mesa-fab-approval/MesaFabApproval.API/Services/CustomerService.cs

using Microsoft.Extensions.Caching.Memory;

namespace MesaFabApproval.API.Services;

public interface ICustomerService {
    Task<IEnumerable<string>> GetCustomerNames();
}

public class CustomerService : ICustomerService {
    private readonly ILogger<CustomerService> _logger;
    private readonly IDalService _dalService;
    private readonly IMemoryCache _cache;

    public CustomerService(ILogger<CustomerService> logger, IDalService dalService, IMemoryCache cache) {
        _logger = logger ?? throw new ArgumentNullException("ILogger not injected");
        _dalService = dalService ?? throw new ArgumentNullException("IDalService not injected");
        _cache = cache ?? throw new ArgumentNullException("IMemoryCache not injected");
    }

    public async Task<IEnumerable<string>> GetCustomerNames() {
        try {
            _logger.LogInformation("Attempting to get customer names");

            IEnumerable<string>? customerNames = _cache.Get<IEnumerable<string>>("allCustomerNames");

            if (customerNames is null) {
                string sql = "select ProductFamily from ProductFamilies;";

                customerNames = (await _dalService.QueryAsync<string>(sql)).ToList();
            }

            return customerNames;
        } catch (Exception ex) {
            _logger.LogError($"Unable to get customer names, because {ex.Message}");
            throw;
        }
    }
}