import pytest

from netbox_services.engine.resolver import Resolver, ConflictError
from netbox_services.models import Service, ServiceResourceBinding, ServiceTemplate


@pytest.fixture
def site(db):
    from dcim.models import Site
    return Site.objects.create(name="resolver-site", slug="resolver-site")


@pytest.fixture
def device_type(db):
    from dcim.models import DeviceType, Manufacturer
    mfr = Manufacturer.objects.create(name="resolver-mfr", slug="resolver-mfr")
    return DeviceType.objects.create(manufacturer=mfr, model="resolver-model", slug="resolver-model")


@pytest.fixture
def role(db):
    from dcim.models import DeviceRole
    return DeviceRole.objects.create(name="resolver-role", slug="resolver-role")


@pytest.fixture
def devices(site, device_type, role, db):
    from dcim.models import Device
    return [
        Device.objects.create(name="dev-a", site=site, device_type=device_type, role=role),
        Device.objects.create(name="dev-b", site=site, device_type=device_type, role=role),
    ]


@pytest.fixture
def prefix(db):
    from ipam.models import Prefix
    return Prefix.objects.create(prefix="10.200.0.0/24")


@pytest.fixture
def tenant(db):
    from tenancy.models import Tenant
    return Tenant.objects.create(name="res-tenant", slug="res-tenant")


@pytest.fixture
def service_with_devices(db, devices, tenant):
    tmpl = ServiceTemplate.objects.create(
        name="dev-tmpl",
        status="active",
        tree=[{
            "name": "routers",
            "object_type": "dcim.device",
            "quantity": 2,
            "selector": {"type": "netbox_filter", "filters": {"role": ["resolver-role"]}},
            "scope": "service",
            "children": [],
        }],
    )
    return Service.objects.create(name="dev-svc", service_template=tmpl, tenant=tenant)


@pytest.fixture
def service_with_ip_alloc(db, prefix, tenant):
    tmpl = ServiceTemplate.objects.create(
        name="ip-tmpl",
        status="active",
        tree=[{
            "name": "ip",
            "object_type": "ipam.ipaddress",
            "quantity": 1,
            "allocation": {
                "strategy": "first_free",
                "prefix": {"type": "prefix", "filters": {}},
            },
            "scope": "service",
            "children": [],
        }],
    )
    return Service.objects.create(name="ip-svc", service_template=tmpl, tenant=tenant)


@pytest.mark.django_db
class TestResolverDryRun:
    def test_dry_run_no_bindings(self, service_with_devices):
        resolver = Resolver()
        result = resolver.resolve(service_with_devices, mode="dry_run")
        assert result.total_planned == 2
        assert ServiceResourceBinding.objects.filter(service=service_with_devices).count() == 0

    def test_dry_run_rolls_back_allocation(self, service_with_ip_alloc):
        from ipam.models import IPAddress
        resolver = Resolver()
        result = resolver.resolve(service_with_ip_alloc, mode="dry_run")
        assert result.total_planned == 1
        assert IPAddress.objects.count() == 0
        assert ServiceResourceBinding.objects.count() == 0


@pytest.mark.django_db
class TestResolverCommit:
    def test_commit_creates_bindings(self, service_with_devices):
        resolver = Resolver()
        result = resolver.resolve(service_with_devices, mode="commit")
        assert result.succeeded
        assert ServiceResourceBinding.objects.filter(service=service_with_devices).count() == 2

    def test_commit_allocates_ip(self, service_with_ip_alloc):
        from ipam.models import IPAddress
        resolver = Resolver()
        result = resolver.resolve(service_with_ip_alloc, mode="commit")
        assert IPAddress.objects.count() == 1
        assert ServiceResourceBinding.objects.filter(service=service_with_ip_alloc).count() == 1

    def test_commit_nested(self, db, devices, prefix, tenant):
        from ipam.models import IPAddress
        from dcim.models import Interface

        for dev in devices:
            Interface.objects.create(device=dev, name="eth0")

        tmpl = ServiceTemplate.objects.create(
            name="nested-tmpl",
            status="active",
            tree=[{
                "name": "routers",
                "object_type": "dcim.device",
                "quantity": 1,
                "selector": {"type": "netbox_filter", "filters": {"role": ["resolver-role"]}},
                "scope": "service",
                "children": [{
                    "name": "ip",
                    "object_type": "ipam.ipaddress",
                    "quantity": 1,
                    "allocation": {
                        "strategy": "first_free",
                        "prefix": {"type": "prefix", "filters": {}},
                    },
                    "scope": "parent",
                    "children": [],
                }],
            }],
        )
        svc = Service.objects.create(name="nested-svc", service_template=tmpl, tenant=tenant)

        resolver = Resolver()
        result = resolver.resolve(svc, mode="commit")
        assert result.succeeded
        assert ServiceResourceBinding.objects.filter(service=svc).count() == 2


@pytest.mark.django_db
class TestReconciliation:
    def test_reresolve_no_change(self, service_with_devices):
        resolver = Resolver()
        resolver.resolve(service_with_devices, mode="commit")
        result = resolver.resolve(service_with_devices, mode="commit")
        assert len(result.to_add) == 0
        assert len(result.to_remove) == 0
        assert ServiceResourceBinding.objects.filter(service=service_with_devices).count() == 2

    def test_reresolve_reuses_allocated(self, service_with_ip_alloc):
        from ipam.models import IPAddress
        resolver = Resolver()
        resolver.resolve(service_with_ip_alloc, mode="commit")
        ip_count_before = IPAddress.objects.count()
        result = resolver.resolve(service_with_ip_alloc, mode="commit")
        assert len(result.to_add) == 0
        assert IPAddress.objects.count() == ip_count_before

    def test_reresolve_removes_stale(self, service_with_devices, devices):
        resolver = Resolver()
        result = resolver.resolve(service_with_devices, mode="commit")
        assert ServiceResourceBinding.objects.filter(service=service_with_devices).count() == 2

        svc_tmpl = service_with_devices.service_template
        svc_tmpl.tree[0]["quantity"] = 1
        # Template is locked — bypass via queryset
        ServiceTemplate.objects.filter(pk=svc_tmpl.pk).update(tree=svc_tmpl.tree)
        service_with_devices.refresh_from_db()
        service_with_devices.service_template.refresh_from_db()

        result2 = resolver.resolve(service_with_devices, mode="commit")
        assert len(result2.to_remove) >= 1
        assert ServiceResourceBinding.objects.filter(service=service_with_devices).count() == 1


@pytest.mark.django_db
class TestConflictDetection:
    def test_exclusion_when_device_already_bound(self, db, site, device_type, role, tenant):
        from dcim.models import Device

        dev = Device.objects.create(name="conflict-dev", site=site, device_type=device_type, role=role)
        tmpl = ServiceTemplate.objects.create(
            name="conflict-tmpl",
            status="active",
            tree=[{
                "name": "dev",
                "object_type": "dcim.device",
                "quantity": 1,
                "selector": {"type": "netbox_filter", "filters": {"role": ["resolver-role"]}},
                "scope": "service",
                "children": [],
            }],
        )
        svc1 = Service.objects.create(name="c-svc-1", service_template=tmpl, tenant=tenant)
        svc2 = Service.objects.create(name="c-svc-2", service_template=tmpl, tenant=tenant)

        resolver = Resolver()
        r1 = resolver.resolve(svc1, mode="commit")
        assert r1.succeeded
        assert ServiceResourceBinding.objects.filter(service=svc1).count() == 1

        r2 = resolver.resolve(svc2, mode="commit")
        assert r2.succeeded
        assert ServiceResourceBinding.objects.filter(service=svc2).count() == 0
        assert any("only 0 of 1" in w for w in r2.warnings)

    def test_no_conflict_different_devices(self, db, devices, tenant):
        tmpl = ServiceTemplate.objects.create(
            name="noconf-tmpl",
            status="active",
            tree=[{
                "name": "dev",
                "object_type": "dcim.device",
                "quantity": 1,
                "selector": {"type": "netbox_filter", "filters": {"role": ["resolver-role"]}},
                "scope": "service",
                "children": [],
            }],
        )
        svc1 = Service.objects.create(name="nc-svc-1", service_template=tmpl, tenant=tenant)
        svc2 = Service.objects.create(name="nc-svc-2", service_template=tmpl, tenant=tenant)

        resolver = Resolver()
        r1 = resolver.resolve(svc1, mode="commit")
        assert r1.succeeded
        r2 = resolver.resolve(svc2, mode="commit")
        assert r2.succeeded

        b1 = ServiceResourceBinding.objects.filter(service=svc1).first()
        b2 = ServiceResourceBinding.objects.filter(service=svc2).first()
        assert b1.object_id != b2.object_id