#!/usr/bin/env python3
"""Bridge desktop-only tools to Hermes-desktop renderer events.

The desktop ``tui_gateway`` installs an emitter via :func:`set_emitter`; elsewhere it
stays ``None`` and tools report "desktop only". Routing keys off ``HERMES_UI_SESSION_ID``
so the event lands on the window that owns the turn (the sink is lock-guarded).
"""

import json
from typing import Callable, Optional

from gateway.session_context import get_session_env
from tools.registry import tool_error

# (sid, event, payload) sink, installed by the desktop gateway.
_emit: Optional[Callable[[str, str, dict], None]] = None


def set_emitter(fn: Optional[Callable[[str, str, dict], None]]) -> None:
    """Install (or clear) the renderer-event sink. Called by the desktop gateway."""
    global _emit
    _emit = fn


def available() -> bool:
    """True when running under the desktop app (an emitter is wired)."""
    return _emit is not None


def user_enabled(setting: str, default: bool) -> bool:
    """Read one of the desktop's Appearance switches from ``display.<setting>``.

    The renderer mirrors these toggles onto the CONNECTED gateway's config, so this
    reads the user's real answer for local/SSH/URL/cloud gateways alike (an env var
    would only describe the process). ``check_fn``s use it to withdraw a tool from the
    schema when the user switched the feature off — Hermes should not be told about
    a surface it may not use. Unreadable config -> ``default`` so a shipped-on
    feature does not vanish on a transient read error.
    """
    try:
        from hermes_cli.config import load_config_readonly

        display = load_config_readonly().get("display")
    except Exception:
        return default
    if not isinstance(display, dict) or setting not in display:
        return default
    return bool(display.get(setting))


def emit(event: str, payload: dict) -> bool:
    """Route ``event`` to the window that owns the current turn.

    Returns ``False`` when no emitter is wired (i.e. not the desktop app)."""
    fn = _emit
    if fn is None:
        return False
    fn(get_session_env("HERMES_UI_SESSION_ID", ""), event, payload)
    return True


def emit_or_error(event: str, payload: dict, fail_prefix: str, desktop_only: str, result: dict) -> str:
    """Emit ``event``; return ``tool_error`` text on failure, else ``result`` as JSON.

    ``fail_prefix`` is prepended to the exception text; ``desktop_only`` is the error
    when no emitter is wired. Looked up as ``desktop_ui.emit`` so tests can patch it.
    """
    try:
        ok = emit(event, payload)
    except Exception as exc:
        return tool_error(f"{fail_prefix}{exc}")
    if not ok:
        return tool_error(desktop_only)
    return json.dumps(result, ensure_ascii=False)


def passthrough_json(raw) -> str:
    """Desktop answers with a JSON object; pass it through, else wrap the raw text."""
    try:
        return json.dumps(json.loads(raw), ensure_ascii=False)
    except (TypeError, ValueError):
        return json.dumps({"text": str(raw)}, ensure_ascii=False)