using MediatR;
using Microsoft.Extensions.Logging;
using TakeoutSaaS.Application.App.Inventory.Commands;
using TakeoutSaaS.Application.App.Inventory.Dto;
using TakeoutSaaS.Domain.Inventory.Repositories;
using TakeoutSaaS.Shared.Abstractions.Constants;
using TakeoutSaaS.Shared.Abstractions.Exceptions;
using TakeoutSaaS.Shared.Abstractions.Tenancy;

namespace TakeoutSaaS.Application.App.Inventory.Handlers;

/// <summary>
/// 库存释放处理器。
/// </summary>
public sealed class ReleaseInventoryCommandHandler(
    IInventoryRepository inventoryRepository,
    ITenantProvider tenantProvider,
    ILogger<ReleaseInventoryCommandHandler> logger)
    : IRequestHandler<ReleaseInventoryCommand, InventoryItemDto>
{
    /// <inheritdoc />
    public async Task<InventoryItemDto> Handle(ReleaseInventoryCommand request, CancellationToken cancellationToken)
    {
        // 1. 读取库存
        var tenantId = tenantProvider.GetCurrentTenantId();
        var item = await inventoryRepository.GetForUpdateAsync(tenantId, request.StoreId, request.ProductSkuId, cancellationToken);
        if (item is null)
        {
            throw new BusinessException(ErrorCodes.NotFound, "库存不存在");
        }

        // 1.1 幂等处理：若提供键且锁记录不存在，直接视为已释放
        if (!string.IsNullOrWhiteSpace(request.IdempotencyKey))
        {
            var lockRecord = await inventoryRepository.FindLockByKeyAsync(tenantId, request.IdempotencyKey, cancellationToken);
            if (lockRecord is not null)
            {
                if (lockRecord.Status != Domain.Inventory.Enums.InventoryLockStatus.Locked)
                {
                    return InventoryMapping.ToDto(item);
                }

                // 将数量同步为锁记录数，避免重复释放不一致
                request = request with { Quantity = lockRecord.Quantity };
                await inventoryRepository.MarkLockStatusAsync(lockRecord, Domain.Inventory.Enums.InventoryLockStatus.Released, cancellationToken);
            }
        }

        // 2. 计算释放
        var isPresale = request.IsPresaleOrder || item.IsPresale;
        if (isPresale)
        {
            if (item.PresaleLocked < request.Quantity)
            {
                throw new BusinessException(ErrorCodes.Conflict, "预售锁定不足");
            }

            item.PresaleLocked -= request.Quantity;
        }
        else
        {
            if (item.QuantityReserved < request.Quantity)
            {
                throw new BusinessException(ErrorCodes.Conflict, "锁定库存不足");
            }

            item.QuantityReserved -= request.Quantity;
        }

        item.IsSoldOut = item.QuantityOnHand - item.QuantityReserved - item.PresaleLocked <= (item.SafetyStock ?? 0);
        await inventoryRepository.UpdateItemAsync(item, cancellationToken);
        await inventoryRepository.SaveChangesAsync(cancellationToken);
        logger.LogInformation("释放库存 门店 {StoreId} SKU {ProductSkuId} 数量 {Quantity}", request.StoreId, request.ProductSkuId, request.Quantity);
        return InventoryMapping.ToDto(item);
    }
}