"""Unit tests for the OpenTelemetry wiring in :mod:`tavolo.app`.

The mixin under test is kaya-otel's :class:`~kaya.otel.OTelMixin`, an
optional dependency (the ``otel`` extra); these tests only verify that
:func:`tavolo.app.otel_mixin_from_settings` maps the ``OTEL_*`` settings
onto mixin construction. The ``kaya.otel`` module is stubbed in
``sys.modules`` so the suite does not need the extra installed.
"""
from __future__ import annotations

import os
import sys
import types
import unittest
from unittest.mock import patch

from tavolo.app import otel_mixin_from_settings
from tavolo.config import Settings


def _settings(env: dict) -> Settings:
    with patch.dict(os.environ, env, clear=True):
        return Settings.from_env()


class _StubOTelMixin:
    def __init__(self, **kwargs):
        self.kwargs = kwargs


def _stub_kaya_otel():
    """Install a fake ``kaya.otel`` module and return it."""
    module = types.ModuleType("kaya.otel")
    module.OTelMixin = _StubOTelMixin  # type: ignore[attr-defined]
    return patch.dict(sys.modules, {"kaya.otel": module})


class OTelMixinFromSettingsTests(unittest.TestCase):
    def test_disabled_by_default(self):
        self.assertIsNone(otel_mixin_from_settings(_settings({})))

    def test_enabled_by_otel_enabled(self):
        with _stub_kaya_otel():
            mixin = otel_mixin_from_settings(_settings({"OTEL_ENABLED": "1"}))
        self.assertIsNotNone(mixin)

    def test_settings_are_passed_through(self):
        with _stub_kaya_otel():
            mixin = otel_mixin_from_settings(_settings({
                "OTEL_ENABLED": "true",
                "OTEL_SERVICE_NAME": "cards",
                "OTEL_EXPORTER_OTLP_ENDPOINT": "http://collector:4318",
                "OTEL_EXPORTER_OTLP_HEADERS": "Authorization=Bearer t, X-Tenant=one",
            }))
        assert isinstance(mixin, _StubOTelMixin)
        self.assertEqual({
            "service_name": "cards",
            "endpoint": "http://collector:4318",
            "headers": {"Authorization": "Bearer t", "X-Tenant": "one"},
            "excluded_paths": ("/api/health",),
        }, mixin.kwargs)

    def test_defaults_when_only_enabled(self):
        with _stub_kaya_otel():
            mixin = otel_mixin_from_settings(_settings({"OTEL_ENABLED": "on"}))
        assert isinstance(mixin, _StubOTelMixin)
        self.assertEqual("tavolo", mixin.kwargs["service_name"])
        self.assertIsNone(mixin.kwargs["endpoint"])
        self.assertIsNone(mixin.kwargs["headers"])
        self.assertEqual(("/api/health",), mixin.kwargs["excluded_paths"])

    def test_excluded_paths_are_passed_through(self):
        with _stub_kaya_otel():
            mixin = otel_mixin_from_settings(_settings({
                "OTEL_ENABLED": "1",
                "OTEL_EXCLUDED_PATHS": "/api/health,/metrics",
            }))
        assert isinstance(mixin, _StubOTelMixin)
        self.assertEqual(("/api/health", "/metrics"), mixin.kwargs["excluded_paths"])

    def test_missing_extra_raises_runtime_error(self):
        with patch.dict(sys.modules, {"kaya.otel": None}):
            with self.assertRaises(RuntimeError):
                otel_mixin_from_settings(_settings({"OTEL_ENABLED": "1"}))


if __name__ == "__main__":
    unittest.main()