from fastapi import HTTPException, Request

from config import PROVIDER_KEYS
from proxy.providers import PROVIDERS, Provider


def _match_provider(token: str) -> tuple[str, str] | None:
    """Return (provider_name, configured_proxy_key) if token matches a known provider key."""
    for name, configured_key in PROVIDER_KEYS.items():
        if configured_key and token == configured_key:
            return name, configured_key
    return None


def resolve_provider(request: Request) -> Provider:
    auth = request.headers.get("Authorization", "")
    parts = auth.split(" ", 1)
    if len(parts) != 2 or parts[0].lower() != "bearer":
        raise HTTPException(status_code=401, detail="Missing or invalid Authorization header. Expected 'Bearer sk-{provider}-...'")

    token = parts[1]
    match = _match_provider(token)
    if match is None:
        raise HTTPException(status_code=401, detail="Unknown proxy key")

    provider_name, _ = match
    return PROVIDERS[provider_name]


def get_real_key(provider: Provider) -> str:
    import os
    key = os.getenv(provider.env_real_key, "")
    if not key:
        raise HTTPException(
            status_code=500,
            detail=f"Provider '{provider.name}' is configured in .env but its real API key ({provider.env_real_key}) is missing"
        )
    return key