"""Provider-declared model capabilities (live) with a short-lived cache.

The curated table in :mod:`backend.model_capabilities` has to be edited by hand
every time a provider ships or renames a model, and it ages badly: Mistral alone
declares ``vision`` on 28 of its models while the curated table knew none of
them (BUG-044). Providers that *do* publish per-model capabilities in their
public models endpoint are therefore asked first; the curated table is only
used to fill the flags the provider stays silent about (e.g. Mistral never
declares ``embedding``, only the absence of ``completion_chat``).

Supported declarations, detected by *payload shape* so a provider that starts
exposing them is picked up without a code change:

* ``capabilities`` dict (Mistral): ``completion_chat`` → ``chat``, ``vision``,
  ``audio_transcription`` (+ ``audio_transcription_realtime``),
  ``audio_speech``.
* ``architecture`` dict (OpenRouter): ``input_modalities`` /
  ``output_modalities`` → ``vision`` (image input), ``images`` (image output),
  ``audio_transcription`` (audio input), ``audio_speech`` (audio output),
  ``video`` (video output), ``chat`` (text output).

The cache is in-process and shared by every request. Its TTL only bounds how
long a *stale* declaration can survive: a fresh provider call (the model list
endpoint) overwrites the provider entry immediately.
"""

from __future__ import annotations

import logging
import os
import time
from typing import Any

logger = logging.getLogger("obsigate.ai.capabilities")

#: How long a provider-declared snapshot stays usable, in seconds.
#: ``0`` disables expiry (the snapshot lives until the next provider call).
TTL_SECONDS = float(os.getenv("AI_CAPABILITIES_TTL_SECONDS", "1800") or 0)

#: Guard against a provider returning a runaway model list.
MAX_MODELS_PER_PROVIDER = 2000

# provider → (timestamp, model count, {normalized model id: declared flags})
_CACHE: dict[str, tuple[float, int, dict[str, dict[str, bool]]]] = {}


def _norm(value: str) -> str:
    """Lower-case and strip the ``models/`` prefix Gemini uses."""
    return (value or "").strip().lower().removeprefix("models/")


def _from_capability_flags(flags: dict[str, Any]) -> dict[str, bool]:
    """Map a Mistral-style ``capabilities`` dict onto ObsiGate flags."""
    declared: dict[str, bool] = {}
    if isinstance(flags.get("completion_chat"), bool):
        declared["chat"] = flags["completion_chat"]
    if isinstance(flags.get("vision"), bool):
        declared["vision"] = flags["vision"]
    transcription = flags.get("audio_transcription")
    realtime = flags.get("audio_transcription_realtime")
    if isinstance(transcription, bool) or isinstance(realtime, bool):
        declared["audio_transcription"] = bool(transcription or realtime)
    if isinstance(flags.get("audio_speech"), bool):
        declared["audio_speech"] = flags["audio_speech"]
    return declared


def _from_architecture(architecture: dict[str, Any]) -> dict[str, bool]:
    """Map an OpenRouter-style ``architecture`` dict onto ObsiGate flags."""
    inputs = architecture.get("input_modalities")
    outputs = architecture.get("output_modalities")
    if not isinstance(inputs, list) and not isinstance(outputs, list):
        return {}
    in_modalities = [str(m).lower() for m in inputs] if isinstance(inputs, list) else []
    out_modalities = [str(m).lower() for m in outputs] if isinstance(outputs, list) else []
    return {
        "chat": "text" in out_modalities,
        "vision": "image" in in_modalities,
        "images": "image" in out_modalities,
        "audio_transcription": "audio" in in_modalities,
        "audio_speech": "audio" in out_modalities,
        "video": "video" in out_modalities,
    }


def parse_declared_capabilities(entry: Any) -> dict[str, bool] | None:
    """Extract the capability flags a single provider model entry declares.

    Args:
        entry: One item of a provider models payload (``/v1/models``).

    Returns:
        A partial ``{flag: bool}`` mapping (only the flags the provider
        actually declares), or ``None`` when the entry declares nothing.
    """
    if not isinstance(entry, dict):
        return None
    flags = entry.get("capabilities")
    declared = _from_capability_flags(flags) if isinstance(flags, dict) else {}
    if not declared:
        architecture = entry.get("architecture")
        declared = _from_architecture(architecture) if isinstance(architecture, dict) else {}
    return declared or None


def remember_declared_capabilities(provider: str, payload: Any) -> int:
    """Cache the capabilities declared by a provider models payload.

    Args:
        provider: Provider identifier (e.g. ``"mistral"``).
        payload: Raw JSON body of the provider models endpoint, or the model
            list itself.

    Returns:
        The number of models with declared capabilities that were cached.
    """
    provider = (provider or "").strip().lower()
    entries: Any = payload.get("data") if isinstance(payload, dict) else payload
    if not isinstance(entries, list):
        return 0

    parsed: dict[str, dict[str, bool]] = {}
    for entry in entries[:MAX_MODELS_PER_PROVIDER]:
        if not isinstance(entry, dict):
            continue
        model_id = entry.get("id") or entry.get("name") or ""
        if not isinstance(model_id, str) or not model_id.strip():
            continue
        declared = parse_declared_capabilities(entry)
        if declared:
            parsed[_norm(model_id)] = declared

    if not parsed:
        return 0
    _CACHE[provider] = (time.time(), len(parsed), parsed)
    logger.info(f"Capabilities declared by {provider}: {len(parsed)} models cached")
    return len(parsed)


def get_declared_capabilities(provider: str, model: str) -> dict[str, bool] | None:
    """Return the cached declared capabilities for one provider/model pair.

    Returns ``None`` when nothing was declared for that pair (cache cold,
    expired, or the provider is silent about this model).
    """
    snapshot = _CACHE.get((provider or "").strip().lower())
    if not snapshot:
        return None
    timestamp, _count, table = snapshot
    if TTL_SECONDS and (time.time() - timestamp) > TTL_SECONDS:
        return None
    declared = table.get(_norm(model))
    return dict(declared) if declared else None


def clear_declared_capabilities(provider: str | None = None) -> None:
    """Drop the cached snapshot for one provider, or all of them (tests/ops)."""
    if provider is None:
        _CACHE.clear()
        return
    _CACHE.pop(provider.strip().lower(), None)


def cache_info() -> dict[str, dict[str, Any]]:
    """Diagnostics: per-provider cache age and model count."""
    now = time.time()
    return {
        provider: {
            "models": count,
            "age_seconds": round(now - timestamp, 1),
            "expired": bool(TTL_SECONDS and (now - timestamp) > TTL_SECONDS),
        }
        for provider, (timestamp, count, _table) in _CACHE.items()
    }