import * as cdk from "aws-cdk-lib";
import * as s3 from "aws-cdk-lib/aws-s3";
import * as iam from "aws-cdk-lib/aws-iam";
import * as guardduty from "aws-cdk-lib/aws-guardduty";
import * as securityhub from "aws-cdk-lib/aws-securityhub";
import * as accessanalyzer from "aws-cdk-lib/aws-accessanalyzer";
import { Construct } from "constructs";

/**
 * Account-level detective controls (audit Day 1).
 *
 * Closes:
 *   H-2  AWS Config recorder + delivery channel (CIS 3.3/3.5)
 *   H-3  GuardDuty detector
 *   H-4  Security Hub with AWS FSBP + CIS v3.0 standards
 *   M-5  IAM Access Analyzer (account-scoped external-access analyzer)
 *
 * Scope is us-east-1 only — all workloads live here (Adam's call, Day 1).
 * Multi-region coverage is a documented follow-up.
 */
export class DetectiveControls extends Construct {
  constructor(scope: Construct, id: string) {
    super(scope, id);

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

    // ──────────────────────────────────────────────────────────────────────
    // H-2  AWS Config
    // ──────────────────────────────────────────────────────────────────────

    // Delivery bucket for Config snapshots/history. Private, TLS-only,
    // versioned, SSE-S3 (Config writes here; SSE-S3 avoids a second KMS-grant
    // failure mode and is sufficient — CIS does not require a CMK here).
    const configBucket = new s3.Bucket(this, "ConfigBucket", {
      bucketName: `seahaven-config-${stack.account}`,
      encryption: s3.BucketEncryption.S3_MANAGED,
      blockPublicAccess: s3.BlockPublicAccess.BLOCK_ALL,
      enforceSSL: true,
      versioned: true,
      lifecycleRules: [
        {
          id: "expire-old-config",
          expiration: cdk.Duration.days(365),
          abortIncompleteMultipartUploadAfter: cdk.Duration.days(7),
        },
      ],
      removalPolicy: cdk.RemovalPolicy.RETAIN,
    });

    // Bucket policy that lets the Config service principal verify ownership
    // and deliver objects (scoped to this account, owner-full-control ACL).
    configBucket.addToResourcePolicy(
      new iam.PolicyStatement({
        sid: "AWSConfigBucketPermissionsCheck",
        effect: iam.Effect.ALLOW,
        principals: [new iam.ServicePrincipal("config.amazonaws.com")],
        actions: ["s3:GetBucketAcl", "s3:ListBucket"],
        resources: [configBucket.bucketArn],
        conditions: {
          StringEquals: { "aws:SourceAccount": stack.account },
        },
      })
    );
    configBucket.addToResourcePolicy(
      new iam.PolicyStatement({
        sid: "AWSConfigBucketDelivery",
        effect: iam.Effect.ALLOW,
        principals: [new iam.ServicePrincipal("config.amazonaws.com")],
        actions: ["s3:PutObject"],
        resources: [
          configBucket.arnForObjects(`AWSLogs/${stack.account}/Config/*`),
        ],
        conditions: {
          StringEquals: {
            "s3:x-amz-acl": "bucket-owner-full-control",
            "aws:SourceAccount": stack.account,
          },
        },
      })
    );

    // Recorder role — assumed by Config. AWS_ConfigRole grants the read/describe
    // permissions Config needs to record every resource type; the inline policy
    // grants delivery to the bucket above. **This role is the Day 1 cross-review
    // item (IAM change per CLAUDE.md).**
    const recorderRole = new iam.Role(this, "ConfigRecorderRole", {
      roleName: "seahaven-config-recorder-role",
      assumedBy: new iam.ServicePrincipal("config.amazonaws.com"),
      managedPolicies: [
        iam.ManagedPolicy.fromAwsManagedPolicyName("service-role/AWS_ConfigRole"),
      ],
    });
    recorderRole.addToPolicy(
      new iam.PolicyStatement({
        sid: "ConfigDeliveryToBucket",
        effect: iam.Effect.ALLOW,
        actions: ["s3:PutObject"],
        resources: [
          configBucket.arnForObjects(`AWSLogs/${stack.account}/Config/*`),
        ],
        conditions: {
          StringEquals: { "s3:x-amz-acl": "bucket-owner-full-control" },
        },
      })
    );
    recorderRole.addToPolicy(
      new iam.PolicyStatement({
        sid: "ConfigBucketAcl",
        effect: iam.Effect.ALLOW,
        actions: ["s3:GetBucketAcl"],
        resources: [configBucket.bucketArn],
      })
    );

    // NOTE — the Config recorder + delivery channel are provisioned via CLI,
    // not CloudFormation. The L1 AWS::Config::ConfigurationRecorder is a
    // stabilizing resource that will not reach CREATE_COMPLETE until recording
    // is active, which needs a delivery channel; the delivery channel cannot be
    // created until the recorder resource completes — a deadlock that hangs the
    // stack indefinitely (observed 2026-06-01). The role + delivery bucket above
    // stay in IaC (the role is the cross-reviewed IAM); the recorder/channel are
    // created with the commands documented in the README, referencing this role
    // ARN and bucket name (exported below).

    new cdk.CfnOutput(this, "ConfigRecorderRoleArn", {
      value: recorderRole.roleArn,
    });

    // ──────────────────────────────────────────────────────────────────────
    // H-3  GuardDuty
    // ──────────────────────────────────────────────────────────────────────
    new guardduty.CfnDetector(this, "GuardDutyDetector", {
      enable: true,
      findingPublishingFrequency: "FIFTEEN_MINUTES",
    });

    // ──────────────────────────────────────────────────────────────────────
    // H-4  Security Hub (FSBP + CIS v3.0)
    // ──────────────────────────────────────────────────────────────────────
    // CIS/FSBP controls evaluate against the Config recording set up via CLI;
    // no CFN dependency is needed (findings populate once Config is recording).
    const hub = new securityhub.CfnHub(this, "SecurityHub", {
      enableDefaultStandards: false,
      controlFindingGenerator: "SECURITY_CONTROL",
      autoEnableControls: true,
    });

    const fsbpArn = cdk.Arn.format(
      {
        service: "securityhub",
        region: stack.region,
        account: "",
        resource: "standards",
        resourceName: "aws-foundational-security-best-practices/v/1.0.0",
      },
      stack
    );
    const cisArn = cdk.Arn.format(
      {
        service: "securityhub",
        region: stack.region,
        account: "",
        resource: "standards",
        resourceName: "cis-aws-foundations-benchmark/v/3.0.0",
      },
      stack
    );

    const fsbp = new securityhub.CfnStandard(this, "StandardFSBP", {
      standardsArn: fsbpArn,
    });
    fsbp.node.addDependency(hub);

    const cis = new securityhub.CfnStandard(this, "StandardCIS", {
      standardsArn: cisArn,
    });
    cis.node.addDependency(hub);

    // ──────────────────────────────────────────────────────────────────────
    // M-5  IAM Access Analyzer (free, account-scoped external-access)
    // ──────────────────────────────────────────────────────────────────────
    new accessanalyzer.CfnAnalyzer(this, "AccountAnalyzer", {
      analyzerName: "seahaven-account-analyzer",
      type: "ACCOUNT",
    });

    new cdk.CfnOutput(this, "ConfigBucketName", {
      value: configBucket.bucketName,
    });
  }
}