example2

public class ClientReturnApiService : IClientReturnApiService
{
    private readonly IV2ReturnService _v2ReturnService;
    private readonly IItemsGateway _itemsGateway;

    private readonly IClientReturnMappingService _mappingService;

    public ClientReturnApiService(
        IV2ReturnService v2ReturnService,
        IItemsGateway itemsGateway,
        IClientReturnMappingService mappingService)
    {
        _mappingService = mappingService;
        _v2ReturnService = v2ReturnService;
        _itemsGateway = itemsGateway;
    }

    public async Task<ClientReturnResponse> GetByNumber(string returnNumber)
    {
        var clientReturn = await _v2ReturnService.GetClientReturn(returnNumber, true, true);

        return clientReturn != null
            ? _mappingService.ToClientReturnResponse(clientReturn)
            : null;
    }

    public async Task<ICollection<ReturnResponse>> GetReturns(long clientId)
    {
        var returns = await _v2ReturnService.GetClientReturns(clientId, true);

        return await Task.WhenAll(returns.Select(ToReturnResponse));
    }

    public async Task<ICollection<ClientReturnResponse>> GetClientReturns(long clientId)
    {
        var returns = await _v2ReturnService.GetClientReturns(clientId, true, true);

        return returns.Select(_mappingService.ToClientReturnResponse).ToArray();
    }

    private async Task<ReturnResponse> ToReturnResponse(ClientReturn clientReturn)
    {
        var items = await GetReturnItemResponses(clientReturn);

        var response = new ReturnResponse
        {
            Id = clientReturn.Id,
            Number = clientReturn.ReturnNumber,
            CreatedAt = clientReturn.Moment,
            Address = clientReturn.Address,
            TimeSlot = new ReturnTimeSlotResponse
            {
                DateFrom = clientReturn.DateFrom,
                DateTo = clientReturn.DateTo
            },
            Items = items,
            Type = clientReturn.Type,
            ClientType = clientReturn.Type.ToNamed(),
            IsDeletable = !_v2ReturnService.ValidateDelete(clientReturn).HasErrors,
            State = clientReturn.State.ToString(),
            ClientState = clientReturn.State.ToNamed(),
            RejectionComment = clientReturn.RejectionComment
        };

        return response;
    }

    private async Task<ReturnItemResponse[]> GetReturnItemResponses(ClientReturn clientReturn)
    {
        var returnItems = clientReturn.Items;

        var itemIds = returnItems.Select(x => x.ItemId).Distinct();

        var photos = returnItems.GroupBy(x => x.ItemId).ToDictionary(x => x.Key, x => x.SelectMany(y => y.Images.Select(z => z.Url)));

        return (await _itemsGateway.GetItemsInfoAndMerchant(itemIds)).Select(x => new ReturnItemResponse
        {
            Id = (int)x.Id,
            ImageUrl = x.Info?.CoverImage,
            Quantity = returnItems.Count(y => y.ItemId == x.Id),
            Photos = photos[x.Id].Distinct()
        }).ToArray();
    }
}