using Api.SeaHavenIndustries.Observability;
using Microsoft.Extensions.Options;
using SeaHaven.Services.Configuration;
using SeaHaven.Services.Interfaces;
using Sentry;

namespace Api.SeaHavenIndustries.HostedServices
{
    public sealed class WorkOrderReconciliationHostedService : BackgroundService
    {
        private readonly IServiceScopeFactory _scopeFactory;
        private readonly IOptionsMonitor<WorkOrderReconciliationOptions> _options;
        private readonly TimeProvider _timeProvider;
        private readonly ILogger<WorkOrderReconciliationHostedService> _logger;
        private readonly IHub _sentryHub;

        public WorkOrderReconciliationHostedService(
            IServiceScopeFactory scopeFactory,
            IOptionsMonitor<WorkOrderReconciliationOptions> options,
            TimeProvider timeProvider,
            ILogger<WorkOrderReconciliationHostedService> logger,
            IHub sentryHub)
        {
            _scopeFactory = scopeFactory;
            _options = options;
            _timeProvider = timeProvider;
            _logger = logger;
            _sentryHub = sentryHub;
        }

        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            var nextScheduledAt = _timeProvider.GetUtcNow();
            if (_options.CurrentValue.Enabled && _options.CurrentValue.RunOnStartup)
            {
                await TriggerAsync("startup", stoppingToken);
                nextScheduledAt = _timeProvider.GetUtcNow().AddMinutes(_options.CurrentValue.ScheduleMinutes);
            }

            while (!stoppingToken.IsCancellationRequested)
            {
                var options = _options.CurrentValue;
                if (options.Enabled)
                {
                    var now = _timeProvider.GetUtcNow();
                    if (now >= nextScheduledAt)
                    {
                        await TriggerAsync("schedule", stoppingToken);
                        nextScheduledAt = now.AddMinutes(options.ScheduleMinutes);
                    }

                    await RunPendingAsync(stoppingToken);
                }

                await Task.Delay(
                    TimeSpan.FromSeconds(Math.Clamp(options.PollSeconds, 1, 300)),
                    _timeProvider,
                    stoppingToken);
            }
        }

        private async Task TriggerAsync(string reason, CancellationToken cancellationToken)
        {
            using var transaction = SentryObservability.BeginBackgroundTransaction(
                _sentryHub,
                "workorders.reconciliation-trigger",
                $"{nameof(WorkOrderReconciliationHostedService)}.{nameof(TriggerAsync)}",
                description: reason);
            try
            {
                await using var scope = _scopeFactory.CreateAsyncScope();
                var runner = scope.ServiceProvider.GetRequiredService<IWorkOrderReconciliationRunner>();
                await runner.TriggerAsync(reason, cancellationToken);
                transaction.FinishOk();
            }
            catch (OperationCanceledException)
            {
                transaction.FinishCancelled();
                throw;
            }
            catch (Exception ex) when (ex is not OperationCanceledException)
            {
                _logger.LogError(ex, "Could not queue procurement reconciliation.");
                transaction.FinishError(ex);
            }
        }

        private async Task RunPendingAsync(CancellationToken cancellationToken)
        {
            using var transaction = SentryObservability.BeginBackgroundTransaction(
                _sentryHub,
                "workorders.reconciliation-run-pending",
                $"{nameof(WorkOrderReconciliationHostedService)}.{nameof(RunPendingAsync)}");
            try
            {
                await using var scope = _scopeFactory.CreateAsyncScope();
                var runner = scope.ServiceProvider.GetRequiredService<IWorkOrderReconciliationRunner>();
                await runner.RunPendingAsync(cancellationToken);
                transaction.FinishOk();
            }
            catch (OperationCanceledException)
            {
                transaction.FinishCancelled();
                throw;
            }
            catch (Exception ex) when (ex is not OperationCanceledException)
            {
                _logger.LogError(ex, "Could not execute procurement reconciliation.");
                transaction.FinishError(ex);
            }
        }
    }
}