using System.Text;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using MotoresArgentinosV2.Core.Entities;
using MotoresArgentinosV2.Infrastructure.Data;

namespace MotoresArgentinosV2.Infrastructure.Services;

/// <summary>
/// Servicio de fondo que genera sitemap.xml dinámicamente.
/// Ejecuta al iniciar la app y luego cada 6 horas.
/// Incluye rutas estáticas del frontend + vehículos activos.
/// </summary>
public class SitemapGeneratorService : BackgroundService
{
    private readonly IServiceProvider _serviceProvider;
    private readonly ILogger<SitemapGeneratorService> _logger;
    private static readonly TimeSpan Interval = TimeSpan.FromHours(6);

    private const string BaseUrl = "https://motoresargentinos.com";

    // Rutas estáticas públicas del frontend con sus prioridades
    private static readonly (string Path, string Priority, string ChangeFreq)[] StaticRoutes =
    [
        ("/",           "1.0", "daily"),
        ("/explorar",   "0.8", "daily"),
        ("/publicar",   "0.6", "monthly"),
        ("/vender",     "0.6", "monthly"),
        ("/condiciones","0.3", "yearly"),
    ];

    public SitemapGeneratorService(IServiceProvider serviceProvider, ILogger<SitemapGeneratorService> logger)
    {
        _serviceProvider = serviceProvider;
        _logger = logger;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        _logger.LogInformation("SitemapGeneratorService iniciado.");

        while (!stoppingToken.IsCancellationRequested)
        {
            try
            {
                await GenerateSitemapAsync();
            }
            catch (OperationCanceledException)
            {
                break;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error generando sitemap.");
            }

            await Task.Delay(Interval, stoppingToken);
        }
    }

    private async Task GenerateSitemapAsync()
    {
        using var scope = _serviceProvider.CreateScope();
        var context = scope.ServiceProvider.GetRequiredService<MotoresV2DbContext>();
        var config = scope.ServiceProvider.GetRequiredService<IConfiguration>();

        // Ruta de salida: configurable para Docker (volumen compartido) o dev local
        var outputPath = config["AppSettings:SitemapOutputPath"] ?? Path.Combine("wwwroot", "sitemap.xml");

        // Obtener todos los avisos activos
        var activeAds = await context.Ads
            .AsNoTracking()
            .Where(a => a.StatusID == (int)AdStatusEnum.Active)
            .Select(a => new { a.AdID, a.PublishedAt })
            .ToListAsync();

        var now = DateTime.UtcNow.ToString("yyyy-MM-dd");
        var sb = new StringBuilder();

        sb.AppendLine("<?xml version=\"1.0\" encoding=\"UTF-8\"?>");
        sb.AppendLine("<urlset xmlns=\"http://www.sitemaps.org/schemas/sitemap/0.9\">");

        // 1. Rutas estáticas
        foreach (var (path, priority, changeFreq) in StaticRoutes)
        {
            sb.AppendLine("  <url>");
            sb.AppendLine($"    <loc>{BaseUrl}{path}</loc>");
            sb.AppendLine($"    <lastmod>{now}</lastmod>");
            sb.AppendLine($"    <changefreq>{changeFreq}</changefreq>");
            sb.AppendLine($"    <priority>{priority}</priority>");
            sb.AppendLine("  </url>");
        }

        // 2. Rutas dinámicas (vehículos activos)
        foreach (var ad in activeAds)
        {
            var lastmod = ad.PublishedAt?.ToString("yyyy-MM-dd") ?? now;

            sb.AppendLine("  <url>");
            sb.AppendLine($"    <loc>{BaseUrl}/vehiculo/{ad.AdID}</loc>");
            sb.AppendLine($"    <lastmod>{lastmod}</lastmod>");
            sb.AppendLine("    <changefreq>weekly</changefreq>");
            sb.AppendLine("    <priority>0.7</priority>");
            sb.AppendLine("  </url>");
        }

        sb.AppendLine("</urlset>");

        // Escritura atómica: escribir en .tmp, luego mover
        var dir = Path.GetDirectoryName(outputPath);
        if (!string.IsNullOrEmpty(dir) && !Directory.Exists(dir))
        {
            Directory.CreateDirectory(dir);
        }

        var tempPath = outputPath + ".tmp";
        await File.WriteAllTextAsync(tempPath, sb.ToString(), Encoding.UTF8);
        File.Move(tempPath, outputPath, overwrite: true);

        var totalUrls = StaticRoutes.Length + activeAds.Count;
        _logger.LogInformation("Sitemap generado con {TotalUrls} URLs ({StaticCount} estáticas + {DynamicCount} vehículos). Archivo: {Path}",
            totalUrls, StaticRoutes.Length, activeAds.Count, outputPath);
    }
}