'use server';

import { getAuthUser } from '@/lib/auth-utils';

const MAX_UPLOAD_SIZE_BYTES = 5 * 1024 * 1024; // 5 MB

function detectSafeImageMimeType(buffer: Buffer): string | null {
  if (buffer.length < 12) return null;

  // JPEG: FF D8 FF
  if (buffer[0] === 0xff && buffer[1] === 0xd8 && buffer[2] === 0xff) {
    return 'image/jpeg';
  }

  // PNG: 89 50 4E 47 0D 0A 1A 0A
  if (
    buffer[0] === 0x89 &&
    buffer[1] === 0x50 &&
    buffer[2] === 0x4e &&
    buffer[3] === 0x47 &&
    buffer[4] === 0x0d &&
    buffer[5] === 0x0a &&
    buffer[6] === 0x1a &&
    buffer[7] === 0x0a
  ) {
    return 'image/png';
  }

  // GIF: GIF87a or GIF89a
  if (
    buffer[0] === 0x47 &&
    buffer[1] === 0x49 &&
    buffer[2] === 0x46 &&
    buffer[3] === 0x38 &&
    (buffer[4] === 0x37 || buffer[4] === 0x39) &&
    buffer[5] === 0x61
  ) {
    return 'image/gif';
  }

  // WebP: RIFF....WEBP
  if (
    buffer[0] === 0x52 &&
    buffer[1] === 0x49 &&
    buffer[2] === 0x46 &&
    buffer[3] === 0x46 &&
    buffer[8] === 0x57 &&
    buffer[9] === 0x45 &&
    buffer[10] === 0x42 &&
    buffer[11] === 0x50
  ) {
    return 'image/webp';
  }

  return null;
}

export async function uploadImage(formData: FormData) {
  try {
    const authUser = await getAuthUser();
    if (!authUser) {
      return { success: false, error: 'Authentification requise' };
    }

    const file = formData.get('file') as File;
    if (!file) {
      return { success: false, error: 'Aucun fichier fourni' };
    }

    if (file.size > MAX_UPLOAD_SIZE_BYTES) {
      return { success: false, error: 'Le fichier dépasse la taille maximale autorisée (5 Mo)' };
    }

    // Convert file to buffer
    const bytes = await file.arrayBuffer();
    const buffer = Buffer.from(bytes);

    if (buffer.length > MAX_UPLOAD_SIZE_BYTES) {
      return { success: false, error: 'Le fichier dépasse la taille maximale autorisée (5 Mo)' };
    }

    // Derive MIME type strictly from binary magic bytes (rejects SVG/HTML/scripts)
    const mimeType = detectSafeImageMimeType(buffer);
    if (!mimeType) {
      return {
        success: false,
        error: 'Format de fichier non autorisé (seuls JPG, PNG, WebP et GIF sont acceptés)',
      };
    }

    // Convert to Base64
    const base64 = buffer.toString('base64');
    const dataUrl = `data:${mimeType};base64,${base64}`;

    // Return the data URL directly (it will be saved in the database)
    return {
      success: true,
      url: dataUrl,
    };
  } catch (error) {
    console.error('Error during image conversion:', error);
    return { success: false, error: "Erreur lors de la conversion de l'image" };
  }
}