File System

/**
 * Get the file system instance
 * @return FileSystem instance
 */
FileSystem fileSystem();

/**
 * File System interface for asynchronous file operations
 */
interface FileSystem {
  /**
   * Read entire file into buffer
   * @param path File path to read
   * @return Future that completes with file contents
   */
  Future<Buffer> readFile(String path);

  /**
   * Write buffer to file
   * @param path File path to write
   * @param data Data to write
   * @return Future that completes when written
   */
  Future<Void> writeFile(String path, Buffer data);

  /**
   * Copy a file
   * @param from Source file path
   * @param to Destination file path
   * @return Future that completes when copied
   */
  Future<Void> copy(String from, String to);

  /**
   * Copy a file with options
   * @param from Source file path
   * @param to Destination file path
   * @param options Copy options
   * @return Future that completes when copied
   */
  Future<Void> copy(String from, String to, CopyOptions options);

  /**
   * Copy recursively
   * @param from Source directory path
   * @param to Destination directory path
   * @return Future that completes when copied
   */
  Future<Void> copyRecursive(String from, String to, boolean recursive);

  /**
   * Move/rename a file
   * @param from Source file path
   * @param to Destination file path
   * @return Future that completes when moved
   */
  Future<Void> move(String from, String to);

  /**
   * Move with options
   * @param from Source file path
   * @param to Destination file path
   * @param options Copy options
   * @return Future that completes when moved
   */
  Future<Void> move(String from, String to, CopyOptions options);

  /**
   * Truncate a file
   * @param path File path
   * @param len New length
   * @return Future that completes when truncated
   */
  Future<Void> truncate(String path, long len);

  /**
   * Change file permissions
   * @param path File path
   * @param perms File permissions
   * @return Future that completes when changed
   */
  Future<Void> chmod(String path, String perms);

  /**
   * Change file permissions recursively
   * @param path Directory path
   * @param perms File permissions
   * @param dirPerms Directory permissions
   * @return Future that completes when changed
   */
  Future<Void> chmodRecursive(String path, String perms, String dirPerms);

  /**
   * Change file owner
   * @param path File path
   * @param user User name
   * @param group Group name
   * @return Future that completes when changed
   */
  Future<Void> chown(String path, String user, String group);

  /**
   * Get file properties
   * @param path File path
   * @return Future that completes with file properties
   */
  Future<FileProps> props(String path);

  /**
   * Get link properties (don't follow symlinks)
   * @param path File path
   * @return Future that completes with file properties
   */
  Future<FileProps> lprops(String path);

  /**
   * Create hard link
   * @param link Link path
   * @param existing Existing file path
   * @return Future that completes when created
   */
  Future<Void> link(String link, String existing);

  /**
   * Create symbolic link
   * @param link Link path
   * @param existing Existing file path
   * @return Future that completes when created
   */
  Future<Void> symlink(String link, String existing);

  /**
   * Delete/unlink a file
   * @param path File path
   * @return Future that completes when deleted
   */
  Future<Void> unlink(String path);

  /**
   * Read symbolic link
   * @param link Link path
   * @return Future that completes with link target
   */
  Future<String> readSymlink(String link);

  /**
   * Delete a file or directory
   * @param path File or directory path
   * @return Future that completes when deleted
   */
  Future<Void> delete(String path);

  /**
   * Delete recursively
   * @param path Directory path
   * @param recursive Whether to delete recursively
   * @return Future that completes when deleted
   */
  Future<Void> deleteRecursive(String path, boolean recursive);

  /**
   * Create directory
   * @param path Directory path
   * @return Future that completes when created
   */
  Future<Void> mkdir(String path);

  /**
   * Create directory with permissions
   * @param path Directory path
   * @param perms Directory permissions
   * @return Future that completes when created
   */
  Future<Void> mkdir(String path, String perms);

  /**
   * Create directories recursively
   * @param path Directory path
   * @return Future that completes when created
   */
  Future<Void> mkdirs(String path);

  /**
   * Create directories with permissions
   * @param path Directory path
   * @param perms Directory permissions
   * @return Future that completes when created
   */
  Future<Void> mkdirs(String path, String perms);

  /**
   * Read directory
   * @param path Directory path
   * @return Future that completes with list of files
   */
  Future<List<String>> readDir(String path);

  /**
   * Read directory with filter
   * @param path Directory path
   * @param filter Filename filter regex
   * @return Future that completes with filtered list of files
   */
  Future<List<String>> readDir(String path, String filter);

  /**
   * Open file for reading/writing
   * @param path File path
   * @param options Open options
   * @return Future that completes with AsyncFile
   */
  Future<AsyncFile> open(String path, OpenOptions options);

  /**
   * Create a new file
   * @param path File path
   * @return Future that completes when created
   */
  Future<Void> createFile(String path);

  /**
   * Create file with permissions
   * @param path File path
   * @param perms File permissions
   * @return Future that completes when created
   */
  Future<Void> createFile(String path, String perms);

  /**
   * Check if file exists
   * @param path File path
   * @return Future that completes with existence check
   */
  Future<Boolean> exists(String path);

  /**
   * Get file system properties
   * @param path Path to check
   * @return Future that completes with filesystem properties
   */
  Future<FileSystemProps> fsProps(String path);

  /**
   * Create temporary directory
   * @param prefix Directory name prefix
   * @return Future that completes with temp directory path
   */
  Future<String> createTempDirectory(String prefix);

  /**
   * Create temporary directory with attributes
   * @param prefix Directory name prefix
   * @param perms Directory permissions
   * @param dir Parent directory
   * @return Future that completes with temp directory path
   */
  Future<String> createTempDirectory(String prefix, String perms, String dir);

  /**
   * Create temporary file
   * @param prefix File name prefix
   * @param suffix File name suffix
   * @return Future that completes with temp file path
   */
  Future<String> createTempFile(String prefix, String suffix);

  /**
   * Create temporary file with attributes
   * @param prefix File name prefix
   * @param suffix File name suffix
   * @param perms File permissions
   * @param dir Parent directory
   * @return Future that completes with temp file path
   */
  Future<String> createTempFile(String prefix, String suffix, String perms, String dir);

  /**
   * Watch a file or directory for changes
   * @param path Path to watch
   * @return Future that completes with file watcher
   */
  Future<Watcher> watch(String path);
}

/**
 * Asynchronous file handle for reading/writing
 */
interface AsyncFile extends ReadStream<Buffer>, WriteStream<Buffer> {
  /**
   * Close the file
   * @return Future that completes when closed
   */
  Future<Void> close();

  /**
   * Write buffer to file
   * @param buffer Data to write
   * @return Future that completes when written
   */
  Future<Void> write(Buffer buffer);

  /**
   * Write buffer at specific position
   * @param buffer Data to write
   * @param position Position to write at
   * @return Future that completes when written
   */
  Future<Void> write(Buffer buffer, long position);

  /**
   * Read from file into buffer
   * @param buffer Buffer to read into
   * @param offset Offset in buffer
   * @param position Position in file
   * @param length Number of bytes to read
   * @return Future that completes with buffer
   */
  Future<Buffer> read(Buffer buffer, int offset, long position, int length);

  /**
   * Flush data to storage
   * @return Future that completes when flushed
   */
  Future<Void> flush();

  /**
   * Set read position
   * @param readPos New read position
   * @return this for chaining
   */
  AsyncFile setReadPos(long readPos);

  /**
   * Set write position
   * @param writePos New write position
   * @return this for chaining
   */
  AsyncFile setWritePos(long writePos);

  /**
   * Get current read position
   * @return Read position
   */
  long getReadPos();

  /**
   * Get current write position
   * @return Write position
   */
  long getWritePos();

  /**
   * Get file size
   * @return Future that completes with file size
   */
  Future<Long> size();

  /**
   * Lock the file
   * @return Future that completes with file lock
   */
  Future<AsyncFileLock> lock();

  /**
   * Lock part of the file
   * @param position Start position
   * @param size Lock size
   * @param shared Whether lock is shared
   * @return Future that completes with file lock
   */
  Future<AsyncFileLock> lock(long position, long size, boolean shared);

  /**
   * Try to lock the file (non-blocking)
   * @return Future that completes with file lock or null
   */
  Future<AsyncFileLock> tryLock();

  /**
   * Try to lock part of the file (non-blocking)
   * @param position Start position
   * @param size Lock size
   * @param shared Whether lock is shared
   * @return Future that completes with file lock or null
   */
  Future<AsyncFileLock> tryLock(long position, long size, boolean shared);
}

/**
 * File lock for controlling access
 */
interface AsyncFileLock {
  /**
   * Get lock position
   * @return Lock position
   */
  long position();

  /**
   * Get lock size
   * @return Lock size
   */
  long size();

  /**
   * Check if lock is shared
   * @return true if shared
   */
  boolean isShared();

  /**
   * Check if lock is valid
   * @return true if valid
   */
  boolean isValid();

  /**
   * Release the lock
   * @return Future that completes when released
   */
  Future<Void> release();
}

/**
 * File properties interface
 */
interface FileProps {
  /**
   * Get creation time
   * @return Creation time
   */
  Instant creationTime();

  /**
   * Get last access time
   * @return Last access time
   */
  Instant lastAccessTime();

  /**
   * Get last modified time
   * @return Last modified time
   */
  Instant lastModifiedTime();

  /**
   * Check if directory
   * @return true if directory
   */
  boolean isDirectory();

  /**
   * Check if other (not regular file, directory, or symlink)
   * @return true if other
   */
  boolean isOther();

  /**
   * Check if regular file
   * @return true if regular file
   */
  boolean isRegularFile();

  /**
   * Check if symbolic link
   * @return true if symbolic link
   */
  boolean isSymbolicLink();

  /**
   * Get file size
   * @return File size in bytes
   */
  long size();

  /**
   * Get file permissions
   * @return File permissions string
   */
  String permissions();
}

/**
 * File system properties interface
 */
interface FileSystemProps {
  /**
   * Get total space
   * @return Total space in bytes
   */
  long totalSpace();

  /**
   * Get unallocated space
   * @return Unallocated space in bytes
   */
  long unallocatedSpace();

  /**
   * Get usable space
   * @return Usable space in bytes
   */
  long usableSpace();
}

/**
 * Options for opening files
 */
class OpenOptions {
  /**
   * Set read mode
   * @param read Whether to open for reading
   * @return this for chaining
   */
  OpenOptions setRead(boolean read);

  /**
   * Set write mode
   * @param write Whether to open for writing
   * @return this for chaining
   */
  OpenOptions setWrite(boolean write);

  /**
   * Set create mode
   * @param create Whether to create if doesn't exist
   * @return this for chaining
   */
  OpenOptions setCreate(boolean create);

  /**
   * Set create new mode
   * @param createNew Whether to create only if doesn't exist
   * @return this for chaining
   */
  OpenOptions setCreateNew(boolean createNew);

  /**
   * Set delete on close
   * @param deleteOnClose Whether to delete when closed
   * @return this for chaining
   */
  OpenOptions setDeleteOnClose(boolean deleteOnClose);

  /**
   * Set truncate existing
   * @param truncateExisting Whether to truncate if exists
   * @return this for chaining
   */
  OpenOptions setTruncateExisting(boolean truncateExisting);

  /**
   * Set sparse file
   * @param sparse Whether to create sparse file
   * @return this for chaining
   */
  OpenOptions setSparse(boolean sparse);

  /**
   * Set sync mode
   * @param sync Whether to sync data and metadata
   * @return this for chaining
   */
  OpenOptions setSync(boolean sync);

  /**
   * Set dsync mode
   * @param dsync Whether to sync data only
   * @return this for chaining
   */
  OpenOptions setDsync(boolean dsync);

  /**
   * Set file permissions
   * @param perms File permissions
   * @return this for chaining
   */
  OpenOptions setPerms(String perms);
}

/**
 * Options for copying files
 */
class CopyOptions {
  /**
   * Set replace existing
   * @param replaceExisting Whether to replace existing files
   * @return this for chaining
   */
  CopyOptions setReplaceExisting(boolean replaceExisting);

  /**
   * Set copy attributes
   * @param copyAttributes Whether to copy file attributes
   * @return this for chaining
   */
  CopyOptions setCopyAttributes(boolean copyAttributes);

  /**
   * Set no follow links
   * @param nofollowLinks Whether to not follow symbolic links
   * @return this for chaining
   */
  CopyOptions setNofollowLinks(boolean nofollowLinks);

  /**
   * Set atomic move
   * @param atomicMove Whether move should be atomic
   * @return this for chaining
   */
  CopyOptions setAtomicMove(boolean atomicMove);
}

/**
 * File system configuration options
 */
class FileSystemOptions {
  FileSystemOptions setClassPathResolvingEnabled(boolean classPathResolvingEnabled);
  FileSystemOptions setFileCachingEnabled(boolean fileCachingEnabled);
}

/**
 * File watcher for monitoring changes
 */
interface Watcher {
  /**
   * Get the watched path
   * @return Watched path
   */
  String path();

  /**
   * Set event handler
   * @param handler Handler for file events
   * @return this for chaining
   */
  Watcher handler(Handler<WatchEvent> handler);

  /**
   * Set exception handler
   * @param handler Exception handler
   * @return this for chaining
   */
  Watcher exceptionHandler(Handler<Throwable> handler);

  /**
   * Close the watcher
   * @return Future that completes when closed
   */
  Future<Void> close();
}

/**
 * File watch event
 */
interface WatchEvent {
  /**
   * Get event type
   * @return Event type
   */
  WatchEventType type();

  /**
   * Get file path
   * @return File path
   */
  String path();
}

/**
 * Types of watch events
 */
enum WatchEventType {
  CREATE,   // File created
  MODIFY,   // File modified
  DELETE    // File deleted
}

/**
 * Exception for file system operation failures
 */
class FileSystemException extends VertxException {
  public FileSystemException(String message);
  public FileSystemException(String message, Throwable cause);
}

import io.vertx.core.file.FileSystem;
import io.vertx.core.buffer.Buffer;

FileSystem fs = vertx.fileSystem();

// Read file
fs.readFile("config.json").onSuccess(buffer -> {
  System.out.println("File contents: " + buffer.toString());
}).onFailure(err -> {
  System.err.println("Failed to read file: " + err.getMessage());
});

// Write file
Buffer data = Buffer.buffer("Hello World!");
fs.writeFile("output.txt", data).onSuccess(v -> {
  System.out.println("File written successfully");
});

// Copy file
fs.copy("source.txt", "destination.txt").onSuccess(v -> {
  System.out.println("File copied");
});

// Check if file exists
fs.exists("somefile.txt").onSuccess(exists -> {
  if (exists) {
    System.out.println("File exists");
  } else {
    System.out.println("File does not exist");
  }
});

// Create directory
fs.mkdir("newdir").onSuccess(v -> {
  System.out.println("Directory created");
});

// Create nested directories
fs.mkdirs("path/to/nested/dir").onSuccess(v -> {
  System.out.println("Nested directories created");
});

// Read directory contents
fs.readDir("mydir").onSuccess(files -> {
  System.out.println("Directory contents:");
  files.forEach(System.out::println);
});

// Read directory with filter
fs.readDir("logs", ".*\\.log").onSuccess(logFiles -> {
  System.out.println("Log files:");
  logFiles.forEach(System.out::println);
});

// Delete directory recursively
fs.deleteRecursive("olddir", true).onSuccess(v -> {
  System.out.println("Directory deleted recursively");
});

import io.vertx.core.file.AsyncFile;
import io.vertx.core.file.OpenOptions;

OpenOptions options = new OpenOptions()
  .setRead(true)
  .setWrite(true)
  .setCreate(true);

fs.open("data.bin", options).onSuccess(file -> {
  // Write data at specific position
  Buffer data = Buffer.buffer("Hello");
  file.write(data, 0).onSuccess(v -> {
    System.out.println("Data written at position 0");
    
    // Read data from specific position
    Buffer readBuffer = Buffer.buffer(5);
    file.read(readBuffer, 0, 0, 5).onSuccess(buffer -> {
      System.out.println("Read: " + buffer.toString());
      
      // Close file
      file.close();
    });
  });
});

// Stream processing with async file
fs.open("largefile.dat", new OpenOptions().setRead(true))
  .onSuccess(file -> {
    file.handler(buffer -> {
      // Process each chunk
      processChunk(buffer);
    });
    
    file.endHandler(v -> {
      System.out.println("File reading completed");
      file.close();
    });
  });

// Get file properties
fs.props("myfile.txt").onSuccess(props -> {
  System.out.println("File size: " + props.size());
  System.out.println("Is directory: " + props.isDirectory());
  System.out.println("Last modified: " + props.lastModifiedTime());
  System.out.println("Permissions: " + props.permissions());
});

// Get filesystem properties
fs.fsProps("/").onSuccess(fsProps -> {
  System.out.println("Total space: " + fsProps.totalSpace());
  System.out.println("Usable space: " + fsProps.usableSpace());
  System.out.println("Unallocated space: " + fsProps.unallocatedSpace());
});

// Change file permissions
fs.chmod("script.sh", "rwxr-xr-x").onSuccess(v -> {
  System.out.println("Permissions changed");
});

import io.vertx.core.file.WatchEvent;
import io.vertx.core.file.WatchEventType;

fs.watch("watchdir").onSuccess(watcher -> {
  watcher.handler(event -> {
    WatchEventType type = event.type();
    String path = event.path();
    
    switch (type) {
      case CREATE:
        System.out.println("File created: " + path);
        break;
      case MODIFY:
        System.out.println("File modified: " + path);
        break;
      case DELETE:
        System.out.println("File deleted: " + path);
        break;
    }
  });
  
  watcher.exceptionHandler(err -> {
    System.err.println("Watcher error: " + err.getMessage());
  });
  
  // Stop watching after 30 seconds
  vertx.setTimer(30000, id -> {
    watcher.close().onSuccess(v -> {
      System.out.println("Watcher closed");
    });
  });
});

fs.open("shared.dat", new OpenOptions().setWrite(true).setRead(true))
  .onSuccess(file -> {
    // Lock entire file exclusively
    file.lock().onSuccess(lock -> {
      System.out.println("File locked exclusively");
      
      // Perform operations on locked file
      file.write(Buffer.buffer("Exclusive data")).onSuccess(v -> {
        // Release lock
        lock.release().onSuccess(released -> {
          System.out.println("Lock released");
          file.close();
        });
      });
    });
  });

// Try to acquire shared lock on part of file
fs.open("database.dat", new OpenOptions().setRead(true))
  .onSuccess(file -> {
    file.tryLock(1000, 500, true).onSuccess(lock -> {
      if (lock != null) {
        System.out.println("Acquired shared lock on bytes 1000-1500");
        // Use the locked region
        lock.release();
      } else {
        System.out.println("Could not acquire lock");
      }
      file.close();
    });
  });