package remote

import (
	"context"
	"crypto/md5"
	"fmt"
	"math/rand"
	"net/http"
	"net/http/httptest"
	"os"
	"testing"
	"time"

	"github.com/go-openapi/strfmt"
	apimodels "github.com/grafana/grafana/pkg/services/ngalert/api/tooling/definitions"
	ngmodels "github.com/grafana/grafana/pkg/services/ngalert/models"
	"github.com/grafana/grafana/pkg/util"
	amv2 "github.com/prometheus/alertmanager/api/v2/models"
	"github.com/stretchr/testify/require"
)

// Valid Grafana Alertmanager configuration.
const testGrafanaConfig = `{"template_files":{},"alertmanager_config":{"route":{"receiver":"grafana-default-email","group_by":["grafana_folder","alertname"]},"templates":null,"receivers":[{"name":"grafana-default-email","grafana_managed_receiver_configs":[{"uid":"","name":"some other name","type":"email","disableResolveMessage":false,"settings":{"addresses":"\u003cexample@email.com\u003e"},"secureSettings":null}]}]}}`

func TestNewAlertmanager(t *testing.T) {
	tests := []struct {
		name     string
		url      string
		tenantID string
		password string
		orgID    int64
		expErr   string
	}{
		{
			name:     "empty URL",
			url:      "",
			tenantID: "1234",
			password: "test",
			orgID:    1,
			expErr:   "empty URL for tenant 1234",
		},
		{
			name:     "valid parameters",
			url:      "http://localhost:8080",
			tenantID: "1234",
			password: "test",
			orgID:    1,
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(tt *testing.T) {
			cfg := AlertmanagerConfig{
				URL:               test.url,
				TenantID:          test.tenantID,
				BasicAuthPassword: test.password,
			}
			am, err := NewAlertmanager(cfg, test.orgID)
			if test.expErr != "" {
				require.EqualError(tt, err, test.expErr)
				return
			}

			require.NoError(tt, err)
			require.Equal(tt, am.tenantID, test.tenantID)
			require.Equal(tt, am.url, test.url)
			require.Equal(tt, am.orgID, test.orgID)
			require.NotNil(tt, am.amClient)
			require.NotNil(tt, am.httpClient)
		})
	}
}

func TestApplyConfig(t *testing.T) {
	errorHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusInternalServerError)
	})
	okHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
	})

	// ApplyConfig performs a readiness check at startup.
	// A non-200 response should result in an error.
	server := httptest.NewServer(errorHandler)
	cfg := AlertmanagerConfig{
		URL: server.URL,
	}
	am, err := NewAlertmanager(cfg, 1)
	require.NoError(t, err)

	config := &ngmodels.AlertConfiguration{}
	ctx := context.Background()
	require.Error(t, am.ApplyConfig(ctx, config))
	require.False(t, am.Ready())

	// A 200 status code response should make the check succeed.
	server.Config.Handler = okHandler
	require.NoError(t, am.ApplyConfig(ctx, config))
	require.True(t, am.Ready())

	// If we already got a 200 status code response, we shouldn't make the HTTP request again.
	server.Config.Handler = errorHandler
	require.NoError(t, am.ApplyConfig(ctx, config))
	require.True(t, am.Ready())
}

func TestIntegrationRemoteAlertmanagerApplyConfigOnlyUploadsOnce(t *testing.T) {
	if testing.Short() {
		t.Skip("skipping integration test")
	}

	amURL, ok := os.LookupEnv("AM_URL")
	if !ok {
		t.Skip("No Alertmanager URL provided")
	}
	tenantID := os.Getenv("AM_TENANT_ID")
	password := os.Getenv("AM_PASSWORD")

	// ApplyConfig performs a readiness check.
	cfg := AlertmanagerConfig{
		URL:               amURL,
		TenantID:          tenantID,
		BasicAuthPassword: password,
	}

	fakeConfigHash := fmt.Sprintf("%x", md5.Sum([]byte(testGrafanaConfig)))
	fakeConfigCreatedAt := time.Date(2020, 6, 5, 12, 6, 0, 0, time.UTC).Unix()
	fakeConfig := &ngmodels.AlertConfiguration{
		ID:                        100,
		AlertmanagerConfiguration: testGrafanaConfig,
		ConfigurationHash:         fakeConfigHash,
		ConfigurationVersion:      "v2",
		CreatedAt:                 fakeConfigCreatedAt,
		Default:                   true,
		OrgID:                     1,
	}

	ctx := context.Background()
	am, err := NewAlertmanager(cfg, 1)
	require.NoError(t, err)

	// We should have no configuration at first.
	{
		_, err = am.mimirClient.GetGrafanaAlertmanagerConfig(ctx)
		require.Error(t, err)
		require.Equal(t, "Error response from the Mimir API: alertmanager storage object not found", err.Error())
	}

	// Using `ApplyConfig` as a heuristic of a function that gets called when the Alertmanager starts
	// We call it as if the Alertmanager were starting.
	{
		require.NoError(t, am.ApplyConfig(ctx, fakeConfig))

		// First, we need to verify that the readiness check passes.
		require.True(t, am.Ready())

		// Next, we need to verify that Mimir received the configuration.
		config, err := am.mimirClient.GetGrafanaAlertmanagerConfig(ctx)
		require.NoError(t, err)
		require.Equal(t, int64(100), config.ID)
		require.Equal(t, testGrafanaConfig, config.GrafanaAlertmanagerConfig)
		require.Equal(t, fakeConfigHash, config.Hash)
		require.Equal(t, fakeConfigCreatedAt, config.CreatedAt)
		require.Equal(t, true, config.Default)

		// TODO: Check that the state was uploaded.
	}

	// Calling `ApplyConfig` again with a changed configuration yields no effect.
	{
		fakeConfig.ID = 30000000000000000
		require.NoError(t, am.ApplyConfig(ctx, fakeConfig))

		// The remote Alertmanager continues to be ready.
		require.True(t, am.Ready())

		// Next, we need to verify that the config that was uploaded remains the same.
		config, err := am.mimirClient.GetGrafanaAlertmanagerConfig(ctx)
		require.NoError(t, err)
		require.Equal(t, int64(100), config.ID)
		require.Equal(t, testGrafanaConfig, config.GrafanaAlertmanagerConfig)
		require.Equal(t, fakeConfigHash, config.Hash)
		require.Equal(t, fakeConfigCreatedAt, config.CreatedAt)
		require.Equal(t, true, config.Default)
	}

	// TODO: Now, shutdown the Alertmanager and we expect the latest configuration to be uploaded.
	{
	}
}

func TestIntegrationRemoteAlertmanagerSilences(t *testing.T) {
	if testing.Short() {
		t.Skip("skipping integration test")
	}

	amURL, ok := os.LookupEnv("AM_URL")
	if !ok {
		t.Skip("No Alertmanager URL provided")
	}
	tenantID := os.Getenv("AM_TENANT_ID")
	password := os.Getenv("AM_PASSWORD")

	cfg := AlertmanagerConfig{
		URL:               amURL,
		TenantID:          tenantID,
		BasicAuthPassword: password,
	}
	am, err := NewAlertmanager(cfg, 1)
	require.NoError(t, err)

	// We should have no silences at first.
	silences, err := am.ListSilences(context.Background(), []string{})
	require.NoError(t, err)
	require.Equal(t, 0, len(silences))

	// Creating a silence should succeed.
	testSilence := genSilence("test")
	id, err := am.CreateSilence(context.Background(), &testSilence)
	require.NoError(t, err)
	require.NotEmpty(t, id)
	testSilence.ID = id

	// We should be able to retrieve a specific silence.
	silence, err := am.GetSilence(context.Background(), testSilence.ID)
	require.NoError(t, err)
	require.Equal(t, testSilence.ID, *silence.ID)

	// Trying to retrieve a non-existing silence should fail.
	_, err = am.GetSilence(context.Background(), util.GenerateShortUID())
	require.Error(t, err)

	// After creating another silence, the total amount should be 2.
	testSilence2 := genSilence("test")
	id, err = am.CreateSilence(context.Background(), &testSilence2)
	require.NoError(t, err)
	require.NotEmpty(t, id)
	testSilence2.ID = id

	silences, err = am.ListSilences(context.Background(), []string{})
	require.NoError(t, err)
	require.Equal(t, 2, len(silences))
	require.True(t, *silences[0].ID == testSilence.ID || *silences[0].ID == testSilence2.ID)
	require.True(t, *silences[1].ID == testSilence.ID || *silences[1].ID == testSilence2.ID)

	// After deleting one of those silences, the total amount should be 2 but one of those should be expired.
	err = am.DeleteSilence(context.Background(), testSilence.ID)
	require.NoError(t, err)

	silences, err = am.ListSilences(context.Background(), []string{})
	require.NoError(t, err)

	for _, s := range silences {
		if *s.ID == testSilence.ID {
			require.Equal(t, *s.Status.State, "expired")
		} else {
			require.Equal(t, *s.Status.State, "pending")
		}
	}

	// When deleting the other silence, both should be expired.
	err = am.DeleteSilence(context.Background(), testSilence2.ID)
	require.NoError(t, err)

	silences, err = am.ListSilences(context.Background(), []string{})
	require.NoError(t, err)
	require.Equal(t, *silences[0].Status.State, "expired")
	require.Equal(t, *silences[1].Status.State, "expired")
}

func TestIntegrationRemoteAlertmanagerAlerts(t *testing.T) {
	if testing.Short() {
		t.Skip("skipping integration test")
	}

	amURL, ok := os.LookupEnv("AM_URL")
	if !ok {
		t.Skip("No Alertmanager URL provided")
	}
	tenantID := os.Getenv("AM_TENANT_ID")
	password := os.Getenv("AM_PASSWORD")

	cfg := AlertmanagerConfig{
		URL:               amURL,
		TenantID:          tenantID,
		BasicAuthPassword: password,
	}
	am, err := NewAlertmanager(cfg, 1)
	require.NoError(t, err)

	// Wait until the Alertmanager is ready to send alerts.
	require.NoError(t, am.checkReadiness(context.Background()))
	require.True(t, am.Ready())

	// We should have no alerts and no groups at first.
	alerts, err := am.GetAlerts(context.Background(), true, true, true, []string{}, "")
	require.NoError(t, err)
	require.Equal(t, 0, len(alerts))

	alertGroups, err := am.GetAlertGroups(context.Background(), true, true, true, []string{}, "")
	require.NoError(t, err)
	require.Equal(t, 0, len(alertGroups))

	// Let's create two active alerts and one expired one.
	alert1 := genAlert(true, map[string]string{"test_1": "test_1"})
	alert2 := genAlert(true, map[string]string{"test_2": "test_2"})
	alert3 := genAlert(false, map[string]string{"test_3": "test_3"})
	postableAlerts := apimodels.PostableAlerts{
		PostableAlerts: []amv2.PostableAlert{alert1, alert2, alert3},
	}
	err = am.PutAlerts(context.Background(), postableAlerts)
	require.NoError(t, err)

	// We should have two alerts and one group now.
	require.Eventually(t, func() bool {
		alerts, err = am.GetAlerts(context.Background(), true, true, true, []string{}, "")
		require.NoError(t, err)
		return len(alerts) == 2
	}, 16*time.Second, 1*time.Second)

	alertGroups, err = am.GetAlertGroups(context.Background(), true, true, true, []string{}, "")
	require.NoError(t, err)
	require.Equal(t, 1, len(alertGroups))

	// Filtering by `test_1=test_1` should return one alert.
	alerts, err = am.GetAlerts(context.Background(), true, true, true, []string{"test_1=test_1"}, "")
	require.NoError(t, err)
	require.Equal(t, 1, len(alerts))
}

func TestIntegrationRemoteAlertmanagerReceivers(t *testing.T) {
	if testing.Short() {
		t.Skip("skipping integration test")
	}

	amURL, ok := os.LookupEnv("AM_URL")
	if !ok {
		t.Skip("No Alertmanager URL provided")
	}

	tenantID := os.Getenv("AM_TENANT_ID")
	password := os.Getenv("AM_PASSWORD")

	cfg := AlertmanagerConfig{
		URL:               amURL,
		TenantID:          tenantID,
		BasicAuthPassword: password,
	}

	am, err := NewAlertmanager(cfg, 1)
	require.NoError(t, err)

	// We should start with the default config.
	rcvs, err := am.GetReceivers(context.Background())
	require.NoError(t, err)
	require.Equal(t, "empty-receiver", *rcvs[0].Name)
}

func genSilence(createdBy string) apimodels.PostableSilence {
	starts := strfmt.DateTime(time.Now().Add(time.Duration(rand.Int63n(9)+1) * time.Second))
	ends := strfmt.DateTime(time.Now().Add(time.Duration(rand.Int63n(9)+10) * time.Second))
	comment := "test comment"
	isEqual := true
	name := "test"
	value := "test"
	isRegex := false
	matchers := amv2.Matchers{&amv2.Matcher{IsEqual: &isEqual, Name: &name, Value: &value, IsRegex: &isRegex}}

	return apimodels.PostableSilence{
		Silence: amv2.Silence{
			Comment:   &comment,
			CreatedBy: &createdBy,
			Matchers:  matchers,
			StartsAt:  &starts,
			EndsAt:    &ends,
		},
	}
}

func genAlert(active bool, labels map[string]string) amv2.PostableAlert {
	endsAt := time.Now()
	if active {
		endsAt = time.Now().Add(1 * time.Minute)
	}

	return amv2.PostableAlert{
		Annotations: map[string]string{"test_annotation": "test_annotation_value"},
		StartsAt:    strfmt.DateTime(time.Now()),
		EndsAt:      strfmt.DateTime(endsAt),
		Alert: amv2.Alert{
			GeneratorURL: "http://localhost:8080",
			Labels:       labels,
		},
	}
}