publicSubnetIds: collapse()

in packages/@aws-cdk/toolkit-lib/lib/context-providers/vpcs.ts [174:252]
56 lines of code
22 McCabe index (conditional complexity)

      publicSubnetIds: collapse(
        flatMap(findGroups(SubnetType.Public, grouped), (group) => group.subnets.map((s) => s.subnetId)),
      ),
      publicSubnetNames: collapse(
        flatMap(findGroups(SubnetType.Public, grouped), (group) => (group.name ? [group.name] : [])),
      ),
      publicSubnetRouteTableIds: collapse(
        flatMap(findGroups(SubnetType.Public, grouped), (group) => group.subnets.map((s) => s.routeTableId)),
      ),
      vpnGatewayId,
      subnetGroups: assymetricSubnetGroups,
    };
  }
}

class RouteTables {
  public readonly mainRouteTable?: RouteTable;

  constructor(private readonly tables: RouteTable[]) {
    this.mainRouteTable = this.tables.find(
      (table) => !!table.Associations && table.Associations.some((assoc) => !!assoc.Main),
    );
  }

  public routeTableIdForSubnetId(subnetId: string | undefined): string | undefined {
    const table = this.tableForSubnet(subnetId);
    return (table && table.RouteTableId) || (this.mainRouteTable && this.mainRouteTable.RouteTableId);
  }

  /**
   * Whether the given subnet has a route to a NAT Gateway
   */
  public hasRouteToNatGateway(subnetId: string | undefined): boolean {
    const table = this.tableForSubnet(subnetId) || this.mainRouteTable;

    return (
      !!table &&
      !!table.Routes &&
      table.Routes.some((route) => !!route.NatGatewayId && route.DestinationCidrBlock === '0.0.0.0/0')
    );
  }

  /**
   * Whether the given subnet has a route to a Transit Gateway
   */
  public hasRouteToTransitGateway(subnetId: string | undefined): boolean {
    const table = this.tableForSubnet(subnetId) || this.mainRouteTable;

    return (
      !!table &&
      !!table.Routes &&
      table.Routes.some((route) => !!route.TransitGatewayId && route.DestinationCidrBlock === '0.0.0.0/0')
    );
  }

  /**
   * Whether the given subnet has a route to an IGW
   */
  public hasRouteToIgw(subnetId: string | undefined): boolean {
    const table = this.tableForSubnet(subnetId) || this.mainRouteTable;

    return (
      !!table && !!table.Routes && table.Routes.some((route) => !!route.GatewayId && route.GatewayId.startsWith('igw-'))
    );
  }

  public tableForSubnet(subnetId: string | undefined) {
    return this.tables.find(
      (table) => !!table.Associations && table.Associations.some((assoc) => assoc.SubnetId === subnetId),
    );
  }
}

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 * Return the value of a tag from a set of tags
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