"""Phase 168 (task 03): Save re-points the two in-process singletons.

The "takes effect on Save" contract (D3): ``invalidate_settings()``
clears the ``get_settings()`` cache (the ~70 per-use settings) AND runs
the registered reset hooks — ``app.api.chat.reset_runtime_caches``
(nulls the shared ``LLMClient`` and the chat concurrency semaphore,
re-registered by ``create_app()`` at the composition root because
``app/core`` must never import ``app/api``, PLAN §3). These pins are
unit level: the chat globals are set directly, the overlay hooks are
registered directly (the autouse fixture gives every test a clean hook
list and restores every global it touches — a leaked ``LLMClient``
holding a test settings snapshot would poison the next suite's
singleton).
"""
from __future__ import annotations

import logging
from collections.abc import Iterator
from pathlib import Path

import pytest

import app.main as app_main
from app.api import chat as chat_api
from app.config import get_settings, invalidate_settings
from app.core import settings_overlay


@pytest.fixture(autouse=True)
def _clean_state() -> Iterator[None]:
    """Clean hook list + saved chat globals, restored on teardown.

    ``reset_state_for_tests()`` clears the process-wide hook list (a
    prior suite's test may have wiped the hook ``app.main`` registered
    at import — these tests register their own); the ``chat_api``
    globals are saved/restored around the test so a built ``LLMClient``
    or semaphore never leaks into another test's singleton slot.
    """
    settings_overlay.reset_state_for_tests()
    saved = {
        "_llm": chat_api._llm,
        "_chat_semaphore": chat_api._chat_semaphore,
        "_chat_active": chat_api._chat_active,
    }
    yield
    chat_api._llm = saved["_llm"]
    chat_api._chat_semaphore = saved["_chat_semaphore"]
    chat_api._chat_active = saved["_chat_active"]
    settings_overlay.reset_state_for_tests()
    # monkeypatch restores BOR_* env first (finalized before this
    # fixture) — the cache clear re-resolves to the conftest-pinned
    # env-only view.
    get_settings.cache_clear()


# ---------------------------------------------------------------------------
# reset_runtime_caches — nulls exactly the two settings snapshots
# ---------------------------------------------------------------------------


def test_reset_nulls_llm_and_semaphore() -> None:
    chat_api._llm = object()
    chat_api._chat_semaphore = object()
    chat_api._chat_active = 7
    chat_api.reset_runtime_caches()
    assert chat_api._llm is None
    assert chat_api._chat_semaphore is None
    # _chat_active counts live turns — a reset must not touch it (the
    # new chat_max_concurrent applies as permits are taken).
    assert chat_api._chat_active == 7


def test_reset_is_idempotent() -> None:
    chat_api.reset_runtime_caches()
    chat_api.reset_runtime_caches()  # a double Save must not raise
    assert chat_api._llm is None
    assert chat_api._chat_semaphore is None


# ---------------------------------------------------------------------------
# get_llm / _get_chat_semaphore — lazy rebuild from the CURRENT settings
# ---------------------------------------------------------------------------


def test_get_llm_singleton_contract() -> None:
    chat_api._llm = None
    first = chat_api.get_llm()
    second = chat_api.get_llm()
    # The singleton contract still holds — the same instance until a
    # reset (the pin that stops an "always construct" shortcut that
    # would break connection pooling).
    assert first is second


def test_get_llm_rebuilds_after_reset() -> None:
    chat_api._llm = None
    first = chat_api.get_llm()
    chat_api.reset_runtime_caches()
    second = chat_api.get_llm()
    assert second is not first
    assert second.settings is get_settings()


def test_get_chat_semaphore_rebuilds_after_reset(
    monkeypatch: pytest.MonkeyPatch,
) -> None:
    chat_api._chat_semaphore = None
    base = chat_api._get_chat_semaphore()
    base_value = base._value  # pyright: ignore[reportPrivateUsage]
    # Drive the cap to a value different from the current one (the
    # env is the base — the kill switch is off, conftest pin), so the
    # rebuild's new _value is unambiguous.
    target = 3 if base_value != 3 else 5
    monkeypatch.setenv("BOR_CHAT_MAX_CONCURRENT", str(target))
    get_settings.cache_clear()
    chat_api.reset_runtime_caches()
    rebuilt = chat_api._get_chat_semaphore()
    assert rebuilt is not base
    assert rebuilt._value == target  # pyright: ignore[reportPrivateUsage]
    # restore: the env reverts via monkeypatch, and the fixture's cache
    # clear re-resolves the settings.
    get_settings.cache_clear()


# ---------------------------------------------------------------------------
# the create_app() wiring — the composition root registers the hook
# ---------------------------------------------------------------------------


def test_create_app_wires_the_reset_hook() -> None:
    """``register_invalidator(reset_runtime_caches)`` inside
    ``create_app`` — the static pin that stops the wiring being
    "cleaned up" (without it a Save silently stops retuning the LLM
    client)."""
    src = Path(app_main.__file__).read_text()
    start = src.index("def create_app(")
    end = src.index("\napp = create_app()", start)
    body = src[start:end]
    assert "register_invalidator(reset_runtime_caches)" in body


def test_app_core_imports_no_app_api() -> None:
    """Dependency direction (PLAN §3): ``app/core/`` never imports an
    ``app.api`` symbol — the hook exists so the composition root can
    wire the reset without inverting it."""
    core = Path(app_main.__file__).resolve().parent / "core"
    for py in sorted(core.glob("*.py")):
        src = py.read_text()
        for line in src.splitlines():
            stripped = line.strip()
            assert not (
                stripped.startswith("from app.api")
                or stripped.startswith("import app.api")
            ), f"{py.name} imports app.api (PLAN §3 direction)"


# ---------------------------------------------------------------------------
# invalidate_settings — cache clear + hook run, a failed reset stands
# ---------------------------------------------------------------------------


def test_invalidate_runs_hooks_and_re_resolves(
    monkeypatch: pytest.MonkeyPatch,
) -> None:
    calls: list[str] = []
    settings_overlay.register_invalidator(lambda: calls.append("hook"))
    get_settings.cache_clear()
    get_settings()  # a cached hit under the ORIGINAL env
    monkeypatch.setenv("BOR_APP_NAME", "Live-Apply-Check")
    invalidate_settings()  # clears the cache + runs the hooks
    assert calls == ["hook"]
    # the re-resolution sees the NEW env — the cache really was cleared
    assert get_settings().app_name == "Live-Apply-Check"


def test_invalidate_survives_a_raising_hook(
    caplog: pytest.LogCaptureFixture,
) -> None:
    """A failed reset must not turn a committed save into a 500 — the
    exception is logged, never propagated."""

    def _boom() -> None:
        raise RuntimeError("boom")

    settings_overlay.register_invalidator(_boom)
    with caplog.at_level(logging.ERROR, logger="app.settings"):
        invalidate_settings()  # must not raise
    assert any("settings invalidator failed" in r.getMessage() for r in caplog.records)