Add route to subnet route table using networkfirewall endpoint from same AZ

[gerardorn]

How should I choose the correct network firewall endpoint for a subnet by using the AZ?

I'm using the golang version of the CDK

Here's what I have tried so far

endpoints := fw.AttrEndpointIds()
// We asign the enpoint in the same AZ as the subnet
for _, tgwSubnet := range *isolatedSubnets {
  for i := 0; i < 4; i++ { // I have 4 subnets mapped to the firewall
    endpointData := awscdk.Fn_Split(jsii.String(":"), awscdk.Fn_Select(jsii.Number(i), endpoints), jsii.Number(2))
    az := awscdk.Fn_Select(jsii.Number(0), endpointData)
    id := awscdk.Fn_Select(jsii.Number(1), endpointData)

    // This is not working
    if awscdk.Token_AsString(az, &awscdk.EncodingOptions{}) == tgwSubnet.AvailabilityZone() {
      // Create new route
      // tgwSubnet.(awsec2.Subnet).AddRoute(jsii.String("tgw-fw-route"), &awsec2.AddRouteOptions{
      // 	RouterType:           awsec2.RouterType_VPC_ENDPOINT,
      // 	DestinationCidrBlock: jsii.String("0.0.0.0/0"),
      // 	RouterId:             id,
      // })
      break
    }

    if awscdk.Token_CompareStrings(az, tgwSubnet.AvailabilityZone()) == awscdk.TokenComparison_SAME() {
     // This is not working either
    }
  }
}

I have also tried creating a map from the endpoints array but no luck either

endpointsMap := make(map[string]*string)
for i := 0; i < 4; i++ {
  endpointData := awscdk.Fn_Split(jsii.String(":"), awscdk.Fn_Select(jsii.Number(i), endpoints), jsii.Number(2))
  endpointsMap[*awscdk.Fn_Select(jsii.Number(0), endpointData)] = awscdk.Fn_Select(jsii.Number(1), endpointData)
}

Then tried this, but I get a nasty memory access error

endpoint := endpointsMap[*tgwSubnet.AvailabilityZone()]
tgwSubnet.(awsec2.Subnet).AddRoute(jsii.String("tgw-fw-route"), &awsec2.AddRouteOptions{
  RouterType:           awsec2.RouterType_VPC_ENDPOINT,
  DestinationCidrBlock: jsii.String("0.0.0.0/0"),
  RouterId:             endpoint,
})

Help please 🙏🏼
thanks in advance