using FastEndpoints;
using GB5Shared.DTO.Framework.Criteria;
using GB5Shared.DTO.Framework.Login;
using GB5Shared.DTO.Framework.ResponseStandard;
using GB5Shared.FastEndPoint;
using PayRollBLL.Periodic;
using System.IO;
using static GB5Shared.GB5Constant.Constant;

namespace PayRollSL.EndPoints.Periodic
{
    // GB4: Periodic.svc/Periodic/Service/Based/Export — IPeriodic.cs WebInvoke attribute:
    // [OperationContract(Name = "PeriodicServiceBasedExport")]
    // UriTemplate = "/Periodic/Service/Based/Export/?PayPeriodId={PayPeriodId}", Method = "POST"
    // → Periodic.svc.cs delegates to a SEPARATE class, DumpPerodicServiceBased (not PeriodicBLL).
    // Called with BOTH real PayPeriodIds and a -1 sentinel by different GB4 callers — same
    // operation both times, no branching here; -1 only matters at the SQL/data level (see
    // PeriodicQB.BuildPeriodicServiceBasedExport's GB4-parity note: there is no -1 wildcard
    // bypass in GB4's underlying query, so a genuine MPAYPERIOD row with PAYPERIODID=-1 must
    // exist in this database for the -1 case to return any data — a pre-existing data
    // dependency, not something introduced or fixed by this migration).
    //
    // GB4 returned Base64-encoded .xlsx bytes as a JSON string body (it wrote the file to disk
    // first, purely as an artifact of returning a "file" through a WCF string). GB5 modernizes
    // this to a real binary file-download response — see PeriodicBLL.PeriodicServiceBasedExport
    // for the full note — following the same HttpContext.Response.SendStreamAsync precedent
    // already established by TMSSL.EndPoints.Certificate.DownloadCertificate (BaseEndpoint's
    // ExecuteAsync contract is fixed to ResponseStandardDTO<object>, so binary downloads write
    // directly to the response and return null!, rather than returning IResult).
    public class PeriodicServiceBasedExport
        : BaseEndpoint<PeriodicServiceBasedExport.Parameters, ResponseStandardDTO<object>>
    {
        private readonly IPeriodicBLL _PeriodicBLL;

        public PeriodicServiceBasedExport(IPeriodicBLL PeriodicBLL)
        {
            _PeriodicBLL = PeriodicBLL;
        }

        public override void Configure()
        {
            Post("/Periodic/Service/Based/Export");
            AllowAnonymous();
        }

        public record Parameters(
            [property: FromHeader] string Login,
            [property: FromBody] CriteriaDTO CriteriaDTO,
            [property: QueryParam] int PayPeriodId
        );

        // Binary export — never cached (matches every other Export* endpoint convention).
        protected override string? GetCacheKey(Parameters req, LoginDTO login) => null;

        protected override async Task<ResponseStandardDTO<object>> ExecuteAsync(
            Parameters req, LoginDTO loginDTO, CancellationToken ct)
        {
            using var ms = new MemoryStream();

            try
            {
                await _PeriodicBLL.PeriodicServiceBasedExport(req.PayPeriodId, req.CriteriaDTO, loginDTO, ms, ct);
            }
            catch (Exception ex)
            {
                return await GB5Shared.ResponseStandard.Response.CreateExceptionError<string>(
                    ex, CacheKeyLevel.NOT_REQUIRED, loginDTO, ex.Message, 500);
            }

            // ── Stream — no more error returns after this point ─────────────────────────
            ms.Position = 0;
            string fileName = $"PeriodicServiceBased_{DateTime.UtcNow:yyyyMMddHHmmss}.xlsx";
            const string contentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";

            await HttpContext.Response.SendStreamAsync(ms, fileName, ms.Length, contentType, cancellation: ct);
            return null!;
        }
    }
}