
                open.Quantity = newQty;
                open.CauseDocType = causeDocType;
                open.CauseDocId = causeDocId;
                open.CauseDocNumber = causeDocNumber;
                open.CauseUserId = causeUserId;
                open.CauseAt = causeAt ?? now;
                open.LastUpdatedAt = now;
            }
        }
        else if (open is not null)
        {
            // Остаток вернулся ≥ 0 — закрываем.
            open.Quantity = newQty;
            open.ResolvedAt = now;
            open.LastUpdatedAt = now;
        }
    }
}