import os
from urllib.parse import urljoin
import xml.etree.ElementTree as ET

import requests
from pydantic import BaseModel


API_BASE_URL = os.environ.get("API_BASE_URL")
FRONTEND_URL = os.environ.get("FRONTEND_URL")
STORAGE_PATH = os.environ.get("STORAGE_PATH", "./static")


class SitemapItem(BaseModel):
    loc: str
    lastmod: str = None


def get_posts():
    url = urljoin(API_BASE_URL, "post")
    response = requests.get(url)
    response.raise_for_status()

    return response.json()


def map_post_to_sitemap_item(post: dict) -> SitemapItem:
    loc = urljoin(FRONTEND_URL, f"post/{post['id']}")
    lastmod = post["published_time"][:10]
    return SitemapItem(loc=loc, lastmod=lastmod)


def generate_sitemap(items: list[SitemapItem]) -> str:
    header = '<?xml version="1.0" encoding="UTF-8"?>\n'
    root = ET.Element("urlset", xmlns="http://www.sitemaps.org/schemas/sitemap/0.9")

    for item in items:
        url_element = ET.SubElement(root, "url")
        ET.SubElement(url_element, "loc").text = item.loc
        if item.lastmod:
            ET.SubElement(url_element, "lastmod").text = item.lastmod

    return header + ET.tostring(root, encoding="unicode")


def main():
    if not API_BASE_URL:
        raise ValueError("API_BASE_URL environment variable is not set.")
    if not FRONTEND_URL:
        raise ValueError("FRONTEND_URL environment variable is not set.")

    posts = get_posts()
    static_pages = [
        SitemapItem(loc=FRONTEND_URL),
        SitemapItem(loc=urljoin(FRONTEND_URL, "post")),
    ]
    sitemap_items = [*static_pages, *map(map_post_to_sitemap_item, posts)]

    sitemap = generate_sitemap(sitemap_items)
    sitemap_path = os.path.join(STORAGE_PATH, "sitemap.xml")
    os.makedirs(STORAGE_PATH, exist_ok=True)
    with open(sitemap_path, "w", encoding="utf-8") as f:
        f.write(sitemap)


if __name__ == "__main__":
    main()