/*
Copyright 2021 The Flux authors

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package providers

import (
	"context"
	"log"
	"net"
	"os"
	"testing"

	monitoring "cloud.google.com/go/monitoring/apiv3/v2"
	"github.com/googleapis/gax-go/v2"
	"github.com/stretchr/testify/assert"
	"google.golang.org/api/option"
	monitoringpb "google.golang.org/genproto/googleapis/monitoring/v3"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
	"google.golang.org/protobuf/proto"
	corev1 "k8s.io/api/core/v1"

	flaggerv1 "github.com/fluxcd/flagger/pkg/apis/flagger/v1beta1"
)

// clientOpt is the option tests should use to connect to the test server.
// It is initialized by TestMain.
var clientOpt option.ClientOption

var mockQueryPolicy mockQueryPolicyServer

type mockQueryPolicyServer struct {
	monitoringpb.QueryServiceServer

	req []proto.Message

	err error

	resps []proto.Message
}

type stackdriverClientMock struct {
	iter *monitoring.TimeSeriesDataIterator
}

func (m *mockQueryPolicyServer) QueryTimeSeries(ctx context.Context, req *monitoringpb.QueryTimeSeriesRequest) (*monitoringpb.QueryTimeSeriesResponse, error) {
	if m.err != nil {
		return nil, m.err
	}
	return m.resps[0].(*monitoringpb.QueryTimeSeriesResponse), nil
}

func (s *stackdriverClientMock) QueryTimeSeries(ctx context.Context, req *monitoringpb.QueryTimeSeriesRequest, opts ...gax.CallOption) *monitoring.TimeSeriesDataIterator {
	return s.iter
}

func TestMain(m *testing.M) {
	serv := grpc.NewServer()
	monitoringpb.RegisterQueryServiceServer(serv, &mockQueryPolicy)
	lis, err := net.Listen("tcp", "localhost:0")
	if err != nil {
		log.Fatal(err)
	}
	go serv.Serve(lis)

	conn, err := grpc.Dial(lis.Addr().String(), grpc.WithInsecure())
	if err != nil {
		log.Fatal(err)
	}
	clientOpt = option.WithGRPCConn(conn)
	os.Exit(m.Run())
}

func TestNewStackDriverProvider(t *testing.T) {
	t.Run("error when project id isn't provided", func(t *testing.T) {
		_, err := NewStackDriverProvider(flaggerv1.MetricTemplateProvider{
			SecretRef: &corev1.LocalObjectReference{
				Name: "test-secret",
			},
		}, map[string][]byte{})

		assert.Error(t, err, "error expected since project id is not given")
	})
}

func TestStackDriverProvider_IsOnline(t *testing.T) {
	t.Run("ok", func(t *testing.T) {
		mockQueryPolicy.err = status.Error(codes.InvalidArgument, "invalid arg")
		c, err := monitoring.NewQueryClient(context.Background(), clientOpt)
		if err != nil {
			t.Fatal(err)
		}
		p := StackDriverProvider{client: c}
		actual, err := p.IsOnline()
		assert.NoError(t, err)
		assert.True(t, actual)
	})

	t.Run("forbidden", func(t *testing.T) {
		mockQueryPolicy.err = status.Error(codes.PermissionDenied, "insufficient permissions")
		c, err := monitoring.NewQueryClient(context.Background(), clientOpt)
		if err != nil {
			t.Fatal(err)
		}
		p := StackDriverProvider{client: c}
		actual, err := p.IsOnline()
		assert.Error(t, err)
		assert.False(t, actual)
	})
}

func TestStackDriverProvider_RunQuery(t *testing.T) {
	query := `
    fetch k8s_container
    | metric 'istio.io/service/server/response_latencies'
    | filter
        (metric.destination_service_name == '{{ service }}-canary'
        && metric.destination_service_namespace == '{{ namespace }}')
    | align delta(1m)
    | every 1m
    | group_by [],
        [value_response_latencies_percentile:
          percentile(value.response_latencies, 99)]
`

	t.Run("ok", func(t *testing.T) {
		var exp float64 = 100
		expectedResponse := &monitoringpb.QueryTimeSeriesResponse{
			NextPageToken: "",
			TimeSeriesData: []*monitoringpb.TimeSeriesData{
				{
					PointData: []*monitoringpb.TimeSeriesData_PointData{
						{
							Values: []*monitoringpb.TypedValue{
								{
									Value: &monitoringpb.TypedValue_DoubleValue{DoubleValue: exp},
								},
							},
						},
					},
				},
			},
		}

		mockQueryPolicy.resps = append(mockQueryPolicy.resps[:0], expectedResponse)
		mockQueryPolicy.err = nil

		c, err := monitoring.NewQueryClient(context.Background(), clientOpt)
		if err != nil {
			t.Fatal(err)
		}
		p := StackDriverProvider{client: c}
		actual, err := p.RunQuery(query)
		assert.NoError(t, err)
		assert.Equal(t, actual, exp)
	})

	t.Run("no values", func(t *testing.T) {
		expectedResps := &monitoringpb.QueryTimeSeriesResponse{
			NextPageToken:  "",
			TimeSeriesData: []*monitoringpb.TimeSeriesData{},
		}

		mockQueryPolicy.resps = append(mockQueryPolicy.resps[:0], expectedResps)
		mockQueryPolicy.err = nil

		c, err := monitoring.NewQueryClient(context.Background(), clientOpt)
		if err != nil {
			t.Fatal(err)
		}
		p := StackDriverProvider{client: c}
		_, err = p.RunQuery(query)
		assert.Error(t, err)
		assert.ErrorIs(t, err, ErrNoValuesFound)
	})
}