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

namespace RecruitmentBLL.Reports.PipelineConversionFunnel
{
    // Phase 5 analytics — pipeline-conversion (funnel) report. CriteriaDTO.Id doubles as an
    // optional SelectionProcessTemplateId filter (same "0/<=0 = unset" convention as
    // ApplicationCycleTimeBLL's JobRequisitionId filter) — a caller who wants every template's
    // funnel for the tenant simply omits it / leaves it 0.
    public class PipelineConversionFunnelBLL : IPipelineConversionFunnelBLL
    {
        private const int DEFAULT_MAX_RESULT_CAP = 500;

        private readonly IPipelineConversionFunnelDAL _dal;

        public PipelineConversionFunnelBLL(IPipelineConversionFunnelDAL dal)
        {
            _dal = dal;
        }

        public async Task<PagedResult<PipelineConversionFunnelDTO>> GetPipelineConversionFunnel(
            int firstNumber, int maxResult, CriteriaDTO? criteriaDTO, LoginDTO login, CancellationToken ct)
        {
            try
            {
                var selectionProcessTemplateId = ResolveTemplateIdFilter(criteriaDTO);
                var cappedMaxResult = maxResult > 0 ? Math.Min(maxResult, DEFAULT_MAX_RESULT_CAP) : DEFAULT_MAX_RESULT_CAP;

                GB5Trace.Step("query-pipeline-conversion-funnel", new { firstNumber, cappedMaxResult, selectionProcessTemplateId });
                return await _dal.GetPipelineConversionFunnel(firstNumber, cappedMaxResult, selectionProcessTemplateId, login, ct).ConfigureAwait(false);
            }
            catch (Exception ex)
            {
                GB5Trace.MarkFailed("pipeline-conversion-funnel-failed", ex);
                throw;
            }
        }

        public async IAsyncEnumerable<PipelineConversionFunnelDTO> GetPipelineConversionFunnelStream(
            int firstNumber, int maxResult, CriteriaDTO? criteriaDTO, LoginDTO login,
            [EnumeratorCancellation] CancellationToken ct)
        {
            var selectionProcessTemplateId = ResolveTemplateIdFilter(criteriaDTO);
            GB5Trace.Step("stream-pipeline-conversion-funnel", new { firstNumber, maxResult, selectionProcessTemplateId });

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

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