using System;
using System.Data.Common;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using GB5Shared.Attachment;
using GB5Shared.DTO.Framework.Login;
using GB5Shared.FileUpload;
using Microsoft.Extensions.Logging;
using AttachmentResolutionEnvelope = FrameworkDAL.DTO.ECM.AttachmentResolutionEnvelope;

namespace FrameworkBLL.Attachment
{
    public class AttachmentResolutionService : IAttachmentResolutionService
    {
        private readonly IAttachmentDAL                          _attachmentDAL;
        private readonly IAttachmentPathResolutionService        _pathResolution;
        private readonly ILogger<AttachmentResolutionService>    _logger;

        public AttachmentResolutionService(
            IAttachmentDAL                       attachmentDAL,
            IAttachmentPathResolutionService     pathResolution,
            ILogger<AttachmentResolutionService> logger)
        {
            _attachmentDAL  = attachmentDAL;
            _pathResolution = pathResolution;
            _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;

            await _attachmentDAL
                .BulkResolveObjectIdAsync(valid, login, tx, ct)
                .ConfigureAwait(false);

            // Phase 2: move deferred attachment files to their real ObjectId paths
            if (envelope.ObjectHeaderTypeId > 0 && envelope.HeaderRowGuid != Guid.Empty)
            {
                await _pathResolution
                    .ResolvePhase2Async(envelope.ObjectHeaderTypeId, envelope.HeaderRowGuid, login, tx, ct)
                    .ConfigureAwait(false);
            }

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