using System;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;
using FrameworkDAL.CustomCode.Promotion;
using GB5Shared.DTO.Framework.Login;
using GB5Shared.DTO.GOP;
using GB5Shared.DTO.Promotion;
using GB5Shared.Promotion;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;

namespace FrameworkBLL.GOP.Worker.NodeExecutors
{
    // ============================================================
    // PromotionIngestNodeExecutor — executes a "PromotionIngest" node type.
    //
    // Destination-side step of the Metadata Promotion flow. Input payload: the
    // PromotionBundleDTO produced by the origin's PromotionExport step, however
    // it physically arrived here (Tier 1 manual upload, Tier 2 Exchange, or
    // Tier 3 direct API — this executor doesn't care which).
    //
    // Re-runs validation independently — never trusts only the origin's copy —
    // and checks MPROMOTIONASSETLINK for a prior promotion of the same
    // (OriginEnvironmentCode, EntityTypeCode, OriginEntityId) triple, so a
    // re-promotion of an updated version is recognized as an update rather than
    // a duplicate. Output feeds GOP's built-in Approval gate next (a separate
    // flow step, NodeType="Approval" — GopExecutionPipeline pauses there before
    // ever dispatching to an INodeExecutor).
    // ============================================================
    public class PromotionIngestNodeExecutor : INodeExecutor
    {
        private readonly IServiceProvider _ServiceProvider;
        private readonly IPromotionAssetLinkDAL _AssetLinkDal;
        private readonly IConfiguration _Configuration;
        private readonly ILogger<PromotionIngestNodeExecutor> _Logger;

        public PromotionIngestNodeExecutor(
            IServiceProvider serviceProvider,
            IPromotionAssetLinkDAL assetLinkDal,
            IConfiguration configuration,
            ILogger<PromotionIngestNodeExecutor> logger)
        {
            _ServiceProvider = serviceProvider;
            _AssetLinkDal    = assetLinkDal;
            _Configuration   = configuration;
            _Logger          = logger;
        }

        public string NodeType => "PromotionIngest";

        public async Task<string?> ExecuteAsync(
            GopFlowSnapshotStepDTO step,
            GopExecutionHeaderDTO  header,
            string?                inputPayloadJson,
            LoginDTO               loginDTO,
            CancellationToken      ct)
        {
            if (string.IsNullOrWhiteSpace(inputPayloadJson))
                throw new InvalidOperationException("PromotionIngestNodeExecutor requires a bundle payload.");

            var bundle = JsonSerializer.Deserialize<PromotionBundleDTO>(inputPayloadJson)
                ?? throw new InvalidOperationException("Promotion bundle could not be parsed.");

            // Own environment identity is server-side config, never accepted from the
            // incoming payload — same rule GopQueueBLL.SubmitExecution already follows for
            // GOP:Environment.
            var thisEnvironmentCode = _Configuration["Promotion:OriginEnvironmentCode"];
            if (string.IsNullOrWhiteSpace(thisEnvironmentCode))
                _Logger.LogWarning(
                    "PromotionIngestNodeExecutor: execution {ExecutionId} — Promotion:OriginEnvironmentCode " +
                    "is not configured on this deployment.", header.ExecutionId);

            var entity = _ServiceProvider.GetKeyedService<IPromotableEntity>(bundle.EntityTypeCode)
                ?? throw new InvalidOperationException(
                    $"No IPromotableEntity registered for EntityTypeCode '{bundle.EntityTypeCode}'.");

            var validation = await entity.ValidateForPromotionAsync(bundle, ct).ConfigureAwait(false);
            if (!validation.IsPromotable)
            {
                var reasons = string.Join("; ", validation.BlockingReasons);
                _Logger.LogWarning(
                    "PromotionIngestNodeExecutor: execution {ExecutionId} blocked at ingest — {Reasons}",
                    header.ExecutionId, reasons);
                throw new InvalidOperationException($"Not promotable: {reasons}");
            }

            var existingLink = await _AssetLinkDal.GetByOrigin(
                bundle.OriginEnvironmentCode, bundle.EntityTypeCode, bundle.OriginEntityId,
                loginDTO, ct).ConfigureAwait(false);

            var result = new PromotionIngestResultDTO
            {
                Bundle                = bundle,
                ExistingDestinationId = existingLink?.DestinationEntityId,
                Validation            = validation
            };

            _Logger.LogInformation(
                "PromotionIngestNodeExecutor: execution {ExecutionId} ingested {EntityTypeCode}/{OriginEntityId} " +
                "from {OriginEnvironmentCode} — isUpdate={IsUpdate}",
                header.ExecutionId, bundle.EntityTypeCode, bundle.OriginEntityId,
                bundle.OriginEnvironmentCode, result.IsUpdateToExistingAsset);

            return JsonSerializer.Serialize(result);
        }
    }
}