using System;
using System.Data.Common;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using GB5Shared.DTO.Framework.Login;
using GB5Shared.QueryExecutor;
using Microsoft.Extensions.Logging;

namespace GB5Shared.FileUpload
{
    public class AttachmentResolutionService : IAttachmentResolutionService
    {
        private readonly IQueryExecutor                          _qe;
        private readonly ILogger<AttachmentResolutionService>   _logger;

        // UPDATE TATTACHMENT — set real ObjectId, clear TempRefKey.
        // Keyed on AttachmentId (returned from the upload response).
        private const string RESOLVE_OBJECTID = @"
            UPDATE TATTACHMENT SET
                OBJECTID             = @ObjectId,
                OBJECTTYPEID         = @ObjectTypeId,
                BIZTRANSACTIONTYPEID = @BizTransactionTypeId,
                TEMPREFKEY           = NULL,
                MODIFIEDBYID         = @ModifiedById,
                MODIFIEDON           = GETUTCDATE()
            WHERE ATTACHMENTID = @AttachmentId;";

        public AttachmentResolutionService(
            IQueryExecutor                        qe,
            ILogger<AttachmentResolutionService>  logger)
        {
            _qe     = qe;
            _logger = logger;
        }

        public async Task ResolveHeaderAsync(
            AttachmentResolutionEnvelope envelope,
            int                          entityId,
            LoginDTO                     login,
            DbTransaction                tx,
            CancellationToken            ct = default)
        {
            foreach (var mapping in envelope.LevelMappings)
                mapping.ObjectId = entityId;

            await ResolveAsync(envelope, login, tx, ct).ConfigureAwait(false);
        }

        public async Task ResolveAsync(
            AttachmentResolutionEnvelope envelope,
            LoginDTO                     login,
            DbTransaction                tx,
            CancellationToken            ct = default)
        {
            if (envelope is null)
                throw new ArgumentNullException(nameof(envelope));

            var valid = envelope.LevelMappings
                .Where(m => m.ObjectId > 0 && m.AttachmentIds.Count > 0)
                .ToList();

            if (valid.Count == 0)
                return;

            foreach (var map in valid)
            {
                foreach (var attachmentId in map.AttachmentIds)
                {
                    await _qe.ExecuteAsync(
                        login,
                        RESOLVE_OBJECTID,
                        new
                        {
                            AttachmentId         = attachmentId,
                            map.ObjectId,
                            map.ObjectTypeId,
                            map.BizTransactionTypeId,
                            ModifiedById         = login.UserId
                        },
                        tx).ConfigureAwait(false);
                }
            }

            _logger.LogInformation(
                "AttachmentResolution: resolved {Count} level(s) for user {UserId}",
                valid.Count, login.UserId);
        }
    }
}