from __future__ import annotations

import re
from urllib.parse import parse_qs, urlencode, urlsplit, urlunsplit

from app.errors import AppError

CATEGORY_PATH_RE = re.compile(r"/cat/([^/?#]+)", re.IGNORECASE)


def parse_category_key(source_url: str) -> str:
    parts = urlsplit(source_url.strip())
    query = parse_qs(parts.query)
    if query.get("cat"):
        return str(query["cat"][0])
    match = CATEGORY_PATH_RE.search(parts.path)
    if match:
        return match.group(1)
    raise AppError(422, "SOURCE_URL_INVALID", "Quellpfad muss eine Geizhals-Kategorie enthalten (cat=…)")


def slugify(value: str) -> str:
    text = value.strip().casefold().translate(str.maketrans("äöüß", "aous"))
    text = re.sub(r"[^a-z0-9]+", "-", text).strip("-")
    return text or "category"


def with_extended_filters(source_url: str) -> str:
    parts = urlsplit(source_url.strip())
    query = [(name, value) for name, value in _query_items(parts.query) if name != "promode"]
    query.append(("promode", "true"))
    return urlunsplit((parts.scheme or "https", parts.netloc, parts.path or "/", urlencode(query), parts.fragment))


def _query_items(query: str) -> list[tuple[str, str]]:
    from urllib.parse import parse_qsl

    return parse_qsl(query, keep_blank_values=True)