using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using PnvPanel.Application.Common.Interfaces;
using PnvPanel.Domain.Nodes;
using PnvPanel.Infrastructure.Persistence;

namespace PnvPanel.Infrastructure.BackgroundJobs;

public sealed class NodeHealthCheckService(
    IServiceScopeFactory scopeFactory,
    ILogger<NodeHealthCheckService> logger
) : BackgroundService
{
    private static readonly TimeSpan Interval = TimeSpan.FromMinutes(2);

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        using var timer = new PeriodicTimer(Interval);
        do
        {
            try
            {
                await CheckAllAsync(stoppingToken);
            }
            catch (Exception ex)
            {
                logger.LogError(ex, "Node health-check failed");
            }
        } while (await timer.WaitForNextTickAsync(stoppingToken));
    }

    private async Task CheckAllAsync(CancellationToken cancellationToken)
    {
        await using var scope = scopeFactory.CreateAsyncScope();
        var dbContext = scope.ServiceProvider.GetRequiredService<AppDbContext>();
        var gateway = scope.ServiceProvider.GetRequiredService<IXuiPanelGateway>();
        var notifier = scope.ServiceProvider.GetRequiredService<IRealtimeNotifier>();

        var nodes = await dbContext.Nodes.Where(n => n.IsEnabled).ToListAsync(cancellationToken);

        foreach (var node in nodes)
        {
            var probe = await gateway.ProbeAsync(node, cancellationToken);
            var newStatus = probe.IsReachable ? NodeStatus.Online : NodeStatus.Offline;

            if (node.Status != newStatus)
            {
                node.UpdateStatus(newStatus);
                await notifier.NotifyNodeStatusChangedAsync(
                    node.Id,
                    newStatus,
                    node.LastSyncAt,
                    cancellationToken
                );
            }
        }

        await dbContext.SaveChangesAsync(cancellationToken);
    }
}