using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Processing;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Logging;
using System.IO;

namespace MotoresArgentinosV2.Infrastructure.Services;

public interface IImageStorageService
{
  Task<string> SaveAdImageAsync(int adId, IFormFile file);
  void DeleteAdImage(string relativePath);
}

public class ImageStorageService : IImageStorageService
{
  private readonly IWebHostEnvironment _env;
  private readonly ILogger<ImageStorageService> _logger;

  public ImageStorageService(IWebHostEnvironment env, ILogger<ImageStorageService> logger)
  {
    _env = env;
    _logger = logger;
  }

  // Firmas de archivos (Magic Numbers) para JPG, PNG, WEBP
  private static readonly Dictionary<string, List<byte[]>> _fileSignatures = new Dictionary<string, List<byte[]>>
{
    { ".jpeg", new List<byte[]> { new byte[] { 0xFF, 0xD8, 0xFF, 0xE0 }, new byte[] { 0xFF, 0xD8, 0xFF, 0xE2 }, new byte[] { 0xFF, 0xD8, 0xFF, 0xE3 } } },
    { ".jpg", new List<byte[]> { new byte[] { 0xFF, 0xD8, 0xFF, 0xE0 }, new byte[] { 0xFF, 0xD8, 0xFF, 0xE1 }, new byte[] { 0xFF, 0xD8, 0xFF, 0xE8 } } },
    { ".png", new List<byte[]> { new byte[] { 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A } } },
    { ".webp", new List<byte[]> { new byte[] { 0x52, 0x49, 0x46, 0x46, 0, 0, 0, 0, 0x57, 0x45, 0x42, 0x50 } } }
};

  public async Task<string> SaveAdImageAsync(int adId, IFormFile file)
  {
    // 1. Validación de Extensión Básica
    var ext = Path.GetExtension(file.FileName).ToLowerInvariant();
    if (string.IsNullOrEmpty(ext) || !_fileSignatures.ContainsKey(ext))
    {
      throw new Exception("Formato de archivo no permitido. Solo JPG, PNG y WEBP.");
    }

    // 2. Validación de Tamaño (Max 3MB)
    if (file.Length > 3 * 1024 * 1024)
    {
      throw new Exception("El archivo excede los 3MB permitidos.");
    }

    // 3. Validación de Magic Numbers (Leer cabecera real)
    using (var stream = file.OpenReadStream())
    using (var reader = new BinaryReader(stream))
    {
      // Leemos hasta 12 bytes que cubren nuestras firmas soportadas
      var headerBytes = reader.ReadBytes(12);
      bool isRealImage = false;

      // A. JPG (Flexible: FF D8)
      if (headerBytes.Length >= 2 && headerBytes[0] == 0xFF && headerBytes[1] == 0xD8)
      {
        isRealImage = true;
      }
      // B. PNG (Sello estricto)
      else if (headerBytes.Length >= 8 && headerBytes.Take(8).SequenceEqual(new byte[] { 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A }))
      {
        isRealImage = true;
      }
      // C. WEBP (RIFF [4 bytes] WEBP)
      else if (headerBytes.Length >= 12 &&
               headerBytes.Take(4).SequenceEqual(new byte[] { 0x52, 0x49, 0x46, 0x46 }) &&
               headerBytes.Skip(8).Take(4).SequenceEqual(new byte[] { 0x57, 0x45, 0x42, 0x50 }))
      {
        isRealImage = true;
      }

      if (!isRealImage)
      {
        string hex = BitConverter.ToString(headerBytes.Take(8).ToArray());
        _logger.LogWarning("Firma de archivo inválida para {Extension}: {HexBytes}", ext, hex);
        throw new Exception($"El archivo parece corrupto o tiene una firma inválida ({hex}). El sistema acepta JPG, PNG y WEBP reales.");
      }
    }
    try
    {
      // 1. Definir rutas
      var uploadFolder = Path.Combine(_env.WebRootPath, "uploads", "ads", adId.ToString());
      if (!Directory.Exists(uploadFolder)) Directory.CreateDirectory(uploadFolder);

      var uniqueName = Guid.NewGuid().ToString();
      var fileName = $"{uniqueName}.jpg";
      var thumbName = $"{uniqueName}_thumb.jpg";

      var filePath = Path.Combine(uploadFolder, fileName);
      var thumbPath = Path.Combine(uploadFolder, thumbName);

      // 2. Cargar y Procesar con ImageSharp
      using (var image = await Image.LoadAsync(file.OpenReadStream()))
      {
        // A. Guardar imagen principal (Optimized: Max width 1280px)
        if (image.Width > 1280)
        {
          image.Mutate(x => x.Resize(new ResizeOptions
          {
            Size = new Size(1280, 0), // 0 mantiene aspect ratio
            Mode = ResizeMode.Max
          }));
        }
        await image.SaveAsJpegAsync(filePath);

        // B. Generar Thumbnail (Max width 400px para grillas)
        image.Mutate(x => x.Resize(new ResizeOptions
        {
          Size = new Size(400, 300),
          Mode = ResizeMode.Crop // Recorte inteligente para que queden parejitas
        }));
        await image.SaveAsJpegAsync(thumbPath);
      }

      // Retornar ruta relativa web de la imagen principal
      return $"/uploads/ads/{adId}/{fileName}";
    }
    catch (Exception ex)
    {
      _logger.LogError(ex, "Error procesando imagen para el aviso {AdId}", adId);
      throw;
    }
  }

  public void DeleteAdImage(string relativePath)
  {
    if (string.IsNullOrEmpty(relativePath)) return;

    try
    {
      // Eliminar archivo principal
      var fullPath = Path.Combine(_env.WebRootPath, relativePath.TrimStart('/').Replace('/', Path.DirectorySeparatorChar));
      if (File.Exists(fullPath)) File.Delete(fullPath);

      // Eliminar thumbnail asociado
      var thumbPath = fullPath.Replace(".jpg", "_thumb.jpg");
      if (File.Exists(thumbPath)) File.Delete(thumbPath);
    }
    catch (Exception ex)
    {
      _logger.LogError(ex, "Error eliminando imagen {Path}", relativePath);
    }
  }
}