<?hh
/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * @package thrift.transport
 */

/**
 * Base interface for a transport agent.
 *
 * @package thrift.transport
 */
abstract class TTransport {

  /**
   * Name of the service targeted (for logging).
   */
  protected ?string $service_ = null;

  /**
   * Whether this transport is open.
   *
   * @return boolean true if open
   */
  public abstract function isOpen(): bool;

  /**
   * Open the transport for reading/writing
   *
   * @throws TTransportException if cannot open
   */
  public abstract function open(): void;

  /**
   * Close the transport.
   */
  public abstract function close(): void;

  /**
   * Read some data into the array.
   *
   * @param int    $len How much to read
   * @return string The data that has been read
   * @throws TTransportException if cannot read any more data
   */
  public abstract function read(int $len): string;

  /**
   * Guarantees that the full amount of data is read.
   *
   * @return string The data, of exact length
   * @throws TTransportException if cannot read data
   */
  public function readAll(int $len): string {
    // return $this->read($len);

    $data = '';
    $got = 0;
    while (($got = strlen($data)) < $len) {
      $data .= $this->read($len - $got);
    }
    return $data;
  }

  /**
   * Writes the given data out.
   *
   * @param string $buf  The data to write
   * @throws TTransportException if writing fails
   */
  public abstract function write(string $buf): void;

  /**
   * Flushes any pending data out of a buffer
   *
   * @throws TTransportException if a writing error occurs
   */
  public function flush(): void {}

  /**
   * Flushes any pending data out of a buffer for a oneway call
   *
   * @throws TTransportException if a writing error occurs
   */
  public function onewayFlush(): void {
    // Default to flush()
    $this->flush();
  }
}