using System;
using System.Collections.Generic;
using System.Runtime.CompilerServices;
using System.Threading;
using System.Threading.Tasks;
using GB5Shared.DTO.Framework.Criteria;
using GB5Shared.DTO.Framework.Login;
using GB5Shared.QueryExecutor;
using GB5Shared.Telemetry;
using RecruitmentDAL.DTO.Reports;
using RecruitmentDAL.Reports;

namespace RecruitmentBLL.Reports
{
    // Recruiter workload/productivity dashboard (Phase 5 of the Recruitment build-out plan) — the
    // operational "what's on my plate" view: open requisitions, pending applications, and
    // requisitions closed in a date range, grouped by TJOBREQUISITION.ASSIGNEDRECRUITERID.
    // Live transactional analytics — CacheKeyLevel.NOT_REQUIRED at the endpoint, never cached, per
    // CLAUDE.md's caching anti-pattern guidance.
    public class RecruiterWorkloadReportBLL : IRecruiterWorkloadReportBLL
    {
        private const int DEFAULT_MAX_RESULT_CAP = 500;

        private readonly IRecruiterWorkloadReportDAL _dal;

        public RecruiterWorkloadReportBLL(IRecruiterWorkloadReportDAL dal)
        {
            _dal = dal;
        }

        public async Task<PagedResult<RecruiterWorkloadDTO>> GetRecruiterWorkload(
            int firstNumber, int maxResult, CriteriaDTO criteriaDTO, LoginDTO login, CancellationToken ct)
        {
            try
            {
                GB5Trace.Step("parse-criteria-recruiter-workload", new { firstNumber, maxResult });
                var criteria = RecruitmentReportCriteriaParser.Parse(criteriaDTO);
                var cappedMaxResult = maxResult > 0 ? Math.Min(maxResult, DEFAULT_MAX_RESULT_CAP) : DEFAULT_MAX_RESULT_CAP;

                GB5Trace.Step("query-recruiter-workload", new { firstNumber, cappedMaxResult });
                return await _dal.GetRecruiterWorkload(firstNumber, cappedMaxResult, criteria, login, ct).ConfigureAwait(false);
            }
            catch (Exception ex)
            {
                GB5Trace.MarkFailed("recruiter-workload-failed", ex);
                throw;
            }
        }

        public async IAsyncEnumerable<RecruiterWorkloadDTO> GetRecruiterWorkloadStream(
            int firstNumber, int maxResult, CriteriaDTO criteriaDTO, LoginDTO login,
            [EnumeratorCancellation] CancellationToken ct)
        {
            GB5Trace.Step("stream-recruiter-workload", new { firstNumber, maxResult });
            var criteria = RecruitmentReportCriteriaParser.Parse(criteriaDTO);
            var cappedMaxResult = maxResult > 0 ? Math.Min(maxResult, DEFAULT_MAX_RESULT_CAP) : DEFAULT_MAX_RESULT_CAP;

            await foreach (var row in _dal.GetRecruiterWorkloadStream(firstNumber, cappedMaxResult, criteria, login, ct).ConfigureAwait(false))
                yield return row;
        }
    }
}