from dataclasses import dataclass
from urllib.parse import urljoin

from bs4 import BeautifulSoup

import switch_client


@dataclass
class MenuItem:
    label: str
    href: str | None
    parent: str | None
    depth: int


def find_frame_src(html: str, frame_id_or_name: str) -> str | None:
    """Search for a <frame>/<iframe> tag by id or name attr, return its src."""
    soup = BeautifulSoup(html, "html.parser")
    tag = soup.find(["frame", "iframe"], id=frame_id_or_name) or soup.find(
        ["frame", "iframe"], attrs={"name": frame_id_or_name}
    )
    if tag is None:
        found = [
            {"tag": t.name, "id": t.get("id"), "name": t.get("name"), "src": t.get("src")}
            for t in soup.find_all(["frame", "iframe"])
        ]
        print(f"WARNING: frame/iframe '{frame_id_or_name}' not found. Frames present: {found}")
        return None
    return tag.get("src")


def get_treeframe_url(session) -> str:
    html = getattr(session, "frameset_html", None)
    if html is None:
        print("WARNING: session has no cached frameset_html from login(), falling back to GET /.")
        html = switch_client.fetch(session, "/")
    src = find_frame_src(html, "treeframe")
    if src is None:
        raise RuntimeError("Could not locate iframe#treeframe on root page.")
    return urljoin(switch_client.BASE_URL + "/", src)


def get_site_links_html(session, treeframe_url: str) -> str:
    html = switch_client.fetch(session, treeframe_url)
    soup = BeautifulSoup(html, "html.parser")

    container = None
    body = soup.find("body", id="sitemap")
    if body is not None:
        sidebar = body.find("div", id="sidebar")
        if sidebar is not None:
            container = sidebar.find("div", id="site_links")

    if container is None:
        print(
            "WARNING: body#sitemap > div#sidebar > div#site_links not found via strict path, "
            "falling back to searching for div#site_links anywhere in the page."
        )
        container = soup.find("div", id="site_links")

    if container is None:
        top_level_ids = [d.get("id") for d in soup.find_all("div") if d.get("id")]
        print(f"WARNING: div#site_links not found at all. Top-level div ids seen: {top_level_ids}")
        raise RuntimeError("Could not locate div#site_links on treeframe page.")

    return str(container)


def parse_menu_tree(site_links_html: str, base_href: str) -> list[MenuItem]:
    soup = BeautifulSoup(site_links_html, "html.parser")
    items: list[MenuItem] = []

    def walk(ul, parent_label, depth):
        for li in ul.find_all("li", recursive=False):
            a = li.find("a", recursive=False)
            nested_ul = li.find("ul", recursive=False)
            if a is not None:
                label = a.get_text(strip=True)
                href = urljoin(base_href, a["href"]) if a.get("href") else None
            else:
                label = li.get_text(strip=True).split("\n")[0].strip()
                href = None
                if not label:
                    print(f"WARNING: <li> with no <a> and no text found at depth {depth}: {li}")
            items.append(MenuItem(label=label, href=href, parent=parent_label, depth=depth))
            if nested_ul is not None:
                walk(nested_ul, label, depth + 1)

    top_ul = soup.find("ul", recursive=False) or soup.find("ul")
    if top_ul is None:
        print(f"WARNING: no <ul> found inside site_links container: {site_links_html[:500]!r}")
        return items
    walk(top_ul, None, 0)
    return items


def get_menu_items(session) -> list[MenuItem]:
    treeframe_url = get_treeframe_url(session)
    site_links_html = get_site_links_html(session, treeframe_url)
    return parse_menu_tree(site_links_html, base_href=treeframe_url)