"""Host placement resolution from profile policy and environment."""

from __future__ import annotations

import os

from sandboxer.models import Profile


def resolve_host(profile: Profile, *, override: str | None = None) -> str:
    if override:
        return override
    env_host = os.environ.get("SANDBOXER_HOST")
    if env_host:
        return env_host
    for candidate in [*profile.placement.prefer, *profile.placement.fallback]:
        mapped = os.environ.get(f"SANDBOXER_HOST_{candidate.upper()}")
        if mapped:
            return mapped
        if candidate in os.environ:
            return os.environ[candidate]
    if profile.placement.prefer:
        return profile.placement.prefer[0]
    if profile.placement.fallback:
        return profile.placement.fallback[0]
    raise ValueError(
        "No host resolved. Set SANDBOXER_HOST or profile placement hosts in environment."
    )