using System.Threading;
using System.Threading.Tasks;
using GB5Shared.DTO.Framework.Login;
using GB5Shared.DTO.GOP;
using Microsoft.Extensions.Logging;

namespace FrameworkBLL.GOP.Worker.NodeExecutors
{
    // ============================================================
    // MapperNodeExecutor — executes a Mapper node type.
    //
    // Delegates to IMappingEngineBLL to transform the input payload
    // using the mapping definition referenced by the step's
    // LogicalServiceName (treated as the MapperCode).
    //
    // Returns the transformed payload JSON.
    // Phase 4 upgrades MappingEngineBLL to support [FactBag] paths.
    // ============================================================
    public class MapperNodeExecutor : INodeExecutor
    {
        private readonly IMappingEngineBLL          _MappingEngine;
        private readonly ILogger<MapperNodeExecutor> _Logger;

        public MapperNodeExecutor(
            IMappingEngineBLL            mappingEngine,
            ILogger<MapperNodeExecutor>  logger)
        {
            _MappingEngine = mappingEngine;
            _Logger        = logger;
        }

        public string NodeType => "Mapper";

        public async Task<string?> ExecuteAsync(
            GopFlowSnapshotStepDTO step,
            GopExecutionHeaderDTO  header,
            string?                inputPayloadJson,
            LoginDTO               loginDTO,
            CancellationToken      ct)
        {
            _Logger.LogDebug(
                "MapperNodeExecutor: execution {ExecutionId} step {NodeCode}",
                header.ExecutionId, step.NodeCode);

            // IMappingEngineBLL.TransformAsync accepts the mapper code + source payload JSON.
            // Phase 4 will add [FactBag] path resolution to the engine.
            var result = await _MappingEngine.TransformAsync(
                step.LogicalServiceName,   // MapperCode stored in LogicalServiceName
                inputPayloadJson ?? "{}",
                loginDTO,
                ct);

            _Logger.LogDebug(
                "MapperNodeExecutor: execution {ExecutionId} step {NodeCode} complete",
                header.ExecutionId, step.NodeCode);

            return result;
        }
    }
}