lumbunglib/lumbunglib/feed.py

import os
import shutil
import time
from hashlib import md5
from ast import literal_eval as make_tuple
from pathlib import Path
from urllib.parse import urlparse

import arrow
import feedparser
import jinja2
import requests
from bs4 import BeautifulSoup
from slugify import slugify


def write_etag(feed_name, feed_data):
    """
    save timestamp of when feed was last modified
    """
    etag = ""
    modified = ""

    if "etag" in feed_data:
        etag = feed_data.etag
    if "modified" in feed_data:
        modified = feed_data.modified

    if etag or modified:
        with open(os.path.join("etags", feed_name + ".txt"), "w") as f:
            f.write(str((etag, modified)))


def get_etag(feed_name):
    """
    return timestamp of when feed was last modified
    """
    fn = os.path.join("etags", feed_name + ".txt")
    etag = ""
    modified = ""

    if os.path.exists(fn):
        etag, modified = make_tuple(open(fn, "r").read())

    return etag, modified


def create_frontmatter(entry):
    """
    parse RSS metadata and return as frontmatter
    """
    if "published" in entry:
        published = entry.published_parsed
    if "updated" in entry:
        published = entry.updated_parsed

    published = arrow.get(published)

    if "author" in entry:
        author = entry.author
    else:
        author = ""

    if "title" in entry:
        title = entry.title
    else:
        title = ""

    tags = []
    if "tags" in entry:
        # TODO finish categories
        for t in entry.tags:
            tags.append(t["term"])

    frontmatter = {
        "title": title,
        "date": published.format(),
        "summary": "",
        "author": author,
        "original_link": entry.link,
        "feed_name": entry["feed_name"],
        "tags": str(tags),
    }

    return frontmatter


def create_post(post_dir, entry):
    """
    write hugo post based on RSS entry
    """
    frontmatter = create_frontmatter(entry)

    if not os.path.exists(post_dir):
        os.makedirs(post_dir)

    if "content" in entry:
        post_content = entry.content[0].value
    else:
        post_content = entry.summary

    parsed_content = parse_posts(post_dir, post_content)

    template_dir = os.path.join(Path(__file__).parent.resolve(), "templates")
    env = jinja2.Environment(loader=jinja2.FileSystemLoader(template_dir))
    template = env.get_template("feed.md")
    with open(os.path.join(post_dir, "index.html"), "w") as f:  # n.b. .html
        post = template.render(frontmatter=frontmatter, content=parsed_content)
        f.write(post)
        print("created post for", entry.title, "({})".format(entry.link))


def grab_media(post_directory, url):
    """
    download media linked in post to have local copy
    if download succeeds return new local path otherwise return url
    """
    image = urlparse(url).path.split("/")[-1]

    try:
        if not os.path.exists(os.path.join(post_directory, image)):
            # TODO: stream is true is a conditional so we could check the headers for things, mimetype etc
            response = requests.get(url, stream=True)
            if response.ok:
                with open(os.path.join(post_directory, image), "wb") as img_file:
                    shutil.copyfileobj(response.raw, img_file)
                    print("Downloaded cover image", image)
                    return image
            return image
        elif os.path.exists(os.path.join(post_directory, image)):
            return image

    except Exception as e:
        print("Failed to download image", url)
        print(e)
    return url


def parse_posts(post_dir, post_content):
    """
    parse the post content to for media items
    replace foreign image with local copy
    filter out iframe sources not in allowlist
    """
    soup = BeautifulSoup(post_content, "html.parser")
    allowed_iframe_sources = ["youtube.com", "vimeo.com", "tv.lumbung.space"]

    for img in soup(["img", "object"]):
        local_image = grab_media(post_dir, img["src"])
        if img["src"] != local_image:
            img["src"] = local_image

    for iframe in soup(["iframe"]):
        if not any(source in iframe["src"] for source in allowed_iframe_sources):
            print("filtered iframe: {}...".format(iframe["src"][:25]))
            iframe.decompose()
    return soup.decode()


def grab_feed(feed_url):
    """
    check whether feed has been updated
    download & return it if it has
    """
    feed_name = urlparse(feed_url).netloc

    etag, modified = get_etag(feed_name)

    try:
        if modified:
            data = feedparser.parse(feed_url, modified=modified)
        elif etag:
            data = feedparser.parse(feed_url, etag=etag)
        else:
            data = feedparser.parse(feed_url)
    except Exception as e:
        print("Error grabbing feed")
        print(feed_name)
        print(e)
        return False

    print(data.status, feed_url)
    if data.status == 200:
        # 304 means the feed has not been modified since we last checked
        write_etag(feed_name, data)
        return data
    return False


def main():
    feed_urls = open("feeds_list.txt", "r").read().splitlines()

    start = time.time()

    if not os.path.exists("etags"):
        os.mkdir("etags")

    output_dir = os.environ.get("OUTPUT_DIR")

    if not os.path.exists(output_dir):
        os.makedirs(output_dir)

    feed_dict = dict()
    for url in feed_urls:
        feed_name = urlparse(url).netloc
        feed_dict[url] = feed_name

    feed_names = feed_dict.values()
    content_dirs = os.listdir(output_dir)
    for i in content_dirs:
        if i not in feed_names:
            shutil.rmtree(os.path.join(output_dir, i))
            print("%s not in feeds_list.txt, removing local data" %(i))

    # add iframe to the allowlist of feedparser's sanitizer,
    # this is now handled in parse_post()
    feedparser.sanitizer._HTMLSanitizer.acceptable_elements |= {"iframe"}

    for feed_url in feed_urls:

        feed_name = feed_dict[feed_url]

        feed_dir = os.path.join(output_dir, feed_name)

        if not os.path.exists(feed_dir):
            os.makedirs(feed_dir)

        existing_posts = os.listdir(feed_dir)

        data = grab_feed(feed_url)

        if data:
            for entry in data.entries:
                # if 'tags' in entry:
                #     for tag in entry.tags:
                #        for x in ['lumbung.space', 'D15', 'lumbung']:
                #            if x in tag['term']:
                #                print(entry.title)
                entry["feed_name"] = feed_name

                post_name = slugify(entry.title)
                # pixelfed returns the whole post text as the post name. max
                # filename length is 255 on many systems. here we're shortening
                # the name and adding a hash to it to avoid a conflict in a
                # situation where 2 posts start with exactly the same text.
                if len(post_name) > 150:
                    post_hash = md5(bytes(post_name, "utf-8"))
                    post_name = post_name[:150] + "-" + post_hash.hexdigest()
                post_dir = os.path.join(output_dir, feed_name, post_name)

                if post_name not in existing_posts:
                    # if there is a blog entry we dont already have, make it
                    create_post(post_dir, entry)

                elif post_name in existing_posts:
                    # if we already have it, update it
                    create_post(post_dir, entry)
                    existing_posts.remove(
                        post_name
                    )  # create list of posts which have not been returned by the feed

            for post in existing_posts:
                # remove blog posts no longer returned by the RSS feed
                print("deleted", post)
                shutil.rmtree(os.path.join(feed_dir, slugify(post)))

    end = time.time()

    print(end - start)