# coding:utf-8
import os.path
from functools import partial
from io import open as iopen
from urllib.parse import urlsplit
from multiprocessing import Pool

import requests


class IMGDownloader(object):
    """图片下载器"""

    IMG_TYPES = ['jpg', 'gif', 'png', 'tif', 'svg', 'jpeg']

    @classmethod
    def download(cls, urls, des='.'):
        """批量下载保存"""

        if not os.path.exists(des):
            os.makedirs(des, exist_ok=True)

        pool = Pool(processes=8)
        pool.map(partial(cls._download, des), urls)
        pool.close()
        pool.join()

    @classmethod
    def _download(cls, des, url):

        try:
            img_type, content = cls.req_img(url)
        except:
            return

        file_name = cls.get_file_name(url, True)

        full_path = os.path.join(des, file_name + '.' + img_type)
        if os.path.exists(full_path):
            return

        with iopen(full_path, 'wb') as img:
            img.write(content)

    @staticmethod
    def get_file_name(url, full_url_path=False):
        """生成图片名称。

        :param url: url 文件url
        :param full_url_path: 是否使用url的全路径作为文件名称，
                              例如：2018/08/03/67867 -> 2018_08_03_67867
        :return:
        """
        split_result = urlsplit(url)
        if full_url_path:
            name = split_result.path.replace('/', '_')
        else:
            name = split_result.path.split('/')[-1]
        if not name:
            raise Exception("请求地址不能为一个跟域名")

        # 判断文件名是否有后缀，如果有则去掉
        return name.rsplit('.', 1)[0]

    @classmethod
    def req_img(cls, url):
        """请求img内容。

        返回一个tuple(图片类型, 图片内容）

        :param url: img url
        :return: (img_name, img_content)
        """
        res = requests.get(url)
        if res.status_code == requests.codes.ok:
            try:
                img_type = res.headers['Content-Type'].split('/')[1]
            except:
                img_type = None

            if img_type not in cls.IMG_TYPES:
                raise requests.RequestException("{img_type}图片格式不允许错误".format(img_type=img_type))

            return img_type, res.content

        raise requests.RequestException("请求错误")


if __name__ == '__main__':
    url = ["https://heras.igengmei.com/slide/2018/06/10/0c09d47759"]
    IMGDownloader.download(url)