/**
 * TASKMATE - File Upload
 * ======================
 * Multer-Konfiguration für Datei-Uploads
 */

const multer = require('multer');
const path = require('path');
const fs = require('fs');
const { v4: uuidv4 } = require('uuid');
const logger = require('../utils/logger');

// Upload-Verzeichnis
const UPLOAD_DIR = process.env.UPLOAD_DIR || path.join(__dirname, '..', 'uploads');

// Verzeichnis erstellen falls nicht vorhanden
if (!fs.existsSync(UPLOAD_DIR)) {
  fs.mkdirSync(UPLOAD_DIR, { recursive: true });
}

// Standard-Werte (Fallback)
let MAX_FILE_SIZE = (parseInt(process.env.MAX_FILE_SIZE_MB) || 15) * 1024 * 1024;
let ALLOWED_MIME_TYPES = [
  'image/jpeg', 'image/png', 'image/gif', 'image/webp', 'image/svg+xml',
  'application/pdf',
  'application/msword', 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
  'application/vnd.ms-excel', 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
  'application/vnd.ms-powerpoint', 'application/vnd.openxmlformats-officedocument.presentationml.presentation',
  'text/plain', 'text/csv', 'text/markdown',
  'application/zip', 'application/x-rar-compressed', 'application/x-7z-compressed',
  'application/json'
];

/**
 * Lädt Upload-Einstellungen aus der Datenbank
 */
function loadUploadSettings() {
  try {
    // Lazy-Load um zirkuläre Abhängigkeiten zu vermeiden
    const { getUploadSettings } = require('../routes/admin');
    const settings = getUploadSettings();

    if (settings) {
      MAX_FILE_SIZE = (settings.maxFileSizeMB || 15) * 1024 * 1024;

      // Erlaubte MIME-Types aus den aktiven Kategorien zusammenstellen
      const types = [];
      if (settings.allowedTypes) {
        Object.values(settings.allowedTypes).forEach(category => {
          if (category.enabled && Array.isArray(category.types)) {
            types.push(...category.types);
          }
        });
      }
      if (types.length > 0) {
        ALLOWED_MIME_TYPES = types;
      }
    }
  } catch (error) {
    // Bei Fehler Standard-Werte beibehalten
    logger.warn('Upload-Einstellungen konnten nicht geladen werden, verwende Standards');
  }
}

/**
 * Aktuelle Einstellungen abrufen (für dynamische Prüfung)
 */
function getCurrentSettings() {
  loadUploadSettings();
  return { maxFileSize: MAX_FILE_SIZE, allowedMimeTypes: ALLOWED_MIME_TYPES };
}

/**
 * Storage-Konfiguration
 */
const storage = multer.diskStorage({
  destination: (req, file, cb) => {
    // Task-ID aus URL oder Body
    const taskId = req.params.taskId || req.body.taskId;

    if (taskId) {
      // Unterordner pro Task
      const taskDir = path.join(UPLOAD_DIR, `task_${taskId}`);
      if (!fs.existsSync(taskDir)) {
        fs.mkdirSync(taskDir, { recursive: true });
      }
      cb(null, taskDir);
    } else {
      cb(null, UPLOAD_DIR);
    }
  },

  filename: (req, file, cb) => {
    // Eindeutiger Dateiname mit Original-Extension
    const ext = path.extname(file.originalname).toLowerCase();
    const uniqueName = `${uuidv4()}${ext}`;
    cb(null, uniqueName);
  }
});

/**
 * Datei-Filter
 */
const fileFilter = (req, file, cb) => {
  // Aktuelle Einstellungen laden
  const settings = getCurrentSettings();

  // MIME-Type prüfen
  if (settings.allowedMimeTypes.includes(file.mimetype)) {
    cb(null, true);
  } else {
    logger.warn(`Abgelehnter Upload: ${file.originalname} (${file.mimetype})`);
    cb(new Error(`Dateityp nicht erlaubt: ${file.mimetype}`), false);
  }
};

/**
 * Dynamische Multer-Instanz erstellen
 */
function createUpload() {
  const settings = getCurrentSettings();
  return multer({
    storage,
    fileFilter,
    limits: {
      fileSize: settings.maxFileSize,
      files: 10 // Maximal 10 Dateien pro Request
    }
  });
}

// Standard-Instanz für Rückwärtskompatibilität
const upload = createUpload();

/**
 * Datei löschen
 */
function deleteFile(filePath) {
  try {
    const fullPath = path.join(UPLOAD_DIR, filePath);
    if (fs.existsSync(fullPath)) {
      fs.unlinkSync(fullPath);
      logger.info(`Datei gelöscht: ${filePath}`);
      return true;
    }
    return false;
  } catch (error) {
    logger.error(`Fehler beim Löschen: ${filePath}`, { error: error.message });
    return false;
  }
}

/**
 * Dateigröße formatieren
 */
function formatFileSize(bytes) {
  if (bytes === 0) return '0 Bytes';

  const k = 1024;
  const sizes = ['Bytes', 'KB', 'MB', 'GB'];
  const i = Math.floor(Math.log(bytes) / Math.log(k));

  return parseFloat((bytes / Math.pow(k, i)).toFixed(2)) + ' ' + sizes[i];
}

/**
 * Ist Bild?
 */
function isImage(mimeType) {
  return mimeType && mimeType.startsWith('image/');
}

/**
 * Datei-Icon basierend auf MIME-Type
 */
function getFileIcon(mimeType) {
  if (mimeType.startsWith('image/')) return 'image';
  if (mimeType === 'application/pdf') return 'pdf';
  if (mimeType.includes('word')) return 'word';
  if (mimeType.includes('excel') || mimeType.includes('spreadsheet')) return 'excel';
  if (mimeType.includes('powerpoint') || mimeType.includes('presentation')) return 'powerpoint';
  if (mimeType.includes('zip') || mimeType.includes('rar') || mimeType.includes('7z')) return 'archive';
  if (mimeType.startsWith('text/')) return 'text';
  return 'file';
}

module.exports = {
  upload,
  createUpload,
  deleteFile,
  formatFileSize,
  isImage,
  getFileIcon,
  getCurrentSettings,
  UPLOAD_DIR,
  MAX_FILE_SIZE,
  ALLOWED_MIME_TYPES
};