class HostCheck {
    [string] $HostName = ""
    [string] $Fqdn = ""
    [string] $CName = ""
    [string] $IpAddress = ""
    [string] $CNameChain = ""
    [bool] $Exists = $false
    [bool] $RegisteredInExternalDNS = $false
    [string] $Owner = ""
    [string] $Comment = ""
}

function HostExistsInExternal ([HostCheck] $hostCheck, [string] $ExternalDNSServer) {
    try {
        $CnameChain = resolve-dnsname -name $hostCheck.Fqdn -NoHostsFile -Server $ExternalDNSServer -ErrorAction Ignore

        for ($i = 0; $i -lt $CnameChain.Count; $i++) {
            $chainItem = $CnameChain[$i]
            if ($chainItem.NameHost) {
                $hostCheck.CNameChain = "$($hostCheck.CNameChain) -> $($chainItem.NameHost)"
                if ($chainItem.NameHost -ieq $hostCheck.CName) {
                    $hostCheck.RegisteredInExternalDNS = $true
                }
            }
        }
    }
    catch {
        $hostCheck.RegisteredInExternalDNS = $false
    }

    return $hostCheck
}

function GetIPAddress ([HostCheck] $hostCheck) {
    try {
        $hostAddresses = [System.Net.Dns]::GetHostAddresses($hostCheck.Fqdn)
        $hostCheck.IpAddress = $hostAddresses.IPAddressToString
        
    }
    catch { 
        try {
            $hostAddresses = [System.Net.Dns]::GetHostAddresses($hostCheck.HostName)

            $hostCheck.IpAddress = $hostAddresses.IPAddressToString
        }
        catch {
            $hostCheck.IpAddress = ""
        }

    }
    return $hostCheck
}

function TestIPConnection ([HostCheck] $hostCheck) {
    try {
        if (Test-Connection -TargetName $hostCheck.IpAddress -Count 1 -Quiet) {
            $hostCheck.Exists = $true
        }
        else {
            $hostCheck.Exists = $false
        }
    }
    catch {
        $hostCheck.Exists = $false
    }
    return $hostCheck
}

function Effectory-DNSVerify-Csv ([string[]] $FileName, [string] $ExternalDNSServer = "8.8.8.8") {
    Clear-DnsClientCache
    
    $DNSRecords = import-csv $FileName 

    # HostName,Cname,Fqdn
    # accept-authorization,authorization-web-api-accept.azurewebsites.net,accept-authorization.effectory.com
    # accept-customer,test-customer-effectory-accept.azurewebsites.net,accept-customer.effectory.com
    # accept-ecestore,test-ecestore-accept.azurewebsites.net,accept-ecestore.effectory.com

    [HostCheck[]]$Result = @()
    foreach ($DNSRecord in $DNSRecords) {

        [HostCheck] $hostCheck = [HostCheck]::new()
        $hostCheck.HostName = $DNSRecord.ExternalDNS
        $hostCheck.CName = $DNSRecord.To
        $hostCheck.Owner = $DNSRecord.Owner
        $hostCheck.Comment = $DNSRecord.Comment
        $hostCheck.Fqdn = "$($DNSRecord.ExternalDNS).effectory.com"

        $hostCheck = HostExistsInExternal -hostCheck $hostCheck -ExternalDNSServer $ExternalDNSServer
        $hostCheck = GetIPAddress -hostCheck $hostCheck
        $hostCheck.Exists = $hostCheck.IpAddress -ne ""

        $Result += $hostCheck
    }
    
    return $Result
}


#Connect-AzAccount

#Effectory-DNSVerify -ZoneName "effectory.com" -DNSServer "DC1.effectory.local" -ExternalDNSServer "8.8.8.8" | Export-Csv -Path ".\2021-06-01 DNS-effectory-com.csv"
#Effectory-DNSVerify -ZoneName "effectory.local" -DNSServer "DC1.effectory.local" -ExternalDNSServer "DC2.effectory.local" -DoIpCheck $true | Export-Csv -Path ".\2021-06-01 DNS-effectory-local.csv" 
#Effectory-DNSVerify-Csv -FileName .\vip-effectory-com.csv -ExternalDNSServer "8.8.8.8" | Export-Csv -Path ".\2021-06-01 DNS-vip-effectory-com.csv"
#Effectory-GetAppServiceHostNames | Export-Csv -Path ".\2021-06-01 AppService Hosts.csv"
#Effectory-GetFrontDoorHostNames | Export-Csv -Path ".\2021-06-01 FrontDoor Hosts.csv"

# | Format-Table
# | Export-Csv -Path .\DNS-xxxx.csv

$foo = Effectory-DNSVerify-Csv -FileName "C:\tmp\Book3.csv" 
$foo | Export-Csv -Path .\DNS.csv