// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: BUSL-1.1

package l7_traffic_management

import (
	"testing"

	"github.com/stretchr/testify/require"

	"github.com/hashicorp/consul/api"
	"github.com/hashicorp/consul/test/integration/consul-container/libs/utils"
	"github.com/hashicorp/consul/testing/deployer/sprawl"
	"github.com/hashicorp/consul/testing/deployer/topology"
)

// TestTrafficManagement_ResolverDefaultSubset_Agentless tests resolver directs traffic to default subset - agentless
//   - Create a topology with static-server (meta version V2) and static-client (with static-server upstream)
//   - Create a service resolver for static-server with V2 as default subset
//   - Resolver directs traffic to the default subset, which is V2
//   - Do a standard upgrade and validate the traffic is still directed to V2
//   - Change the default version in serviceResolver to v1 and the client to server request fails
//     since we only have V2 instance
//   - Change the default version in serviceResolver to v2 and the client to server request succeeds
//     (V2 instance is available and traffic is directed to it)
func TestTrafficManagement_ResolverDefaultSubset_Agentless(t *testing.T) {
	t.Parallel()

	ct := NewCommonTopo(t)
	ct.Cfg.Clusters[0].InitialConfigEntries = append(ct.Cfg.Clusters[0].InitialConfigEntries,
		newServiceResolver(staticServerSID.Name, "v2"))

	ct.Launch(t)

	resolverV2AssertFn := func() {
		cluster := ct.Sprawl.Topology().Clusters[dc1]
		staticClientWorkload := cluster.WorkloadByID(
			topology.NewNodeID("dc1-client2", defaultPartition),
			ct.StaticClientSID,
		)
		ct.Assert.FortioFetch2HeaderEcho(t, staticClientWorkload, &topology.Destination{
			ID:        ct.StaticServerSID,
			LocalPort: 5000,
		})
		ct.Assert.FortioFetch2FortioName(t, staticClientWorkload, &topology.Destination{
			ID:        ct.StaticServerSID,
			LocalPort: 5000,
		}, dc1, staticServerSID)
		ct.Assert.DestinationEndpointStatus(t, staticClientWorkload, "v2.static-server.default", "HEALTHY", 1)
	}
	resolverV2AssertFn()

	t.Log("Start standard upgrade ...")
	sp := ct.Sprawl
	cfg := sp.Config()
	require.NoError(t, ct.Sprawl.LoadKVDataToCluster("dc1", 1, &api.WriteOptions{}))
	require.NoError(t, sp.Upgrade(cfg, "dc1", sprawl.UpgradeTypeStandard, utils.TargetImages(), nil))
	t.Log("Finished standard upgrade ...")

	// verify data is not lost
	data, err := ct.Sprawl.GetKV("dc1", "key-0", &api.QueryOptions{})
	require.NoError(t, err)
	require.NotNil(t, data)

	ct.ValidateWorkloads(t)
	resolverV2AssertFn()

	// Change the default version in serviceResolver to v1 and the client to server request fails
	cluster := ct.Sprawl.Topology().Clusters[dc1]
	cl, err := ct.Sprawl.APIClientForCluster(cluster.Name, "")
	require.NoError(t, err)
	configEntry := cl.ConfigEntries()
	_, err = configEntry.Delete(api.ServiceResolver, staticServerSID.Name, nil)
	require.NoError(t, err)
	_, _, err = configEntry.Set(newServiceResolver(staticServerSID.Name, "v1"), nil)
	require.NoError(t, err)
	ct.ValidateWorkloads(t)

	resolverV1AssertFn := func() {
		cluster := ct.Sprawl.Topology().Clusters[dc1]
		staticClientWorkload := cluster.WorkloadByID(
			topology.NewNodeID("dc1-client2", defaultPartition),
			ct.StaticClientSID,
		)
		ct.Assert.FortioFetch2ServiceUnavailable(t, staticClientWorkload, &topology.Destination{
			ID:        ct.StaticServerSID,
			LocalPort: 5000,
		})
	}
	resolverV1AssertFn()

	// Change the default version in serviceResolver to v2 and the client to server request succeeds
	configEntry = cl.ConfigEntries()
	_, err = configEntry.Delete(api.ServiceResolver, staticServerSID.Name, nil)
	require.NoError(t, err)
	_, _, err = configEntry.Set(newServiceResolver(staticServerSID.Name, "v2"), nil)
	require.NoError(t, err)
	ct.ValidateWorkloads(t)
	resolverV2AssertFn()
}

func newServiceResolver(serviceResolverName string, defaultSubset string) api.ConfigEntry {
	return &api.ServiceResolverConfigEntry{
		Kind:          api.ServiceResolver,
		Name:          serviceResolverName,
		DefaultSubset: defaultSubset,
		Subsets: map[string]api.ServiceResolverSubset{
			"v1": {
				Filter: "Service.Meta.version == v1",
			},
			"v2": {
				Filter: "Service.Meta.version == v2",
			},
		},
	}
}