"""backend/api/deploy.py — S750: CI status + deploy trigger (Railway) + S754-C: Quick Preview."""
import os, time, json, pathlib, asyncio, secrets as _prv_secrets, mimetypes as _prv_mimetypes
from fastapi import APIRouter, HTTPException, Request
from fastapi.responses import HTMLResponse as _HtmlResp, Response as _BinResp
from pydantic import BaseModel
import httpx
import logging
_logger = logging.getLogger("agente_ai")  # S-BUGFIX

router = APIRouter()

_GH_TOKEN  = os.getenv("GITHUB_TOKEN", "")
_CF_TOKEN  = os.getenv("CF_API_TOKEN", os.getenv("CLOUDFLARE_API_TOKEN", ""))
_CF_ACCT   = os.getenv("CF_ACCOUNT_ID", "")
_HF_TOKEN  = os.getenv("HF_TOKEN", "")
_INT_TOKEN = os.getenv("INTERNAL_TOKEN", "")
# GAP-M: rimosso _REPLIT_DEPLOY_URL — Replit si addormenta dopo 30min → deploy notturni falliscono.
# CF Pages deploy ora sempre via GitHub Actions dispatch (cloudflare-deploy.yml).

# S-GAP4: parametrizzati da env — portabili su qualsiasi repo
GH_OWNER   = os.getenv("GH_OWNER", "Baida98")
GH_REPO    = os.getenv("GH_REPO",  "AI")
HF_SPACE_ID = os.getenv("HF_SPACE_ID", "Arjanit98/Terminal")  # GAP-3: parametrizzato da env


def _auth(request: Request) -> None:
    if not _INT_TOKEN:
        return
    tok = request.headers.get("x-internal-token", "")
    if tok != _INT_TOKEN:
        raise HTTPException(status_code=401, detail="Unauthorized")


@router.get("/api/ci/status")
async def ci_status(request: Request):
    """Controlla stato GitHub Actions + ultimo deploy CF Pages."""
    _auth(request)
    result: dict = {
        "ci_ok": False, "billing_ok": True,
        "last_run_status": "unknown", "last_run_conclusion": "unknown",
        "last_deploy": None, "message": "",
    }
    headers = {"Accept": "application/vnd.github.v3+json"}
    if _GH_TOKEN:
        headers["Authorization"] = f"token {_GH_TOKEN}"

    async with httpx.AsyncClient(timeout=10) as c:
        try:
            r = await c.get(
                f"https://api.github.com/repos/{GH_OWNER}/{GH_REPO}/actions/runs?per_page=6",
                headers=headers,
            )
            if r.status_code == 200:
                runs = r.json().get("workflow_runs", [])
                if runs:
                    latest = runs[0]
                    conclusion = latest.get("conclusion", "")
                    status    = latest.get("status", "")
                    result["last_run_status"]     = status
                    result["last_run_conclusion"] = conclusion
                    result["last_deploy"]         = latest.get("created_at", "")
                    all_failed = len(runs) >= 4 and all(
                        r2.get("conclusion") == "failure" for r2 in runs[:4]
                    )
                    result["ci_ok"]      = conclusion in ("success", "skipped") or status == "in_progress"
                    result["billing_ok"] = not all_failed
        except Exception as e:
            result["message"] = f"GitHub API error: {e}"

    if result["ci_ok"]:
        result["message"] = "✅ CI attiva — deploy automatico su ogni push"
    elif not result["billing_ok"]:
        result["message"] = "⚠️ GitHub Actions bloccate (budget esaurito). Deploy manuale disponibile."
    else:
        result["message"] = "⏳ Deploy in corso o in attesa"

    return result


class DeployRequest(BaseModel):
    reason: str = "deploy manuale"
    skip_hf: bool = False
    skip_cf: bool = False




# ── Deploy Status multi-target (S-DEPLOY-UNIFY) ──────────────────────────────
@router.get("/api/deploy/status")
async def deploy_status_all(request: Request):
    """
    S-DEPLOY-UNIFY: Stato in tempo reale di tutti e 3 i target di deploy.

    Controlla in parallelo (asyncio.gather, timeout 5s per target):
    - CF Pages:   ultimo deployment via Cloudflare API
    - Railway:    health check HTTP con latenza
    - HF Space:   runtime stage via HuggingFace API pubblica

    Non richiede token se _CF_TOKEN è assente: risponde ugualmente con stato parziale.
    """
    _auth(request)
    checked_at = time.strftime('%Y-%m-%dT%H:%M:%SZ', time.gmtime())

    async def _check_cloudflare() -> dict:
        r: dict = {
            "ok": False, "status": "unknown",
            "url": "https://agente-ai.pages.dev",
            "last_deploy": None, "deployment_id": None, "error": None,
        }
        if not _CF_TOKEN or not _CF_ACCT:
            r["status"] = "no_token"
            r["error"] = "CF_API_TOKEN o CF_ACCOUNT_ID non configurati su Railway"
            return r
        try:
            async with httpx.AsyncClient(timeout=5) as c:
                resp = await c.get(
                    f"https://api.cloudflare.com/client/v4/accounts/{_CF_ACCT}"
                    f"/pages/projects/agente-ai/deployments?per_page=1",
                    headers={"Authorization": f"Bearer {_CF_TOKEN}"},
                )
                if resp.status_code == 200:
                    deps = resp.json().get("result", [])
                    if deps:
                        d = deps[0]
                        stage = (d.get("latest_stage") or {}).get("status", "unknown")
                        r["ok"]           = stage in ("success", "idle")
                        r["status"]       = stage
                        r["last_deploy"]  = d.get("created_on")
                        r["deployment_id"] = (d.get("id") or "")[:8]
                    else:
                        r["status"] = "no_deployments"
                else:
                    r["error"] = f"HTTP {resp.status_code}"
        except Exception as e:
            r["error"] = str(e)[:80]
        return r

    async def _check_railway() -> dict:
        url = "https://ai-production-4c06.up.railway.app"
        r: dict = {"ok": False, "status": "unknown", "url": url, "latency_ms": None, "error": None}
        t0 = time.monotonic()
        try:
            async with httpx.AsyncClient(timeout=5) as c:
                resp = await c.get(f"{url}/health")
                r["latency_ms"] = round((time.monotonic() - t0) * 1000)
                r["ok"]         = resp.status_code == 200
                r["status"]     = "up" if r["ok"] else f"HTTP {resp.status_code}"
        except httpx.TimeoutException:
            r["status"] = "timeout"; r["error"] = "Timeout dopo 5s"
        except Exception as e:
            r["status"] = "down"; r["error"] = str(e)[:80]
        return r

    async def _check_huggingface() -> dict:
        r: dict = {
            "ok": False, "status": "unknown",
            "url": f"https://huggingface.co/spaces/{HF_SPACE_ID}",
            "sdk": None, "error": None,
        }
        try:
            async with httpx.AsyncClient(timeout=5) as c:
                resp = await c.get(f"https://huggingface.co/api/spaces/{HF_SPACE_ID}")
                if resp.status_code == 200:
                    data    = resp.json()
                    runtime = data.get("runtime") or {}
                    stage   = runtime.get("stage", "UNKNOWN")
                    r["ok"]     = stage in ("RUNNING", "BUILDING")
                    r["status"] = stage
                    r["sdk"]    = data.get("sdk", "unknown")
                else:
                    r["error"] = f"HTTP {resp.status_code}"
        except Exception as e:
            r["error"] = str(e)[:80]
        return r

    cf, railway, hf = await asyncio.gather(
        _check_cloudflare(),
        _check_railway(),
        _check_huggingface(),
    )

    return {
        "targets": {"cloudflare": cf, "railway": railway, "huggingface": hf},
        "checked_at": checked_at,
    }


# ── Auto-gestione deploy (S-AUTO) ─────────────────────────────────────────────
class AutoRepairRequest(BaseModel):
    targets: list[str] = ["cloudflare", "railway", "huggingface"]
    dry_run: bool = False  # True = diagnostica senza eseguire azioni


@router.post("/api/deploy/auto")
async def deploy_auto(body: AutoRepairRequest, request: Request):
    """
    S-AUTO: Diagnostica + auto-riparazione di tutti i target in un'unica chiamata.

    Logica per target:
    - CF Pages:   dispatch cloudflare-deploy.yml (build + deploy completo)
    - Railway:    wake-up ping × 5 con backoff 2s; se ancora down → dispatch backend-deploy.yml
    - HF Space:   GET wake-up sulla URL pubblica; se ancora sleeping → dispatch backend-deploy.yml

    dry_run=True restituisce il piano senza eseguire azioni reali.
    """
    _auth(request)
    t0      = time.time()
    actions: list[str] = []
    fixed:   list[str] = []
    broken:  list[str] = []

    gh_headers = {"Accept": "application/vnd.github.v3+json"}
    if _GH_TOKEN:
        gh_headers["Authorization"] = f"token {_GH_TOKEN}"

    # ── Helper: dispatch GitHub Actions workflow ──────────────────────────────
    async def _dispatch(workflow_file: str, inputs: dict | None = None) -> tuple[bool, str]:
        if not _GH_TOKEN:
            return False, "GITHUB_TOKEN non configurato"
        try:
            async with httpx.AsyncClient(timeout=15) as c:
                r = await c.post(
                    f"https://api.github.com/repos/{GH_OWNER}/{GH_REPO}"
                    f"/actions/workflows/{workflow_file}/dispatches",
                    headers={**gh_headers, "Content-Type": "application/json"},
                    content=json.dumps({"ref": "main", "inputs": inputs or {}}).encode(),
                )
                return r.status_code in (204, 200), f"HTTP {r.status_code}"
        except Exception as e:
            return False, str(e)[:60]

    # ── CF Pages ──────────────────────────────────────────────────────────────
    if "cloudflare" in body.targets:
        if not body.dry_run:
            # Controlla stato prima di dispatchare inutilmente
            cf_stage = "unknown"
            if _CF_TOKEN and _CF_ACCT:
                try:
                    async with httpx.AsyncClient(timeout=5) as c:
                        r = await c.get(
                            f"https://api.cloudflare.com/client/v4/accounts/{_CF_ACCT}"
                            f"/pages/projects/agente-ai/deployments?per_page=1",
                            headers={"Authorization": f"Bearer {_CF_TOKEN}"},
                        )
                        if r.status_code == 200:
                            deps = r.json().get("result", [])
                            cf_stage = (deps[0].get("latest_stage") or {}).get("status", "unknown") if deps else "no_deployments"
                except Exception as _exc:
                    _logger.debug("[deploy] silenced %s", type(_exc).__name__)  # noqa: BLE001

            if cf_stage in ("success", "idle"):
                actions.append("✅ CF Pages già live — nessun deploy necessario")
                fixed.append("cloudflare")
            else:
                actions.append(f"⚠️  CF Pages status={cf_stage!r} — avvio cloudflare-deploy.yml")
                ok, msg = await _dispatch("cloudflare-deploy.yml")
                if ok:
                    actions.append("  ✅ CF Pages: Actions avviato — deploy live in ~3 min")
                    fixed.append("cloudflare")
                else:
                    actions.append(f"  ❌ CF Pages dispatch fallito: {msg}")
                    broken.append("cloudflare")
        else:
            actions.append("[dry_run] CF Pages: dispatch cloudflare-deploy.yml se non live")
            fixed.append("cloudflare")

    # ── Railway ───────────────────────────────────────────────────────────────
    if "railway" in body.targets:
        if not body.dry_run:
            railway_url = "https://ai-production-4c06.up.railway.app/health"
            alive = False
            for attempt in range(1, 6):
                try:
                    async with httpx.AsyncClient(timeout=8) as c:
                        r = await c.get(railway_url)
                        if r.status_code == 200:
                            alive = True
                            actions.append(f"✅ Railway attivo (ping {attempt}/5 — HTTP 200)")
                            fixed.append("railway")
                            break
                        else:
                            actions.append(f"  Railway ping {attempt}/5: HTTP {r.status_code}")
                except Exception as e:
                    actions.append(f"  Railway ping {attempt}/5: {str(e)[:50]}")
                if attempt < 5:
                    await asyncio.sleep(2)

            if not alive:
                actions.append("  ⚠️  Railway non risponde — avvio re-deploy via backend-deploy.yml")
                ok, msg = await _dispatch("backend-deploy.yml", {"target": "railway"})
                if ok:
                    actions.append("  ✅ Railway re-deploy avviato — attivo entro ~2 min")
                    fixed.append("railway")
                else:
                    actions.append(f"  ❌ Railway dispatch fallito: {msg}")
                    broken.append("railway")
        else:
            actions.append("[dry_run] Railway: ping × 5, se down → dispatch backend-deploy.yml(railway)")
            fixed.append("railway")

    # ── HuggingFace Space ─────────────────────────────────────────────────────
    if "huggingface" in body.targets:
        if not body.dry_run:
            # Controlla stage runtime
            hf_stage = "UNKNOWN"
            try:
                async with httpx.AsyncClient(timeout=5) as c:
                    r = await c.get(f"https://huggingface.co/api/spaces/{HF_SPACE_ID}")
                    if r.status_code == 200:
                        hf_stage = (r.json().get("runtime") or {}).get("stage", "UNKNOWN")
            except Exception as _exc:
                _logger.debug("[deploy] silenced %s", type(_exc).__name__)  # noqa: BLE001

            if hf_stage == "RUNNING":
                actions.append("✅ HF Space già RUNNING — nessuna azione")
                fixed.append("huggingface")
            elif hf_stage == "BUILDING":
                actions.append("ℹ️  HF Space in BUILDING — deploy già in corso, attendi ~1 min")
                fixed.append("huggingface")
            else:
                actions.append(f"⚠️  HF Space status={hf_stage!r} — invio GET wake-up")
                # GET la URL pubblica → HF Spaces si svegliano automaticamente su GET
                woke = False
                try:
                    async with httpx.AsyncClient(timeout=15, follow_redirects=True) as c:
                        wr = await c.get("https://arjanit98-terminal.hf.space")
                        woke = wr.status_code < 500
                        actions.append(f"  GET wake-up: HTTP {wr.status_code}")
                except Exception as e:
                    actions.append(f"  GET wake-up: {str(e)[:50]}")

                if woke:
                    actions.append("  ✅ HF Space: wake-up inviato — running entro ~30s")
                    fixed.append("huggingface")
                else:
                    actions.append("  ⚠️  Wake-up non sufficiente — dispatch backend-deploy.yml(hf)")
                    ok, msg = await _dispatch("backend-deploy.yml", {"target": "hf"})
                    if ok:
                        actions.append("  ✅ HF Space re-deploy avviato via GitHub Actions")
                        fixed.append("huggingface")
                    else:
                        actions.append(f"  ❌ HF Space dispatch fallito: {msg}")
                        broken.append("huggingface")
        else:
            actions.append("[dry_run] HF Space: GET wake-up → se sleeping → dispatch backend-deploy.yml(hf)")
            fixed.append("huggingface")

    all_ok = len(broken) == 0
    parts  = []
    if fixed:  parts.append(f"Risolti: {', '.join(fixed)}")
    if broken: parts.append(f"Non risolti: {', '.join(broken)}")

    return {
        "ok":      all_ok,
        "fixed":   fixed,
        "broken":  broken,
        "actions": actions,
        "dry_run": body.dry_run,
        "message": " · ".join(parts) if parts else "Tutto OK",
        "elapsed": round(time.time() - t0, 1),
    }


@router.post("/api/deploy-trigger")
async def deploy_trigger_endpoint(body: DeployRequest, request: Request):
    """Triggera deploy: prima Actions dispatch, poi fallback HF + Replit CF."""
    _auth(request)
    t0    = time.time()
    steps: list[str] = []

    headers = {"Accept": "application/vnd.github.v3+json"}
    if _GH_TOKEN:
        headers["Authorization"] = f"token {_GH_TOKEN}"

    async with httpx.AsyncClient(timeout=30) as c:
        # GAP-M: rimossa euristica billing (all_failed) — poco affidabile e bloccava dispatch validi.
        # Path 1: SEMPRE tenta GitHub Actions dispatch (cloudflare-deploy.yml).
        #         Build + quality check + CF Pages deploy in ~3 min.
        # Path 2: HF Space sync backend (fallback — non dipende da Actions).
        # Rimosso path Replit: Replit si addormenta dopo 30min → deploy notturni fallivano silenziosamente.
        if not body.skip_cf and _GH_TOKEN:
            try:
                wf_r = await c.post(
                    f"https://api.github.com/repos/{GH_OWNER}/{GH_REPO}/actions/workflows/cloudflare-deploy.yml/dispatches",
                    headers={**headers, "Content-Type": "application/json"},
                    content=json.dumps({"ref": "main", "inputs": {}}).encode(),
                )
                if wf_r.status_code in (204, 200):
                    # GAP-2: poll breve (1×3s) per verificare che GitHub Actions abbia accodato il run.
                    # deploy_verify=True  → run già visibile nelle Actions (GH fast path)
                    # deploy_verify=False → run ancora in coda, normale nei primi ~10s
                    await asyncio.sleep(3)
                    deploy_verify = False
                    try:
                        r_check = await c.get(
                            f"https://api.github.com/repos/{GH_OWNER}/{GH_REPO}/actions/runs?per_page=2",
                            headers=headers, timeout=5,
                        )
                        if r_check.status_code == 200:
                            _runs = r_check.json().get("workflow_runs", [])
                            deploy_verify = bool(
                                _runs and _runs[0].get("status") in ("queued", "in_progress", "completed")
                            )
                    except Exception:
                        pass  # poll non bloccante — mai nasconde il successo del dispatch
                    return {
                        "ok": True, "mode": "ci_dispatch",
                        "deploy_verify": deploy_verify,
                        "steps": [
                            "✅ GitHub Actions avviato — build + deploy CF Pages live in ~3 min"
                            + (" · run confermato ✓" if deploy_verify else " · run in coda (attendi ~10s)"),
                        ],
                        "url": "https://agente-ai.pages.dev",
                        "elapsed": round(time.time() - t0, 1),
                    }
                steps.append(f"⚠️ workflow_dispatch CF Pages: HTTP {wf_r.status_code} — controlla billing/token GitHub")
            except Exception as e:
                steps.append(f"⚠️ GitHub Actions dispatch: {str(e)[:80]}")
        elif not body.skip_cf:
            steps.append("ℹ️ CF Pages: GITHUB_TOKEN non configurato — impossibile triggerare Actions")

        # Path 2: HF Space sync backend (Python puro — sempre disponibile su Railway)
        if not body.skip_hf and _HF_TOKEN:
            try:
                backend_dir = pathlib.Path(__file__).parent.parent
                files = []
                for p in backend_dir.rglob("*"):
                    if p.is_file() and "__pycache__" not in str(p) and not str(p).endswith(".pyc"):
                        try:
                            files.append({
                                "path": str(p.relative_to(backend_dir)),
                                "content": p.read_text(errors="replace"),
                            })
                        except Exception as _exc:
                            _logger.debug("[deploy] silenced %s", type(_exc).__name__)  # noqa: BLE001
                payload = json.dumps({
                    "summary": f"deploy: {body.reason} — {time.strftime('%Y-%m-%d %H:%M UTC', time.gmtime())}",
                    "files": files,
                }).encode("utf-8")
                hf_r = await c.post(
                    f"https://huggingface.co/api/spaces/{HF_SPACE_ID}/commit/main",
                    headers={"Authorization": f"Bearer {_HF_TOKEN}", "Content-Type": "application/json"},
                    content=payload, timeout=90,
                )
                if hf_r.status_code in (200, 201):
                    steps.append("✅ Backend HuggingFace sincronizzato")
                else:
                    steps.append(f"⚠️ HF sync: HTTP {hf_r.status_code}")
            except Exception as e:
                steps.append(f"⚠️ HF sync: {str(e)[:80]}")

    ok = any("✅" in s for s in steps)
    return {
        "ok": ok, "mode": "direct",
        "steps": steps,
        "url": f"https://huggingface.co/spaces/{HF_SPACE_ID}",
        "elapsed": round(time.time() - t0, 1),
    }


# ── Quick Preview (S754-C) ─────────────────────────────────────────────────────
# Serve una preview HTML/CSS/JS dal backend HF Space in modo istantaneo.
# File salvati in /data/previews/ (volume persistente HF Spaces, fallback /tmp/).
# Nessun deploy esterno: URL pubblico disponibile in < 1 secondo.

def _resolve_preview_dir() -> pathlib.Path:
    for candidate in [pathlib.Path('/data/previews'), pathlib.Path('/tmp/previews')]:
        try:
            candidate.mkdir(parents=True, exist_ok=True)
            return candidate
        except (PermissionError, OSError):
            continue
    return pathlib.Path('/tmp/previews')

_PREVIEW_DIR    = _resolve_preview_dir()
_MAX_PREVIEWS   = 20       # LRU: mantieni solo le ultime 20 preview
_MAX_FILE_BYTES = 524_288  # 512 KB per file
_MAX_FILES      = 50       # max file per singola preview request


class QuickPreviewRequest(BaseModel):
    files: dict[str, str]   # filename → contenuto (HTML/CSS/JS/ecc.)
    title: str = "preview"


def _cleanup_old_previews_sync() -> None:
    """Rimuove le preview più vecchie oltre _MAX_PREVIEWS (versione sync per asyncio.to_thread)."""
    try:
        import shutil as _sh
        dirs = sorted(
            (p for p in _PREVIEW_DIR.iterdir() if p.is_dir()),
            key=lambda p: p.stat().st_mtime,
        )
        while len(dirs) > _MAX_PREVIEWS:
            _sh.rmtree(dirs.pop(0), ignore_errors=True)
    except Exception as _exc:
        _logger.debug("[deploy] silenced %s", type(_exc).__name__)  # noqa: BLE001


async def _cleanup_old_previews() -> None:
    """
    Rimuove le preview più vecchie oltre _MAX_PREVIEWS.
    Eseguito in thread separato per non bloccare l'event loop durante l'iterazione su disco.
    """
    try:
        await asyncio.to_thread(_cleanup_old_previews_sync)
    except Exception as _exc:
        _logger.debug("[deploy] silenced %s", type(_exc).__name__)  # noqa: BLE001


def _get_base_url(request: Request) -> str:
    """
    Determina l'URL pubblico del backend (HF Space o Railway).

    IMPORTANTE — NON usare Origin o Host header:
      - Origin: è l'URL del CALLER (es. 'https://agente-ai.pages.dev') — non del backend.
      - Host:   è l'hostname interno del container, non il dominio pubblico.
    Usare Origin come URL del backend genera URL pubblici che puntano a CF Pages
    invece che al backend HF/Railway → 404 garantito in produzione.

    Priorità corretta:
    1. HF_SPACE_URL env var — config esplicita, raccomandata (es. 'https://arjanit98-terminal.hf.space')
    2. SPACE_HOST env var  — iniettata da HF Spaces automaticamente (es. 'arjanit98-terminal.hf.space')
    3. X-Forwarded-Host    — iniettato da proxy/ingress Railway o Traefik
    4. '' (stringa vuota)  — nessuna fonte disponibile → quick_preview risponde con errore strutturato
    """
    # 1. Variabile esplicita: HF_SPACE_URL=https://arjanit98-terminal.hf.space
    explicit = os.getenv('HF_SPACE_URL', '').rstrip('/')
    if explicit:
        return explicit
    # 2. SPACE_HOST — iniettata da HF Spaces (es. 'arjanit98-terminal.hf.space')
    space_host = os.getenv('SPACE_HOST', '')
    if space_host:
        return f'https://{space_host}'
    # 3. X-Forwarded-Host — iniettato da proxy/ingress come Railway o Traefik
    fwd_host = request.headers.get('x-forwarded-host', '')
    if fwd_host:
        proto = request.headers.get('x-forwarded-proto', 'https')
        return f'{proto}://{fwd_host}'
    # NON usare Origin (URL del caller) né Host (hostname interno del container)
    return ''


# Header condivisi per le route /preview/* — CORS aperto + no-cache
_PREVIEW_HEADERS = {
    'Access-Control-Allow-Origin':  '*',
    'Access-Control-Allow-Methods': 'GET, OPTIONS',
    'Access-Control-Allow-Headers': 'Content-Type',
    'Cache-Control':                'no-store, no-cache',
    'X-Content-Type-Options':       'nosniff',
}


@router.post('/api/preview/quick')
async def quick_preview(body: QuickPreviewRequest, request: Request):
    """
    S754-C: Deploy rapido su backend HF Space.
    Salva i file in /data/previews/<id>/ → restituisce URL pubblico < 1s.

    Input:  {files: {"index.html": "<html>...", "style.css": "..."}, title: "..."}
    Output: {ok: true, url: "https://<space>/preview/<id>/", preview_id: "...", ...}
             oppure {ok: false, error: "...", hint: "..."} se URL backend non rilevabile.
    """
    if not body.files:
        raise HTTPException(400, 'Nessun file fornito')
    if len(body.files) > _MAX_FILES:
        raise HTTPException(400, f'Troppi file: max {_MAX_FILES} per preview')

    preview_id  = _prv_secrets.token_urlsafe(10)
    preview_dir = _PREVIEW_DIR / preview_id
    preview_dir.mkdir(parents=True, exist_ok=True)

    saved: list[str] = []
    for raw_name, content in body.files.items():
        # Sanitizza: no path traversal, niente nomi nascosti
        safe_name = pathlib.Path(raw_name).name
        if not safe_name or safe_name.startswith('.'):
            safe_name = 'index.html'
        # Tronca file troppo grandi
        encoded = content.encode('utf-8', errors='replace')
        if len(encoded) > _MAX_FILE_BYTES:
            content = encoded[:_MAX_FILE_BYTES].decode('utf-8', errors='replace')
        (preview_dir / safe_name).write_text(content, encoding='utf-8', errors='replace')
        saved.append(safe_name)

    # Cleanup asincrono — non blocca l'event loop (iterazione su disco in thread separato)
    # GAP-P4: add_done_callback per loggare eccezioni inattese (fire-and-forget safety).
    def _log_cleanup_error(task: asyncio.Task) -> None:
        if not task.cancelled() and task.exception() is not None:
            import logging as _log
            _log.getLogger('agente_ai').warning('preview cleanup error: %s', task.exception())
    _cleanup_task = asyncio.create_task(_cleanup_old_previews())
    _cleanup_task.add_done_callback(_log_cleanup_error)

    base_url = _get_base_url(request)
    if not base_url:
        # URL backend non rilevabile — risposta strutturata con hint per il debug
        return {
            'ok':         False,
            'preview_id': preview_id,
            'url':        None,
            'files':      saved,
            'error':      'URL backend non rilevabile: nessun env var HF_SPACE_URL / SPACE_HOST trovato.',
            'hint':       (
                'Imposta la variabile d\'ambiente HF_SPACE_URL=https://arjanit98-terminal.hf.space '
                'nelle impostazioni del backend (Railway → Variables o HF Space → Settings → Variables). '
                'I file della preview sono stati salvati con ID: ' + preview_id
            ),
        }

    preview_url = f'{base_url}/preview/{preview_id}/'
    return {
        'ok':         True,
        'preview_id': preview_id,
        'url':        preview_url,
        'files':      saved,
        'ephemeral':  True,
        'note':       'URL live mentre il backend è attivo.',
    }


@router.get('/preview/{preview_id}')
@router.get('/preview/{preview_id}/')
async def serve_preview_index(preview_id: str):
    """Serve index.html della preview."""
    preview_dir = _PREVIEW_DIR / preview_id
    for candidate in ('index.html', 'index.htm'):
        f = preview_dir / candidate
        if f.exists():
            return _HtmlResp(
                content=f.read_text(encoding='utf-8', errors='replace'),
                headers=_PREVIEW_HEADERS,
            )
    raise HTTPException(404, f'Preview {preview_id!r} non trovata o scaduta.')


@router.get('/preview/{preview_id}/{filename:path}')
async def serve_preview_file(preview_id: str, filename: str):
    """Serve file statici della preview (CSS, JS, immagini, ecc.)."""
    preview_dir = _PREVIEW_DIR / preview_id
    # Sicurezza: usa solo il nome file, no traversal
    safe_name = pathlib.Path(filename).name
    file_path = preview_dir / safe_name
    if not file_path.exists():
        raise HTTPException(404, f'File {safe_name!r} non trovato nella preview.')
    content_type, _ = _prv_mimetypes.guess_type(str(file_path))
    return _BinResp(
        content=file_path.read_bytes(),
        media_type=content_type or 'application/octet-stream',
        headers=_PREVIEW_HEADERS,
    )