import base64
import random
from pathlib import Path


def image_to_base64(file_path: Path) -> str | None:
    """图片转 base64,文件不存在时返回 None"""
    if not file_path.is_file():
        return None
    with open(file_path, "rb") as f:
        return "base64://" + base64.b64encode(f.read()).decode()


def audio_to_base64(file_path: Path) -> str:
    """音频转 base64"""
    with open(file_path, "rb") as f:
        return "base64://" + base64.b64encode(f.read()).decode()


def random_audio(dir_path: Path) -> str | None:
    """随机取目录下的一个语音文件并转 base64,目录不存在或为空时返回 None"""
    if not dir_path.is_dir():
        return None
    files = [p for p in dir_path.iterdir() if p.is_file()]
    if not files:
        return None
    return audio_to_base64(random.choice(files))