function Invoke-Monitor {
    param(
        [string[]] $comps
    )
    # Ask to notify
    # Initialize computer sessions
    
}

class WatchDog {
    [string]$Hostname
    [PSSession]$Session
    [string]$LastUser
    WatchDog() { $this.Init(@{})}
    WatchDog([hashtable]$Properties) { $this.Init($Properties)}
    WatchDog([string]$Hostname) { $this.Init(@{Hostname = $Hostname})}
    [void] Init([hashtable]$Properties){
        foreach ($prop in $Properties.Keys) {
            $this.$prop = $Properties.$prop
        }
    }
    # Returns true if a value was updated
    [bool] Update() {
        $old = $this
        if ((Test-Connection -ComputerName $this.Hostnmae -Count 1)) {
            $this.Session = $null 
            return -not ($old.Session)
        }
        if (-not ($this.Session)) {
            $this.Session = New-PSSession -ComputerName $this.Hostname -SessionOption (New-PSSessionOption -NoMachineProfile)
        }
        $this.LastUser = $(Invoke-Command -Session $this.Session {Get-ComputerInfo}).CSUserName
        if($null -eq $this.LastUser){

            $this.LastUser = (Invoke-Command -Session $this.Session -ScriptBlock {Get-Process Explorer -IncludeUsername  | Where-Object { $_.Username -notlike "*SYSTEM" }} ).Username
            
            if($null -ne $this.LastUser){
                $this.LastUser = "$($this.LastUser) (RDP/Inactive)"
            }
            else{
                $this.LastUser = $null
            }
        }
        return (($this.Session -ne $old.Session) -or ($this.LastUser -ne $old.LastUser)) 
    }
}