"""The address lamps use to reach Home Assistant. Deliberately free of Home Assistant imports."""

from __future__ import annotations

from urllib.parse import urlsplit

from .const import FIRMWARE_KEY_LENGTH, FIRMWARE_URL_PREFIX, MAX_LAMP_URL_LENGTH


def firmware_url(base: str, key: str) -> str:
    return f"{base.rstrip('/')}{FIRMWARE_URL_PREFIX}{key}"


def validate_lamp_base_url(url: str) -> str | None:
    """Return None if usable, else the error key for the options form."""
    try:
        parts = urlsplit(url)
        port_ok = parts.port is None or parts.port > 0
    except ValueError:
        return "invalid_base_url"
    if (
        parts.scheme != "http"
        or not parts.hostname
        or not port_ok
        or parts.username
        or parts.password
        or parts.query
        or parts.fragment
        or parts.path not in ("", "/")
    ):
        return "invalid_base_url"
    if len(firmware_url(url, "k" * FIRMWARE_KEY_LENGTH)) > MAX_LAMP_URL_LENGTH:
        return "base_url_too_long"
    return None