bknd/app/src/cli/utils/cli.ts

const _SPEEDUP = process.env.LOCAL;

const DEFAULT_WAIT = _SPEEDUP ? 0 : 250;
export async function wait(factor: number = 1, strict?: boolean) {
   const ms = strict === true ? factor : DEFAULT_WAIT * factor;
   return new Promise((r) => setTimeout(r, ms));
}

// from https://github.com/chalk/ansi-regex/blob/main/index.js
export default function ansiRegex({ onlyFirst = false } = {}) {
   // Valid string terminator sequences are BEL, ESC\, and 0x9c
   const ST = "(?:\\u0007|\\u001B\\u005C|\\u009C)";
   const pattern = [
      `[\\u001B\\u009B][[\\]()#;?]*(?:(?:(?:(?:;[-a-zA-Z\\d\\/#&.:=?%@~_]+)*|[a-zA-Z\\d]+(?:;[-a-zA-Z\\d\\/#&.:=?%@~_]*)*)?${ST})`,
      "(?:(?:\\d{1,4}(?:;\\d{0,4})*)?[\\dA-PR-TZcf-nq-uy=><~]))"
   ].join("|");

   return new RegExp(pattern, onlyFirst ? undefined : "g");
}

const DEFAULT_WAIT_WRITER = _SPEEDUP ? 0 : 20;
export async function* typewriter(
   text: string,
   transform?: (char: string) => string,
   _delay?: number
) {
   const delay = DEFAULT_WAIT_WRITER * (_delay ?? 1);
   const regex = ansiRegex();
   const parts: string[] = [];
   let match: RegExpExecArray | null;
   let lastIndex = 0;

   // Extract ANSI escape sequences as standalone units
   // biome-ignore lint/suspicious/noAssignInExpressions: <explanation>
   while ((match = regex.exec(text)) !== null) {
      if (lastIndex < match.index) {
         parts.push(...text.slice(lastIndex, match.index).split(""));
      }
      parts.push(match[0]); // Add the ANSI escape sequence as a full chunk
      lastIndex = regex.lastIndex;
   }

   // Add any remaining characters after the last ANSI sequence
   if (lastIndex < text.length) {
      parts.push(...text.slice(lastIndex).split(""));
   }

   // Yield characters or ANSI sequences in order
   for (const chunk of parts) {
      yield transform ? transform(chunk) : chunk;
      // Delay only for normal characters, not ANSI codes
      if (!regex.test(chunk)) {
         await wait(delay, true);
      }
   }
}