"""backend/api/telemetry.py — Timing + repair metrics endpoint (BG-3).

Endpoint: GET /api/telemetry

Ritorna avg/p50/p90 per ogni chiave in _TIMING_STORE e contatori _REPAIR_STATS.
Response: { ok, timing: { <key>: { avg, p50, p90, n } }, repair: { <key>: int } }

Nessuna autenticazione richiesta (dati aggregati, zero PII).
"""
import statistics
from fastapi import APIRouter
from fastapi.responses import JSONResponse

router = APIRouter()


def _percentile(data: list[float], p: int) -> float:
    if not data:
        return 0.0
    sorted_data = sorted(data)
    k = max(0, int(len(sorted_data) * p / 100) - 1)
    return round(sorted_data[k], 2)


@router.get("/api/telemetry")
async def get_telemetry() -> JSONResponse:
    """Aggrega _TIMING_STORE e _REPAIR_STATS, ritorna avg/p50/p90."""
    try:
        from api.state import _TIMING_STORE, _REPAIR_STATS
    except ImportError:
        return JSONResponse({"ok": False, "error": "state module non disponibile"}, status_code=503)

    timing: dict[str, dict] = {}
    for key, buf in _TIMING_STORE.items():
        samples = list(buf)  # snapshot thread-safe (list.append è GIL-safe)
        if samples:
            timing[key] = {
                "avg": round(sum(samples) / len(samples), 2),
                "p50": _percentile(samples, 50),
                "p90": _percentile(samples, 90),
                "n":   len(samples),
            }
        else:
            timing[key] = {"avg": 0.0, "p50": 0.0, "p90": 0.0, "n": 0}

    repair = dict(_REPAIR_STATS)

    return JSONResponse({"ok": True, "timing": timing, "repair": repair})



# ── P20-F1: Fast-pass telemetry endpoint ─────────────────────────────────────
@router.get("/api/telemetry/fast-pass")
async def get_fast_pass_stats() -> JSONResponse:
    """P20-F1: Statistiche fast-pass (short-circuit goal verifier) aggregate.

    fast_pass_true  = goal soddisfatto al primo check (nessun repair).
    fast_pass_false = repair necessario (coverage < soglia).
    fast_pass_rate  = true / total (0.0–1.0, ideale > 0.7 → pochi repair).
    """
    try:
        from api.state import _REPAIR_STATS
    except ImportError:
        return JSONResponse({"ok": False, "error": "state module non disponibile"},
                            status_code=503)

    stats    = dict(_REPAIR_STATS)
    fp_true  = int(stats.get("fast_pass_true",  0))
    fp_false = int(stats.get("fast_pass_false", 0))
    total    = fp_true + fp_false
    rate     = round(fp_true / total, 4) if total else 0.0

    p36_hits = int(stats.get("p36_fast_path_hit", 0))
    return JSONResponse({
        "ok":                True,
        "fast_pass_true":    fp_true,
        "fast_pass_false":   fp_false,
        "total_checks":      total,
        "fast_pass_rate":    rate,
        "p36_fast_path_hit": p36_hits,  # P36: chiamate python_analyze via fast-path (<5ms)
        "_note": (
            "fast_pass_true = goal già soddisfatto al primo check; "
            "fast_pass_false = repair necessario. "
            "Fonte: _REPAIR_STATS['fast_pass_true/false'] in api.state."
        ),
    })

# ── GAP-NEW-5: Telemetry alert loop ─────────────────────────────────────────
# Campiona _REPAIR_STATS e _TIMING_STORE ogni 5 min.
# Se una soglia è superata → notifica Telegram via telegram_notify.notify_task_error().

_ALERT_THRESHOLDS: dict[str, float] = {
    "repair_per_5min":    50.0,    # > 50 riparazioni in 5 min → alert
    "p90_tool_call_ms":   50_000.0, # p90 latenza tool > 50s → alert
}

_alert_prev_repair: dict[str, int] = {}   # snapshot precedente _REPAIR_STATS
_alert_error_count: int = 0               # errori consecutivi rilevati


async def telemetry_alert_loop() -> None:
    """GAP-NEW-5: Loop background — campiona metriche ogni 5 min, alert su soglie.

    Avviato da main.py _on_startup() con asyncio.create_task().
    Fire-and-forget: non solleva mai eccezioni al caller.
    Usa notify_task_error() per l'invio Telegram (già rate-limited + retry).
    """
    global _alert_prev_repair, _alert_error_count
    import asyncio as _aio
    # Prima run: attende 5 min così il server è a regime
    await _aio.sleep(300)

    while True:
        try:
            from api.state import _TIMING_STORE, _REPAIR_STATS
            from api.telegram_notify import notify_task_error as _tg_err

            alerts: list[str] = []

            # ── Controllo 1: repair rate ──────────────────────────────────
            current_repair = dict(_REPAIR_STATS)
            if _alert_prev_repair:
                delta = {
                    k: current_repair.get(k, 0) - _alert_prev_repair.get(k, 0)
                    for k in current_repair
                }
                total_repairs = sum(v for v in delta.values() if v > 0)
                if total_repairs > _ALERT_THRESHOLDS["repair_per_5min"]:
                    alerts.append(
                        f"⚠️ Repair rate elevato: {total_repairs} riparazioni in 5 min "
                        f"(soglia: {int(_ALERT_THRESHOLDS['repair_per_5min'])}). "
                        f"Dettaglio: {dict(list(delta.items())[:5])}"
                    )
            _alert_prev_repair = current_repair

            # ── Controllo 2: p90 latenza tool ────────────────────────────
            for key, buf in _TIMING_STORE.items():
                samples = list(buf)
                if len(samples) < 10:
                    continue  # troppo pochi campioni — ignora
                sorted_s = sorted(samples)
                p90_ms = sorted_s[max(0, int(len(sorted_s) * 0.90) - 1)]
                if p90_ms > _ALERT_THRESHOLDS["p90_tool_call_ms"]:
                    alerts.append(
                        f"🐌 Latenza p90 elevata: {key} = {p90_ms/1000:.1f}s "
                        f"(soglia: {_ALERT_THRESHOLDS['p90_tool_call_ms']/1000:.0f}s)"
                    )

            # ── Invia alert se necessario ─────────────────────────────────
            if alerts:
                _alert_error_count += 1
                alert_body = "\n".join(alerts)
                # Usa task_id fittizio "telemetry-watchdog" per dedup (max 1 alert/5min)
                await _tg_err(
                    task_id=f"telemetry-watchdog-{_alert_error_count}",
                    goal="Monitoraggio telemetria automatica",
                    error=alert_body[:600],
                )
            else:
                _alert_error_count = 0  # reset streak se tutto ok

        except Exception as _tel_loop_err:
            # Silent — il loop non deve mai crashare il server
            import logging as _log
            _log.getLogger("agente_ai").debug("telemetry_alert_loop error: %s", str(_tel_loop_err)[:80])

        await _aio.sleep(300)  # 5 min tra ogni campionamento