import { Transform } from "stream";

export default class LineSplitter extends Transform {
  private forEachLine: (l: string) => any;
  private buffer: string | undefined = "";

  constructor(forEachLine = l => l, encoding = "utf8") {
    super({ encoding });
    this.forEachLine = forEachLine;
  }

  _transform(chunk, encoding, done) {
    this.buffer += chunk.toString();
    let lines = this.buffer!.split(/\r?\n/);
    this.buffer = lines.pop();
    lines.forEach(line => this.push(this.forEachLine(line)));
    done();
  }

  _flush(done) {
    if (this.buffer) this.push(this.forEachLine(this.buffer));
    this.buffer = "";
    done();
  }
}