"""Remote model catalog fetcher.

The Hermes docs site hosts a JSON manifest of curated models for providers
we want to update without shipping a release (currently OpenRouter and
Nous Portal). This module fetches, validates, and caches that manifest,
falling back to the in-repo hardcoded lists when the network is unavailable.

Pipeline
--------
1. ``get_catalog()`` — returns a parsed manifest dict.
   - Checks in-process cache (invalidated by TTL).
   - Reads disk cache at ``~/.hermes/cache/model_catalog.json``.
   - Fetches the master URL if disk cache is stale or missing.
   - On any fetch failure, keeps using the stale cache (or empty dict).

2. ``get_curated_openrouter_models()`` / ``get_curated_nous_models()`` —
   thin accessors returning the shapes existing callers expect. Each
   falls back to the in-repo hardcoded list on any lookup failure.

Schema (version 1)
------------------
::

    {
      "version": 1,
      "updated_at": "2026-04-25T22:00:00Z",
      "metadata": {...},                # free-form
      "providers": {
        "openrouter": {
          "metadata": {...},            # free-form
          "models": [
            {"id": "vendor/model", "description": "recommended",
             "metadata": {...}}          # free-form, model-level
          ]
        },
        "nous": {...}
      }
    }

Unknown fields are ignored — extra metadata can be added at either level
without bumping ``version``. ``version`` bumps are reserved for
breaking changes (renaming ``providers``, changing ``models`` shape).
"""

from __future__ import annotations

import json
import logging
import time
import urllib.error
import urllib.request
from pathlib import Path
from typing import Any

from hermes_cli import __version__ as _HERMES_VERSION
from utils import atomic_replace

logger = logging.getLogger(__name__)

# ---------------------------------------------------------------------------
# Constants
# ---------------------------------------------------------------------------

DEFAULT_CATALOG_URL = (
    "https://hermes-agent.nousresearch.com/docs/api/model-catalog.json"
)
# Fallback fetch chain. The Docusaurus site is served through Vercel, which
# occasionally returns HTTP 403 + x-vercel-mitigated: challenge for non-
# browser clients (urllib, curl). When that happens the disk cache goes
# stale and new model releases never reach the picker. The raw GitHub URL
# is the same manifest published from the same repo and is not bot-gated,
# so we fall through to it whenever the primary URL fails.
DEFAULT_CATALOG_FALLBACK_URLS: tuple[str, ...] = (
    "https://raw.githubusercontent.com/NousResearch/hermes-agent/main/website/static/api/model-catalog.json",
)
DEFAULT_TTL_HOURS = 1
DEFAULT_FETCH_TIMEOUT = 8.0
SUPPORTED_SCHEMA_VERSION = 1

_HERMES_USER_AGENT = f"hermes-cli/{_HERMES_VERSION}"

# In-process cache to avoid repeated disk + parse work across multiple
# calls within the same session. Invalidated by TTL against the disk file's
# mtime, so calling code never has to think about this.
_catalog_cache: dict[str, Any] | None = None
_catalog_cache_source_mtime: float = 0.0


# ---------------------------------------------------------------------------
# Config
# ---------------------------------------------------------------------------


def _load_catalog_config() -> dict[str, Any]:
    """Load the ``model_catalog`` config block with defaults filled in."""
    try:
        from hermes_cli.config import load_config
        cfg = load_config() or {}
    except Exception:
        cfg = {}

    raw = cfg.get("model_catalog")
    if not isinstance(raw, dict):
        raw = {}

    return {
        "enabled": bool(raw.get("enabled", True)),
        "url": str(raw.get("url") or DEFAULT_CATALOG_URL),
        "ttl_hours": float(raw.get("ttl_hours") or DEFAULT_TTL_HOURS),
        "providers": raw.get("providers") if isinstance(raw.get("providers"), dict) else {},
    }


def _cache_path() -> Path:
    """Return the disk cache path. Import lazily so tests can monkeypatch home."""
    from hermes_constants import get_hermes_home
    return get_hermes_home() / "cache" / "model_catalog.json"


# ---------------------------------------------------------------------------
# Fetch + validate + cache
# ---------------------------------------------------------------------------


def _fetch_manifest(url: str, timeout: float) -> dict[str, Any] | None:
    """HTTP GET the manifest URL and return a parsed dict, or None on failure."""
    try:
        req = urllib.request.Request(
            url,
            headers={
                "Accept": "application/json",
                "User-Agent": _HERMES_USER_AGENT,
            },
        )
        with urllib.request.urlopen(req, timeout=timeout) as resp:
            data = json.loads(resp.read().decode())
    except (urllib.error.URLError, TimeoutError, json.JSONDecodeError, OSError) as exc:
        logger.info("model catalog fetch failed (%s): %s", url, exc)
        return None
    except Exception as exc:  # pragma: no cover — defensive
        logger.info("model catalog fetch errored (%s): %s", url, exc)
        return None

    if not _validate_manifest(data):
        logger.info("model catalog at %s failed schema validation", url)
        return None

    return data


def _fetch_manifest_with_fallback(
    primary_url: str,
    timeout: float,
    fallback_urls: tuple[str, ...] = DEFAULT_CATALOG_FALLBACK_URLS,
) -> dict[str, Any] | None:
    """Try ``primary_url`` first, then walk ``fallback_urls``.

    Returns the first manifest that fetches and validates, or None when
    every URL fails. Skips fallback URLs identical to the primary so an
    operator who configured the catalog URL to point at the raw GitHub
    copy doesn't double-fetch.
    """
    data = _fetch_manifest(primary_url, timeout)
    if data is not None:
        return data
    for url in fallback_urls:
        if not url or url == primary_url:
            continue
        data = _fetch_manifest(url, timeout)
        if data is not None:
            logger.info("model catalog primary URL failed; using fallback %s", url)
            return data
    return None


def _validate_manifest(data: Any) -> bool:
    """Return True when ``data`` matches the minimum manifest shape."""
    if not isinstance(data, dict):
        return False
    version = data.get("version")
    if not isinstance(version, int) or version > SUPPORTED_SCHEMA_VERSION:
        # Future schema version we don't understand — refuse rather than
        # guess. Older schemas (version < 1) aren't supported either.
        return False
    providers = data.get("providers")
    if not isinstance(providers, dict):
        return False
    for pname, pblock in providers.items():
        if not isinstance(pname, str) or not isinstance(pblock, dict):
            return False
        models = pblock.get("models")
        if not isinstance(models, list):
            return False
        for m in models:
            if not isinstance(m, dict):
                return False
            if not isinstance(m.get("id"), str) or not m["id"].strip():
                return False
    return True


def _read_disk_cache() -> tuple[dict[str, Any] | None, float]:
    """Return ``(data_or_none, mtime)``. mtime is 0 if file is missing."""
    path = _cache_path()
    try:
        mtime = path.stat().st_mtime
    except (OSError, FileNotFoundError):
        return (None, 0.0)
    try:
        with open(path, encoding="utf-8") as fh:
            data = json.load(fh)
    except (OSError, json.JSONDecodeError):
        return (None, 0.0)
    if not _validate_manifest(data):
        return (None, 0.0)
    return (data, mtime)


def _write_disk_cache(data: dict[str, Any]) -> None:
    path = _cache_path()
    try:
        path.parent.mkdir(parents=True, exist_ok=True)
        tmp = path.with_suffix(path.suffix + ".tmp")
        with open(tmp, "w", encoding="utf-8") as fh:
            json.dump(data, fh, indent=2)
            fh.write("\n")
        atomic_replace(tmp, path)
    except OSError as exc:
        logger.info("model catalog cache write failed: %s", exc)


# ---------------------------------------------------------------------------
# Public API
# ---------------------------------------------------------------------------


def get_catalog(*, force_refresh: bool = False) -> dict[str, Any]:
    """Return the parsed model catalog manifest, or an empty dict on failure.

    Callers should treat a missing provider/model as "use the in-repo fallback"
    — never raise from this function so the CLI keeps working offline.
    """
    global _catalog_cache, _catalog_cache_source_mtime

    cfg = _load_catalog_config()
    if not cfg["enabled"]:
        return {}

    ttl_seconds = max(0.0, cfg["ttl_hours"] * 3600.0)

    disk_data, disk_mtime = _read_disk_cache()
    now = time.time()
    disk_fresh = disk_data is not None and (now - disk_mtime) < ttl_seconds

    # In-process cache hit: disk hasn't changed since we loaded it and still fresh.
    if (
        not force_refresh
        and _catalog_cache is not None
        and disk_data is not None
        and disk_mtime == _catalog_cache_source_mtime
        and disk_fresh
    ):
        return _catalog_cache

    # Disk is fresh enough — use it without a network hit.
    if not force_refresh and disk_fresh and disk_data is not None:
        _catalog_cache = disk_data
        _catalog_cache_source_mtime = disk_mtime
        return disk_data

    # Need to (re)fetch. If it fails, fall back to any stale disk copy.
    fetched = _fetch_manifest_with_fallback(cfg["url"], DEFAULT_FETCH_TIMEOUT)
    if fetched is not None:
        _write_disk_cache(fetched)
        new_disk_data, new_mtime = _read_disk_cache()
        if new_disk_data is not None:
            _catalog_cache = new_disk_data
            _catalog_cache_source_mtime = new_mtime
            return new_disk_data
        _catalog_cache = fetched
        _catalog_cache_source_mtime = now
        return fetched

    if disk_data is not None:
        _catalog_cache = disk_data
        _catalog_cache_source_mtime = disk_mtime
        return disk_data

    return {}


def _fetch_provider_override(provider: str) -> dict[str, Any] | None:
    """If ``model_catalog.providers.<name>.url`` is set, fetch that instead."""
    cfg = _load_catalog_config()
    if not cfg["enabled"]:
        return None
    provider_cfg = cfg["providers"].get(provider)
    if not isinstance(provider_cfg, dict):
        return None
    override_url = provider_cfg.get("url")
    if not isinstance(override_url, str) or not override_url.strip():
        return None
    # Override fetches skip the disk cache because they're usually
    # third-party self-hosted. Re-request on every call but with a short
    # timeout so they don't block the picker.
    return _fetch_manifest(override_url.strip(), DEFAULT_FETCH_TIMEOUT)


def _get_provider_block(provider: str) -> dict[str, Any] | None:
    """Return the provider's manifest block, respecting per-provider overrides."""
    override = _fetch_provider_override(provider)
    if override is not None:
        block = override.get("providers", {}).get(provider)
        if isinstance(block, dict):
            return block

    catalog = get_catalog()
    if not catalog:
        return None
    block = catalog.get("providers", {}).get(provider)
    return block if isinstance(block, dict) else None


def get_curated_openrouter_models() -> list[tuple[str, str]] | None:
    """Return OpenRouter's curated ``[(id, description), ...]`` from the manifest.

    Returns ``None`` when the manifest is unavailable, so callers can fall
    back to their hardcoded list.
    """
    block = _get_provider_block("openrouter")
    if not block:
        return None
    out: list[tuple[str, str]] = []
    for m in block.get("models", []):
        mid = str(m.get("id") or "").strip()
        if not mid:
            continue
        desc = str(m.get("description") or "")
        out.append((mid, desc))
    return out or None


def get_curated_nous_models() -> list[str] | None:
    """Return Nous Portal's curated list of model ids from the manifest.

    Returns ``None`` when the manifest is unavailable.
    """
    block = _get_provider_block("nous")
    if not block:
        return None
    out: list[str] = []
    for m in block.get("models", []):
        mid = str(m.get("id") or "").strip()
        if mid:
            out.append(mid)
    return out or None


def reset_cache() -> None:
    """Clear the in-process cache. Used by tests and ``hermes model --refresh``."""
    global _catalog_cache, _catalog_cache_source_mtime
    _catalog_cache = None
    _catalog_cache_source_mtime = 0.0