"""
Module for processing Sitemaps.

Note: The main purpose of this module is to provide support for the
SitemapSpider, its API is subject to change without notice.
"""

from __future__ import annotations

from typing import TYPE_CHECKING, Any
from urllib.parse import urljoin

import lxml.etree

if TYPE_CHECKING:
    from collections.abc import Iterable, Iterator


class Sitemap:
    """Class to parse Sitemap (type=urlset) and Sitemap Index
    (type=sitemapindex) files"""

    def __init__(self, xmltext: str | bytes):
        xmlp = lxml.etree.XMLParser(
            recover=True, remove_comments=True, resolve_entities=False
        )
        self._root = lxml.etree.fromstring(xmltext, parser=xmlp)
        rt = self._root.tag
        assert isinstance(rt, str)
        self.type = rt.split("}", 1)[1] if "}" in rt else rt

    def __iter__(self) -> Iterator[dict[str, Any]]:
        for elem in self._root.getchildren():
            d: dict[str, Any] = {}
            for el in elem.getchildren():
                tag = el.tag
                assert isinstance(tag, str)
                name = tag.split("}", 1)[1] if "}" in tag else tag

                if name == "link":
                    if "href" in el.attrib:
                        d.setdefault("alternate", []).append(el.get("href"))
                else:
                    d[name] = el.text.strip() if el.text else ""

            if "loc" in d:
                yield d


def sitemap_urls_from_robots(
    robots_text: str, base_url: str | None = None
) -> Iterable[str]:
    """Return an iterator over all sitemap urls contained in the given
    robots.txt file
    """
    for line in robots_text.splitlines():
        if line.lstrip().lower().startswith("sitemap:"):
            url = line.split(":", 1)[1].strip()
            yield urljoin(base_url or "", url)
