camelCaseKey

/**
 * @param {unknown} input
 * @return {unknown}
 */
export default function camelCaseKeys(input) {
  // Helper function to convert snake_case -> camelCase.
  function toCamelCase(str) {
    const camel = str.replace(/_([a-zA-Z])/g, (_, char) => {
      return char.toUpperCase();
    });
    return camel.charAt(0).toLowerCase() + camel.slice(1);
  }

  // Base case:
  // If value is an array, recursively transform each item.
  if (Array.isArray(input)) {
    return input.map((item) => camelCaseKeys(item));
  }

  // If value is an object, transform all keys recursively.
  if (input !== null && typeof input === 'object') {
    const result = {};

    // Iterate through all keys in the object.
    for (const key in input) {
      // Convert current key to camelCase.
      const camelKey = toCamelCase(key);
      // Recursively transform nested values.
      result[camelKey] = camelCaseKeys(input[key]);
    }

    return result;
  }

  // Primitive values (string, number, boolean, null, etc.)
  // should be returned as-is.
  return input;
}

/**
camelCaseKeys({ foo_bar: true });
// { fooBar: true }

camelCaseKeys({ foo_bar: true, bar_baz: { baz_qux: '1' } });
// { fooBar: true, barBaz: { bazQux: '1' } }

camelCaseKeys([{ baz_qux: true }, { foo: true, bar: [{ foo_bar: 'hello' }] }]);
// [{ bazQux: true }, { foo: true, bar: [{ fooBar: 'hello' }] }]
 */