"""Fast-mode (service tier) session scoping in the TUI gateway (desktop backend).

Sibling of test_reasoning_session_scope.py — the ``reasoning`` key was made
session-scoped when a session is targeted, but ``fast`` kept writing the
global ``agent.service_tier`` to config.yaml on every call. The desktop's
per-model presets call ``config.set key=fast`` on every model selection, so
toggling fast in ONE session silently flipped the tier for every other
session, profile, CLI, and gateway build ("switch one session, switches
everywhere").

Contract under test:

1. ``config.set key=fast`` with a session must NOT write config.yaml; it pins
   ``create_service_tier_override`` ("priority" / "" for explicit normal) so
   lazily-built sessions and rebuilds keep the choice.
2. Without a session it persists globally, unchanged.
3. ``config.get key=fast`` must read a pre-build session's pin.
"""

from __future__ import annotations

from types import SimpleNamespace
from unittest.mock import patch

import tui_gateway.server as server

FAST_OVERRIDES = {"service_tier": "priority"}


def _agent(service_tier=None):
    return SimpleNamespace(
        reasoning_config=None,
        service_tier=service_tier,
        request_overrides={},
        model="gpt-6",
        provider="openai",
        session_id="sess-key",
    )


def _set(params: dict) -> dict:
    return server._methods["config.set"]("rid-1", params)


def _get(params: dict) -> dict:
    return server._methods["config.get"]("rid-1", params)


class TestConfigSetFastSessionScope:
    """Session-targeted fast changes must never touch global config."""

    def test_session_scoped_fast_skips_global_write(self) -> None:
        agent = _agent()
        session = {"session_key": "k1", "agent": agent}
        with patch.dict(server._sessions, {"s1": session}, clear=False), \
                patch.object(server, "_write_config_key") as write_key, \
                patch.object(server, "_persist_live_session_runtime"), \
                patch.object(server, "_emit"), \
                patch(
                    "hermes_cli.models.resolve_fast_mode_overrides",
                    return_value=FAST_OVERRIDES,
                ):
            resp = _set({"key": "fast", "session_id": "s1", "value": "fast"})
        assert resp["result"]["value"] == "fast"
        assert agent.service_tier == "priority"
        assert session["create_service_tier_override"] == "priority"
        write_key.assert_not_called()

    def test_session_scoped_normal_pins_explicit_normal(self) -> None:
        agent = _agent(service_tier="priority")
        session = {"session_key": "k2", "agent": agent}
        with patch.dict(server._sessions, {"s2": session}, clear=False), \
                patch.object(server, "_write_config_key") as write_key, \
                patch.object(server, "_persist_live_session_runtime"), \
                patch.object(server, "_emit"):
            resp = _set({"key": "fast", "session_id": "s2", "value": "normal"})
        assert resp["result"]["value"] == "normal"
        assert agent.service_tier is None
        # "" (not absent) so a rebuild pins normal instead of re-reading the
        # global default.
        assert session["create_service_tier_override"] == ""
        write_key.assert_not_called()

    def test_lazy_session_pins_create_override(self) -> None:
        """A pre-build (agent=None) session must keep the change for the
        deferred agent build instead of dropping it."""
        session = {
            "session_key": "k3",
            "agent": None,
            "model_override": {"model": "gpt-6", "provider": "openai"},
        }
        with patch.dict(server._sessions, {"s3": session}, clear=False), \
                patch.object(server, "_write_config_key") as write_key, \
                patch(
                    "hermes_cli.models.resolve_fast_mode_overrides",
                    return_value=FAST_OVERRIDES,
                ):
            resp = _set({"key": "fast", "session_id": "s3", "value": "fast"})
        assert resp["result"]["value"] == "fast"
        assert session["create_service_tier_override"] == "priority"
        write_key.assert_not_called()

    def test_lazy_session_validates_fast_against_session_model(self) -> None:
        """Fast support is checked against the session's picked model, not the
        global default the session will never use."""
        session = {
            "session_key": "k4",
            "agent": None,
            "model_override": {"model": "session-model", "provider": "openai"},
        }
        with patch.dict(server._sessions, {"s4": session}, clear=False), \
                patch.object(server, "_write_config_key"), \
                patch(
                    "hermes_cli.models.resolve_fast_mode_overrides",
                    return_value=FAST_OVERRIDES,
                ) as resolve:
            _set({"key": "fast", "session_id": "s4", "value": "fast"})
        resolve.assert_called_once_with("session-model")

    def test_toggle_flips_prebuild_pin(self) -> None:
        """An empty value toggles from the session's pin, not the global."""
        session = {
            "session_key": "k5",
            "agent": None,
            "create_service_tier_override": "priority",
        }
        with patch.dict(server._sessions, {"s5": session}, clear=False), \
                patch.object(server, "_write_config_key") as write_key:
            resp = _set({"key": "fast", "session_id": "s5", "value": ""})
        assert resp["result"]["value"] == "normal"
        assert session["create_service_tier_override"] == ""
        write_key.assert_not_called()

    def test_no_session_persists_globally(self) -> None:
        with patch.object(server, "_write_config_key") as write_key:
            resp = _set({"key": "fast", "value": "normal"})
        assert resp["result"]["value"] == "normal"
        write_key.assert_called_once_with("agent.service_tier", "normal")


class TestConfigGetFastSessionScope:
    def test_reads_prebuild_pin(self) -> None:
        session = {
            "session_key": "k6",
            "agent": None,
            "create_service_tier_override": "priority",
        }
        with patch.dict(server._sessions, {"s6": session}, clear=False):
            resp = _get({"key": "fast", "session_id": "s6"})
        assert resp["result"]["value"] == "fast"

    def test_reads_live_agent_tier(self) -> None:
        session = {"session_key": "k7", "agent": _agent(service_tier="priority")}
        with patch.dict(server._sessions, {"s7": session}, clear=False):
            resp = _get({"key": "fast", "session_id": "s7"})
        assert resp["result"]["value"] == "fast"

    def test_falls_back_to_global(self) -> None:
        with patch.object(server, "_load_service_tier", return_value="priority"):
            resp = _get({"key": "fast"})
        assert resp["result"]["value"] == "fast"