/*
Copyright 2020 VMware, Inc.
SPDX-License-Identifier: Apache-2.0
*/

package credentialrequest

import (
	"context"
	"crypto/x509/pkix"
	"errors"
	"fmt"
	"testing"
	"time"

	"github.com/golang/mock/gomock"
	"github.com/sclevine/spec"
	"github.com/stretchr/testify/require"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apiserver/pkg/authentication/authenticator"
	"k8s.io/apiserver/pkg/authentication/user"
	genericapirequest "k8s.io/apiserver/pkg/endpoints/request"
	"k8s.io/apiserver/pkg/registry/rest"
	"k8s.io/klog/v2"

	"github.com/suzerain-io/placeholder-name/internal/mocks/mockcertissuer"
	"github.com/suzerain-io/placeholder-name/internal/testutil"
	placeholderapi "github.com/suzerain-io/placeholder-name/kubernetes/1.19/api/apis/placeholder"
)

type contextKey struct{}

type FakeToken struct {
	calledWithToken                       string
	calledWithContext                     context.Context
	timeout                               time.Duration
	reachedTimeout                        bool
	cancelled                             bool
	webhookStartedRunningNotificationChan chan bool
	returnResponse                        *authenticator.Response
	returnUnauthenticated                 bool
	returnErr                             error
}

func (f *FakeToken) AuthenticateToken(ctx context.Context, token string) (*authenticator.Response, bool, error) {
	f.calledWithToken = token
	f.calledWithContext = ctx
	if f.webhookStartedRunningNotificationChan != nil {
		f.webhookStartedRunningNotificationChan <- true
	}
	afterCh := time.After(f.timeout)
	select {
	case <-afterCh:
		f.reachedTimeout = true
	case <-ctx.Done():
		f.cancelled = true
	}
	return f.returnResponse, !f.returnUnauthenticated, f.returnErr
}

func TestCreate(t *testing.T) {
	spec.Run(t, "create", func(t *testing.T, when spec.G, it spec.S) {
		var r *require.Assertions
		var ctrl *gomock.Controller
		var logger *testutil.TranscriptLogger

		it.Before(func() {
			r = require.New(t)
			ctrl = gomock.NewController(t)
			logger = testutil.NewTranscriptLogger(t)
			klog.SetLogger(logger) // this is unfortunately a global logger, so can't run these tests in parallel :(
		})

		it.After(func() {
			klog.SetLogger(nil)
			ctrl.Finish()
		})

		it("CreateSucceedsWhenGivenATokenAndTheWebhookAuthenticatesTheToken", func() {
			webhook := FakeToken{
				returnResponse: &authenticator.Response{
					User: &user.DefaultInfo{
						Name:   "test-user",
						UID:    "test-user-uid",
						Groups: []string{"test-group-1", "test-group-2"},
					},
				},
				returnUnauthenticated: false,
			}

			issuer := mockcertissuer.NewMockCertIssuer(ctrl)
			issuer.EXPECT().IssuePEM(
				pkix.Name{
					CommonName:   "test-user",
					Organization: []string{"test-group-1", "test-group-2"}},
				[]string{},
				1*time.Hour,
			).Return([]byte("test-cert"), []byte("test-key"), nil)

			storage := NewREST(&webhook, issuer)
			requestToken := "a token"

			response, err := callCreate(context.Background(), storage, validCredentialRequestWithToken(requestToken))

			r.NoError(err)
			r.IsType(&placeholderapi.CredentialRequest{}, response)

			expires := response.(*placeholderapi.CredentialRequest).Status.Credential.ExpirationTimestamp
			r.NotNil(expires)
			r.InDelta(time.Now().Add(1*time.Hour).Unix(), expires.Unix(), 5)
			response.(*placeholderapi.CredentialRequest).Status.Credential.ExpirationTimestamp = metav1.Time{}

			r.Equal(response, &placeholderapi.CredentialRequest{
				Status: placeholderapi.CredentialRequestStatus{
					Credential: &placeholderapi.CredentialRequestCredential{
						ExpirationTimestamp:   metav1.Time{},
						ClientCertificateData: "test-cert",
						ClientKeyData:         "test-key",
					},
				},
			})
			r.Equal(requestToken, webhook.calledWithToken)
			requireOneLogStatement(r, logger, `"success" userID:test-user-uid,idpAuthenticated:true`)
		})

		it("CreateFailsWithValidTokenWhenCertIssuerFails", func() {
			webhook := FakeToken{
				returnResponse: &authenticator.Response{
					User: &user.DefaultInfo{
						Name:   "test-user",
						Groups: []string{"test-group-1", "test-group-2"},
					},
				},
				returnUnauthenticated: false,
			}

			issuer := mockcertissuer.NewMockCertIssuer(ctrl)
			issuer.EXPECT().
				IssuePEM(gomock.Any(), gomock.Any(), gomock.Any()).
				Return(nil, nil, fmt.Errorf("some certificate authority error"))

			storage := NewREST(&webhook, issuer)
			requestToken := "a token"

			response, err := callCreate(context.Background(), storage, validCredentialRequestWithToken(requestToken))
			requireSuccessfulResponseWithAuthenticationFailureMessage(t, err, response)
			r.Equal(requestToken, webhook.calledWithToken)
			requireOneLogStatement(r, logger, `"failure" failureType:cert issuer,msg:some certificate authority error`)
		})

		it("CreateSucceedsWithAnUnauthenticatedStatusWhenGivenATokenAndTheWebhookReturnsUnauthenticatedWithUserId", func() {
			webhook := FakeToken{
				returnResponse: &authenticator.Response{
					User: &user.DefaultInfo{UID: "test-user-uid"},
				},
				returnUnauthenticated: true,
			}
			storage := NewREST(&webhook, nil)
			requestToken := "a token"

			response, err := callCreate(context.Background(), storage, validCredentialRequestWithToken(requestToken))

			requireSuccessfulResponseWithAuthenticationFailureMessage(t, err, response)
			r.Equal(requestToken, webhook.calledWithToken)
			requireOneLogStatement(r, logger, `"success" userID:test-user-uid,idpAuthenticated:false,placeholderNameAuthenticated:false`)
		})

		it("CreateSucceedsWithAnUnauthenticatedStatusWhenGivenATokenAndTheWebhookReturnsUnauthenticatedWithNilUser", func() {
			webhook := FakeToken{
				returnResponse:        &authenticator.Response{User: nil},
				returnUnauthenticated: true,
			}
			storage := NewREST(&webhook, nil)
			requestToken := "a token"

			response, err := callCreate(context.Background(), storage, validCredentialRequestWithToken(requestToken))

			requireSuccessfulResponseWithAuthenticationFailureMessage(t, err, response)
			r.Equal(requestToken, webhook.calledWithToken)
			requireOneLogStatement(r, logger, `"success" userID:<none>,idpAuthenticated:false,placeholderNameAuthenticated:false`)
		})

		it("CreateSucceedsWithAnUnauthenticatedStatusWhenWebhookFails", func() {
			webhook := FakeToken{
				returnErr: errors.New("some webhook error"),
			}
			storage := NewREST(&webhook, nil)

			response, err := callCreate(context.Background(), storage, validCredentialRequest())

			requireSuccessfulResponseWithAuthenticationFailureMessage(t, err, response)
			requireOneLogStatement(r, logger, `"failure" failureType:webhook authentication,msg:some webhook error`)
		})

		it("CreateSucceedsWithAnUnauthenticatedStatusWhenWebhookDoesNotReturnAnyUserInfo", func() {
			webhook := FakeToken{
				returnResponse:        &authenticator.Response{},
				returnUnauthenticated: false,
			}
			storage := NewREST(&webhook, nil)

			response, err := callCreate(context.Background(), storage, validCredentialRequest())

			requireSuccessfulResponseWithAuthenticationFailureMessage(t, err, response)
			requireOneLogStatement(r, logger, `"success" userID:<none>,idpAuthenticated:true,placeholderNameAuthenticated:false`)
		})

		it("CreateSucceedsWithAnUnauthenticatedStatusWhenWebhookReturnsAnEmptyUsername", func() {
			webhook := FakeToken{
				returnResponse: &authenticator.Response{
					User: &user.DefaultInfo{
						Name: "",
					},
				},
			}
			storage := NewREST(&webhook, nil)

			response, err := callCreate(context.Background(), storage, validCredentialRequest())

			requireSuccessfulResponseWithAuthenticationFailureMessage(t, err, response)
			requireOneLogStatement(r, logger, `"success" userID:,idpAuthenticated:true,placeholderNameAuthenticated:false`)
		})

		it("CreateDoesNotPassAdditionalContextInfoToTheWebhook", func() {
			webhook := FakeToken{
				returnResponse: webhookSuccessResponse(),
			}
			storage := NewREST(&webhook, successfulIssuer(ctrl))
			ctx := context.WithValue(context.Background(), contextKey{}, "context-value")

			_, err := callCreate(ctx, storage, validCredentialRequest())

			r.NoError(err)
			r.Nil(webhook.calledWithContext.Value("context-key"))
		})

		it("CreateFailsWhenGivenTheWrongInputType", func() {
			notACredentialRequest := runtime.Unknown{}
			response, err := NewREST(&FakeToken{}, nil).Create(
				genericapirequest.NewContext(),
				&notACredentialRequest,
				rest.ValidateAllObjectFunc,
				&metav1.CreateOptions{})

			requireAPIError(t, response, err, apierrors.IsBadRequest, "not a CredentialRequest")
			requireOneLogStatement(r, logger, `"failure" failureType:request validation,msg:not a CredentialRequest`)
		})

		it("CreateFailsWhenTokenIsNilInRequest", func() {
			storage := NewREST(&FakeToken{}, nil)
			response, err := callCreate(context.Background(), storage, credentialRequest(placeholderapi.CredentialRequestSpec{
				Type:  placeholderapi.TokenCredentialType,
				Token: nil,
			}))

			requireAPIError(t, response, err, apierrors.IsInvalid,
				`.placeholder.suzerain-io.github.io "request name" is invalid: spec.token.value: Required value: token must be supplied`)
			requireOneLogStatement(r, logger, `"failure" failureType:request validation,msg:token must be supplied`)
		})

		it("CreateFailsWhenTypeInRequestIsMissing", func() {
			storage := NewREST(&FakeToken{}, nil)
			response, err := callCreate(context.Background(), storage, credentialRequest(placeholderapi.CredentialRequestSpec{
				Type:  "",
				Token: &placeholderapi.CredentialRequestTokenCredential{Value: "a token"},
			}))

			requireAPIError(t, response, err, apierrors.IsInvalid,
				`.placeholder.suzerain-io.github.io "request name" is invalid: spec.type: Required value: type must be supplied`)
			requireOneLogStatement(r, logger, `"failure" failureType:request validation,msg:type must be supplied`)
		})

		it("CreateFailsWhenTypeInRequestIsNotLegal", func() {
			storage := NewREST(&FakeToken{}, nil)
			response, err := callCreate(context.Background(), storage, credentialRequest(placeholderapi.CredentialRequestSpec{
				Type:  "this in an invalid type",
				Token: &placeholderapi.CredentialRequestTokenCredential{Value: "a token"},
			}))

			requireAPIError(t, response, err, apierrors.IsInvalid,
				`.placeholder.suzerain-io.github.io "request name" is invalid: spec.type: Invalid value: "this in an invalid type": unrecognized type`)
			requireOneLogStatement(r, logger, `"failure" failureType:request validation,msg:unrecognized type`)
		})

		it("CreateFailsWhenTokenValueIsEmptyInRequest", func() {
			storage := NewREST(&FakeToken{}, nil)
			response, err := callCreate(context.Background(), storage, credentialRequest(placeholderapi.CredentialRequestSpec{
				Type:  placeholderapi.TokenCredentialType,
				Token: &placeholderapi.CredentialRequestTokenCredential{Value: ""},
			}))

			requireAPIError(t, response, err, apierrors.IsInvalid,
				`.placeholder.suzerain-io.github.io "request name" is invalid: spec.token.value: Required value: token must be supplied`)
			requireOneLogStatement(r, logger, `"failure" failureType:request validation,msg:token must be supplied`)
		})

		it("CreateFailsWhenValidationFails", func() {
			storage := NewREST(&FakeToken{}, nil)
			response, err := storage.Create(
				context.Background(),
				validCredentialRequest(),
				func(ctx context.Context, obj runtime.Object) error {
					return fmt.Errorf("some validation error")
				},
				&metav1.CreateOptions{})
			r.Nil(response)
			r.EqualError(err, "some validation error")
			requireOneLogStatement(r, logger, `"failure" failureType:validation webhook,msg:some validation error`)
		})

		it("CreateDoesNotAllowValidationFunctionToMutateRequest", func() {
			webhook := FakeToken{
				returnResponse: webhookSuccessResponse(),
			}
			storage := NewREST(&webhook, successfulIssuer(ctrl))
			requestToken := "a token"
			response, err := storage.Create(
				context.Background(),
				validCredentialRequestWithToken(requestToken),
				func(ctx context.Context, obj runtime.Object) error {
					credentialRequest, _ := obj.(*placeholderapi.CredentialRequest)
					credentialRequest.Spec.Token.Value = "foobaz"
					return nil
				},
				&metav1.CreateOptions{})
			r.NoError(err)
			r.NotEmpty(response)
			r.Equal(requestToken, webhook.calledWithToken) // i.e. not called with foobaz
		})

		it("CreateDoesNotAllowValidationFunctionToSeeTheActualRequestToken", func() {
			webhook := FakeToken{
				returnResponse: webhookSuccessResponse(),
			}

			storage := NewREST(&webhook, successfulIssuer(ctrl))
			validationFunctionWasCalled := false
			var validationFunctionSawTokenValue string
			response, err := storage.Create(
				context.Background(),
				validCredentialRequest(),
				func(ctx context.Context, obj runtime.Object) error {
					credentialRequest, _ := obj.(*placeholderapi.CredentialRequest)
					validationFunctionWasCalled = true
					validationFunctionSawTokenValue = credentialRequest.Spec.Token.Value
					return nil
				},
				&metav1.CreateOptions{})
			r.NoError(err)
			r.NotEmpty(response)
			r.True(validationFunctionWasCalled)
			r.Empty(validationFunctionSawTokenValue)
		})

		it("CreateFailsWhenRequestOptionsDryRunIsNotEmpty", func() {
			response, err := NewREST(&FakeToken{}, nil).Create(
				genericapirequest.NewContext(),
				validCredentialRequest(),
				rest.ValidateAllObjectFunc,
				&metav1.CreateOptions{
					DryRun: []string{"some dry run flag"},
				})

			requireAPIError(t, response, err, apierrors.IsInvalid,
				`.placeholder.suzerain-io.github.io "request name" is invalid: dryRun: Unsupported value: []string{"some dry run flag"}`)
			requireOneLogStatement(r, logger, `"failure" failureType:request validation,msg:dryRun not supported`)
		})

		it("CreateCancelsTheWebhookInvocationWhenTheCallToCreateIsCancelledItself", func() {
			webhookStartedRunningNotificationChan := make(chan bool)
			webhook := FakeToken{
				timeout:                               time.Second * 2,
				webhookStartedRunningNotificationChan: webhookStartedRunningNotificationChan,
				returnResponse:                        webhookSuccessResponse(),
			}
			storage := NewREST(&webhook, successfulIssuer(ctrl))
			ctx, cancel := context.WithCancel(context.Background())

			c := make(chan bool)
			go func() {
				_, err := callCreate(ctx, storage, validCredentialRequest())
				c <- true
				r.NoError(err)
			}()

			r.False(webhook.cancelled)
			r.False(webhook.reachedTimeout)
			<-webhookStartedRunningNotificationChan // wait long enough to make sure that the webhook has started
			cancel()                                // cancel the context that was passed to storage.Create() above
			<-c                                     // wait for the above call to storage.Create() to be finished
			r.True(webhook.cancelled)
			r.False(webhook.reachedTimeout)
			r.Equal(context.Canceled, webhook.calledWithContext.Err()) // the inner context is cancelled
		})

		it("CreateAllowsTheWebhookInvocationToFinishWhenTheCallToCreateIsNotCancelledItself", func() {
			webhookStartedRunningNotificationChan := make(chan bool)
			webhook := FakeToken{
				timeout:                               0,
				webhookStartedRunningNotificationChan: webhookStartedRunningNotificationChan,
				returnResponse:                        webhookSuccessResponse(),
			}
			storage := NewREST(&webhook, successfulIssuer(ctrl))
			ctx, cancel := context.WithCancel(context.Background())
			defer cancel()

			c := make(chan bool)
			go func() {
				_, err := callCreate(ctx, storage, validCredentialRequest())
				c <- true
				r.NoError(err)
			}()

			r.False(webhook.cancelled)
			r.False(webhook.reachedTimeout)
			<-webhookStartedRunningNotificationChan // wait long enough to make sure that the webhook has started
			<-c                                     // wait for the above call to storage.Create() to be finished
			r.False(webhook.cancelled)
			r.True(webhook.reachedTimeout)
			r.Equal(context.Canceled, webhook.calledWithContext.Err()) // the inner context is cancelled (in this case by the "defer")
		})
	}, spec.Sequential())
}

func requireOneLogStatement(r *require.Assertions, logger *testutil.TranscriptLogger, messageContains string) {
	r.Len(logger.Transcript, 1)
	r.Equal("info", logger.Transcript[0].Level)
	r.Contains(logger.Transcript[0].Message, messageContains)
}

func callCreate(ctx context.Context, storage *REST, credentialRequest *placeholderapi.CredentialRequest) (runtime.Object, error) {
	return storage.Create(
		ctx,
		credentialRequest,
		rest.ValidateAllObjectFunc,
		&metav1.CreateOptions{
			DryRun: []string{},
		})
}

func validCredentialRequest() *placeholderapi.CredentialRequest {
	return validCredentialRequestWithToken("some token")
}

func validCredentialRequestWithToken(token string) *placeholderapi.CredentialRequest {
	return credentialRequest(placeholderapi.CredentialRequestSpec{
		Type:  placeholderapi.TokenCredentialType,
		Token: &placeholderapi.CredentialRequestTokenCredential{Value: token},
	})
}

func credentialRequest(spec placeholderapi.CredentialRequestSpec) *placeholderapi.CredentialRequest {
	return &placeholderapi.CredentialRequest{
		TypeMeta: metav1.TypeMeta{},
		ObjectMeta: metav1.ObjectMeta{
			Name: "request name",
		},
		Spec: spec,
	}
}

func webhookSuccessResponse() *authenticator.Response {
	return &authenticator.Response{User: &user.DefaultInfo{
		Name:   "some-user",
		UID:    "",
		Groups: []string{},
		Extra:  nil,
	}}
}

func requireAPIError(t *testing.T, response runtime.Object, err error, expectedErrorTypeChecker func(err error) bool, expectedErrorMessage string) {
	t.Helper()
	require.Nil(t, response)
	require.True(t, expectedErrorTypeChecker(err))
	var status apierrors.APIStatus
	errors.As(err, &status)
	require.Contains(t, status.Status().Message, expectedErrorMessage)
}

func requireSuccessfulResponseWithAuthenticationFailureMessage(t *testing.T, err error, response runtime.Object) {
	t.Helper()
	require.NoError(t, err)
	require.Equal(t, response, &placeholderapi.CredentialRequest{
		Status: placeholderapi.CredentialRequestStatus{
			Credential: nil,
			Message:    stringPtr("authentication failed"),
		},
	})
}

func successfulIssuer(ctrl *gomock.Controller) CertIssuer {
	issuer := mockcertissuer.NewMockCertIssuer(ctrl)
	issuer.EXPECT().
		IssuePEM(gomock.Any(), gomock.Any(), gomock.Any()).
		Return([]byte("test-cert"), []byte("test-key"), nil)
	return issuer
}

func stringPtr(s string) *string {
	return &s
}