"""Generic managed-tool gateway helpers for Nous-hosted vendor passthroughs."""

from __future__ import annotations

import json
import logging
import os
from datetime import datetime, timezone
from dataclasses import dataclass
from typing import Callable, Optional

from hermes_constants import get_hermes_home
from tools.tool_backend_helpers import managed_nous_tools_enabled

logger = logging.getLogger(__name__)

_DEFAULT_TOOL_GATEWAY_DOMAIN = "nousresearch.com"
_DEFAULT_TOOL_GATEWAY_SCHEME = "https"
_NOUS_ACCESS_TOKEN_REFRESH_SKEW_SECONDS = 120


@dataclass(frozen=True)
class ManagedToolGatewayConfig:
    vendor: str
    gateway_origin: str
    nous_user_token: str
    managed_mode: bool


def _clean(value: object) -> Optional[str]:
    """*value* stripped when it is a non-blank string, else None."""
    return value.strip() if isinstance(value, str) and value.strip() else None


def auth_json_path():
    """Return the Hermes auth store path, respecting HERMES_HOME overrides."""
    return get_hermes_home() / "auth.json"


def _read_nous_provider_state() -> Optional[dict]:
    try:
        path = auth_json_path()
        if not path.is_file():
            return None
        providers = json.loads(path.read_text(encoding="utf-8-sig")).get("providers", {})
        nous_provider = providers.get("nous", {}) if isinstance(providers, dict) else None
        return nous_provider if isinstance(nous_provider, dict) else None
    except Exception:
        return None


def _parse_timestamp(value: object) -> Optional[datetime]:
    normalized = _clean(value)
    if normalized is None:
        return None
    try:
        parsed = datetime.fromisoformat(normalized[:-1] + "+00:00" if normalized.endswith("Z") else normalized)
    except ValueError:
        return None
    return (parsed if parsed.tzinfo is not None else parsed.replace(tzinfo=timezone.utc)).astimezone(timezone.utc)


def _access_token_is_expiring(expires_at: object, skew_seconds: int) -> bool:
    expires = _parse_timestamp(expires_at)
    return expires is None or (expires - datetime.now(timezone.utc)).total_seconds() <= max(0, int(skew_seconds))


def _read_user_token_override() -> Optional[str]:
    """Read the TOOL_GATEWAY_USER_TOKEN override through the secret scope. Scope verdict is authoritative
    when installed (a scoped miss must NOT borrow the process env under multiplex); ``os.environ`` only when unscoped."""
    try:
        from agent.secret_scope import UnscopedSecretError, get_secret

        try:
            explicit = get_secret("TOOL_GATEWAY_USER_TOKEN")
        except UnscopedSecretError:
            explicit = os.getenv("TOOL_GATEWAY_USER_TOKEN")
    except Exception:
        explicit = os.getenv("TOOL_GATEWAY_USER_TOKEN")
    return _clean(explicit)


def peek_nous_access_token() -> Optional[str]:
    """Cheap token probe: env override or cached auth-store token, no expiry check and no network —
    availability scans must stay off the synchronous OAuth refresh path (:func:`read_nous_access_token`)."""
    return _read_user_token_override() or _clean((_read_nous_provider_state() or {}).get("access_token"))


def read_nous_access_token() -> Optional[str]:
    """Read a Nous Subscriber OAuth access token from auth store or env override."""
    if explicit := _read_user_token_override():
        return explicit
    nous_provider = _read_nous_provider_state() or {}
    cached_token = peek_nous_access_token()
    if cached_token and not _access_token_is_expiring(nous_provider.get("expires_at"), _NOUS_ACCESS_TOKEN_REFRESH_SKEW_SECONDS):
        return cached_token
    try:
        from hermes_cli.auth import resolve_nous_access_token

        if refreshed_token := _clean(resolve_nous_access_token(refresh_skew_seconds=_NOUS_ACCESS_TOKEN_REFRESH_SKEW_SECONDS)):
            return refreshed_token
    except Exception as exc:
        logger.debug("Nous access token refresh failed: %s", exc)
    return cached_token


def get_tool_gateway_scheme() -> str:
    """Return configured shared gateway URL scheme."""
    scheme = os.getenv("TOOL_GATEWAY_SCHEME", "").strip().lower() or _DEFAULT_TOOL_GATEWAY_SCHEME
    if scheme not in {"http", "https"}:
        raise ValueError("TOOL_GATEWAY_SCHEME must be 'http' or 'https'")
    return scheme


def build_vendor_gateway_url(vendor: str) -> str:
    """Return the gateway origin for a specific vendor."""
    if explicit_vendor_url := os.getenv(f"{vendor.upper().replace('-', '_')}_GATEWAY_URL", "").strip().rstrip("/"):
        return explicit_vendor_url
    shared_domain = os.getenv("TOOL_GATEWAY_DOMAIN", "").strip().strip("/") or _DEFAULT_TOOL_GATEWAY_DOMAIN
    return f"{get_tool_gateway_scheme()}://{vendor}-gateway.{shared_domain}"


def resolve_managed_tool_gateway(
    vendor: str, gateway_builder: Optional[Callable[[str], str]] = None,
    token_reader: Optional[Callable[[], Optional[str]]] = None) -> Optional[ManagedToolGatewayConfig]:
    """Resolve shared managed-tool gateway config for a vendor."""
    if not managed_nous_tools_enabled():
        return None
    gateway_origin = (gateway_builder or build_vendor_gateway_url)(vendor)
    nous_user_token = (token_reader or read_nous_access_token)()
    if not gateway_origin or not nous_user_token:
        return None
    return ManagedToolGatewayConfig(vendor=vendor, gateway_origin=gateway_origin, nous_user_token=nous_user_token, managed_mode=True)


def is_managed_tool_gateway_ready(
    vendor: str, gateway_builder: Optional[Callable[[str], str]] = None,
    token_reader: Optional[Callable[[], Optional[str]]] = None) -> bool:
    """True when a gateway URL and a likely-usable Nous token are present. Defaults to
    :func:`peek_nous_access_token` (no OAuth refresh); callers about to make a real request use
    :func:`resolve_managed_tool_gateway` instead."""
    return resolve_managed_tool_gateway(vendor, gateway_builder=gateway_builder, token_reader=token_reader or peek_nous_access_token) is not None


# ---- BEGIN PLUGIN-COMPAT (revert-scheduled; see COMPAT_MANIFEST.md) ----
# Names external plugins imported from this module before the Sep 2026 decomposition.
# Internal code MUST NOT use these (scripts/check_compat_pointers.py fails CI if it does).
# The whole block is removed by reverting the commit that added it.
from urllib.parse import urlsplit  # noqa: F401,E402
from urllib.parse import urlsplit  # noqa: F401,E402

_MANAGED_GATEWAY_VENDOR = "tool"

def is_managed_nous_gateway_url(
    url: object,
    gateway_builder: Optional[Callable[[str], str]] = None,
) -> bool:
    """True when ``url`` is on the Nous tool-gateway origin this client builds.

    Anything granting a URL extra trust — our bearer, reading files off disk to
    upload — must gate on this rather than on a name, so an arbitrary URL can
    never inherit that trust.
    """
    if not isinstance(url, str) or not url.strip():
        return False

    builder = gateway_builder or build_vendor_gateway_url
    try:
        expected = urlsplit(builder(_MANAGED_GATEWAY_VENDOR))
        actual = urlsplit(url.strip())
    except ValueError:
        return False

    return bool(actual.scheme) and (actual.scheme, actual.netloc) == (expected.scheme, expected.netloc)

def managed_gateway_auth_headers(
    url: object,
    gateway_builder: Optional[Callable[[str], str]] = None,
    token_reader: Optional[Callable[[], Optional[str]]] = None,
) -> dict:
    """Live auth headers for a managed gateway URL, or ``{}`` when not managed.

    Read fresh on every call rather than cached: a Nous access token expires
    within the hour, and a long session would otherwise keep presenting a dead
    bearer. Returns ``{}`` rather than raising when no token is available, so a
    caller can report "sign in" instead of sending an unauthenticated request.
    """
    if not is_managed_nous_gateway_url(url, gateway_builder):
        return {}

    resolved_token_reader = token_reader or read_nous_access_token
    try:
        token = resolved_token_reader()
    except Exception as exc:  # pragma: no cover — defensive
        logger.debug("Managed gateway token read failed for %s: %s", url, exc)
        return {}
    if not isinstance(token, str) or not token.strip():
        return {}

    return {"Authorization": f"Bearer {token.strip()}"}

_MEDIA_UPLOAD_PRESIGN_TIMEOUT_SECONDS = 15.0

_MEDIA_UPLOAD_PUT_READ_TIMEOUT_SECONDS = 60.0

_MEDIA_UPLOAD_PUT_WRITE_TIMEOUT_SECONDS = 300.0

def _describe_media_upload_refusal(response) -> str:
    """A model-actionable reason from a gateway refusal, or a generic one.

    The gateway's 4xx bodies carry deliberate guidance (rate-limit waits, size
    caps, "you could not submit anyway"), so surface `error.message` verbatim
    rather than a bare status code.
    """
    try:
        payload = response.json()
        message = payload.get("error", {}).get("message")
        if isinstance(message, str) and message.strip():
            return message.strip()
    except Exception:
        pass
    return f"the gateway refused the upload (HTTP {response.status_code})"

def build_managed_media_uploader(
    server_url: object,
    upload_path: object,
    gateway_builder: Optional[Callable[[str], str]] = None,
    token_reader: Optional[Callable[[], Optional[str]]] = None,
) -> Optional[Callable]:
    """Async ``(data, mime) -> argument value`` uploader for one managed vendor.

    Returns ``None`` when there is no usable upload endpoint (not a managed
    Nous URL, or no ``upload_path``); callers then refuse local paths with a
    clear message instead of silently forwarding them.

    The three steps of the protocol:

    1. POST ``origin + upload_path`` with the declared content type and exact
       byte length, using the same live auth headers as the vendor calls.
       The gateway answers with a presigned single-object PUT URL (short
       expiry; type and length are signed into it) and an upload token.
    2. PUT the bytes to that URL. This goes directly to storage — never
       through the gateway — which is what removes the request-size ceiling.
    3. Return ``nous-upload:<token>`` for the tool argument. The token is
       bound to this Nous principal and is redeemable only through the
       gateway, so it is inert anywhere else it might end up.
    """
    if not is_managed_nous_gateway_url(server_url, gateway_builder):
        return None
    if not isinstance(upload_path, str) or not upload_path.startswith("/"):
        return None

    parts = urlsplit(str(server_url).strip())
    origin = f"{parts.scheme}://{parts.netloc}"
    presign_url = f"{origin}{upload_path}"

    async def upload(data: bytes, mime: str) -> str:
        import httpx

        from tools.url_safety import create_ssrf_safe_async_client

        headers = managed_gateway_auth_headers(server_url, gateway_builder, token_reader)
        if not headers:
            raise RuntimeError("no Nous credential is available for the upload")

        # Two clients on purpose, split by whose address we are trusting.
        #
        # The presign POST goes to `presign_url`, which is entirely determined
        # by the managed gateway origin (already validated by
        # is_managed_nous_gateway_url) plus the pinned upload_path — the same
        # first-party host the vendor calls go to freely. SSRF-guarding it
        # protects against nothing and would reject a local gateway on
        # 127.0.0.1, so it uses a plain client. The PUT target, by contrast, is
        # a URL the gateway *returned*, so it keeps the SSRF-safe client as
        # defense in depth (real presigned URLs are public R2, which it allows).
        presign_timeout = httpx.Timeout(_MEDIA_UPLOAD_PRESIGN_TIMEOUT_SECONDS)
        async with httpx.AsyncClient(timeout=presign_timeout) as client:
            presign = await client.post(
                presign_url,
                headers=headers,
                json={"contentType": mime, "contentLength": len(data)},
            )
        if presign.status_code != 200:
            raise RuntimeError(_describe_media_upload_refusal(presign))

        try:
            payload = presign.json()
        except Exception:
            payload = None
        upload_url = payload.get("uploadUrl") if isinstance(payload, dict) else None
        token = payload.get("token") if isinstance(payload, dict) else None
        if not (isinstance(upload_url, str) and upload_url and isinstance(token, str) and token):
            raise RuntimeError("the gateway's upload response was malformed")

        put_timeout = httpx.Timeout(
            _MEDIA_UPLOAD_PRESIGN_TIMEOUT_SECONDS,
            read=_MEDIA_UPLOAD_PUT_READ_TIMEOUT_SECONDS,
            write=_MEDIA_UPLOAD_PUT_WRITE_TIMEOUT_SECONDS,
        )
        async with create_ssrf_safe_async_client(timeout=put_timeout) as client:
            # The presigned URL signs the exact Content-Type and Content-Length,
            # so this PUT must send precisely what was declared above.
            put = await client.put(upload_url, content=data, headers={"Content-Type": mime})
        if put.status_code != 200:
            raise RuntimeError(f"storage refused the upload (HTTP {put.status_code})")

        return f"nous-upload:{token}"

    return upload

def managed_vendor_base_path(vendor: str) -> str:
    """Base path for a managed vendor's REST routes on the gateway host."""
    return f"/api/{vendor}"

def managed_vendor_upload_path(vendor: str) -> str:
    """Media upload endpoint for a managed vendor, on the same host."""
    return f"/api/uploads/{vendor}"

def managed_vendor_endpoints(
    vendor: str,
    gateway_builder: Optional[Callable[[str], str]] = None,
) -> Optional[dict]:
    """Absolute URLs for a managed vendor, or ``None`` when none resolves.

    Address resolution only: entitlement is deliberately not consulted here.
    What an account may spend on a managed vendor is the gateway's own
    decision, stated in its refusals, and re-deciding it on the client can only
    ever disagree with the server. A caller that wants to hide its tools from
    users who could not call them at all does that in its ``check_fn``.

    ``None`` means no origin could be resolved — a misconfigured
    ``TOOL_GATEWAY_SCHEME`` — so there is nothing to call.
    """
    builder = gateway_builder or build_vendor_gateway_url
    try:
        origin = builder(_MANAGED_GATEWAY_VENDOR).rstrip("/")
    except ValueError:
        return None
    if not origin:
        return None

    return {
        "origin": origin,
        "base_url": f"{origin}{managed_vendor_base_path(vendor)}",
        "upload_path": managed_vendor_upload_path(vendor),
    }
# ---- END PLUGIN-COMPAT ----
