using FastEndpoints;
using GB5Shared.DTO.Framework.Login;
using GB5Shared.DTO.Framework.ResponseStandard;
using GB5Shared.FastEndPoint;
using PayRollBLL.SAP;
using System;
using System.IO;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using static GB5Shared.GB5Constant.Constant;

namespace PayRollSL.EndPoints.SAP
{
    /// <summary>
    /// GET /SAP/DownloadITDeclarationJson
    /// Streams a JSON file download for a single SAP infotype.
    /// Requires Infotype parameter (580–586).
    /// </summary>
    public class DownloadITDeclarationJson
        : BaseEndpoint<DownloadITDeclarationJson.DownloadITDeclarationJsonParameters, ResponseStandardDTO<object>>
    {
        private readonly IITDeclarationSapBLL _bll;

        public DownloadITDeclarationJson(IITDeclarationSapBLL bll) => _bll = bll;

        public override void Configure()
        {
            Get("/SAP/DownloadITDeclarationJson");
            AllowAnonymous();
        }

        public record DownloadITDeclarationJsonParameters(
            [property: FromHeader] string Login,
            [property: QueryParam] int DeclarationId,
            [property: QueryParam] int EmployeeId,
            [property: QueryParam] int PeriodId,
            [property: QueryParam] int Infotype,       // required: 580–586
            [property: QueryParam] string? Date,
            [property: QueryParam] string? Remarks
        );

        protected override string? GetCacheKey(DownloadITDeclarationJsonParameters req, LoginDTO login) => null;

        protected override async Task<ResponseStandardDTO<object>> ExecuteAsync(
            DownloadITDeclarationJsonParameters req,
            LoginDTO login,
            CancellationToken ct)
        {
            try
            {
                if (req.Infotype == 0)
                    throw new ArgumentException("Infotype must be specified (580–586) for download.");

                string date = string.IsNullOrWhiteSpace(req.Date)
                    ? DateTime.Today.ToString("dd.MM.yyyy")
                    : req.Date;

                var payloads = await _bll.GenerateSapPayloadsAsync(
                    req.DeclarationId,
                    req.EmployeeId,
                    req.PeriodId,
                    req.Infotype,
                    date,
                    req.Remarks ?? string.Empty,
                    login,
                    ct);

                string json = payloads.TryGetValue(req.Infotype, out var j) ? j : "{}";
                string fileName = $"ITDeclaration_{req.Infotype}_{DateTime.Today:yyyyMMdd}.json";

                using var ms = new MemoryStream(Encoding.UTF8.GetBytes(json));
                await Send.StreamAsync(
                    ms,
                    contentType: "application/json",
                    fileName: fileName,
                    cancellation: ct);

                return default!;   // response already sent via stream
            }
            catch (Exception ex)
            {
                return await GB5Shared.ResponseStandard.Response
                    .CreateExceptionError<string>(ex, CacheKeyLevel.NOT_REQUIRED, login, ex.Message, 500);
            }
        }
    }
}