using System.Runtime.CompilerServices;
using GB5Shared.DTO.Framework.Criteria;
using GB5Shared.DTO.Framework.Login;
using GB5Shared.QueryExecutor;
using GB5Shared.Telemetry;
using RecruitmentDAL.CustomeCode.Reports.ApplicationCycleTime;
using RecruitmentDAL.DTO.Reports;

namespace RecruitmentBLL.Reports.ApplicationCycleTime
{
    // Phase 5 analytics — cycle-time report. CriteriaDTO.Id doubles as an optional
    // JobRequisitionId filter (GB5's own "0/<=0 = unset" sentinel convention — see
    // CandidateConversionBLL's request-field validation for the same "-1 = unset" style used
    // elsewhere in this module); a caller who wants every requisition for the tenant simply omits
    // it / leaves it 0.
    public class ApplicationCycleTimeBLL : IApplicationCycleTimeBLL
    {
        private const int DEFAULT_MAX_RESULT_CAP = 500;

        private readonly IApplicationCycleTimeDAL _dal;

        public ApplicationCycleTimeBLL(IApplicationCycleTimeDAL dal)
        {
            _dal = dal;
        }

        public async Task<PagedResult<ApplicationCycleTimeDTO>> GetApplicationCycleTime(
            int firstNumber, int maxResult, CriteriaDTO? criteriaDTO, LoginDTO login, CancellationToken ct)
        {
            try
            {
                var jobRequisitionId = ResolveJobRequisitionIdFilter(criteriaDTO);
                var cappedMaxResult = maxResult > 0 ? Math.Min(maxResult, DEFAULT_MAX_RESULT_CAP) : DEFAULT_MAX_RESULT_CAP;

                GB5Trace.Step("query-application-cycle-time", new { firstNumber, cappedMaxResult, jobRequisitionId });
                return await _dal.GetApplicationCycleTime(firstNumber, cappedMaxResult, jobRequisitionId, login, ct).ConfigureAwait(false);
            }
            catch (Exception ex)
            {
                GB5Trace.MarkFailed("application-cycle-time-failed", ex);
                throw;
            }
        }

        public async IAsyncEnumerable<ApplicationCycleTimeDTO> GetApplicationCycleTimeStream(
            int firstNumber, int maxResult, CriteriaDTO? criteriaDTO, LoginDTO login,
            [EnumeratorCancellation] CancellationToken ct)
        {
            var jobRequisitionId = ResolveJobRequisitionIdFilter(criteriaDTO);
            GB5Trace.Step("stream-application-cycle-time", new { firstNumber, maxResult, jobRequisitionId });

            await foreach (var row in _dal.GetApplicationCycleTimeStream(jobRequisitionId, login, ct).ConfigureAwait(false))
                yield return row;
        }

        private static int? ResolveJobRequisitionIdFilter(CriteriaDTO? criteriaDTO)
            => criteriaDTO != null && criteriaDTO.Id > 0 ? criteriaDTO.Id : null;
    }
}