using System;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;
using FrameworkBLL.Promotion;
using GB5Shared.DTO.Framework.Login;
using GB5Shared.DTO.GOP;
using Microsoft.Extensions.Logging;

namespace FrameworkBLL.GOP.Worker.NodeExecutors
{
    // ============================================================
    // PromotionExportNodeExecutor — executes a "PromotionExport" node type.
    //
    // NOT the primary export path — the "Export Package" HTTP endpoint calls
    // IPromotionBLL.BuildExportBundleAsync directly and synchronously, because a
    // file-download response needs its result immediately and GOP execution is
    // deliberately async/queued (GopQueueBLL.SubmitExecution enqueues and
    // returns; a background worker runs it later). This node type is kept as a
    // valid, DI-registered GOP step for a possible future scheduled/automated
    // export trigger, delegating to the same IPromotionBLL logic so there is
    // exactly one implementation of "resolve entity + export + validate," not
    // two. See /Users/venkatv/.claude/plans/as-part-of-developement-indexed-stonebraker.md.
    //
    // Input payload: {"EntityTypeCode":"MENU","OriginEntityId":123}.
    // Output payload: the serialized PromotionBundleDTO.
    // ============================================================
    public class PromotionExportNodeExecutor : INodeExecutor
    {
        private readonly IPromotionBLL _PromotionBLL;
        private readonly ILogger<PromotionExportNodeExecutor> _Logger;

        public PromotionExportNodeExecutor(
            IPromotionBLL promotionBLL,
            ILogger<PromotionExportNodeExecutor> logger)
        {
            _PromotionBLL = promotionBLL;
            _Logger       = logger;
        }

        public string NodeType => "PromotionExport";

        private class ExportRequest
        {
            public string EntityTypeCode { get; set; } = string.Empty;
            public int    OriginEntityId { get; set; }
        }

        public async Task<string?> ExecuteAsync(
            GopFlowSnapshotStepDTO step,
            GopExecutionHeaderDTO  header,
            string?                inputPayloadJson,
            LoginDTO               loginDTO,
            CancellationToken      ct)
        {
            if (string.IsNullOrWhiteSpace(inputPayloadJson))
                throw new InvalidOperationException(
                    "PromotionExportNodeExecutor requires an input payload with EntityTypeCode/OriginEntityId.");

            var request = JsonSerializer.Deserialize<ExportRequest>(inputPayloadJson)
                ?? throw new InvalidOperationException("PromotionExport payload could not be parsed.");

            _Logger.LogDebug(
                "PromotionExportNodeExecutor: execution {ExecutionId} exporting {EntityTypeCode}/{OriginEntityId}",
                header.ExecutionId, request.EntityTypeCode, request.OriginEntityId);

            // Permanent failures (validation blocks) propagate as-is — this flow step's config
            // should set MaxRetries=0 so GOP doesn't waste attempts re-running the same validation.
            var bundle = await _PromotionBLL.BuildExportBundleAsync(
                request.EntityTypeCode, request.OriginEntityId, loginDTO, ct).ConfigureAwait(false);

            _Logger.LogDebug(
                "PromotionExportNodeExecutor: execution {ExecutionId} export complete for {EntityTypeCode}/{OriginEntityId}",
                header.ExecutionId, request.EntityTypeCode, request.OriginEntityId);

            return JsonSerializer.Serialize(bundle);
        }
    }
}