using Microsoft.Extensions.Caching.Memory;

namespace MesaFabApproval.API.Services;

public interface IECNService {
    Task<bool> IsValidECNNumber(int number);
}

public class ECNService : IECNService {
    private readonly ILogger<ECNService> _logger;
    private readonly IMemoryCache _cache;
    private readonly IDalService _dalService;

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

    public async Task<bool> IsValidECNNumber(int number) {
        try {
            _logger.LogInformation($"Attempting to determine if {number} is a valid ECN#");

            if (number <= 0) return false;

            IEnumerable<int> ecnNumbers = _cache.Get<IEnumerable<int>>("ecnNumbers") ?? new HashSet<int>();

            if (ecnNumbers.Contains(number)) return true;

            string sql = $"select count(ECNNumber) as count from ECN where ECNNumber={number}";

            int rowsReturned = (await _dalService.QueryAsync<int>(sql)).FirstOrDefault();

            if (rowsReturned > 0) {
                ecnNumbers.Append(number);
                _cache.Set("ecnNumbers", ecnNumbers);
                return true;
            }

            return false;
        } catch (Exception ex) {
            _logger.LogError($"Unable to determine if {number} is a valid ECN#, because {ex.Message}");
            throw;
        }
    }
}