"""
Routing-Gateway-Service: liest/schreibt die LiteLLM-Config und prüft die
Erreichbarkeit. MC verwaltet damit die Modell-Zuordnung (welcher llama-swap-Alias
ist fast/heavy/vision/coder) und die Routing-Regeln.
"""

import httpx

from config import GATEWAY_CONFIG_PATH, GATEWAY_URL, yaml


def read_gateway_config() -> dict:
    if not GATEWAY_CONFIG_PATH.exists():
        return {"model_list": [], "litellm_settings": {}, "router_settings": {}}
    with GATEWAY_CONFIG_PATH.open("r", encoding="utf-8") as f:
        return yaml.load(f) or {}


def write_gateway_config(cfg: dict) -> None:
    import os
    GATEWAY_CONFIG_PATH.parent.mkdir(parents=True, exist_ok=True)
    tmp = GATEWAY_CONFIG_PATH.with_name(GATEWAY_CONFIG_PATH.name + ".tmp")
    with tmp.open("w", encoding="utf-8") as f:
        yaml.dump(cfg, f)
    os.replace(tmp, GATEWAY_CONFIG_PATH)


def routing_summary() -> dict:
    """Kompakte Sicht für die UI: welcher Backend-Alias steckt hinter welchem
    Gateway-Modellnamen + die Fallback-Ketten."""
    cfg = read_gateway_config()
    routes = []
    for entry in cfg.get("model_list") or []:
        params = entry.get("litellm_params") or {}
        routes.append({
            "name": entry.get("model_name"),
            "target": str(params.get("model", "")),
            "api_base": params.get("api_base"),
        })
    settings = cfg.get("litellm_settings") or {}
    return {
        "routes": routes,
        "fallbacks": settings.get("fallbacks") or [],
        "context_window_fallbacks": settings.get("context_window_fallbacks") or [],
    }


def set_route(name: str, target_alias: str, api_base: str = "http://127.0.0.1:8080/v1") -> None:
    """Einen Gateway-Modellnamen (z.B. 'fast') auf einen llama-swap-Alias mappen."""
    cfg = read_gateway_config()
    ml = cfg.setdefault("model_list", [])
    params = {"model": f"openai/{target_alias}", "api_base": api_base, "api_key": "sk-noauth"}
    for entry in ml:
        if entry.get("model_name") == name:
            entry["litellm_params"] = params
            break
    else:
        ml.append({"model_name": name, "litellm_params": params})
    write_gateway_config(cfg)


def gateway_reachable() -> bool:
    try:
        with httpx.Client(timeout=3.0) as c:
            # LiteLLM hat /health/liveliness; /v1/models tut's auch.
            r = c.get(f"{GATEWAY_URL}/v1/models")
            return r.status_code in (200, 401)
    except Exception:
        return False