foreign/node/src/wire/stream/stream.utils.ts

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you 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,
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import { toDate } from '../serialize.utils.js';
import { deserializePrefixedOptions, type ParsedOptions } from '../options.utils.js';

/**
 * Stream information returned from the server.
 */
export type Stream = {
  /** Stream ID */
  id: number,
  /** Stream name */
  name: string,
  /** Number of topics in the stream */
  topicsCount: number,
  /** Total size of the stream in bytes */
  sizeBytes: bigint,
  /** Total number of messages in the stream */
  messagesCount: bigint,
  /** Stream creation timestamp */
  createdAt: Date,
  /** Options the client explicitly sent at create */
  options: ParsedOptions
}

/**
 * Result of deserializing a stream.
 */
type StreamDeserialized = {
  /** Number of bytes consumed */
  bytesRead: number,
  /** Deserialized stream data */
  data: Stream
};

/**
 * Deserializes a stream from a buffer.
 *
 * @param r - Buffer containing serialized stream data
 * @param pos - Starting position in the buffer
 * @returns Object with bytes read and deserialized stream data
 * @throws Error if the buffer is empty (stream does not exist)
 */
export const deserializeToStream = (r: Buffer, pos = 0): StreamDeserialized => {
  if (r.length === 0)
    throw new Error('Steam does not exist');

  const id = r.readUInt32LE(pos);
  const createdAt = toDate(r.readBigUint64LE(pos + 4));
  const topicsCount = r.readUInt32LE(pos + 12);
  const sizeBytes = r.readBigUint64LE(pos + 16);
  const messagesCount = r.readBigUint64LE(pos + 24);
  const nameLength = r.readUInt8(pos + 32);
  const name = r.subarray(pos + 33, pos + 33 + nameLength).toString();
  const { bytesRead: optionsBytes, options } =
    deserializePrefixedOptions(r, pos + 33 + nameLength);

  return {
    bytesRead: 33 + nameLength + optionsBytes,
    data: {
      id, name, topicsCount, messagesCount, sizeBytes, createdAt, options
    }
  };
};