gemini-cli/packages/core/src/utils/textUtils.ts

/**
 * @license
 * Copyright 2025 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

/**
 * Safely replaces text with literal strings, avoiding ECMAScript GetSubstitution issues.
 * Escapes $ characters to prevent template interpretation.
 */
export function safeLiteralReplace(
  str: string,
  oldString: string,
  newString: string,
): string {
  if (oldString === '' || !str.includes(oldString)) {
    return str;
  }

  if (!newString.includes('$')) {
    return str.replaceAll(oldString, newString);
  }

  const escapedNewString = newString.replaceAll('$', '$$$$');
  return str.replaceAll(oldString, escapedNewString);
}

/**
 * Checks if a Buffer is likely binary by testing for the presence of a NULL byte.
 * The presence of a NULL byte is a strong indicator that the data is not plain text.
 * @param data The Buffer to check.
 * @param sampleSize The number of bytes from the start of the buffer to test.
 * @returns True if a NULL byte is found, false otherwise.
 */
export function isBinary(
  data: Buffer | null | undefined,
  sampleSize = 512,
): boolean {
  if (!data) {
    return false;
  }

  const sample = data.length > sampleSize ? data.subarray(0, sampleSize) : data;

  for (const byte of sample) {
    // The presence of a NULL byte (0x00) is one of the most reliable
    // indicators of a binary file. Text files should not contain them.
    if (byte === 0) {
      return true;
    }
  }

  // If no NULL bytes were found in the sample, we assume it's text.
  return false;
}

/**
 * Truncates a string to a maximum length, appending a suffix if truncated.
 * @param str The string to truncate.
 * @param maxLength The maximum length of the string.
 * @param suffix The suffix to append if truncated (default: '...[TRUNCATED]').
 * @returns The truncated string.
 */
export function truncateString(
  str: string,
  maxLength: number,
  suffix = '...[TRUNCATED]',
): string {
  if (str.length <= maxLength) {
    return str;
  }
  return str.slice(0, maxLength) + suffix;
}