export enum Case {
  camelCase,
  snake_case,
}

export function changeStringCase<T>(
  str: string,
  currentCase: Case,
  newCase: Case,
): string {
  if (currentCase === newCase) {
    return str;
  }

  const currentSeparator = currentCase === Case.snake_case ? "_" : /(?=[A-Z])/;
  const words = str.split(currentSeparator);

  return words
    .map((word, index) => {
      switch (newCase) {
        case Case.camelCase:
          if (index === 0) {
            return word.toLowerCase();
          }

          return word[0].toUpperCase() + word.slice(1).toLowerCase();
        case Case.snake_case:
          return word.toLowerCase();
        default:
          throw new Error("Unknown case");
      }
    })
    .join(newCase === Case.snake_case ? "_" : "");
}