terminal-control.ts

const ESC = '\u001b';
const BEL = '\u0007';

const COMPLETE_TERMINAL_CONTROL_RE =
  /(?:\u001b\][\s\S]*?(?:\u0007|\u001b\\)|\u001b\[[0-?]*[ -/]*[@-~]|\u001b[@-Z\\-_]|\u009b[0-?]*[ -/]*[@-~])/g;

function hasOscTerminator(value: string): boolean {
  return value.includes(BEL) || value.includes(`${ESC}\\`);
}

function hasCsiFinalByte(value: string): boolean {
  return /[\x40-\x7e]/.test(value.slice(2));
}

function splitIncompleteControlTail(value: string): [string, string] {
  const escIndex = value.lastIndexOf(ESC);
  const csiIndex = value.lastIndexOf('\u009b');
  const index = Math.max(escIndex, csiIndex);
  if (index < 0) return [value, ''];

  const tail = value.slice(index);
  if (tail === ESC || tail === '\u009b') return [value.slice(0, index), tail];

  if (tail.startsWith(`${ESC}]`)) {
    return hasOscTerminator(tail) ? [value, ''] : [value.slice(0, index), tail];
  }

  if (tail.startsWith(`${ESC}[`)) {
    return hasCsiFinalByte(tail) ? [value, ''] : [value.slice(0, index), tail];
  }

  if (tail.startsWith('\u009b')) {
    return /[\x40-\x7e]/.test(tail.slice(1))
      ? [value, '']
      : [value.slice(0, index), tail];
  }

  return [value, ''];
}

export function stripTerminalControlSequences(value: string): string {
  return value.replace(COMPLETE_TERMINAL_CONTROL_RE, '');
}

export class TerminalControlSequenceStripper {
  #pending = '';

  write(chunk: unknown): string {
    const value = `${this.#pending}${typeof chunk === 'string' ? chunk : String(chunk)}`;
    this.#pending = '';
    const [ready, pending] = splitIncompleteControlTail(value);
    this.#pending = pending;
    return stripTerminalControlSequences(ready);
  }

  flush(): string {
    this.#pending = '';
    return '';
  }
}