import * as ec2 from 'aws-cdk-lib/aws-ec2';
import * as ecs from 'aws-cdk-lib/aws-ecs';
import * as elbv2 from 'aws-cdk-lib/aws-elasticloadbalancingv2';
import * as iam from 'aws-cdk-lib/aws-iam';
import * as logs from 'aws-cdk-lib/aws-logs';
import * as route53 from 'aws-cdk-lib/aws-route53';
import * as route53Targets from 'aws-cdk-lib/aws-route53-targets';
import * as secretsmanager from 'aws-cdk-lib/aws-secretsmanager';
import * as cdk from 'aws-cdk-lib/core';
import { Construct } from 'constructs';

/**
 * Container definition for the service
 */
export interface ContainerConfig {
  /** Docker image URI (e.g., nexus.kodeniks.com/docker-hosted/my-app:latest) */
  image: string;

  /** Container port */
  port: number;

  /** CPU units (256 = 0.25 vCPU) */
  cpu?: number;

  /** Memory in MiB */
  memory?: number;

  /** Memory reservation (soft limit) in MiB */
  memoryReservation?: number;

  /** Environment variables */
  environment?: Record<string, string>;

  /** Secrets from Secrets Manager (key = env var name, value = secret ARN or ARN:key) */
  secrets?: Record<string, string>;

  /** Health check command */
  healthCheck?: {
    command: string[];
    interval?: number;
    timeout?: number;
    retries?: number;
    startPeriod?: number;
  };

  /** Container command override */
  command?: string[];

  /** Entry point override */
  entryPoint?: string[];
}

/**
 * Capacity provider strategy for mixed EC2/Fargate deployments
 */
export interface CapacityProviderStrategyItem {
  /** Capacity provider name (e.g., 'FARGATE', 'FARGATE_SPOT', or EC2 provider name) */
  capacityProvider: string;

  /** Base count - minimum tasks on this provider */
  base?: number;

  /** Weight for distributing tasks above base */
  weight: number;
}

/**
 * Auto-scaling configuration
 */
export interface ServiceScalingConfig {
  /** Minimum number of tasks */
  minCapacity: number;

  /** Maximum number of tasks */
  maxCapacity: number;

  /** Target CPU utilization percentage (0-100) */
  targetCpuUtilization?: number;

  /** Target memory utilization percentage (0-100) */
  targetMemoryUtilization?: number;

  /** Target requests per task per minute */
  targetRequestsPerTarget?: number;

  /** Scale-in cooldown in seconds */
  scaleInCooldown?: number;

  /** Scale-out cooldown in seconds */
  scaleOutCooldown?: number;
}

/**
 * Health check configuration for ALB target group
 */
export interface HealthCheckConfig {
  /** Health check path */
  path: string;

  /** Health check interval in seconds */
  interval?: number;

  /** Health check timeout in seconds */
  timeout?: number;

  /** Healthy threshold count */
  healthyThresholdCount?: number;

  /** Unhealthy threshold count */
  unhealthyThresholdCount?: number;

  /** HTTP codes to consider healthy */
  healthyHttpCodes?: string;
}

/**
 * Blue/Green DNS configuration
 *
 * Note: Both DNS records are created and point to the same ALB.
 * The isActive flag is informational only - routing is controlled by ALB listener rule priorities.
 */
export interface BlueGreenDnsConfig {
  /** Active hostname (e.g., api.example.com) */
  activeHostname: string;

  /** Inactive hostname (e.g., inactive-api.example.com) */
  inactiveHostname: string;

  /** Route53 hosted zone ID */
  hostedZoneId: string;

  /**
   * Whether this is the active service (informational only)
   *
   * Note: This flag doesn't affect DNS record creation - both records are always created.
   * Actual routing is controlled by ALB listener rule priorities:
   * - Active service: Lower priority (e.g., 100) for active hostname
   * - Inactive service: Higher priority (e.g., 200) for inactive hostname
   */
  isActive?: boolean;
}

/**
 * Load balancer routing configuration
 */
export interface LoadBalancerRoutingConfig {
  /**
   * Reference the bg-common ALB (from persistent ALB stack)
   *
   * **Recommended approach**: Deploy ALB separately using SpicyAlbStack (or spicyALB pipeline function), then reference it here.
   * This allows the ALB to persist across service stack deletions, keeping DNS stable.
   *
   * Can be provided as:
   * - ALB ARN string (will be imported)
   * - ALB object (from SpicyAlb construct)
   *
   * If not provided, uses cluster ALB (if externalListenerArn/internalListenerArn are set).
   */
  existingALB?: elbv2.IApplicationLoadBalancer | string;

  /** Use cluster's external (internet-facing) ALB */
  external?: boolean;

  /** Use cluster's internal ALB */
  internal?: boolean;

  /** Host header for routing (e.g., api.example.com) */
  hostHeader?: string;

  /** Path patterns for routing (e.g., /api/*) */
  pathPatterns?: string[];

  /** Listener rule priority (lower = higher priority) */
  priority?: number;

  /** Enable session stickiness (default: true for individual ALB, false for cluster ALB) */
  stickiness?: boolean;

  /** Stickiness duration in seconds */
  stickinessDuration?: number;

  /** Deregistration delay in seconds */
  deregistrationDelay?: number;

  /** Blue/Green DNS configuration (for individual ALB) */
  blueGreenDns?: BlueGreenDnsConfig;

  /**
   * HTTPS listener ARN for bg-common ALB (required when using existingALB with certificate)
   * Only one listener type is needed since bg-common ALB is either external OR internal (not both)
   */
  httpsListenerArn?: string;

  /**
   * HTTP listener ARN for bg-common ALB (required when using existingALB without certificate)
   * Only one listener type is needed since bg-common ALB is either external OR internal (not both)
   */
  httpListenerArn?: string;
}

/**
 * Route53 DNS configuration
 */
export interface DnsConfig {
  /** Hosted zone ID */
  hostedZoneId: string;

  /** Hosted zone name (e.g., example.com) */
  zoneName: string;

  /** Record name (e.g., api for api.example.com) */
  recordName: string;
}

/**
 * Deployment configuration
 */
export interface DeploymentConfig {
  /** Minimum healthy percent during deployment */
  minHealthyPercent?: number;

  /** Maximum percent during deployment */
  maxPercent?: number;

  /** Enable circuit breaker with rollback */
  circuitBreaker?: boolean;

  /** Enable ECS Exec for debugging */
  enableExecuteCommand?: boolean;
}

/**
 * Tags for the service
 */
export interface SpicyEcsServiceTags {
  owner: string;
  product: string;
  component: string;
  environment: string;
  build?: string;
}

/**
 * Properties for SpicyEcsService construct
 */
export interface SpicyEcsServiceProps {
  /** ECS Cluster to deploy to */
  readonly cluster: ecs.ICluster;

  /** VPC for networking */
  readonly vpc: ec2.IVpc;

  /** Service name */
  readonly serviceName: string;

  /** Container configuration */
  readonly container: ContainerConfig;

  /**
   * Capacity provider strategy for mixed deployments
   * If not specified, uses cluster default
   */
  readonly capacityProviderStrategy?: CapacityProviderStrategyItem[];

  /**
   * Desired number of tasks
   * @default 2
   */
  readonly desiredCount?: number;

  /** Auto-scaling configuration */
  readonly scaling?: ServiceScalingConfig;

  /** Health check configuration */
  readonly healthCheck?: HealthCheckConfig;

  /** Load balancer routing */
  readonly routing?: LoadBalancerRoutingConfig;

  /** External ALB listener ARN (from cluster) */
  readonly externalListenerArn?: string;

  /** Internal ALB listener ARN (from cluster) */
  readonly internalListenerArn?: string;

  /** External ALB (for target group VPC) */
  readonly externalLoadBalancer?: elbv2.IApplicationLoadBalancer;

  /** Internal ALB (for target group VPC) */
  readonly internalLoadBalancer?: elbv2.IApplicationLoadBalancer;

  /** Route53 DNS configuration */
  readonly dns?: DnsConfig;

  /** Deployment configuration */
  readonly deployment?: DeploymentConfig;

  /** Subnets for tasks (for awsvpc network mode) */
  readonly taskSubnets?: ec2.SubnetSelection;

  /** Security groups for tasks */
  readonly securityGroups?: ec2.ISecurityGroup[];

  /** Additional IAM policies for task role */
  readonly taskRolePolicies?: iam.PolicyStatement[];

  /** Required tags */
  readonly tags: SpicyEcsServiceTags;
}

/**
 * SpicyEcsService - ECS Service with:
 * - Mixed capacity provider strategy (EC2 + Fargate burst)
 * - Auto-scaling on CPU/Memory/Requests
 * - ALB integration with host/path routing
 * - Optional Route53 DNS
 * - Deployment circuit breaker
 * - ECS Exec support
 */
export class SpicyEcsService extends Construct {
  /** The ECS service */
  public readonly service: ecs.BaseService;

  /** The task definition */
  public readonly taskDefinition: ecs.TaskDefinition;

  /** The target group */
  public targetGroup?: elbv2.ApplicationTargetGroup;

  /** ALB reference (bg-common ALB when using existingALB) */
  public alb?: elbv2.IApplicationLoadBalancer;

  /** ALB HTTP listener (when using bg-common ALB) */
  public httpListener?: elbv2.ApplicationListener;

  /** ALB HTTPS listener (when using bg-common ALB) */
  public httpsListener?: elbv2.ApplicationListener;

  /** CloudWatch log group */
  public readonly logGroup: logs.LogGroup;

  /** Task role */
  public readonly taskRole: iam.Role;

  /** Task execution role */
  public readonly executionRole: iam.Role;

  constructor(scope: Construct, id: string, props: SpicyEcsServiceProps) {
    super(scope, id);

    const stack = cdk.Stack.of(this);

    // Defaults
    const desiredCount = props.desiredCount ?? 2;
    const container = props.container;
    const cpu = container.cpu ?? 256;
    const memory = container.memory ?? 512;
    const memoryReservation = container.memoryReservation ?? memory;

    const deployment = {
      minHealthyPercent: props.deployment?.minHealthyPercent ?? 50,
      maxPercent: props.deployment?.maxPercent ?? 200,
      circuitBreaker: props.deployment?.circuitBreaker ?? true,
      enableExecuteCommand: props.deployment?.enableExecuteCommand ?? true,
    };

    const healthCheck = {
      path: props.healthCheck?.path ?? '/',
      interval: props.healthCheck?.interval ?? 15,
      timeout: props.healthCheck?.timeout ?? 14,
      healthyThresholdCount: props.healthCheck?.healthyThresholdCount ?? 2,
      unhealthyThresholdCount: props.healthCheck?.unhealthyThresholdCount ?? 7,
      healthyHttpCodes: props.healthCheck?.healthyHttpCodes ?? '200-299',
    };

    // Determine if we're using Fargate (for network mode)
    const usesFargate = Boolean(
      props.capacityProviderStrategy?.some(
        (s) => s.capacityProvider === 'FARGATE' || s.capacityProvider === 'FARGATE_SPOT'
      )
    );

    // CloudWatch Log Group
    this.logGroup = new logs.LogGroup(this, 'LogGroup', {
      logGroupName: `/ecs/${props.serviceName}`,
      retention: logs.RetentionDays.ONE_MONTH,
      removalPolicy: cdk.RemovalPolicy.DESTROY,
    });
    (this.logGroup.node.defaultChild as logs.CfnLogGroup).overrideLogicalId('LogGroup');

    // Task Execution Role (for pulling images, logging)
    this.executionRole = new iam.Role(this, 'ExecutionRole', {
      assumedBy: new iam.ServicePrincipal('ecs-tasks.amazonaws.com'),
      managedPolicies: [iam.ManagedPolicy.fromAwsManagedPolicyName('service-role/AmazonECSTaskExecutionRolePolicy')],
    });
    (this.executionRole.node.defaultChild as iam.CfnRole).overrideLogicalId('ExecutionRole');

    // Allow pulling from Nexus (private registry)
    this.executionRole.addToPolicy(
      new iam.PolicyStatement({
        actions: ['ecr:GetAuthorizationToken'],
        resources: ['*'],
      })
    );

    // Task Role (for application permissions)
    this.taskRole = new iam.Role(this, 'TaskRole', {
      assumedBy: new iam.ServicePrincipal('ecs-tasks.amazonaws.com'),
    });
    (this.taskRole.node.defaultChild as iam.CfnRole).overrideLogicalId('TaskRole');

    // Add custom policies
    if (props.taskRolePolicies) {
      for (const policy of props.taskRolePolicies) {
        this.taskRole.addToPolicy(policy);
      }
    }

    // ECS Exec permissions
    if (deployment.enableExecuteCommand) {
      this.taskRole.addToPolicy(
        new iam.PolicyStatement({
          actions: [
            'ssmmessages:CreateControlChannel',
            'ssmmessages:CreateDataChannel',
            'ssmmessages:OpenControlChannel',
            'ssmmessages:OpenDataChannel',
          ],
          resources: ['*'],
        })
      );
    }

    // Task Definition
    // Use EC2 compatibility for mixed strategies, Fargate-only if no EC2
    const compatibility = usesFargate ? ecs.Compatibility.EC2_AND_FARGATE : ecs.Compatibility.EC2;

    this.taskDefinition = new ecs.TaskDefinition(this, 'TaskDefinition', {
      compatibility,
      networkMode: usesFargate ? ecs.NetworkMode.AWS_VPC : ecs.NetworkMode.BRIDGE,
      cpu: usesFargate ? String(cpu) : undefined,
      memoryMiB: usesFargate ? String(memory) : undefined,
      executionRole: this.executionRole,
      taskRole: this.taskRole,
      family: props.serviceName,
    });
    (this.taskDefinition.node.defaultChild as ecs.CfnTaskDefinition).overrideLogicalId('TaskDefinition');

    // Build secrets
    const secrets: Record<string, ecs.Secret> = {};
    if (container.secrets) {
      for (const [envName, secretArn] of Object.entries(container.secrets)) {
        // Handle ARN:key format
        const [arn, key] =
          secretArn.includes(':') && !secretArn.startsWith('arn:') ? [secretArn, undefined] : secretArn.split('::');

        const secret = secretsmanager.Secret.fromSecretCompleteArn(this, `Secret-${envName}`, arn);
        secrets[envName] = key ? ecs.Secret.fromSecretsManager(secret, key) : ecs.Secret.fromSecretsManager(secret);

        // Grant read access
        secret.grantRead(this.executionRole);
      }
    }

    // Container Definition
    const containerDef = this.taskDefinition.addContainer('Container', {
      containerName: props.serviceName,
      image: ecs.ContainerImage.fromRegistry(container.image),
      cpu: usesFargate ? undefined : cpu,
      memoryLimitMiB: usesFargate ? undefined : memory,
      memoryReservationMiB: usesFargate ? undefined : memoryReservation,
      environment: container.environment,
      secrets,
      logging: ecs.LogDriver.awsLogs({
        logGroup: this.logGroup,
        streamPrefix: props.serviceName,
      }),
      command: container.command,
      entryPoint: container.entryPoint,
      healthCheck: container.healthCheck
        ? {
            command: container.healthCheck.command,
            interval: cdk.Duration.seconds(container.healthCheck.interval ?? 30),
            timeout: cdk.Duration.seconds(container.healthCheck.timeout ?? 5),
            retries: container.healthCheck.retries ?? 3,
            startPeriod: cdk.Duration.seconds(container.healthCheck.startPeriod ?? 60),
          }
        : undefined,
      essential: true,
    });

    // Port mapping
    containerDef.addPortMappings({
      containerPort: container.port,
      protocol: ecs.Protocol.TCP,
    });

    // Security Group for tasks (awsvpc mode)
    let taskSecurityGroup: ec2.SecurityGroup | undefined;
    if (usesFargate) {
      taskSecurityGroup = new ec2.SecurityGroup(this, 'TaskSecurityGroup', {
        vpc: props.vpc,
        description: `Security group for ${props.serviceName} tasks`,
        allowAllOutbound: true,
      });
      (taskSecurityGroup.node.defaultChild as ec2.CfnSecurityGroup).overrideLogicalId('TaskSecurityGroup');
    }

    // Determine if we're using bg-common ALB or cluster ALB
    // bg-common stack is always created, so it's either:
    // 1. Use bg-common ALB (via existingALB)
    // 2. Use cluster ALB
    const existingALB = props.routing?.existingALB;

    // Use bg-common ALB if provided (persistent ALB from separate stack)
    if (existingALB) {
      // Validate required listener ARN for bg-common ALB
      // bg-common ALB has only one scheme (either external OR internal, not both)
      // But it can have both HTTP and HTTPS listeners (like the old template)
      const httpsListenerArn = props.routing?.httpsListenerArn;
      const httpListenerArn = props.routing?.httpListenerArn;

      if (!httpsListenerArn && !httpListenerArn) {
        throw new Error(
          'When using bg-common ALB (existingALB), either httpsListenerArn or httpListenerArn must be provided in routing config'
        );
      }

      // Import ALB if ARN string provided, otherwise use object directly
      const alb =
        typeof existingALB === 'string'
          ? elbv2.ApplicationLoadBalancer.fromApplicationLoadBalancerAttributes(this, 'ExistingALB', {
              loadBalancerArn: existingALB,
              loadBalancerDnsName: '', // Not needed for routing
              securityGroupId: 'sg-placeholder', // Placeholder - not used for routing
            })
          : existingALB;
      this.useExistingALB(props, alb, healthCheck, usesFargate, container.port, taskSecurityGroup);
    } else if (props.routing && (props.externalListenerArn || props.internalListenerArn)) {
      // Use cluster ALB
      // Validate that only one listener is used (external OR internal, not both)
      if (props.externalListenerArn && props.internalListenerArn) {
        throw new Error(
          'Cannot use both externalListenerArn and internalListenerArn. Choose either external OR internal, not both'
        );
      }
      if (props.routing.external && props.routing.internal) {
        throw new Error(
          'Cannot use both routing.external and routing.internal. Choose either external OR internal, not both'
        );
      }
      // Validate that routing config matches listener ARNs
      if (props.routing.external && !props.externalListenerArn) {
        throw new Error('routing.external=true requires externalListenerArn to be provided');
      }
      if (props.routing.internal && !props.internalListenerArn) {
        throw new Error('routing.internal=true requires internalListenerArn to be provided');
      }

      this.createClusterALBRouting(props, healthCheck, usesFargate, container.port, taskSecurityGroup);
    } else if (props.routing) {
      // Routing config provided but no ALB/listener ARNs - this is an error
      throw new Error(
        'Routing configuration provided but no ALB found. Either provide existingALB (for bg-common ALB) or externalListenerArn/internalListenerArn (for cluster ALB)'
      );
    }
    // If no routing config, service runs without ALB (valid for workers, pub/sub, etc.)

    // Allow traffic from ALB to tasks
    if (taskSecurityGroup) {
      if (existingALB) {
        // Allow from bg-common ALB
        taskSecurityGroup.addIngressRule(
          ec2.Peer.ipv4(props.vpc.vpcCidrBlock),
          ec2.Port.tcp(container.port),
          'Allow traffic from bg-common ALB'
        );
      } else if (props.externalLoadBalancer || props.internalLoadBalancer) {
        // Allow from cluster ALB
        taskSecurityGroup.addIngressRule(
          ec2.Peer.ipv4(props.vpc.vpcCidrBlock),
          ec2.Port.tcp(container.port),
          'Allow traffic from VPC (ALB)'
        );
      }
    }

    // Create Service
    const serviceProps: ecs.Ec2ServiceProps | ecs.FargateServiceProps = {
      cluster: props.cluster,
      taskDefinition: this.taskDefinition,
      desiredCount,
      serviceName: props.serviceName,
      minHealthyPercent: deployment.minHealthyPercent,
      maxHealthyPercent: deployment.maxPercent,
      circuitBreaker: deployment.circuitBreaker ? { rollback: true } : undefined,
      enableExecuteCommand: deployment.enableExecuteCommand,
      capacityProviderStrategies: props.capacityProviderStrategy?.map((s) => ({
        capacityProvider: s.capacityProvider,
        base: s.base,
        weight: s.weight,
      })),
    };

    // Create appropriate service type
    if (usesFargate) {
      this.service = new ecs.FargateService(this, 'Service', {
        ...serviceProps,
        assignPublicIp: false,
        vpcSubnets: props.taskSubnets ?? { subnetType: ec2.SubnetType.PRIVATE_WITH_EGRESS },
        securityGroups: taskSecurityGroup ? [taskSecurityGroup, ...(props.securityGroups ?? [])] : props.securityGroups,
        platformVersion: ecs.FargatePlatformVersion.LATEST,
      } as ecs.FargateServiceProps);
    } else {
      this.service = new ecs.Ec2Service(this, 'Service', {
        ...serviceProps,
        placementStrategies: [
          ecs.PlacementStrategy.spreadAcrossInstances(),
          ecs.PlacementStrategy.spreadAcross(ecs.BuiltInAttributes.AVAILABILITY_ZONE),
        ],
      } as ecs.Ec2ServiceProps);
    }
    (this.service.node.defaultChild as ecs.CfnService).overrideLogicalId('Service');

    // Attach to target group
    if (this.targetGroup) {
      this.service.attachToApplicationTargetGroup(this.targetGroup);
    }

    // Auto-scaling
    if (props.scaling) {
      this.configureAutoScaling(props.scaling);
    }

    // Route53 DNS (for cluster ALB mode only - bg-common ALB handles DNS in useExistingALB)
    // Note: For bg-common ALB with blue/green, DNS is configured in useExistingALB() via blueGreenDns
    if (props.dns && !existingALB && (props.externalLoadBalancer || props.internalLoadBalancer)) {
      this.configureDns(props.dns, props.externalLoadBalancer ?? props.internalLoadBalancer!);
    }

    // Apply tags
    this.applyTags(props.tags);

    // Outputs
    this.addOutputs(props);
  }

  /**
   * Use existing ALB (from persistent ALB stack)
   */
  private useExistingALB(
    props: SpicyEcsServiceProps,
    existingALB: elbv2.IApplicationLoadBalancer,
    healthCheck: {
      path: string;
      interval: number;
      timeout: number;
      healthyThresholdCount: number;
      unhealthyThresholdCount: number;
      healthyHttpCodes: string;
    },
    usesFargate: boolean,
    containerPort: number,
    taskSecurityGroup: ec2.SecurityGroup | undefined
  ): void {
    const routing = props.routing!;

    // Store reference to existing ALB
    this.alb = existingALB;

    // Create Target Group
    // Default stickiness to true for individual ALB (matches legacy)
    const stickinessEnabled = routing.stickiness ?? true;
    this.targetGroup = new elbv2.ApplicationTargetGroup(this, 'TargetGroup', {
      vpc: props.vpc,
      port: containerPort,
      protocol: elbv2.ApplicationProtocol.HTTP,
      targetType: usesFargate ? elbv2.TargetType.IP : elbv2.TargetType.INSTANCE,
      healthCheck: {
        path: healthCheck.path,
        interval: cdk.Duration.seconds(healthCheck.interval),
        timeout: cdk.Duration.seconds(healthCheck.timeout),
        healthyThresholdCount: healthCheck.healthyThresholdCount,
        unhealthyThresholdCount: healthCheck.unhealthyThresholdCount,
        healthyHttpCodes: healthCheck.healthyHttpCodes,
      },
      deregistrationDelay: cdk.Duration.seconds(routing.deregistrationDelay ?? 60),
      stickinessCookieDuration: stickinessEnabled
        ? cdk.Duration.seconds(routing.stickinessDuration ?? 86400)
        : undefined,
    });
    (this.targetGroup.node.defaultChild as elbv2.CfnTargetGroup).overrideLogicalId('TargetGroup');

    // Get listeners from existing ALB
    // bg-common ALB can have both HTTP and HTTPS listeners (like the old template)
    const httpsListenerArn = routing.httpsListenerArn;
    const httpListenerArn = routing.httpListenerArn;

    if (!httpsListenerArn && !httpListenerArn) {
      throw new Error(
        'When using existingALB, either httpsListenerArn or httpListenerArn must be provided in routing config'
      );
    }

    // Build conditions for listener rule
    const conditions: elbv2.ListenerCondition[] = [];
    if (routing.hostHeader) {
      conditions.push(elbv2.ListenerCondition.hostHeaders([routing.hostHeader]));
    }
    if (routing.pathPatterns && routing.pathPatterns.length > 0) {
      conditions.push(elbv2.ListenerCondition.pathPatterns(routing.pathPatterns));
    }
    if (conditions.length === 0) {
      conditions.push(elbv2.ListenerCondition.pathPatterns(['/*']));
    }

    // Create listener references and add rules (like the old template - rules on both HTTP and HTTPS)
    const placeholderSG = ec2.SecurityGroup.fromSecurityGroupId(this, 'ExistingListenerSG', 'sg-placeholder', {
      allowAllOutbound: true,
    });

    // HTTPS listener rule (if HTTPS listener provided)
    if (httpsListenerArn) {
      const httpsListener = elbv2.ApplicationListener.fromApplicationListenerAttributes(this, 'ExistingHTTPSListener', {
        listenerArn: httpsListenerArn,
        securityGroup: placeholderSG,
      });

      new elbv2.ApplicationListenerRule(this, 'HTTPSListenerRule', {
        listener: httpsListener,
        priority: routing.priority ?? 100,
        conditions,
        targetGroups: [this.targetGroup],
      });
    }

    // HTTP listener rule (if HTTP listener provided)
    if (httpListenerArn) {
      const httpListener = elbv2.ApplicationListener.fromApplicationListenerAttributes(this, 'ExistingHTTPListener', {
        listenerArn: httpListenerArn,
        securityGroup: placeholderSG,
      });

      new elbv2.ApplicationListenerRule(this, 'HTTPListenerRule', {
        listener: httpListener,
        priority: routing.priority ?? 100,
        conditions,
        targetGroups: [this.targetGroup],
      });
    }

    // Configure Blue/Green DNS if provided (for bg-common ALB)
    // Note: Both active and inactive DNS records are created and point to the same ALB.
    // Routing is controlled by ALB listener rule priorities, not DNS changes.
    // The isActive flag in BlueGreenDnsConfig is informational - both records are always created.
    // Actual routing is determined by which service stack has the lower priority listener rule.
    //
    // Testing: To verify blue/green DNS:
    // 1. Check both DNS records exist: `dig api.example.com` and `dig inactive-api.example.com`
    // 2. Both should resolve to the same ALB DNS name
    // 3. Verify listener rules: Active service should have priority 100, inactive should have priority 200
    // 4. Test routing: curl -H "Host: api.example.com" <ALB_DNS> should hit active service
    // 5. Test routing: curl -H "Host: inactive-api.example.com" <ALB_DNS> should hit inactive service
    if (routing.blueGreenDns) {
      this.configureBlueGreenDns(routing.blueGreenDns, existingALB);
    }
  }

  /**
   * Create cluster ALB routing (existing behavior)
   */
  private createClusterALBRouting(
    props: SpicyEcsServiceProps,
    healthCheck: {
      path: string;
      interval: number;
      timeout: number;
      healthyThresholdCount: number;
      unhealthyThresholdCount: number;
      healthyHttpCodes: string;
    },
    usesFargate: boolean,
    containerPort: number,
    taskSecurityGroup: ec2.SecurityGroup | undefined
  ): void {
    const routing = props.routing!;

    // Create Target Group
    // Default stickiness to false for cluster ALB (existing behavior)
    const stickinessEnabled = routing.stickiness ?? false;
    this.targetGroup = new elbv2.ApplicationTargetGroup(this, 'TargetGroup', {
      vpc: props.vpc,
      port: containerPort,
      protocol: elbv2.ApplicationProtocol.HTTP,
      targetType: usesFargate ? elbv2.TargetType.IP : elbv2.TargetType.INSTANCE,
      healthCheck: {
        path: healthCheck.path,
        interval: cdk.Duration.seconds(healthCheck.interval),
        timeout: cdk.Duration.seconds(healthCheck.timeout),
        healthyThresholdCount: healthCheck.healthyThresholdCount,
        unhealthyThresholdCount: healthCheck.unhealthyThresholdCount,
        healthyHttpCodes: healthCheck.healthyHttpCodes,
      },
      deregistrationDelay: cdk.Duration.seconds(routing.deregistrationDelay ?? 60),
      stickinessCookieDuration: stickinessEnabled
        ? cdk.Duration.seconds(routing.stickinessDuration ?? 86400)
        : undefined,
    });
    (this.targetGroup.node.defaultChild as elbv2.CfnTargetGroup).overrideLogicalId('TargetGroup');

    // Add listener rules
    if (props.externalListenerArn && routing.external) {
      this.addListenerRule('External', props.externalListenerArn, routing);
    }

    if (props.internalListenerArn && routing.internal) {
      this.addListenerRule('Internal', props.internalListenerArn, routing);
    }
  }

  /**
   * Configure Blue/Green DNS (active and inactive hostnames)
   *
   * IMPORTANT: Both DNS records are created and point to the SAME ALB.
   * Traffic routing is controlled by ALB listener rule priorities, NOT by DNS changes.
   *
   * How it works:
   * 1. Both active and inactive hostnames resolve to the same ALB DNS name
   * 2. ALB listener rules use hostname conditions to route traffic
   * 3. The active service has a lower priority rule (e.g., 100) for the active hostname
   * 4. The inactive service has a higher priority rule (e.g., 200) for the inactive hostname
   * 5. When swapping, only the listener rule priorities are updated (via CDK deployment)
   * 6. DNS records never change - they always point to the same ALB
   *
   * The isActive flag in BlueGreenDnsConfig is informational only - both records are always created.
   * The actual routing is determined by which service stack has the lower priority listener rule.
   */
  private configureBlueGreenDns(_dns: BlueGreenDnsConfig, _loadBalancer: elbv2.IApplicationLoadBalancer): void {
    // DNS records are NOT created here. They belong to the persistent ALB stack (spicy-alb.ts),
    // which owns the Route53 A records pointing to the load balancer. Creating them here would
    // cause CloudFormation conflicts when both blue and green service stacks attempt to manage
    // the same DNS records.
    //
    // Traffic routing between blue/green services is controlled entirely by ALB listener rule
    // priorities — not by DNS changes. Both hostnames always resolve to the same ALB.
  }

  /**
   * Add listener rule for ALB routing
   */
  private addListenerRule(name: string, listenerArn: string, routing: LoadBalancerRoutingConfig): void {
    const conditions: elbv2.ListenerCondition[] = [];

    if (routing.hostHeader) {
      conditions.push(elbv2.ListenerCondition.hostHeaders([routing.hostHeader]));
    }

    if (routing.pathPatterns && routing.pathPatterns.length > 0) {
      conditions.push(elbv2.ListenerCondition.pathPatterns(routing.pathPatterns));
    }

    // If no conditions, use a catch-all path
    if (conditions.length === 0) {
      conditions.push(elbv2.ListenerCondition.pathPatterns(['/*']));
    }

    const placeholderSG = ec2.SecurityGroup.fromSecurityGroupId(this, `${name}ListenerSG`, 'sg-placeholder', {
      allowAllOutbound: true,
    });
    const listener = elbv2.ApplicationListener.fromApplicationListenerAttributes(this, `${name}Listener`, {
      listenerArn,
      securityGroup: placeholderSG,
    });

    new elbv2.ApplicationListenerRule(this, `${name}ListenerRule`, {
      listener,
      priority: routing.priority ?? 100,
      conditions,
      targetGroups: [this.targetGroup!],
    });

    // HTTP redirect rule (if external)
    if (name === 'External' && routing.hostHeader) {
      // Note: HTTP redirect should be handled at the ALB level, not per-service
      // The cluster ALB already has a default HTTP→HTTPS redirect
    }
  }

  /**
   * Configure auto-scaling
   */
  private configureAutoScaling(scaling: ServiceScalingConfig): void {
    const scalableTarget = this.service.autoScaleTaskCount({
      minCapacity: scaling.minCapacity,
      maxCapacity: scaling.maxCapacity,
    });

    const cooldown = {
      scaleInCooldown: cdk.Duration.seconds(scaling.scaleInCooldown ?? 300),
      scaleOutCooldown: cdk.Duration.seconds(scaling.scaleOutCooldown ?? 60),
    };

    // CPU utilization scaling
    if (scaling.targetCpuUtilization) {
      scalableTarget.scaleOnCpuUtilization('CpuScaling', {
        targetUtilizationPercent: scaling.targetCpuUtilization,
        ...cooldown,
      });
    }

    // Memory utilization scaling
    if (scaling.targetMemoryUtilization) {
      scalableTarget.scaleOnMemoryUtilization('MemoryScaling', {
        targetUtilizationPercent: scaling.targetMemoryUtilization,
        ...cooldown,
      });
    }

    // Request count scaling (requires target group)
    if (scaling.targetRequestsPerTarget && this.targetGroup) {
      scalableTarget.scaleOnRequestCount('RequestScaling', {
        requestsPerTarget: scaling.targetRequestsPerTarget,
        targetGroup: this.targetGroup,
        ...cooldown,
      });
    }
  }

  /**
   * Configure Route53 DNS
   */
  private configureDns(dns: DnsConfig, loadBalancer: elbv2.IApplicationLoadBalancer): void {
    const hostedZone = route53.HostedZone.fromHostedZoneAttributes(this, 'HostedZone', {
      hostedZoneId: dns.hostedZoneId,
      zoneName: dns.zoneName,
    });

    new route53.ARecord(this, 'DnsRecord', {
      zone: hostedZone,
      recordName: dns.recordName,
      target: route53.RecordTarget.fromAlias(new route53Targets.LoadBalancerTarget(loadBalancer)),
    });
  }

  /**
   * Apply tags
   */
  private applyTags(tags: SpicyEcsServiceTags): void {
    const stack = cdk.Stack.of(this);

    cdk.Tags.of(this).add('Name', stack.stackName);
    cdk.Tags.of(this).add('Owner', tags.owner);
    cdk.Tags.of(this).add('Product', tags.product);
    cdk.Tags.of(this).add('Component', tags.component);
    cdk.Tags.of(this).add('Environment', tags.environment);
    if (tags.build) {
      cdk.Tags.of(this).add('Build', tags.build);
    }
  }

  /**
   * Add CloudFormation outputs
   */
  private addOutputs(props: SpicyEcsServiceProps): void {
    const stack = cdk.Stack.of(this);

    const serviceNameOutput = new cdk.CfnOutput(this, 'ServiceNameOutput', {
      value: props.serviceName,
      description: 'ECS Service Name',
      exportName: `${stack.stackName}-service-name`,
    });
    serviceNameOutput.overrideLogicalId('ServiceName');

    const serviceArnOutput = new cdk.CfnOutput(this, 'ServiceArnOutput', {
      value: this.service.serviceArn,
      description: 'ECS Service ARN',
      exportName: `${stack.stackName}-service-arn`,
    });
    serviceArnOutput.overrideLogicalId('ServiceArn');

    const taskDefOutput = new cdk.CfnOutput(this, 'TaskDefinitionArnOutput', {
      value: this.taskDefinition.taskDefinitionArn,
      description: 'Task Definition ARN',
      exportName: `${stack.stackName}-task-definition-arn`,
    });
    taskDefOutput.overrideLogicalId('TaskDefinitionArn');

    const logGroupOutput = new cdk.CfnOutput(this, 'LogGroupNameOutput', {
      value: this.logGroup.logGroupName,
      description: 'CloudWatch Log Group',
      exportName: `${stack.stackName}-log-group`,
    });
    logGroupOutput.overrideLogicalId('LogGroupName');

    if (this.targetGroup) {
      const targetGroupOutput = new cdk.CfnOutput(this, 'TargetGroupArnOutput', {
        value: this.targetGroup.targetGroupArn,
        description: 'Target Group ARN',
        exportName: `${stack.stackName}-target-group-arn`,
      });
      targetGroupOutput.overrideLogicalId('TargetGroupArn');
    }

    // Note: When using existing ALB (bg-common pattern), outputs come from ALB stack, not service stack
  }
}