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$fs     = 100			# fetch_size
$offset = 1				# offset
$seen   = 1;			# first offset is 1, not 0
while ( $seen -lt $devicecount)
{
	# Outer loop, grab a batch (defined by fetch_size) of devices
	$url = -join ("http://", $sonar, "/api/v1/devices/?offset=", $offset,  "&fetch_size=", $fs)
	$devices = Invoke-RestMethod $url -Credential $credential
	$i = 1
	while ($i -lt $devices.count)
	{
		# inner loop - process individual devices in this batch
		# We want to populate some of the data fields in the CSV file - what can we fill in just from the DEVICES end point
		$row = New-Object System.Object		
		$row | Add-Member -MemberType NoteProperty -Name "DeviceID" -Value $dev.device_id
		
		# If the path was only partly successful we might not have a serial number. However we can safely store the empty string.
		# if you are processing RestAPI using PHP or a different scripting language that is stricter about handling undefined variables,
		# you need error handling code around here too.
		$row | Add-Member -MemberType NoteProperty -Name "Serial-Number" -Value $dev.serial_number
		
		# For certain devices, for example some SNMP devices, or for storage devices we might not get a hostname! Explicitly call out a device with no hostname. 
		# Also if hostname is not defined, there will be no qualified name(s)
		if (!$devices[$i].host_name)
		{
			# Hostname is not defined
			$row | Add-Member -MemberType NoteProperty -Name "Hostname" -Value "(undefined)"
			$row | Add-Member -MemberType NoteProperty -Name "FQDN" -Value "(undefined)"
			$row | Add-Member -MemberType NoteProperty -Name "DNSFQDN" -Value "(undefined)"
		}
		else {
			# Hostname is defined
			$row | Add-Member -MemberType NoteProperty -Name "Hostname" -Value $dev.host_name
			# If the array is not present, $num gets value 0, and so the inner loop will not fire
			# we have already set FQDN and DNSFQDN to "(undefined)" where there is no hostname, but we can sometimes have a hostname but no FQDN
			$num = $devices[$i].qualified_name.count
			if ($num -eq 0)
			{
				$row | Add-Member -MemberType NoteProperty -Name "FQDN" -Value "(undefined)"
				$row | Add-Member -MemberType NoteProperty -Name "DNSFQDN" -Value "(undefined)"
			}
			else
			{
				$j   = 0
				$fqdn = "(No FQDN)"
				while ($j -lt $num)
				{
					if ($devices[$i].qualified_name[$j].name_type -eq "DNSFQDN")
					{
						# DNSFQDN can also be used for FQDN.
						$fqdn = $devices[$i].qualified_name[$j].name
						$row | Add-Member -MemberType NoteProperty -Name "DNSFQDN" -Value $devices[$i].qualified_name[$j].name
						$row | Add-Member -MemberType NoteProperty -Name "FQDN" -Value $devices[$i].qualified_name[$j].name
					}
					elseif ($devices[$i].qualified_name[$j].name_type -eq "FQDN")
					{
						$row | Add-Member -MemberType NoteProperty -Name "FQDN" -Value $devices[$i].qualified_name[$j].name
					}
					$j = $j + 1
				}
			}		
		}
		# Locations is an array containing one or more locations. We can store locations[0].name as the location
		$row | Add-Member -MemberType NoteProperty -Name "Location" -Value $devices[$i].locations[0].name

		# The Last Scan Date should always be there, but if absent PowerShell will happily record a NULL value for us.
		$row | Add-Member -MemberType NoteProperty -Name "LastScanDate" -Value $devices[$i].last_scan
				
		$csv += $row
		$i = $i + 1;		# keep track for inner loop
		$seen = $seen + 1;  # keep track for outer loop
	}
	# Finished this batch
	$offset = $seen
}