import os
import argparse
import logging
import xml.etree.ElementTree as ET
import requests
from datetime import datetime, timezone

LOGGER = logging.getLogger(__name__)
LOGGER.setLevel(logging.INFO)

ch = logging.StreamHandler()
ch.setLevel(logging.INFO)
formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
ch.setFormatter(formatter)

LOGGER.addHandler(ch)


def tag(tagname: str) -> str:
    el_prefix = '{http://www.w3.org/2005/Atom}'
    return el_prefix + tagname


class Entry:
    def __init__(self, entry):
        self.title = entry.find(tag('title')).text
        self.url = entry.find(tag('id')).text
        self.author = entry.find(tag('author')).find(tag('name')).text
        self.date = datetime.fromisoformat(entry.find(tag('published')).text)

    def __str__(self):
        return f'New post by {self.author}: {self.title}\n{self.url}'


def get_last_update_time(file: str) -> datetime:
    try:
        stat = os.stat(file)
        return datetime.fromtimestamp(stat.st_mtime,
                                      datetime.now().astimezone().tzinfo)
    except FileNotFoundError:
        return datetime.now(timezone.utc)


def update_rss_file(file, feed):
    r = requests.get(feed, stream=True)
    with open(file, 'w') as fd:
        for chunk in r.iter_content(chunk_size=1024, decode_unicode=True):
            fd.write(chunk)


def parse_rss_file(file) -> ET.Element:
    tree = ET.parse(file)
    return tree.getroot()


def get_new_posts(time, root) -> list[Entry]:
    posts = []
    for entry in root.findall(tag('entry')):
        e = Entry(entry)
        if e.date > time:
            posts.append(e)
    return posts


def send_message(entry, url) -> int:
    obj = {
            'content': str(entry)
            }
    r = requests.post(url, obj)
    return r.status_code

# Check last mod date of current rss file
# Download new version of file
# Iterate over entries, storing ones with a newer date in an array
# send POST to discord webhook


if __name__ == "__main__":
    parser = argparse.ArgumentParser(
            prog='discussfeed',
            description='Checks for new entries from an atom feed and sends them to a discord webhook')
    parser.add_argument('-w', '--webhook')
    parser.add_argument('feed_url')
    args = parser.parse_args()

    filename = os.path.basename(args.feed_url)
    last_updated = get_last_update_time(filename)
    LOGGER.info(f'last updated: {last_updated}')

    update_rss_file(filename, args.feed_url)
    root = parse_rss_file(filename)
    posts = get_new_posts(last_updated, root)
    posts.sort(key=lambda post: post.date)
    LOGGER.info(f'found {len(posts)} new posts')

    for post in posts:
        status = send_message(post, args.webhook)
        if status >= 300:
            LOGGER.error(f'Response code {status}')
        else:
            LOGGER.info(f'response code {status}')