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 * as cr from "aws-cdk-lib/custom-resources";
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)
 *
 * Serves both the management-account baseline (namePrefix "seahaven") and
 * member-account baselines (e.g. "seahaven-extdev") — physical resource names
 * are prefix-parameterized, structure is identical.
 *
 * Scope is us-east-1 only — all workloads live here (Adam's call, Day 1).
 * Multi-region coverage is a documented follow-up.
 */
export interface DetectiveControlsProps {
  /**
   * Physical-name prefix for account-scoped resources (bucket, roles, recorder,
   * delivery channel, analyzer). Also baked into the custom resources'
   * PhysicalResourceId strings — changing it on a deployed stack REPLACES the
   * custom resources; keep it stable per account.
   */
  readonly namePrefix: string;
  /**
   * Create the account-local GuardDuty detector + Security Hub hub. Default
   * TRUE (pre-delegation accounts own these). Set FALSE for accounts enrolled
   * by the org delegated admin (post 2026-07-14): the org creates the
   * detector/hub itself and a CFN-owned duplicate fails (one per account).
   * ALWAYS created regardless of this flag (security review SH-DEV-001 /
   * SH-DEVBASE-002): Security Hub STANDARDS (org AutoEnableStandards is NONE —
   * DEFAULT would enroll legacy CIS v1.2.0, so IaC owns FSBP + CIS v3.0;
   * CfnStandard attaches fine to an org-enabled hub), the account Access
   * Analyzer (the ORGANIZATION analyzer treats the whole org as trusted and
   * cannot flag intra-org exposure — e.g. to the isolated contractor account;
   * both analyzer types coexist, verified live), and the Config recorder
   * (recorders stay per-account, delegation never makes one).
   */
  readonly localDetectiveServices?: boolean;
}

export class DetectiveControls extends Construct {
  constructor(scope: Construct, id: string, props: DetectiveControlsProps) {
    super(scope, id);

    const stack = cdk.Stack.of(this);
    const prefix = props.namePrefix;

    // ──────────────────────────────────────────────────────────────────────
    // 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: `${prefix}-config-${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: `${prefix}-config-recorder-role`,
      assumedBy: new iam.ServicePrincipal("config.amazonaws.com"),
      managedPolicies: [
        iam.ManagedPolicy.fromAwsManagedPolicyName("service-role/AWS_ConfigRole"),
      ],
    });
    recorderRole.addToPolicy(
      new iam.PolicyStatement({
        sid: "ConfigDeliveryToBucket",
        effect: iam.Effect.ALLOW,
        actions: ["s3:PutObject"],
        resources: [
          configBucket.arnForObjects(`AWSLogs/${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],
      })
    );

    // ── AWS Config recorder + delivery channel (INFRA-17) ──────────────────
    //
    // The L1 AWS::Config::ConfigurationRecorder is a stabilizing resource that
    // deadlocks the stack: it never reaches CREATE_COMPLETE until recording is
    // active, which requires a delivery channel, which can't be created until
    // the recorder is complete (observed 2026-06-01).
    //
    // Fix: an AwsCustomResource calls the Config SDK directly — Put* is an
    // upsert, so the deploy converges the existing CLI-created recorder/channel
    // without destroying and recreating them, and active recording is never
    // interrupted. Sequence: PutConfigurationRecorder → PutDeliveryChannel →
    // StartConfigurationRecorder.
    //
    // onDelete stops recording (rather than deleting the recorder, which is a
    // per-account singleton — deleting it via CFN would wipe all Config history).
    //
    // IAM additions on the custom-resource role (MANDATORY cross-reviewed per
    // CLAUDE.md — see PR description for cross-review output):
    //   config:PutConfigurationRecorder
    //   config:PutDeliveryChannel
    //   config:StartConfigurationRecorder
    //   config:StopConfigurationRecorder
    //   iam:PassRole  (scoped to the recorder role)

    // Custom-resource role. Principle of least privilege: only the four Config
    // actions + PassRole for the recorder role.
    const configCustomResourceRole = new iam.Role(
      this,
      "ConfigCustomResourceRole",
      {
        roleName: `${prefix}-config-custom-resource-role`,
        assumedBy: new iam.ServicePrincipal("lambda.amazonaws.com"),
        managedPolicies: [
          iam.ManagedPolicy.fromAwsManagedPolicyName(
            "service-role/AWSLambdaBasicExecutionRole"
          ),
        ],
        inlinePolicies: {
          ConfigRecorderAdoption: new iam.PolicyDocument({
            statements: [
              new iam.PolicyStatement({
                sid: "ConfigRecorderManage",
                effect: iam.Effect.ALLOW,
                actions: [
                  "config:PutConfigurationRecorder",
                  "config:PutDeliveryChannel",
                  "config:StartConfigurationRecorder",
                  "config:StopConfigurationRecorder",
                ],
                // Config recorder/channel are account-level singletons with no
                // ARN in resource policies — the API only accepts "*" here.
                resources: ["*"],
              }),
              new iam.PolicyStatement({
                sid: "PassRecorderRole",
                effect: iam.Effect.ALLOW,
                actions: ["iam:PassRole"],
                // Scoped to exactly the recorder role this stack manages.
                resources: [recorderRole.roleArn],
                conditions: {
                  StringEquals: {
                    "iam:PassedToService": "config.amazonaws.com",
                  },
                },
              }),
            ],
          }),
        },
      }
    );

    // SDK call payloads — defined once, reused for onCreate + onUpdate so both
    // paths converge identically (Put* is idempotent/upsert).
    const putRecorderCall: cr.AwsSdkCall = {
      service: "ConfigService",
      action: "putConfigurationRecorder",
      parameters: {
        ConfigurationRecorder: {
          name: `${prefix}-config-recorder`,
          roleARN: recorderRole.roleArn,
          recordingGroup: {
            allSupported: true,
            includeGlobalResourceTypes: true,
          },
        },
      },
      // No meaningful response data to extract.
      physicalResourceId: cr.PhysicalResourceId.of(`${prefix}-config-recorder`),
    };

    const putChannelCall: cr.AwsSdkCall = {
      service: "ConfigService",
      action: "putDeliveryChannel",
      parameters: {
        DeliveryChannel: {
          name: `${prefix}-config-delivery`,
          s3BucketName: configBucket.bucketName,
          configSnapshotDeliveryProperties: {
            deliveryFrequency: "TwentyFour_Hours",
          },
        },
      },
      physicalResourceId: cr.PhysicalResourceId.of(
        `${prefix}-config-delivery`
      ),
    };

    const startRecorderCall: cr.AwsSdkCall = {
      service: "ConfigService",
      action: "startConfigurationRecorder",
      parameters: {
        ConfigurationRecorderName: `${prefix}-config-recorder`,
      },
      physicalResourceId: cr.PhysicalResourceId.of(
        `${prefix}-config-recorder-start`
      ),
    };

    // Step 1: put the recorder (upsert).
    // policy is not needed — all permissions are on configCustomResourceRole.
    const putRecorder = new cr.AwsCustomResource(this, "ConfigPutRecorder", {
      onCreate: putRecorderCall,
      onUpdate: putRecorderCall,
      // onDelete: nothing — do not delete the singleton recorder; recording
      // continuity takes priority over stack-delete cleanup.
      role: configCustomResourceRole,
      installLatestAwsSdk: false,
    });

    // Step 2: put the delivery channel (upsert). Requires recorder to exist.
    const putChannel = new cr.AwsCustomResource(this, "ConfigPutChannel", {
      onCreate: putChannelCall,
      onUpdate: putChannelCall,
      role: configCustomResourceRole,
      installLatestAwsSdk: false,
    });
    putChannel.node.addDependency(putRecorder);

    // Step 3: start recording. Requires both recorder + channel to exist.
    // onDelete stops recording rather than deleting the singleton recorder —
    // deleting the recorder would wipe Config history and has no CFN resource
    // type to reconstruct it anyway.
    const startRecorder = new cr.AwsCustomResource(
      this,
      "ConfigStartRecorder",
      {
        onCreate: startRecorderCall,
        onUpdate: startRecorderCall,
        onDelete: {
          service: "ConfigService",
          action: "stopConfigurationRecorder",
          parameters: {
            ConfigurationRecorderName: `${prefix}-config-recorder`,
          },
          physicalResourceId: cr.PhysicalResourceId.of(
            `${prefix}-config-recorder-stop`
          ),
        },
        role: configCustomResourceRole,
        installLatestAwsSdk: false,
      }
    );
    startRecorder.node.addDependency(putChannel);

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

    // ──────────────────────────────────────────────────────────────────────
    // H-3  GuardDuty detector + H-4 Security Hub hub — skipped when the org
    // delegated admin owns them (localDetectiveServices: false). Standards and
    // the analyzer below are created UNCONDITIONALLY (see props doc).
    // ──────────────────────────────────────────────────────────────────────
    const localDetection = props.localDetectiveServices ?? true;
    let hub: securityhub.CfnHub | undefined;
    if (localDetection) {
      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 managed by the
    // custom resource above; no CFN dependency needed (findings populate once
    // recording is active).
    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
    );

    // When the hub is org-managed (localDetection false) it already exists
    // before this stack deploys (enrollment is a deploy precondition), so the
    // standards attach without a CFN dependency.
    const fsbp = new securityhub.CfnStandard(this, "StandardFSBP", {
      standardsArn: fsbpArn,
    });
    if (hub) {
      fsbp.node.addDependency(hub);
    }

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

    // ──────────────────────────────────────────────────────────────────────
    // M-5  IAM Access Analyzer (free, account-scoped external-access) —
    // always created: the ORGANIZATION analyzer cannot flag intra-org
    // exposure (SH-DEVBASE-002).
    // ──────────────────────────────────────────────────────────────────────
    new accessanalyzer.CfnAnalyzer(this, "AccountAnalyzer", {
      analyzerName: `${prefix}-account-analyzer`,
      type: "ACCOUNT",
    });

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