/// <reference types="node" />

import * as stream from "stream";

type Callback = (err?: Error, records?: unknown) => void;

export class Generator extends stream.Readable {
  constructor(options?: Options);

  readonly options: Options;
}

export type ColumnsFunctionArgs = {
  options: Options;
  state: State;
};
export type ColumnsFunction = (args: ColumnsFunctionArgs) => string;

export type State = {
  start_time: number;
  fixed_size_buffer: number;
  count_written: number;
  count_created: number;
};

export interface Options extends stream.ReadableOptions {
  /**
   * Define the number of generated fields and the generation method.
   */
  columns?: number | (string | ColumnsFunction)[];
  /**
   * Set the field delimiter.
   */
  delimiter?: string;
  /**
   * Period to run in milliseconds.
   */
  duration?: number;
  /**
   * If specified, then buffers will be decoded to strings using the specified encoding.
   */
  encoding?: BufferEncoding | undefined;
  /**
   * When to stop the generation.
   */
  end?: number | Date;
  /**
   * One or multiple characters to print at the end of the file; only apply when objectMode is disabled.
   */
  eof?: boolean | string;
  /**
   * Generate buffers equals length as defined by the `highWaterMark` option.
   */
  fixed_size?: boolean;
  fixedSize?: boolean;
  /**
   * The maximum number of bytes to store in the internal buffer before ceasing to read from the underlying resource.
   */
  high_water_mark?: number;
  highWaterMark?: number;
  /**
   * Number of lines or records to generate.
   */
  length?: number;
  /**
   * Maximum number of characters per word.
   */
  max_word_length?: number;
  maxWordLength?: number;
  /**
   * Whether this stream should behave as a stream of objects.
   */
  object_mode?: boolean;
  objectMode?: boolean;
  /**
   * One or multiple characters used to delimit records.
   */
  row_delimiter?: string;
  /**
   * Generate idempotent random characters if a number provided.
   */
  seed?: boolean | number;
  /**
   * The time to wait between the generation of each records
   */
  sleep?: number;
}

declare function generate(options?: Options, callback?: Callback): Generator;
declare function generate(callback?: Callback): Generator;

// export default generate;
export { generate };