import pytest
from django.contrib.auth import get_user_model
from django.core.cache import cache

from infrasynth.features.models import FeatureFlag, FeatureFlagOverride
from infrasynth.features.registry import FeatureRegistry
from infrasynth.features.services import FeatureService

UserModel = get_user_model()


@pytest.fixture(autouse=True)
def clean_registry(clean_feature_registry):
    cache.clear()
    cache.clear()
    yield


@pytest.fixture
def user(db):
    return UserModel.objects.create_user(username="testuser", password="pass123")


@pytest.fixture
def service():
    return FeatureService()


class TestIsEnabled:
    def test_registry_default_when_no_db_flag(self, service, db):
        FeatureRegistry.register("my.flag", default=True)
        assert service.is_enabled("my.flag") is True

    def test_registry_default_false_when_no_db_flag(self, service, db):
        FeatureRegistry.register("my.flag", default=False)
        assert service.is_enabled("my.flag") is False

    def test_fallback_default_when_not_registered(self, service, db):
        assert service.is_enabled("unknown.flag") is False

    def test_fallback_default_explicit(self, service, db):
        assert service.is_enabled("unknown.flag", default=True) is True

    def test_db_flag_overrides_registry_default(self, service, db):
        FeatureRegistry.register("my.flag", default=False)
        FeatureFlag.objects.create(slug="my.flag", is_active=True)
        assert service.is_enabled("my.flag") is True

    def test_db_flag_false_overrides_registry(self, service, db):
        FeatureRegistry.register("my.flag", default=True)
        FeatureFlag.objects.create(slug="my.flag", is_active=False)
        assert service.is_enabled("my.flag") is False

    def test_user_override_enables(self, service, user, db):
        FeatureRegistry.register("my.flag", default=False)
        flag = FeatureFlag.objects.create(slug="my.flag", is_active=False)
        FeatureFlagOverride.objects.create(flag=flag, user=user, is_enabled=True)
        assert service.is_enabled("my.flag", user=user) is True

    def test_user_override_disables(self, service, user, db):
        FeatureRegistry.register("my.flag", default=True)
        flag = FeatureFlag.objects.create(slug="my.flag", is_active=True)
        FeatureFlagOverride.objects.create(flag=flag, user=user, is_enabled=False)
        assert service.is_enabled("my.flag", user=user) is False

    def test_user_override_wins_over_db(self, service, user, db):
        FeatureRegistry.register("my.flag", default=False)
        flag = FeatureFlag.objects.create(slug="my.flag", is_active=True)
        FeatureFlagOverride.objects.create(flag=flag, user=user, is_enabled=False)
        assert service.is_enabled("my.flag", user=user) is False

    def test_unauthenticated_user_ignores_override(self, service, db):
        FeatureRegistry.register("my.flag", default=True)
        anon = UserModel.objects.create(username="anon", password="x")
        assert service.is_enabled("my.flag", user=anon) is True

    def test_tenant_id_scope(self, service, tenant):
        FeatureRegistry.register("tenant.flag", default=False)
        FeatureFlag.all_objects.create(slug="tenant.flag", is_active=True, tenant=tenant)
        assert service.is_enabled("tenant.flag", tenant_id=tenant.pk) is True

    def test_global_fallback_used_when_no_tenant_override(self, service, tenant):
        FeatureRegistry.register("g.flag", default=False)
        FeatureFlag.all_objects.create(slug="g.flag", is_active=True, tenant=None)
        # Resolution: tenant override -> global default -> registry (TENANCY.md §5)
        assert service.is_enabled("g.flag", tenant_id=tenant.pk) is True

    def test_tenant_specific_flag(self, service, tenant):
        from infrasynth.tenancy.models import Tenant

        FeatureRegistry.register("t.flag", default=False)
        other = Tenant.objects.create(slug="other-ws", name="Other")
        FeatureFlag.all_objects.create(slug="t.flag", is_active=True, tenant=tenant)
        assert service.is_enabled("t.flag", tenant_id=tenant.pk) is True
        assert service.is_enabled("t.flag", tenant_id=other.pk) is False


class TestGetActiveFlags:
    def test_returns_registry_flags_when_no_db(self, service, db):
        FeatureRegistry.register("flag.a", default=True)
        FeatureRegistry.register("flag.b", default=False)
        FeatureRegistry.register("flag.c", default=True)
        result = service.get_active_flags()
        assert result == {"flag.a": True, "flag.b": False, "flag.c": True}

    def test_includes_db_only_flags(self, service, db):
        FeatureFlag.objects.create(slug="db_only", is_active=True)
        result = service.get_active_flags()
        assert "db_only" in result

    def test_respects_user_overrides(self, service, user, db):
        FeatureRegistry.register("my.flag", default=False)
        flag = FeatureFlag.objects.create(slug="my.flag", is_active=False)
        FeatureFlagOverride.objects.create(flag=flag, user=user, is_enabled=True)
        result = service.get_active_flags(user=user)
        assert result["my.flag"] is True


class TestRollout:
    def test_zero_percent_disables_everyone(self, service, user, db):
        FeatureFlag.objects.create(slug="rollout.zero", is_active=True, rollout_percentage=0)
        assert service.is_enabled("rollout.zero", user=user) is False

    def test_hundred_percent_enables_everyone(self, service, user, db):
        FeatureFlag.objects.create(slug="rollout.all", is_active=True, rollout_percentage=100)
        assert service.is_enabled("rollout.all", user=user) is True

    def test_partial_rollout_is_deterministic(self, service, user, db):
        FeatureFlag.objects.create(slug="rollout.partial", is_active=True, rollout_percentage=50)
        first = service.is_enabled("rollout.partial", user=user)
        second = service.is_enabled("rollout.partial", user=user)
        assert first == second

    def test_environment_targeting(self, service, user, settings, db):
        settings.ENVIRONMENT = "production"
        FeatureFlag.objects.create(slug="rollout.env", is_active=True, rollout_percentage=100, environments=["staging"])
        assert service.is_enabled("rollout.env", user=user) is False