"""
工具函数模块
提供通用的辅助功能
"""

import os
import hashlib
import requests
from urllib.parse import urljoin
from .config import HEADERS


def ensure_dir(path: str) -> None:
    """确保目录存在，不存在则创建"""
    os.makedirs(path, exist_ok=True)


def get_file_hash(url: str) -> str:
    """根据URL生成唯一文件名哈希"""
    return hashlib.md5(url.encode()).hexdigest()[:12]


def get_file_extension(url: str) -> str:
    """从URL获取文件扩展名"""
    # 移除查询参数
    clean_url = url.split('?')[0]
    ext = os.path.splitext(clean_url)[1].lower()
    if ext not in ['.jpg', '.jpeg', '.png', '.gif', '.webp', '.bmp', '.svg']:
        ext = '.jpg'  # 默认扩展名
    return ext


def download_image(img_url: str, save_dir: str, timeout: int = 15) -> str | None:
    """
    下载图片到本地
    
    Args:
        img_url: 图片URL
        save_dir: 保存目录
        timeout: 超时时间
    
    Returns:
        本地文件路径，失败返回 None
    """
    try:
        ensure_dir(save_dir)
        
        url_hash = get_file_hash(img_url)
        ext = get_file_extension(img_url)
        local_filename = f"{url_hash}{ext}"
        local_path = os.path.join(save_dir, local_filename)
        
        # 如果已下载过，直接返回路径
        if os.path.exists(local_path):
            return local_path
        
        # 下载图片
        response = requests.get(img_url, headers=HEADERS, timeout=timeout)
        if response.status_code == 200:
            with open(local_path, 'wb') as f:
                f.write(response.content)
            return local_path
        else:
            print(f"  图片下载失败 ({response.status_code}): {img_url}")
            return None
    except Exception as e:
        print(f"  图片下载出错: {img_url} - {e}")
        return None


def safe_filename(name: str, max_length: int = 50) -> str:
    """
    生成安全的文件名
    
    Args:
        name: 原始名称
        max_length: 最大长度
    
    Returns:
        安全的文件名
    """
    # 移除或替换不安全字符
    unsafe_chars = ['/', '\\', ':', '*', '?', '"', '<', '>', '|', '\n', '\r', '\t']
    for char in unsafe_chars:
        name = name.replace(char, '_')
    
    # 去除首尾空格
    name = name.strip()
    
    # 截断长度
    if len(name) > max_length:
        name = name[:max_length]
    
    return name


def make_absolute_url(base_url: str, relative_url: str) -> str:
    """将相对URL转为绝对URL"""
    return urljoin(base_url, relative_url)