"""
backend/api/agent_telemetry.py — Sync verdetti agentTelemetry.ts cross-session/device.

Gap N4: agentTelemetry.ts usava solo localStorage → dati di calibrazione persi su
altri device o dopo clear della cache. Questo endpoint li persiste su /data/ del
volume HF Space (stesso usato dalla memoria episodica — mai si perde tra restart).

Endpoints:
  POST /api/agent-telemetry/sync  — riceve TelemetryStore dal client, merge server,
                                    persiste, ritorna il merged aggiornato.
  GET  /api/agent-telemetry/sync  — ritorna store server-side (load al boot del client).
  DELETE /api/agent-telemetry/sync — reset admin/debug.

Auth: nessuna (dati aggregati, zero PII — stesso pattern di /api/telemetry esistente).
Rate limit: middleware globale 120 req/min/IP già applicato da main.py.
Merge: additive — per ogni (system, verdict) prende max(count) e max(lastSeenMs).
       I contatori non diminuiscono mai (protezione da client con dati parziali).
"""
import os, json, logging, time, asyncio
from pathlib import Path
from fastapi import APIRouter, Depends
from .auth_guard import require_role, AuthRole
from fastapi.responses import JSONResponse
from pydantic import BaseModel

router = APIRouter( dependencies=[Depends(require_role(AuthRole.MACHINE))])  # GAP-1-fix: router-level auth
_logger = logging.getLogger("agente_ai")

# ─── Storage ──────────────────────────────────────────────────────────────────
_DATA_DIR = Path(os.getenv("DATA_DIR", "/data"))
_TEL_FILE = _DATA_DIR / "agent_telemetry.json"
_MAX_STORE  = 500  # max entry totali prima del pruning
# Serializza write concorrenti: due POST simultanei da device diversi leggerebbero
# lo stesso store e si sovrascriverebbero. asyncio.Lock() è safe a livello di modulo
# in Python 3.10+ (non richiede event loop attivo all'init del modulo).
_store_lock = asyncio.Lock()
_RUNTIME_PHASES = ('auth', 'queue', 'provider', 'tool', 'persistence')
_RUNTIME_MAX_SAMPLES = 200
_runtime_lock = asyncio.Lock()
_runtime_store: dict[str, dict] = {
    phase: {'samples_ms': [], 'ok': 0, 'errors': {}}
    for phase in _RUNTIME_PHASES
}


async def record_runtime_phase(phase: str, duration_ms: float = 0.0,
                               outcome: str = 'ok', error_class: str | None = None) -> None:
    if phase not in _runtime_store:
        return
    async with _runtime_lock:
        bucket = _runtime_store[phase]
        samples = bucket['samples_ms']
        samples.append(max(0.0, round(float(duration_ms), 2)))
        if len(samples) > _RUNTIME_MAX_SAMPLES:
            del samples[:-_RUNTIME_MAX_SAMPLES]
        if outcome == 'ok':
            bucket['ok'] += 1
        else:
            key = error_class or outcome or 'unknown'
            bucket['errors'][key] = bucket['errors'].get(key, 0) + 1


def _percentile(samples: list[float], percentile: float) -> float:
    if not samples:
        return 0.0
    ordered = sorted(samples)
    index = min(len(ordered) - 1, int(round((percentile / 100) * (len(ordered) - 1))))
    return ordered[index]


async def runtime_snapshot() -> dict[str, dict]:
    async with _runtime_lock:
        return {
            phase: {
                'count': len(bucket['samples_ms']),
                'ok': bucket['ok'],
                'errors': dict(bucket['errors']),
                'p50_ms': _percentile(bucket['samples_ms'], 50),
                'p95_ms': _percentile(bucket['samples_ms'], 95),
            }
            for phase, bucket in _runtime_store.items()
        }

# ─── Store helpers ────────────────────────────────────────────────────────────

def _load_store() -> dict:
    """Carica /data/agent_telemetry.json. Ritorna {} in caso di errore."""
    try:
        if _TEL_FILE.exists():
            return json.loads(_TEL_FILE.read_text("utf-8"))
    except Exception as exc:
        _logger.warning("agent_telemetry: load error — %s", exc)
    return {}


def _save_store(store: dict) -> None:
    """Persiste store su disco. Fail-open."""
    try:
        _DATA_DIR.mkdir(parents=True, exist_ok=True)
        _TEL_FILE.write_text(json.dumps(store, separators=(",", ":")), "utf-8")
    except Exception as exc:
        _logger.warning("agent_telemetry: save error — %s", exc)


def _merge(server: dict, client: dict) -> dict:
    """
    Merge additive cross-device.
    Regola: per ogni (system, verdict) prende max(count) e max(lastSeenMs).
    Un client con dati parziali non può mai ridurre i contatori server.
    """
    merged: dict = {k: dict(v) for k, v in server.items()}
    for sys_name, verdicts in client.items():
        if not isinstance(verdicts, dict):
            continue
        if sys_name not in merged:
            merged[sys_name] = {}
        srv_sys = merged[sys_name]
        for verdict, stats in verdicts.items():
            if not isinstance(stats, dict):
                continue
            c_count = int(stats.get("count", 0))
            c_ts    = int(stats.get("lastSeenMs", 0))
            prev    = srv_sys.get(verdict, {"count": 0, "lastSeenMs": 0})
            srv_sys[verdict] = {
                "count":      max(int(prev.get("count", 0)), c_count),
                "lastSeenMs": max(int(prev.get("lastSeenMs", 0)), c_ts),
            }
    return merged


def _prune(store: dict) -> dict:
    """Se totale entry > _MAX_STORE, sacrifica i sistemi meno usati."""
    total = sum(len(v) for v in store.values())
    if total <= _MAX_STORE:
        return store
    sorted_sys = sorted(
        store.items(),
        key=lambda kv: sum(s.get("count", 0) for s in kv[1].values()),
        reverse=True,
    )
    pruned: dict = {}
    kept = 0
    for sys_name, verdicts in sorted_sys:
        n = len(verdicts)
        if kept + n > _MAX_STORE:
            break
        pruned[sys_name] = verdicts
        kept += n
    return pruned


# ─── Pydantic models ──────────────────────────────────────────────────────────

class TelemetrySyncBody(BaseModel):
    """
    Payload POST dal client — struttura identica a TelemetryStore di agentTelemetry.ts:
    { "crossCritic": { "pass": {"count": 5, "lastSeenMs": 1718000000000} }, ... }
    """
    data: dict


# ─── Endpoints ────────────────────────────────────────────────────────────────

@router.get("/api/agent-telemetry/runtime")
async def get_runtime_telemetry() -> JSONResponse:
    return JSONResponse({'ok': True, 'phases': await runtime_snapshot(), 'server_ts': int(time.time() * 1000)})


@router.post("/api/agent-telemetry/sync")
async def post_agent_telemetry(body: TelemetrySyncBody) -> JSONResponse:
    """
    POST /api/agent-telemetry/sync

    Riceve il TelemetryStore locale del client (agentTelemetry.ts localStorage).
    Lo merge con lo store server-side (additive — max count), lo persiste su
    /data/agent_telemetry.json, e ritorna il merged.

    Il client sostituisce il suo localStorage con il merged ricevuto:
    i dati da altri device sono ora disponibili localmente.
    """
    try:
        async with _store_lock:
            server  = _load_store()
            merged  = _prune(_merge(server, body.data))
            _save_store(merged)
        return JSONResponse({
            "ok":        True,
            "merged":    merged,
            "server_ts": int(time.time() * 1000),
        })
    except Exception as exc:
        _logger.error("agent_telemetry POST error: %s", exc)
        return JSONResponse({"ok": False, "error": str(exc)[:120]}, status_code=500)


@router.get("/api/agent-telemetry/sync")
async def get_agent_telemetry() -> JSONResponse:
    """
    GET /api/agent-telemetry/sync

    Ritorna lo store server-side. Il client lo carica all'avvio e lo mergia
    con il localStorage locale (additive — max count) prima di iniziare
    a registrare nuovi eventi.
    """
    try:
        store = _load_store()
        return JSONResponse({
            "ok":        True,
            "data":      store,
            "server_ts": int(time.time() * 1000),
        })
    except Exception as exc:
        _logger.error("agent_telemetry GET error: %s", exc)
        return JSONResponse({"ok": False, "error": str(exc)[:120]}, status_code=500)


@router.delete("/api/agent-telemetry/sync")
async def delete_agent_telemetry() -> JSONResponse:
    """
    DELETE /api/agent-telemetry/sync — solo per admin/debug.
    Cancella lo store server-side. Non tocca il localStorage dei client.
    """
    try:
        async with _store_lock:
            if _TEL_FILE.exists():
                _TEL_FILE.unlink()
        return JSONResponse({"ok": True, "deleted": True})
    except Exception as exc:
        _logger.error("agent_telemetry DELETE error: %s", exc)
        return JSONResponse({"ok": False, "error": str(exc)[:120]}, status_code=500)