Invalid reference in Terraform using Powershell - powershell

Question

Getting an error on my Terraform deployment for the following. I think it's because it's using a mixture of Terraform variables and Powershell I may have confused myself on the syntax.
Here is the Code:
data "template_file" "ad-join-template" {
template = <<EOF
<powershell>
# Set-DefaultAWSRegion -Region eu-west-2
# Set-Variable -name instance_id -value (Invoke-Restmethod -uri http://169.254.169.254/latest/meta-data/instance-id)
# # New-SSMAssociation -target key=InstanceIds,Values=$instance_id -Name "${aws_ssm_document.ad-join-domain.name}"
# New-SSMAssociation `
# -Name ad-join-domain `
# -Target #{
# "Key"="InstanceIds"
# "Values"="$($instance_id)"
# }
$apiurl = "${var.API}"
$tajdns = #("${taj_dns_server[0]}","[${taj_dns_server[1]}")
$count = 0
foreach ($dns in $tajdns){
$returnedRecords = (Resolve-DnsName -Name $apiurl -Server $dns).IPAddress
New-Variable -Name "dnsRecords$count" -Value $returnedRecords -Force
$count++
}
$allDNSrecords += $dnsRecords0
$allDNSrecords += $dnsRecords1
$allDNSrecords = $allDNSrecords | Select-Object -Unique
Add-Content C:\windows\system32\drivers\etc\hosts "`n***.**.*.* ssm.eu-west-2.amazonaws.com `
`n***.**.*.* ssm.eu-west-2.amazonaws.com `
`n***.**.*.* ssm.eu-west-2.amazonaws.com `
`n***.**.*.* ssmmessages.eu-west-2.amazonaws.com `
`n***.**.*.* ssmmessages.eu-west-2.amazonaws.com `
`n***.**.*.* ssmmessages.eu-west-2.amazonaws.com `
`n$allDNSrecords[0] ${var.API}`
`n$allDNSrecords[1] ${var.API}"
$nicDetails = Get-NetAdapter
Set-DnsClientServerAddress -InterfaceIndex $nicDetails.ifIndex -ServerAddresses (${local.concat_dns_servers_join})
$domain = "${aws_directory_service_directory.ad.name}"
$password = "${aws_directory_service_directory.ad.password}" | ConvertTo-SecureString -asPlainText -Force
$username = "admin#$($domain)"
$credential = New-Object System.Management.Automation.PSCredential($username,$password)
Add-Computer -DomainName $domain -Credential $credential
Restart-Computer -Force
</powershell>
EOF
}
In the [${taj_dns_server[0]}]" this is pulling a Terraform variable out of list and populating it in to the script. Can you see if my syntax is correct?
Here is the Error:
│ Error: Invalid reference
136│
137│ on asg.tf line 19, in data "template_file" "ad-join-template":
138│ 19: $tajdns = #("[${taj_dns_server[0]}]","[${taj_dns_server[1]}]")
139│
140│ A reference to a resource type must be followed by at least one attribute
141│ access, specifying the resource name.
142╵
143╷
144│ Error: Invalid reference
145│
146│ on asg.tf line 19, in data "template_file" "ad-join-template":
147│ 19: $tajdns = #("[${taj_dns_server[0]}]","[${taj_dns_server[1]}]")
148│
149│ A reference to a resource type must be followed by at least one attribute
150│ access, specifying the resource name.
151╵