Download chromecast background

chromecastdownloader.py

#!/usr/bin/env python3
import collections
import concurrent.futures
import json
import os
import pathlib
import re

import requests

CHROMECAST_HOME = 'https://clients3.google.com/cast/chromecast/home/v/c9541b08'
PROJECT_DIR = pathlib.Path(__file__).parent

Background = collections.namedtuple('Background', [
    'href',
    'author',
])


def find_backgrounds(chromecast_url):
    """Find the background from chromecast"""
    r = requests.get(chromecast_url)
    r.raise_for_status()
    body = r.content
    if isinstance(body, bytes):
        body = body.decode()
    match = re.search(r'JSON\.parse\(([^\)]+)', body)
    if not match:
        raise SystemExit('Unable to find background, the page content may have'
                         'changed.')
    raw_text = match.group(1).encode('utf-8').decode('unicode_escape')\
            .replace('\\u003d', '=')\
            .replace('\\', '')\
            .replace("'", '')\
            .replace("s1280-w1280-h720", "s1920-w1920-h1200")\
            .replace('\n', '')
    js = json.loads(raw_text)
    for background in js[0]:
        bg = Background(*background[:2])
        if not any(x is None for x in [bg.href, bg.author]):
            yield bg


def download_image_as(href, local_path):
    r = requests.get(href)
    r.raise_for_status()
    with open(local_path, 'wb') as f:
        for chunk in r.iter_content(chunk_size=1024):
            if chunk:
                f.write(chunk)
    return local_path


def main():
    """Do the main things"""
    output_dir = PROJECT_DIR / 'output'
    if not output_dir.is_dir():
        output_dir.mkdir()

    with concurrent.futures.ThreadPoolExecutor(max_workers=5) as pool:
        downloaders = []
        for background in find_backgrounds(CHROMECAST_HOME):
            output_name = output_dir / (os.path.basename(background.href) + '.jpg')
            if output_name.is_file():
                print('Skipping known image:', output_name)
                continue

            downloaders.append(pool.submit(
                download_image_as,
                background.href,
                str(output_name)
            ))
        for download in concurrent.futures.as_completed(downloaders):
            if download.exception():
                print('Error during download:', download.exception())
            else:
                print('finished download:', download.result())


if __name__ == '__main__':
    main()