from datetime import datetime
import sqlite3

from bs4 import BeautifulSoup
from markdown import markdown

def soup_append_multiple_tags(soup: BeautifulSoup, children: dict) -> None:
    for name, string in children.items():
        soup.append(soup.new_tag(name))
        soup.find_all(name)[-1].string = string

def post_find_first_plain_line(post: str) -> str:
    while post:
        if post[0].isalnum():
            break
        end = post.find("\n")
        post = post[end+1:]
    end = post.find("\n")
    return post[:end]

def generate_feed(db):
    soup = BeautifulSoup(features="xml")

    soup.append(soup.new_tag("rss", version="2.0"))
    rss = soup.rss
    rss["xmlns:atom"] = "http://www.w3.org/2005/Atom"
    rss["xmlns:content"] = "http://purl.org/rss/1.0/modules/content/"

    rss.append(soup.new_tag("channel"))
    channel = rss.channel

    channel_children = {
        "description": "Blog posts from allsparkinfinite's blog",
        "link": "https://blog.allsparkinfinite.name",
        "title": "blogsparkinfinite",
        "docs": "https://rssboard.org/rss-specification",
        "language": "en-IN",
        "lastBuildDate": datetime.now().strftime("%a, %d %b %Y %T +0530"),
        "ttl": "240",
    }
    soup_append_multiple_tags(channel, channel_children)

    channel.append(channel.new_tag("atom:link"))
    channel.find_all("atom:link")[-1]["href"] = "https://blog.allsparkinfinite.name/rss/"
    channel.find_all("atom:link")[-1]["rel"] = "self"
    channel.find_all("atom:link")[-1]["type"] = "application/rss+xml"

    channel.append(channel.new_tag("atom:link"))
    channel.find_all("atom:link")[-1]["href"] = "https://blog.allsparkinfinite.name/"
    channel.find_all("atom:link")[-1]["rel"] = "alternate"
    channel.find_all("atom:link")[-1]["type"] = "text/html"

    posts = db.execute("SELECT * FROM post").fetchall()
    posts.reverse()

    for post in posts:
        channel.append(soup.new_tag("item"))
        item = channel.find_all("item")[-1]
        item_children = {
            "description": post_find_first_plain_line(post[4]),
            "guid": f"https://blog.allsparkinfinite.name/{post[0]}/",
            "pubDate": datetime.strptime(post[2], "%Y-%m-%d %T").strftime("%a, %d %b %Y %T GMT"),
            "title": post[3],
            "content:encoded": markdown(post[4]),
        }
        soup_append_multiple_tags(item, item_children)

    with open("flaskr/static/rss.xml", "w") as f:
        f.write(soup.prettify())