import * as cdk from "aws-cdk-lib";
import * as kms from "aws-cdk-lib/aws-kms";
import * as iam from "aws-cdk-lib/aws-iam";
import * as events from "aws-cdk-lib/aws-events";
import * as backup from "aws-cdk-lib/aws-backup";
import { Construct } from "constructs";

/**
 * Primary AWS Backup vault + plan for Sea Haven (account 328440206208), us-east-1.
 *
 * Closes audit finding C-7 (AWS Backup entirely unused) together with
 * backup-offsite-stack. Phase 1 ("critical data first"): protect the data
 * stores with no offsite leg today and copy each recovery point cross-region
 * to the GOVERNANCE-locked `seahaven-offsite` vault (us-west-2).
 *
 * Coexistence: this SUPPLEMENTS the existing EBS DLM snapshots and DynamoDB
 * PITR — it does not replace them. It adds the missing Copy3 (offsite) +
 * immutability leg. The DLM/PITR overlap is rationalized in a later phase.
 *
 * Selection is by explicit ARN (not tag-based) so we don't have to tag — and
 * drift — resources owned by other stacks (proposal-system, payments-dashboard).
 * Switch to tag-based selection when expanding past the phase-1 set.
 *
 * Departed resources were removed from the selections on 2026-10-01 so the
 * daily job stops failing on missing ARNs. The vaults, plan, role, and lock
 * stay. `amazon-po` stays selected: the bucket exists and is versioned, and
 * its job fails for a reason that is not "bucket gone".
 */
export class BackupStack extends cdk.Stack {
  constructor(scope: Construct, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    // CMK encrypting the primary (operational) vault. RETAIN + rotation.
    const vaultKey = new kms.Key(this, "PrimaryVaultKey", {
      alias: "backup-primary-vault",
      description: "Encrypts primary AWS Backup recovery points (us-east-1)",
      enableKeyRotation: true,
      removalPolicy: cdk.RemovalPolicy.RETAIN,
    });

    // The L2 BackupVault does NOT grant the backup service use of a customer
    // CMK; the default key policy only delegates to account IAM. Grant
    // backup.amazonaws.com the minimum KMS actions (incl. CreateGrant for
    // RDS/EBS recovery points) so backup jobs can write to this vault.
    vaultKey.addToResourcePolicy(
      new iam.PolicyStatement({
        sid: "AllowAwsBackupUseOfTheKey",
        principals: [new iam.ServicePrincipal("backup.amazonaws.com")],
        // Action set matches AWS's documented Backup vault-key policy; scoped
        // to this account so only this account's Backup service can use it.
        actions: [
          "kms:Decrypt",
          "kms:GenerateDataKey",
          "kms:GenerateDataKeyWithoutPlaintext",
          "kms:ReEncrypt*",
          "kms:DescribeKey",
        ],
        resources: ["*"],
        conditions: { StringEquals: { "aws:SourceAccount": this.account } },
      })
    );
    vaultKey.addToResourcePolicy(
      new iam.PolicyStatement({
        sid: "AllowAwsBackupCreateGrant",
        principals: [new iam.ServicePrincipal("backup.amazonaws.com")],
        actions: ["kms:CreateGrant"],
        resources: ["*"],
        conditions: {
          Bool: { "kms:GrantIsForAWSResource": "true" },
          StringEquals: { "aws:SourceAccount": this.account },
        },
      })
    );

    // Primary vault — GOVERNANCE Vault Lock (INFRA-89). Codifies the lock applied
    // out-of-band 2026-06: MinRetention 1d, MaxRetention 2555d (~7y), no
    // `changeableFor` (LockDate null = admin-removable, GOVERNANCE not
    // COMPLIANCE) so it stays adjustable while the plan is validated. This block
    // is written to MATCH the live lock exactly, so the deploy diff is a no-op
    // adoption — it does not change the live vault.
    //
    // NOTE: the scoped vault access policy is (re)introduced below (INFRA-94)
    // with the fix for the two lockout-class bugs that got it split out of
    // INFRA-89: the deny statement now exempts THREE principals via
    // StringNotLike on aws:PrincipalArn — the SSO AdministratorAccess role (break
    // glass), the backup service role, AND the CDK CFN execution role. The
    // CFN-exec-role exemption is MANDATORY: without it CloudFormation cannot
    // re-assert the vault lock config / manage the vault and the deploy strands
    // the policy (this happened 2026-06-08). NotPrincipal is deliberately NOT
    // used (it rejects wildcard ARNs). Governance lock codify + backup
    // selections land here.
    const primaryVault = new backup.BackupVault(this, "PrimaryVault", {
      backupVaultName: "seahaven-primary",
      encryptionKey: vaultKey,
      removalPolicy: cdk.RemovalPolicy.RETAIN,
      lockConfiguration: {
        minRetention: cdk.Duration.days(1),
        maxRetention: cdk.Duration.days(2555),
        // No `changeableFor` → GOVERNANCE mode, admin-removable (matches live).
      },
    });

    // Vault access policy (INFRA-94): Deny the destructive recovery-point and
    // vault-lifecycle actions to EVERY principal EXCEPT the three operational
    // identities below. This is defense-in-depth on top of the GOVERNANCE lock —
    // it blocks manual deletion / lifecycle tampering even from accounts that
    // hold the equivalent IAM permissions.
    //
    // Deny (not Allow): a resource-policy Deny overrides any identity-based
    // Allow, which is exactly what we want for a guardrail. The StringNotLike
    // condition means "this Deny applies UNLESS the caller's ARN matches one of
    // the exempted patterns" — i.e. the three exempt principals are NOT denied.
    //
    // Exemptions (all THREE required):
    //  1. SSO AdministratorAccess role — break-glass human admin path. Matched by
    //     wildcard because the AWSReservedSSO role name carries a permission-set
    //     hash suffix.
    //  2. seahaven-backup-service-role — AWS Backup uses it for lifecycle
    //     expiry of recovery points; denying it would break the plan's
    //     deleteAfter cleanup.
    //  3. cdk-hnb659fds-cfn-exec-role — the CloudFormation execution role. CFN
    //     re-asserts the vault lock config and manages the vault on every deploy;
    //     omitting it strands the policy and fails the deploy (INFRA-94,
    //     2026-06-08). Wildcard-suffixed to cover the region-qualified name.
    //
    // NotPrincipal is intentionally avoided — it does not accept wildcard ARNs.
    primaryVault.addToAccessPolicy(
      new iam.PolicyStatement({
        sid: "DenyDestructiveActionsExceptOperationalRoles",
        effect: iam.Effect.DENY,
        principals: [new iam.AnyPrincipal()],
        actions: [
          "backup:DeleteRecoveryPoint",
          "backup:UpdateRecoveryPointLifecycle",
          "backup:DeleteBackupVault",
          "backup:DeleteBackupVaultAccessPolicy",
          "backup:DeleteBackupVaultLockConfiguration",
          "backup:PutBackupVaultLockConfiguration",
        ],
        resources: ["*"],
        conditions: {
          StringNotLike: {
            "aws:PrincipalArn": [
              // 1. SSO AdministratorAccess (break-glass human admin)
              `arn:aws:iam::${this.account}:role/aws-reserved/sso.amazonaws.com/*AWSReservedSSO_AdministratorAccess*`,
              // 2. AWS Backup service role (lifecycle expiry of recovery points)
              `arn:aws:iam::${this.account}:role/seahaven-backup-service-role`,
              // 3. CDK CloudFormation execution role (MANDATORY — manages vault)
              `arn:aws:iam::${this.account}:role/cdk-hnb659fds-cfn-exec-role-*`,
            ],
          },
        },
      })
    );

    // Cross-region copy destination, referenced by literal ARN (the offsite
    // stack is in another region; a literal ARN avoids crossRegionReferences /
    // SSM exports). Stack ordering is enforced via addStackDependency in bin/app.ts.
    const offsiteVault = backup.BackupVault.fromBackupVaultArn(
      this,
      "OffsiteVaultRef",
      `arn:aws:backup:us-west-2:${this.account}:backup-vault:seahaven-offsite`
    );

    // AWS Backup service role. Explicit (not auto-generated) because S3 backup
    // needs the S3-specific managed policy on top of the standard backup one.
    // Least-privilege: BACKUP + S3-backup only. Restore policies
    // (AWSBackupServiceRolePolicyForRestores / ...ForS3Restore) and
    // BackupSelection allowRestores are intentionally NOT granted — restores
    // are a deliberate, audited action and will get their own scoped role/path
    // once a restore-test process exists (cross-review F-1/F-2). A known role
    // name lets the deploy role's iam:PassRole be scoped to this exact ARN.
    // NOTE: creating this role is an IAM change → Sea Haven cross-review gate.
    const backupRole = new iam.Role(this, "BackupRole", {
      roleName: "seahaven-backup-service-role",
      assumedBy: new iam.ServicePrincipal("backup.amazonaws.com"),
      description: "AWS Backup service role (backup-only) for seahaven-primary",
      managedPolicies: [
        iam.ManagedPolicy.fromAwsManagedPolicyName(
          "service-role/AWSBackupServiceRolePolicyForBackup"
        ),
        iam.ManagedPolicy.fromAwsManagedPolicyName(
          "AWSBackupServiceRolePolicyForS3Backup"
        ),
      ],
    });

    // Daily backup → primary vault (35d), cross-region copy → offsite (90d).
    const plan = new backup.BackupPlan(this, "Plan", {
      backupPlanName: "seahaven-critical-daily",
      backupVault: primaryVault,
      backupPlanRules: [
        new backup.BackupPlanRule({
          ruleName: "daily-crr-offsite",
          backupVault: primaryVault,
          // 06:00 UTC — offset from the file-share DLM run.
          scheduleExpression: events.Schedule.cron({ hour: "6", minute: "0" }),
          startWindow: cdk.Duration.hours(1),
          completionWindow: cdk.Duration.hours(6),
          deleteAfter: cdk.Duration.days(35),
          copyActions: [
            {
              destinationBackupVault: offsiteVault,
              deleteAfter: cdk.Duration.days(90),
            },
          ],
        }),
      ],
    });

    // Phase-1 critical set, by explicit ARN.
    // Removed 2026-10-01 (resources gone; jobs were failing or about to):
    // RDS proposal-system-db, DynamoDB PaymentsDashboard, S3
    // seahaven-payments-csv-328440206208. database-1 was removed 2026-06-03
    // (audit H-19); its final recovery point stays in the offsite vault.
    plan.addSelection("CriticalResources", {
      backupSelectionName: "critical-data",
      role: backupRole,
      // allowRestores omitted (defaults false) — backup-only, see role comment.
      resources: [
        backup.BackupResource.fromArn(
          `arn:aws:dynamodb:us-east-1:${this.account}:table/purchase-orders`
        ),
        backup.BackupResource.fromArn("arn:aws:s3:::accounting.seahaven.com"),
        backup.BackupResource.fromArn(
          "arn:aws:s3:::google-workspace-seahavenind.com"
        ),
      ],
    });

    // Phase-2 selection, same plan and role as phase-1. Explicit ARN, not tags:
    // the tables are owned by other stacks.
    //
    // Removed 2026-10-01 (resources gone; jobs failing nightly): DynamoDB
    // afterhours-shifts, front-sla-alerts, meal-order-manager-orders; every
    // EBS volume (no instances remain); S3 seahaven-kb-docs-328440206208,
    // seahaven-payroll-emails-328440206208,
    // proposal-system-uploads-328440206208,
    // proposal-system-generated-328440206208.
    // amazon-po stays. The bucket exists and versioning is enabled, but the
    // backup job fails with a generic message.
    // LedgerFlow tables were excluded 2026-06-03 when that stack was deleted.
    plan.addSelection("Phase2Resources", {
      backupSelectionName: "phase2-offsite-everything",
      role: backupRole,
      resources: [
        ...[
          "SiteAssignments",
          "VendorReplies",
          "WorkOrderComments",
          "WorkOrders",
          "last-war-bot",
          "pending-site-review",
          "verified-sites",
        ].map((t) =>
          backup.BackupResource.fromArn(
            `arn:aws:dynamodb:us-east-1:${this.account}:table/${t}`
          )
        ),
        ...["amazon-po", "extracted-amazon-po"].map((b) =>
          backup.BackupResource.fromArn(`arn:aws:s3:::${b}`)
        ),
      ],
    });

    cdk.Tags.of(this).add("Project", "account-baseline");
    cdk.Tags.of(this).add("Owner", "adam@seahavenind.com");
    cdk.Tags.of(this).add("Environment", "prod");
    cdk.Tags.of(this).add("ManagedBy", "cdk");

    new cdk.CfnOutput(this, "PrimaryVaultName", { value: "seahaven-primary" });
    new cdk.CfnOutput(this, "PrimaryVaultKmsKeyArn", { value: vaultKey.keyArn });
    new cdk.CfnOutput(this, "BackupPlanId", { value: plan.backupPlanId });
    new cdk.CfnOutput(this, "BackupRoleArn", { value: backupRole.roleArn });
  }
}