import { Filesystem, Directory, Encoding } from '@capacitor/filesystem';
import { db } from '../db/database.js';

class FileSystemService {
  constructor() {
    this.directory = Directory.Documents;
    this.baseFolder = 'SchoolMind';
  }

  async init() {
    try {
      await Filesystem.mkdir({
        path: this.baseFolder,
        directory: this.directory,
        recursive: true
      });
    } catch (e) {}

    try {
      await Filesystem.mkdir({
        path: `${this.baseFolder}/.trash`,
        directory: this.directory,
        recursive: true
      });
    } catch (e) {}
    
    // Run trash cleanup on init
    this.cleanupTrash();
  }

  /**
   * Liest alle Dateien in einem Ordner.
   */
  async readDir(path = '') {
    try {
      const fullPath = path ? `${this.baseFolder}/${path}` : this.baseFolder;
      const result = await Filesystem.readdir({
        path: fullPath,
        directory: this.directory
      });
      // Filter out internal .trash folder
      return result.files.filter(f => {
        const name = typeof f === 'string' ? f : f.name;
        return name && !name.includes('.trash');
      });
    } catch (e) {
      console.error('Error reading directory:', e);
      return [];
    }
  }

  /**
   * Liest den Inhalt einer Datei als String.
   */
  async readFile(filePath) {
    try {
      const fullPath = `${this.baseFolder}/${filePath}`;
      const result = await Filesystem.readFile({
        path: fullPath,
        directory: this.directory,
        encoding: Encoding.UTF8
      });
      return result.data;
    } catch (e) {
      console.error('Error reading file:', e);
      return null;
    }
  }

  /**
   * Liest eine Datei als Base64-String.
   */
  async readBinaryFile(filePath) {
    try {
      const fullPath = `${this.baseFolder}/${filePath}`;
      const result = await Filesystem.readFile({
        path: fullPath,
        directory: this.directory
      });
      return result.data; // returns base64
    } catch (e) {
      console.error('Error reading binary file:', e);
      return null;
    }
  }

  /**
   * Speichert einen Text in einer Datei (überschreibt bestehende).
   */
  async writeFile(filePath, data) {
    try {
      const fullPath = `${this.baseFolder}/${filePath}`;
      // Ensure parent directory exists first by getting the dir part
      const parts = fullPath.split('/');
      parts.pop();
      if (parts.length > 1) {
        const parentDir = parts.join('/');
        try {
          await Filesystem.mkdir({
            path: parentDir,
            directory: this.directory,
            recursive: true
          });
        } catch (e) {
          // ignore "Directory exists" error
        }
      }

      await Filesystem.writeFile({
        path: fullPath,
        data: data,
        directory: this.directory,
        encoding: Encoding.UTF8
      });
      return true;
    } catch (e) {
      console.error('Error writing file:', e);
      return false;
    }
  }

  /**
   * Speichert eine binäre Datei (z.B. PDF) aus einem Base64 String.
   */
  async writeBinaryFile(filePath, base64Data) {
    try {
      const fullPath = `${this.baseFolder}/${filePath}`;
      const parts = fullPath.split('/');
      parts.pop();
      if (parts.length > 1) {
        const parentDir = parts.join('/');
        try {
          await Filesystem.mkdir({ path: parentDir, directory: this.directory, recursive: true });
        } catch (e) {}
      }

      await Filesystem.writeFile({
        path: fullPath,
        data: base64Data, // without encoding it writes binary
        directory: this.directory
      });
      return true;
    } catch (e) {
      console.error('Error writing binary file:', e);
      return false;
    }
  }

  /**
   * Erstellt einen neuen Ordner.
   */
  async createFolder(path) {
    try {
      const fullPath = `${this.baseFolder}/${path}`;
      await Filesystem.mkdir({
        path: fullPath,
        directory: this.directory,
        recursive: true
      });
      return true;
    } catch (e) {
      console.error('Error creating folder:', e);
      return false;
    }
  }

  /**
   * Löscht eine Datei oder einen Ordner.
   */
  async deletePath(path, isDir = false) {
    try {
      const fullPath = `${this.baseFolder}/${path}`;
      if (isDir) {
        await Filesystem.rmdir({
          path: fullPath,
          directory: this.directory,
          recursive: true
        });
      } else {
        await Filesystem.deleteFile({
          path: fullPath,
          directory: this.directory
        });
      }
      return true;
    } catch (e) {
      console.error('Error deleting path:', e);
      return false;
    }
  }

  /**
   * Verschiebt eine Datei oder einen Ordner in den Papierkorb (.trash).
   */
  async moveToTrash(path, isDir = false) {
    try {
      const id = 'trash_' + Date.now();
      const fromPath = `${this.baseFolder}/${path}`;
      const toPath = `${this.baseFolder}/.trash/${id}`;
      
      await Filesystem.rename({
        from: fromPath,
        to: toPath,
        directory: this.directory
      });
      
      db.addTrashItem(id, path, isDir);
      return true;
    } catch (e) {
      console.error('Error moving to trash:', e);
      alert('Konnte Element nicht in den Papierkorb verschieben: ' + e.message);
      return false;
    }
  }

  /**
   * Stellt ein Element aus dem Papierkorb wieder her.
   */
  async restoreFromTrash(id) {
    try {
      const items = db.getTrashItems();
      const item = items.find(i => i.id === id);
      if (!item) return false;

      const fromPath = `${this.baseFolder}/.trash/${id}`;
      let toPath = `${this.baseFolder}/${item.original_path}`;

      // Verify the source file actually exists
      try {
        await Filesystem.stat({
          path: fromPath,
          directory: this.directory
        });
      } catch (e) {
        // If it doesn't exist, remove from DB and clean up the UI
        db.removeTrashItem(id);
        alert('Dieses Element konnte nicht wiederhergestellt werden, da die eigentliche Datei nicht mehr im Papierkorb-Ordner gefunden wurde (vermutlich wurde sie bereits gelöscht). Der fehlerhafte Eintrag wird jetzt entfernt.');
        return false;
      }

      // Ensure parent directory exists for the restored item
      const parts = toPath.split('/');
      parts.pop();
      if (parts.length > 1) {
        const parentDir = parts.join('/');
        try {
          await Filesystem.mkdir({
            path: parentDir,
            directory: this.directory,
            recursive: true
          });
        } catch (e) {}
      }

      // Conflict resolution: Check if destination already exists
      let finalToPath = toPath;
      let suffix = 1;
      let nameWithoutExt = item.original_path;
      let ext = '';
      
      const isDir = item.is_dir === 1;
      if (!isDir && item.original_path.includes('.')) {
        const lastDot = item.original_path.lastIndexOf('.');
        nameWithoutExt = item.original_path.substring(0, lastDot);
        ext = item.original_path.substring(lastDot);
      }

      while (true) {
        try {
          await Filesystem.stat({
            path: finalToPath,
            directory: this.directory
          });
          // If stat succeeds, file exists! We must try a new name.
          finalToPath = `${this.baseFolder}/${nameWithoutExt} (${suffix})${ext}`;
          suffix++;
        } catch (e) {
          // Stat failed, meaning file does NOT exist. We found a valid path!
          break;
        }
      }

      await Filesystem.rename({
        from: fromPath,
        to: finalToPath,
        directory: this.directory
      });

      // If the name changed and it was a folder, we might want to update metadata if needed, but it's okay, it just loses its custom icon if renamed.
      
      db.removeTrashItem(id);
      return true;
    } catch (e) {
      console.error('Error restoring from trash:', e);
      alert('Restore Error: ' + e.message);
      return false;
    }
  }

  /**
   * Löscht endgültig alle Elemente, die älter als 30 Tage sind.
   */
  async cleanupTrash() {
    try {
      const items = db.getTrashItems();
      const THIRTY_DAYS_MS = 30 * 24 * 60 * 60 * 1000;
      const now = Date.now();

      for (const item of items) {
        const deletedAt = new Date(item.deleted_at).getTime();
        if (now - deletedAt > THIRTY_DAYS_MS) {
          const isDir = item.is_dir === 1;
          const success = await this.deletePath(`.trash/${item.id}`, isDir);
          if (success) {
            db.removeTrashItem(item.id);
          }
        }
      }
    } catch (e) {
      console.error('Error during trash cleanup:', e);
    }
  }
}

export const fsService = new FileSystemService();