using FrameworkBLL.AuditQuery;
using FrameworkDAL.CustomCode.Archive;
using GB5Shared.DTO.Framework.Login;
using GB5Shared.QueryExecutor;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using System;
using System.Threading;
using System.Threading.Tasks;

namespace FrameworkBLL.Archive
{
    public sealed class EventLogArchiveBLL : IEventLogArchiveBLL
    {
        private readonly IEventLogArchiveDAL        _dal;
        private readonly IQueryExecutor             _qe;
        private readonly IOptions<ArchiveSettings>  _settings;
        private readonly ILogger<EventLogArchiveBLL> _logger;

        public EventLogArchiveBLL(
            IEventLogArchiveDAL dal,
            IQueryExecutor qe,
            IOptions<ArchiveSettings> settings,
            ILogger<EventLogArchiveBLL> logger)
        {
            _dal      = dal;
            _qe       = qe;
            _settings = settings;
            _logger   = logger;
        }

        public async Task ArchiveForTenantAsync(LoginDTO login, CancellationToken ct = default)
        {
            var retentionMonths = _settings.Value.RetentionMonths;
            var cutoffDate      = DateTime.UtcNow.AddMonths(-retentionMonths);

            _logger.LogInformation(
                "EventLogArchive: starting for TenantId={TenantId} CutoffDate={CutoffDate} RetentionMonths={Months}",
                login.ClientId, cutoffDate, retentionMonths);

            // Stats before
            var (hotBefore, archiveBefore) = await _dal.GetStatsAsync(login, ct).ConfigureAwait(false);
            _logger.LogInformation(
                "EventLogArchive: before — hot={Hot} archive={Archive} TenantId={TenantId}",
                hotBefore, archiveBefore, login.ClientId);

            // Move + delete in a single transaction
            var tx = await _qe.BeginTransactionAsync(login).ConfigureAwait(false);
            try
            {
                await _dal.MoveToArchiveAsync(cutoffDate, login, tx, ct).ConfigureAwait(false);
                await _dal.DeleteHotRowsAsync(cutoffDate, login, tx, ct).ConfigureAwait(false);
                await _qe.CommitAsync(tx).ConfigureAwait(false);
            }
            catch
            {
                await _qe.RollbackAsync(tx).ConfigureAwait(false);
                throw;
            }

            // Stats after
            var (hotAfter, archiveAfter) = await _dal.GetStatsAsync(login, ct).ConfigureAwait(false);
            _logger.LogInformation(
                "EventLogArchive: done — hot={Hot} archive={Archive} moved={Moved} TenantId={TenantId}",
                hotAfter, archiveAfter, hotBefore - hotAfter, login.ClientId);
        }
    }
}