"""Health surface.

The point of these tests is the negative cases. An endpoint that returns 200
under every condition tells an orchestrator nothing, and the failure is silent
exactly when it matters.
"""

from __future__ import annotations

from pathlib import Path

import pytest
from alembic import command
from alembic.config import Config
from alembic.script import ScriptDirectory
from fastapi.testclient import TestClient

from canned_prompts_service.api import create_app
from canned_prompts_service.db import check_readiness, make_engine
from canned_prompts_service.settings import Settings

ROOT = Path(__file__).resolve().parents[1]


def expected_head() -> str:
    """Computed, not hardcoded: a new migration must not fail these tests."""
    config = Config(str(ROOT / "alembic.ini"))
    config.set_main_option("script_location", str(ROOT / "migrations"))
    return ScriptDirectory.from_config(config).get_current_head()


def migrated_url(tmp_path: Path) -> str:
    url = f"sqlite:///{tmp_path / 'svc.db'}"
    config = Config(str(ROOT / "alembic.ini"))
    config.set_main_option("script_location", str(ROOT / "migrations"))
    config.set_main_option("sqlalchemy.url", url)
    command.upgrade(config, "head")
    return url


@pytest.fixture()
def ready_client(tmp_path: Path) -> TestClient:
    url = migrated_url(tmp_path)
    return TestClient(create_app(Settings(database_url=url), make_engine(url)))


def test_healthz_is_up_without_a_database() -> None:
    """Liveness must not depend on the database, or a DB blip restarts pods."""
    client = TestClient(create_app(Settings(), None))
    assert client.get("/healthz").json() == {"status": "ok"}


def test_readyz_fails_without_a_database() -> None:
    client = TestClient(create_app(Settings(), None))
    response = client.get("/readyz")
    assert response.status_code == 503
    assert response.json()["ready"] is False
    assert "no database" in response.json()["detail"]


def test_readyz_fails_when_the_database_is_unreachable(tmp_path: Path) -> None:
    engine = make_engine("sqlite:////nonexistent/dir/does-not-exist.db")
    client = TestClient(create_app(Settings(database_url="x"), engine))
    response = client.get("/readyz")
    assert response.status_code == 503
    assert response.json()["ready"] is False


def test_readyz_fails_when_the_schema_is_not_migrated(tmp_path: Path) -> None:
    """Reachable but unmigrated is not ready — it would 500 on the first query."""
    engine = make_engine(f"sqlite:///{tmp_path / 'empty.db'}")
    client = TestClient(create_app(Settings(database_url="x"), engine))
    response = client.get("/readyz")
    assert response.status_code == 503
    assert response.json()["detail"] == "schema not migrated"


def test_readyz_reports_the_migration_when_ready(ready_client: TestClient) -> None:
    body = ready_client.get("/readyz").json()
    assert body["ready"] is True
    assert body["migration"] == expected_head()


def test_state_health_matches_the_fleet_shape(ready_client: TestClient) -> None:
    body = ready_client.get("/state/health").json()
    assert body["status"] == "ok"
    assert body["service"] == "canned-prompts"
    assert body["db"] == "connected"
    assert body["migration"] == expected_head()


def test_state_health_degrades_rather_than_lying() -> None:
    client = TestClient(create_app(Settings(), None))
    response = client.get("/state/health")
    assert response.status_code == 503
    assert response.json()["status"] == "degraded"


def test_settings_have_no_database_fallback() -> None:
    """Falling back to a local database when misconfigured hides the mistake."""
    assert Settings().database_url == ""
    assert Settings().configured is False