"""Issuer logos, as T-Invest publishes them (kept out of `sources/`: the API needs the URL,
not the whole source registry).

Every instrument the API describes carries a `brand` block: the name of a logo file and the
brand's own colour. The pictures live on T-Bank's public CDN, need no key and answer with
`access-control-allow-origin: *`, so a browser client can load them straight from there.
"""

from __future__ import annotations

LOGO_HOST = "https://invest-brands.cdn-tinkoff.ru"
LOGO_SIZE = 160
"""The CDN serves 160, 320 and 640 px squares; a list row never needs more than the first."""


def logo_url(logo_name: str | None) -> str | None:
    """`sber.png` -> the URL of its 160 px picture; None when the instrument has no logo."""
    if not logo_name:
        return None
    stem = logo_name.rsplit(".", 1)[0]
    return f"{LOGO_HOST}/{stem}x{LOGO_SIZE}.png"