// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0

// Package cloudformation provides functionality to deploy CLI concepts with AWS CloudFormation.
package cloudformation

import (
	"context"
	"errors"
	"fmt"
	"io"
	"os"
	"os/signal"
	"strings"
	"syscall"
	"time"

	"github.com/aws/copilot-cli/internal/pkg/aws/ecr"
	"github.com/aws/copilot-cli/internal/pkg/deploy/cloudformation/stack"

	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/session"
	sdkcloudformation "github.com/aws/aws-sdk-go/service/cloudformation"
	"github.com/aws/copilot-cli/internal/pkg/aws/cloudformation"
	"github.com/aws/copilot-cli/internal/pkg/aws/cloudformation/stackset"
	"github.com/aws/copilot-cli/internal/pkg/aws/cloudwatch"
	"github.com/aws/copilot-cli/internal/pkg/aws/codepipeline"
	"github.com/aws/copilot-cli/internal/pkg/aws/codestar"
	"github.com/aws/copilot-cli/internal/pkg/aws/ecs"
	"github.com/aws/copilot-cli/internal/pkg/aws/s3"
	"github.com/aws/copilot-cli/internal/pkg/deploy"
	"github.com/aws/copilot-cli/internal/pkg/stream"
	"github.com/aws/copilot-cli/internal/pkg/term/color"
	"github.com/aws/copilot-cli/internal/pkg/term/log"
	"github.com/aws/copilot-cli/internal/pkg/term/progress"
	"golang.org/x/sync/errgroup"
)

const (
	// waitForStackTimeout is how long we're willing to wait for a stack to go from in progress to a complete state.
	waitForStackTimeout = 1*time.Hour + 30*time.Minute

	// CloudFormation resource types.
	ecsServiceResourceType    = "AWS::ECS::Service"
	envControllerResourceType = "Custom::EnvControllerFunction"
)

// CloudFormation's error types to compare against.
var (
	errNotFound *cloudformation.ErrStackNotFound
)

// StackConfiguration represents the set of methods needed to deploy a cloudformation stack.
type StackConfiguration interface {
	StackName() string
	Template() (string, error)
	Parameters() ([]*sdkcloudformation.Parameter, error)
	Tags() []*sdkcloudformation.Tag
	SerializedParameters() (string, error)
}

// An Overrider transforms the content in body to out.
type Overrider interface {
	Override(body []byte) (out []byte, err error)
}

// overridableStack is a StackConfiguration with overrides applied.
type overridableStack struct {
	StackConfiguration
	overrider Overrider
}

// Template returns the overriden CloudFormation stack template.
func (s *overridableStack) Template() (string, error) {
	tpl, err := s.StackConfiguration.Template()
	if err != nil {
		return "", fmt.Errorf("generate stack template: %w", err)
	}
	out, err := s.overrider.Override([]byte(tpl))
	if err != nil {
		return "", fmt.Errorf("override template: %w", err)
	}
	return string(out), nil
}

// WrapWithTemplateOverrider returns a wrapped stack, such that Template calls returns an overriden stack template.
func WrapWithTemplateOverrider(stack StackConfiguration, overrider Overrider) StackConfiguration {
	return &overridableStack{
		StackConfiguration: stack,
		overrider:          overrider,
	}
}

type ecsClient interface {
	stream.ECSServiceDescriber
}

type cwClient interface {
	stream.CloudWatchDescriber
}

type cfnClient interface {
	// Methods augmented by the aws wrapper struct.
	Create(*cloudformation.Stack) (string, error)
	CreateAndWait(*cloudformation.Stack) error
	WaitForCreate(ctx context.Context, stackName string) error
	Update(*cloudformation.Stack) (string, error)
	UpdateAndWait(*cloudformation.Stack) error
	WaitForUpdate(ctx context.Context, stackName string) error
	Delete(stackName string) error
	DeleteAndWait(stackName string) error
	DeleteAndWaitWithRoleARN(stackName, roleARN string) error
	Describe(stackName string) (*cloudformation.StackDescription, error)
	DescribeChangeSet(changeSetID, stackName string) (*cloudformation.ChangeSetDescription, error)
	TemplateBody(stackName string) (string, error)
	TemplateBodyFromChangeSet(changeSetID, stackName string) (string, error)
	Events(stackName string) ([]cloudformation.StackEvent, error)
	ListStacksWithTags(tags map[string]string) ([]cloudformation.StackDescription, error)
	ErrorEvents(stackName string) ([]cloudformation.StackEvent, error)
	Outputs(stack *cloudformation.Stack) (map[string]string, error)
	StackResources(name string) ([]*cloudformation.StackResource, error)
	Metadata(opts cloudformation.MetadataOpts) (string, error)
	CancelUpdateStack(stackName string) error

	// Methods vended by the aws sdk struct.
	DescribeStackEvents(*sdkcloudformation.DescribeStackEventsInput) (*sdkcloudformation.DescribeStackEventsOutput, error)
}

type codeStarClient interface {
	WaitUntilConnectionStatusAvailable(ctx context.Context, connectionARN string) error
}

type codePipelineClient interface {
	RetryStageExecution(pipelineName, stageName string) error
}

type s3Client interface {
	Upload(bucket, fileName string, data io.Reader) (string, error)
	EmptyBucket(bucket string) error
}

type imageRemover interface {
	ClearRepository(repoName string) error
}

type stackSetClient interface {
	Create(name, template string, opts ...stackset.CreateOrUpdateOption) error
	CreateInstances(name string, accounts, regions []string) (string, error)
	CreateInstancesAndWait(name string, accounts, regions []string) error
	Update(name, template string, opts ...stackset.CreateOrUpdateOption) (string, error)
	UpdateAndWait(name, template string, opts ...stackset.CreateOrUpdateOption) error
	Describe(name string) (stackset.Description, error)
	DescribeOperation(name, opID string) (stackset.Operation, error)
	InstanceSummaries(name string, opts ...stackset.InstanceSummariesOption) ([]stackset.InstanceSummary, error)
	DeleteInstance(name, account, region string) (string, error)
	DeleteAllInstances(name string) (string, error)
	Delete(name string) error
	WaitForStackSetLastOperationComplete(name string) error
	WaitForOperation(name, opID string) error
}

// OptFn represents an optional configuration function for the CloudFormation client.
type OptFn func(cfn *CloudFormation)

// WithProgressTracker updates the CloudFormation client to write stack updates to a file.
func WithProgressTracker(fw progress.FileWriter) OptFn {
	return func(cfn *CloudFormation) {
		cfn.console = fw
	}
}

// discardFile represents a fake file where all Writes succeeds and are not written anywhere.
type discardFile struct{}

// Write implements the io.Writer interface and discards p.
func (f *discardFile) Write(p []byte) (n int, err error) { return io.Discard.Write(p) }

// Fd returns stderr as the file descriptor.
// The file descriptor value shouldn't matter as long as it's a valid value as all writes are gone to io.Discard.
func (f *discardFile) Fd() uintptr {
	return os.Stderr.Fd()
}

// CloudFormation wraps the CloudFormationAPI interface
type CloudFormation struct {
	cfnClient         cfnClient
	codeStarClient    codeStarClient
	cpClient          codePipelineClient
	ecsClient         ecsClient
	cwClient          cwClient
	regionalClient    func(region string) cfnClient
	appStackSet       stackSetClient
	s3Client          s3Client
	regionalS3Client  func(region string) s3Client
	regionalECRClient func(region string) imageRemover
	region            string
	console           progress.FileWriter

	// cached variables.
	cachedDeployedStack *cloudformation.StackDescription

	// Overridden in tests.
	renderStackSet               func(input renderStackSetInput) error
	dnsDelegatedAccountsForStack func(stack *sdkcloudformation.Stack) []string
	notifySignals                func() chan os.Signal
}

// New returns a configured CloudFormation client.
func New(sess *session.Session, opts ...OptFn) CloudFormation {
	client := CloudFormation{
		cfnClient:      cloudformation.New(sess),
		codeStarClient: codestar.New(sess),
		cpClient:       codepipeline.New(sess),
		ecsClient:      ecs.New(sess),
		cwClient:       cloudwatch.New(sess),
		regionalClient: func(region string) cfnClient {
			return cloudformation.New(sess.Copy(&aws.Config{
				Region: aws.String(region),
			}))
		},
		regionalECRClient: func(region string) imageRemover {
			return ecr.New(sess.Copy(&aws.Config{
				Region: aws.String(region),
			}))
		},
		appStackSet: stackset.New(sess),
		s3Client:    s3.New(sess),
		regionalS3Client: func(region string) s3Client {
			return s3.New(sess.Copy(&aws.Config{
				Region: aws.String(region),
			}))
		},
		region:  aws.StringValue(sess.Config.Region),
		console: new(discardFile),
	}
	for _, opt := range opts {
		opt(&client)
	}
	client.renderStackSet = client.renderStackSetImpl
	client.dnsDelegatedAccountsForStack = stack.DNSDelegatedAccountsForStack
	client.notifySignals = notifySignals
	return client
}

// Template returns a deployed stack's template.
func (cf CloudFormation) Template(stackName string) (string, error) {
	return cf.cfnClient.TemplateBody(stackName)
}

// IsEmptyErr returns true if the error occurred because the cloudformation resource does not exist or does not contain any sub-resources.
func IsEmptyErr(err error) bool {
	type isEmpty interface {
		IsEmpty() bool
	}

	var emptyErr isEmpty
	return errors.As(err, &emptyErr)
}

// errorEvents returns the list of status reasons of failed resource events
func (cf CloudFormation) errorEvents(stackName string) ([]string, error) {
	events, err := cf.cfnClient.ErrorEvents(stackName)
	if err != nil {
		return nil, err
	}
	var reasons []string
	for _, event := range events {
		// CFN error messages end with a '. (Service' and only the first sentence is useful, the rest is error codes.
		reasons = append(reasons, strings.Split(aws.StringValue(event.ResourceStatusReason), ". (Service")[0])
	}
	return reasons, nil
}

type executeAndRenderChangeSetInput struct {
	stackName        string
	stackDescription string
	createChangeSet  func() (string, error)
	enableInterrupt  bool
}

type executeAndRenderChangeSetOption func(in *executeAndRenderChangeSetInput)

func withEnableInterrupt() executeAndRenderChangeSetOption {
	return func(in *executeAndRenderChangeSetInput) {
		in.enableInterrupt = true
	}
}

func (cf CloudFormation) newCreateChangeSetInput(w progress.FileWriter, stack *cloudformation.Stack) *executeAndRenderChangeSetInput {
	in := &executeAndRenderChangeSetInput{
		stackName:        stack.Name,
		stackDescription: fmt.Sprintf("Creating the infrastructure for stack %s", stack.Name),
	}
	in.createChangeSet = func() (string, error) {
		spinner := progress.NewSpinner(w)
		label := fmt.Sprintf("Proposing infrastructure changes for stack %s", stack.Name)
		spinner.Start(label)

		var errAlreadyExists *cloudformation.ErrStackAlreadyExists
		changeSetID, err := cf.cfnClient.Create(stack)
		if err != nil && !errors.As(err, &errAlreadyExists) {
			spinner.Stop(log.Serrorf("%s\n", label))
			return "", cf.handleStackError(stack.Name, err)
		}
		spinner.Stop(log.Ssuccessf("%s\n", label))
		return changeSetID, err
	}
	return in
}

func (cf CloudFormation) newUpsertChangeSetInput(w progress.FileWriter, stack *cloudformation.Stack, opts ...executeAndRenderChangeSetOption) *executeAndRenderChangeSetInput {
	in := &executeAndRenderChangeSetInput{
		stackName:        stack.Name,
		stackDescription: fmt.Sprintf("Creating the infrastructure for stack %s", stack.Name),
	}
	in.createChangeSet = func() (changeSetID string, err error) {
		spinner := progress.NewSpinner(w)
		label := fmt.Sprintf("Proposing infrastructure changes for stack %s", stack.Name)
		spinner.Start(label)
		changeSetID, err = cf.cfnClient.Create(stack)
		if err == nil {
			// Successfully created the change set to create the stack.
			spinner.Stop(log.Ssuccessf("%s\n", label))
			return changeSetID, nil
		}

		var errAlreadyExists *cloudformation.ErrStackAlreadyExists
		if !errors.As(err, &errAlreadyExists) {
			// Unexpected error trying to create a stack.
			spinner.Stop(log.Serrorf("%s\n", label))
			return "", cf.handleStackError(stack.Name, err)
		}

		// We have to create an update stack change set instead.
		in.stackDescription = fmt.Sprintf("Updating the infrastructure for stack %s", stack.Name)
		changeSetID, err = cf.cfnClient.Update(stack)
		if err != nil {
			msg := log.Serrorf("%s\n", label)
			var errChangeSetEmpty *cloudformation.ErrChangeSetEmpty
			if errors.As(err, &errChangeSetEmpty) {
				msg = fmt.Sprintf("- No new infrastructure changes for stack %s\n", stack.Name)
			}
			spinner.Stop(msg)
			return "", cf.handleStackError(stack.Name, err)
		}
		spinner.Stop(log.Ssuccessf("%s\n", label))
		return changeSetID, nil
	}
	for _, opt := range opts {
		opt(in)
	}
	return in
}

func (cf CloudFormation) executeAndRenderChangeSet(in *executeAndRenderChangeSetInput) error {
	changeSetID, err := in.createChangeSet()
	if err != nil {
		return err
	}
	var sigChannel chan os.Signal
	if in.enableInterrupt {
		sigChannel = cf.notifySignals()
	}
	g, ctx := errgroup.WithContext(context.Background())
	ctx, cancel := context.WithCancel(ctx)
	defer cancel()
	g.Go(func() error {
		defer cancel()
		if err := cf.renderChangeSet(ctx, changeSetID, in); err != nil {
			if !errors.Is(err, context.Canceled) {
				return err
			}
		}
		return nil
	})
	if in.enableInterrupt {
		g.Go(func() error {
			return cf.waitForSignalAndHandleInterrupt(ctx, cancel, sigChannel, in.stackName)
		})
	}
	return g.Wait()
}

func (cf CloudFormation) renderChangeSet(ctx context.Context, changeSetID string, in *executeAndRenderChangeSetInput) error {
	if _, ok := cf.console.(*discardFile); ok { // If we don't have to render skip the additional network calls.
		return nil
	}
	waitCtx, cancelWait := context.WithTimeout(ctx, waitForStackTimeout)
	defer cancelWait()
	g, ctx := errgroup.WithContext(waitCtx)

	renderer, err := cf.createChangeSetRenderer(g, ctx, changeSetID, in.stackName, in.stackDescription, progress.RenderOptions{})
	if err != nil {
		return err
	}
	g.Go(func() error {
		_, err := progress.Render(ctx, progress.NewTabbedFileWriter(cf.console), renderer)
		return err
	})
	if err := g.Wait(); err != nil {
		return err
	}
	if err := cf.errOnFailedStack(in.stackName); err != nil {
		return err
	}
	return nil
}

func (cf CloudFormation) waitForSignalAndHandleInterrupt(ctx context.Context, cancelFn context.CancelFunc, sigCh chan os.Signal, stackName string) error {
	for {
		select {
		case <-sigCh:
			cancelFn()
			stopCatchSignals(sigCh)
			stackDescr, err := cf.cfnClient.Describe(stackName)
			if err != nil {
				return fmt.Errorf("describe stack %s: %w", stackName, err)
			}
			switch aws.StringValue(stackDescr.StackStatus) {
			case sdkcloudformation.StackStatusCreateInProgress:
				log.Infof(`Received Interrupt for Ctrl-C.
Pressing Ctrl-C again will exit immediately but the deletion of stack %s will continue
`, stackName)
				description := fmt.Sprintf("Delete stack %s", stackName)
				if err := cf.deleteAndRenderStack(stackName, description, func() error {
					return cf.cfnClient.DeleteAndWait(stackName)
				}); err != nil {
					return err
				}
				return &ErrStackDeletedOnInterrupt{stackName: stackName}
			case sdkcloudformation.StackStatusUpdateInProgress:
				log.Infof(`Received Interrupt for Ctrl-C.
Pressing Ctrl-C again will exit immediately but stack %s rollback will continue
`, stackName)
				description := fmt.Sprintf("Canceling stack update %s", stackName)
				if err := cf.cancelUpdateAndRender(&cancelUpdateAndRenderInput{
					stackName:   stackName,
					description: description,
					cancelUpdateFn: func() error {
						return cf.cfnClient.CancelUpdateStack(stackName)
					},
				}); err != nil {
					return err
				}
				return &ErrStackUpdateCanceledOnInterrupt{stackName: stackName}
			}
			return nil
		case <-ctx.Done():
			stopCatchSignals(sigCh)
			return nil
		}
	}
}

type cancelUpdateAndRenderInput struct {
	stackName      string
	description    string
	cancelUpdateFn func() error
}

func (cf CloudFormation) cancelUpdateAndRender(in *cancelUpdateAndRenderInput) error {
	stackDescr, err := cf.cfnClient.Describe(in.stackName)
	if err != nil {
		return fmt.Errorf("describe stack %s: %w", in.stackName, err)
	}
	if stackDescr.ChangeSetId == nil {
		return fmt.Errorf("ChangeSetID not found for stack %s", in.stackName)

	}
	ctx, cancel := context.WithTimeout(context.Background(), waitForStackTimeout)
	defer cancel()
	g, ctx := errgroup.WithContext(ctx)
	renderer, err := cf.createChangeSetRenderer(g, ctx, aws.StringValue(stackDescr.ChangeSetId), in.stackName, in.description, progress.RenderOptions{})
	if err != nil {
		return err
	}
	g.Go(in.cancelUpdateFn)
	g.Go(func() error {
		_, err := progress.Render(ctx, progress.NewTabbedFileWriter(cf.console), renderer)
		return err
	})
	if err := g.Wait(); err != nil {
		return err
	}
	return cf.errOnFailedCancelUpdate(in.stackName)
}
func (cf CloudFormation) errOnFailedCancelUpdate(stackName string) error {
	stack, err := cf.cfnClient.Describe(stackName)
	if err != nil {
		return fmt.Errorf("describe stack %s: %w", stackName, err)
	}
	status := aws.StringValue(stack.StackStatus)
	if status != sdkcloudformation.StackStatusUpdateRollbackComplete {
		return fmt.Errorf("stack %s did not rollback successfully and exited with status %s", stackName, status)
	}
	return nil
}

func notifySignals() chan os.Signal {
	sigCh := make(chan os.Signal, 1)
	signal.Notify(sigCh, syscall.SIGINT)
	return sigCh
}

func stopCatchSignals(sigCh chan os.Signal) {
	signal.Stop(sigCh)
	close(sigCh)
}

// ErrStackDeletedOnInterrupt means stack is deleted on interrupt.
type ErrStackDeletedOnInterrupt struct {
	stackName string
}

func (e *ErrStackDeletedOnInterrupt) Error() string {
	return fmt.Sprintf("stack %s was deleted on interrupt signal", e.stackName)
}

// ErrStackUpdateCanceledOnInterrupt means stack update is canceled on interrupt.
type ErrStackUpdateCanceledOnInterrupt struct {
	stackName string
}

func (e *ErrStackUpdateCanceledOnInterrupt) Error() string {
	return fmt.Sprintf("update for stack %s was canceled on interrupt signal", e.stackName)
}

func (cf CloudFormation) createChangeSetRenderer(group *errgroup.Group, ctx context.Context, changeSetID, stackName, description string, opts progress.RenderOptions) (progress.DynamicRenderer, error) {
	changeSet, err := cf.cfnClient.DescribeChangeSet(changeSetID, stackName)
	if err != nil {
		return nil, err
	}
	body, err := cf.cfnClient.TemplateBodyFromChangeSet(changeSetID, stackName)
	if err != nil {
		return nil, err
	}
	descriptions, err := cloudformation.ParseTemplateDescriptions(body)
	if err != nil {
		return nil, fmt.Errorf("parse cloudformation template for resource descriptions: %w", err)
	}

	streamer := stream.NewStackStreamer(cf.cfnClient, stackName, changeSet.CreationTime)
	children, err := cf.changeRenderers(changeRenderersInput{
		g:                  group,
		ctx:                ctx,
		stackName:          stackName,
		stackStreamer:      streamer,
		changes:            changeSet.Changes,
		changeSetTimestamp: changeSet.CreationTime,
		descriptions:       descriptions,
		opts:               progress.NestedRenderOptions(opts),
	})
	if err != nil {
		return nil, err
	}
	renderer := progress.ListeningChangeSetRenderer(streamer, stackName, description, children, opts)
	group.Go(func() error {
		return stream.Stream(ctx, streamer)
	})
	return renderer, nil
}

type changeRenderersInput struct {
	g                  *errgroup.Group             // Group that all goroutines belong.
	ctx                context.Context             // Context associated with the group.
	stackName          string                      // Name of the stack.
	stackStreamer      progress.StackSubscriber    // Streamer for the stack where changes belong.
	changes            []*sdkcloudformation.Change // List of changes that will be applied to the stack.
	changeSetTimestamp time.Time                   // ChangeSet creation time.
	descriptions       map[string]string           // Descriptions for the logical IDs of the changes.
	opts               progress.RenderOptions      // Display options that should be applied to the changes.
}

// changeRenderers filters changes by resources that have a description and returns the appropriate progress.Renderer for each resource type.
func (cf CloudFormation) changeRenderers(in changeRenderersInput) ([]progress.Renderer, error) {
	var resources []progress.Renderer
	for _, change := range in.changes {
		logicalID := aws.StringValue(change.ResourceChange.LogicalResourceId)
		description, ok := in.descriptions[logicalID]
		if !ok {
			continue
		}
		var renderer progress.Renderer
		switch {
		case aws.StringValue(change.ResourceChange.ResourceType) == envControllerResourceType:
			r, err := cf.createEnvControllerRenderer(&envControllerRendererInput{
				g:                 in.g,
				ctx:               in.ctx,
				workloadStackName: in.stackName,
				workloadTimestamp: in.changeSetTimestamp,
				change:            change,
				description:       description,
				serviceStack:      in.stackStreamer,
				renderOpts:        in.opts,
			})
			if err != nil {
				return nil, err
			}
			renderer = r
		case aws.StringValue(change.ResourceChange.ResourceType) == ecsServiceResourceType:
			renderer = progress.ListeningECSServiceResourceRenderer(progress.ECSServiceRendererCfg{
				Streamer:    in.stackStreamer,
				ECSClient:   cf.ecsClient,
				CWClient:    cf.cwClient,
				LogicalID:   logicalID,
				Description: description,
			},
				progress.ECSServiceRendererOpts{
					Group:      in.g,
					Ctx:        in.ctx,
					RenderOpts: in.opts,
				})
		case change.ResourceChange.ChangeSetId != nil:
			// The resource change is a nested stack.
			changeSetID := aws.StringValue(change.ResourceChange.ChangeSetId)
			stackName := parseStackNameFromARN(aws.StringValue(change.ResourceChange.PhysicalResourceId))

			r, err := cf.createChangeSetRenderer(in.g, in.ctx, changeSetID, stackName, description, in.opts)
			if err != nil {
				return nil, err
			}
			renderer = r
		default:
			renderer = progress.ListeningResourceRenderer(in.stackStreamer, logicalID, description, progress.ResourceRendererOpts{
				RenderOpts: in.opts,
			})
		}
		resources = append(resources, renderer)
	}
	return resources, nil
}

type envControllerRendererInput struct {
	g                 *errgroup.Group
	ctx               context.Context
	workloadStackName string
	workloadTimestamp time.Time
	change            *sdkcloudformation.Change
	description       string
	serviceStack      progress.StackSubscriber
	renderOpts        progress.RenderOptions
}

func (cf CloudFormation) createEnvControllerRenderer(in *envControllerRendererInput) (progress.DynamicRenderer, error) {
	workload, err := cf.cfnClient.Describe(in.workloadStackName)
	if err != nil {
		return nil, err
	}
	envStackName := fmt.Sprintf("%s-%s", parseAppNameFromTags(workload.Tags), parseEnvNameFromTags(workload.Tags))
	body, err := cf.cfnClient.TemplateBody(envStackName)
	if err != nil {
		return nil, err
	}
	envResourceDescriptions, err := cloudformation.ParseTemplateDescriptions(body)
	if err != nil {
		return nil, fmt.Errorf("parse cloudformation template for resource descriptions: %w", err)
	}
	envStreamer := stream.NewStackStreamer(cf.cfnClient, envStackName, in.workloadTimestamp)
	ctx, cancel := context.WithCancel(in.ctx)
	in.g.Go(func() error {
		if err := stream.Stream(ctx, envStreamer); err != nil {
			if errors.Is(err, context.Canceled) {
				// The stack streamer was canceled on purposed, do not return an error.
				// This occurs if we detect that the environment stack has no updates.
				return nil
			}
			return err
		}
		return nil
	})
	return progress.ListeningEnvControllerRenderer(progress.EnvControllerConfig{
		Description:     in.description,
		RenderOpts:      in.renderOpts,
		ActionStreamer:  in.serviceStack,
		ActionLogicalID: aws.StringValue(in.change.ResourceChange.LogicalResourceId),
		EnvStreamer:     envStreamer,
		CancelEnvStream: cancel,
		EnvStackName:    envStackName,
		EnvResources:    envResourceDescriptions,
	}), nil
}

type renderStackInput struct {
	group *errgroup.Group // Group of go routines.

	// Stack metadata.
	stackName      string            // Name of the stack.
	stackID        string            // ID of the stack.
	description    string            // Descriptive text for the stack mutation.
	descriptionFor map[string]string // Descriptive text for each resource in the stack.
	startTime      time.Time         // Timestamp for when the stack mutation started.
}

func (cf CloudFormation) stackRenderer(ctx context.Context, in renderStackInput) progress.DynamicRenderer {
	streamer := stream.NewStackStreamer(cf.cfnClient, in.stackID, in.startTime)
	renderer := progress.ListeningStackRenderer(streamer, in.stackName, in.description, in.descriptionFor, progress.RenderOptions{})
	in.group.Go(func() error {
		return stream.Stream(ctx, streamer)
	})
	return renderer
}

func (cf CloudFormation) deleteAndRenderStack(name, description string, deleteFn func() error) error {
	body, err := cf.cfnClient.TemplateBody(name)
	if err != nil {
		if !errors.As(err, &errNotFound) {
			return fmt.Errorf("get template body of stack %q: %w", name, err)
		}
		return nil // stack already deleted.
	}
	descriptionFor, err := cloudformation.ParseTemplateDescriptions(body)
	if err != nil {
		return fmt.Errorf("parse resource descriptions in template of stack %q: %w", name, err)
	}

	stack, err := cf.cfnClient.Describe(name)
	if err != nil {
		if !errors.As(err, &errNotFound) {
			return fmt.Errorf("retrieve the stack ID for stack %q: %w", name, err)
		}
		return nil // stack already deleted.
	}

	waitCtx, cancelWait := context.WithTimeout(context.Background(), waitForStackTimeout)
	defer cancelWait()
	g, ctx := errgroup.WithContext(waitCtx)
	now := time.Now()
	g.Go(deleteFn)
	renderer := cf.stackRenderer(ctx, renderStackInput{
		group:          g,
		stackID:        aws.StringValue(stack.StackId),
		stackName:      name,
		description:    description,
		descriptionFor: descriptionFor,
		startTime:      now,
	})
	g.Go(func() error {
		w := progress.NewTabbedFileWriter(cf.console)
		nl, err := progress.Render(ctx, w, renderer)
		if err != nil {
			return fmt.Errorf("render stack %q progress: %w", name, err)
		}
		_, err = progress.EraseAndRender(w, progress.LineRenderer(log.Ssuccess(description), 0), nl)
		if err != nil {
			return fmt.Errorf("erase and render stack %q progress: %w", name, err)
		}
		return nil
	})
	if err := g.Wait(); err != nil {
		if !errors.As(err, &errNotFound) {
			return err
		}
	}
	return nil
}

type errFailedService struct {
	stackName    string
	resourceType string
	status       string
}

func (e *errFailedService) RecommendActions() string {
	if e.resourceType == "AWS::AppRunner::Service" {
		return fmt.Sprintf("You may fix the error by updating the service code or the manifest configuration.\n"+
			"You can then retry deploying your service by running %s.", color.HighlightCode("copilot svc deploy"))
	}
	return ""
}
func (e *errFailedService) Error() string {
	return fmt.Sprintf("stack %s did not complete successfully and exited with status %s", e.stackName, e.status)
}

func (cf CloudFormation) errOnFailedStack(stackName string) error {
	stack, err := cf.cfnClient.Describe(stackName)
	if err != nil {
		return err
	}
	status := aws.StringValue(stack.StackStatus)
	if cloudformation.StackStatus(status).IsFailure() {
		events, _ := cf.cfnClient.ErrorEvents(stackName)
		var failedResourceType string
		if len(events) > 0 {
			failedResourceType = aws.StringValue(events[0].ResourceType)
		}
		return &errFailedService{
			stackName:    stackName,
			resourceType: failedResourceType,
			status:       status,
		}
	}
	return nil
}

func toStack(config StackConfiguration) (*cloudformation.Stack, error) {
	template, err := config.Template()
	if err != nil {
		return nil, err
	}
	stack := cloudformation.NewStack(config.StackName(), template)
	stack.Parameters, err = config.Parameters()
	if err != nil {
		return nil, err
	}
	stack.Tags = config.Tags()
	return stack, nil
}

func toStackFromS3(config StackConfiguration, s3url string) (*cloudformation.Stack, error) {
	stack := cloudformation.NewStackWithURL(config.StackName(), s3url)
	var err error
	stack.Parameters, err = config.Parameters()
	if err != nil {
		return nil, err
	}
	stack.Tags = config.Tags()
	return stack, nil
}

func toMap(tags []*sdkcloudformation.Tag) map[string]string {
	m := make(map[string]string)
	for _, t := range tags {
		m[aws.StringValue(t.Key)] = aws.StringValue(t.Value)
	}
	return m
}

// parseStackNameFromARN retrieves "my-nested-stack" from an input like:
// arn:aws:cloudformation:us-west-2:123456789012:stack/my-nested-stack/d0a825a0-e4cd-xmpl-b9fb-061c69e99205
func parseStackNameFromARN(stackARN string) string {
	return strings.Split(stackARN, "/")[1]
}

func parseAppNameFromTags(tags []*sdkcloudformation.Tag) string {
	for _, t := range tags {
		if aws.StringValue(t.Key) == deploy.AppTagKey {
			return aws.StringValue(t.Value)
		}
	}
	return ""
}

func parseEnvNameFromTags(tags []*sdkcloudformation.Tag) string {
	for _, t := range tags {
		if aws.StringValue(t.Key) == deploy.EnvTagKey {
			return aws.StringValue(t.Value)
		}
	}
	return ""
}

func stopSpinner(spinner *progress.Spinner, err error, label string) {
	if err == nil {
		spinner.Stop(log.Ssuccessf("%s\n", label))
		return
	}
	var existsErr *cloudformation.ErrStackAlreadyExists
	if errors.As(err, &existsErr) {
		spinner.Stop(log.Ssuccessf("%s\n", label))
		return
	}
	spinner.Stop(log.Serrorf("%s\n", label))
}