/**
 * useAIHealthCheck.ts — Hook per testare la latenza dei provider AI via backend
 *
 * Chiama GET /api/ai/health (FastAPI HF Space) che esegue probe parallelo
 * su tutti i provider configurati (openrouter, gemini, groq, hf).
 * Cache in-memory 60s lato client — non chiama il backend ad ogni render.
 *
 * Usage:
 *   const { data, loading, error, refresh } = useAIHealthCheck();
 *
 * Distinto da useProviderHealth (Sessione 8) che monitora il runtime locale.
 */
import { useState, useCallback, useRef } from "react";
import { makeTimedSignal } from "@/lib/agentLoop/networkConstants"; // Loop-12: iOS-safe

const _BACKEND = (import.meta.env.VITE_BACKEND_URL ?? "").replace(/\/$/, "");
const CACHE_TTL_MS = 60_000;

export interface AIProviderResult {
  name:       string;
  ok:         boolean;
  latency_ms: number;
  model:      string;
  error?:     string;
}

export interface AIHealthData {
  providers:  AIProviderResult[];
  tested_at:  number;
}

export function useAIHealthCheck() {
  const [data,    setData]    = useState<AIHealthData | null>(null);
  const [loading, setLoading] = useState(false);
  const [error,   setError]   = useState<string | null>(null);
  const cacheRef = useRef<{ data: AIHealthData; at: number } | null>(null);

  const refresh = useCallback(async (force = false) => {
    if (!_BACKEND) {
      setError("VITE_BACKEND_URL non configurato");
      return;
    }
    // Cache hit (skip se force=true)
    if (!force && cacheRef.current && Date.now() - cacheRef.current.at < CACHE_TTL_MS) {
      setData(cacheRef.current.data);
      return;
    }
    setLoading(true);
    setError(null);
    try {
      const res = await fetch(`${_BACKEND}/api/ai/health`, {
        signal: makeTimedSignal(15_000),
      });
      if (!res.ok) throw new Error(`HTTP ${res.status}`);
      const json = (await res.json()) as AIHealthData;
      cacheRef.current = { data: json, at: Date.now() };
      setData(json);
    } catch (err: unknown) {
      setError((err as Error).message ?? "Errore sconosciuto");
    } finally {
      setLoading(false);
    }
  }, []);

  return { data, loading, error, refresh };
}