#
# PRTG Pause
#
# Simple HTTP Listener to accept HTTP-GET from 
#
# Must run as Administrator to create a HTTP Web Listener
# http(s)://prtg_server_address/api/function?Username=uid&passhash=hash&params
#
# 20140611  Ver 1.0  Initiale public Version
# 20140612  Ver 1.1  Sonderfall trailing? und favicon.ico
# 20140612  Ver 1.2  Erweiterung um Template und Alert, Bugfix StatUsermittlung
#						Added ScanNow, errors in Red, Hyperlink to DeviceID
#						Errorausgabe im HTML addiert
# 20140718  Ver 1.3  Abschalten der DNS Abfragen,da diese bei "nichtauflösbarkeit" zu lange brauchen.
#						Systeme müssen in PRTG über die IP-Adresse gepflegt werden
#						Funktioniert nicht sicher, wenn mehrere Systeme die gleiche IP-Adresse haben (z.B. mehrere Kunden)
#						Exclude von abruf des /favicon.ico addiert
# 20140718  Ver 1.4  Try to match Hostname based on ReverseDNS
#						Additional Errorhandling if Lisatener Listener not bound

param (
           [string]$prtgserveruri="https://prtg.netatwork.de", # URL of PRTG Web Frontend
           [string]$prtgUsername="prtgpause",   # Username
           [string]$prtgpasshash="2039135208" ,   # hash instead of password
           [string]$listenport = "81",
		   [string]$htmltemplatefile  = "./prtgpause-template.htm",
		   [int]$devicecacheage = 10  # age of Device List Cache in seconds
)
 
set-psdebug -strict   # make sure that e throw an error für uninitialize variables etc
[string]$script:lasterror=""
# Emulate function on PowerShell 2.0 Systems
function Invoke-WebRequest ([string]$uri) {
	$webclient = new-object System.Net.WebClient
	try {
		$webclient.downloadstring($uri)
	}
	catch {
		$script:lasterror  = $_.Exception.Message
		write-host ("ERROR" + $script:lasterror)
	}
}

write-host "PRTGPause: Start"


write-host "PRTGPause: Check HTML-Template"
try {
	[string]$htmltemplate=get-content $htmltemplatefile 
}
catch {
	write-error "Unable to load THML-Template: $htmltemplatefile "
	exit
}
write-host "PRTGPause: Check HTML-Template - SUCCESS"

write-host "PRTGPause: Check PRTG Connectivity by reading Status"
try {
	[xml]$data=Invoke-WebRequest -Uri ($prtgserveruri+"/api/getstatus.xml?id=0&Username="+$prtgUsername+"&passhash="+$prtgpasshash)
	write-host ("PRTG-Version:"+ $data.status.Version)
	write-host ("PRTG-Clock  :"+ $data.status.Clock)
}
catch {
	write-error "Unable to load sensortree. Check PRTG URL, Username and Hash"
	exit
}
write-host "PRTGPause: Check PRTG Connectivity - SUCCESS"

write-host "PRTGPause: Start HTTP listener on Port: $listenport"
$listener = New-Object System.Net.HttpListener
$listener.Prefixes.Add('http://+:'+$listenport+'/')  # Must GENAU mit der Angabe in NETSH übereinstimmen 
$listener.Start()
write-host "PRTGPause: Start HTTP listener on Port: $listenport  SUCCESS"
if ($error) {
	write-host "Error on starting Listener"
	exit
}
#$Host.UI.RawUI.FlushInputBuffer()
#[console]::TreatControlCAsInput = $true
#write-host "CTRL-C ist disabled"

[datetime]$devicelistage = get-date "01.01.2014"   # initialze Age
[hashtable]$devicelist = @{}
[bool]$quit=$false
while ((!($quit))) {
	[string]$script:lasterror=""
	write-host ("Listening on " + $listener.Prefixes )
	$context = $listener.GetContext() # Warte auf eingehende Anfragen
	write-host "------- New Request arrived ------------"
	$request = $context.Request
	write-host (" URL.AbsoluteUri:" + $request.URL.AbsoluteUri)
	write-host (" HttpMethod     :" + $request.HttpMethod)
	[string]$remoteip = $Request.RemoteEndPoint.Address.IPAddressToString
	write-host (" RemoteIP       :" + $remoteip)
	write-host (" Method         :" + $Request.HttpMethod)
	write-host (" RAWURL         :" + $Request.RawURL)
	#[System.Net.Dns]::GetHostByAddress($request.RemoteEndPoint.address).hostname

	if ($Request.RawURL -eq ("/")) {
		write-host "Statuspage Request found, Check für Cache Update"
		write-host ("Last Cache Update:" + $devicelistage.tostring())
		write-host ("Now               " + (Get-date).tostring())
		if (((get-date) - $devicelistage).totalseconds -ge $devicecacheage) {   
			write-host "---------- DeviceList to old. start Update --------------"
			[hashtable]$devicelist.clear()
			write-host "  Loading Device XML"
			[xml]$data= Invoke-WebRequest -Uri ($prtgserveruri+"/api/table.xml?content=devices&output=xml&columns=device,host,objid&Username="+$prtgUsername+"&passhash="+$prtgpasshash)
			foreach ($device in ($data.devices.item)){
				write-host ("found Device:"+$device.name+"   Host:"+$device.host) -nonewline
				if ($device.host -eq "127.0.0.1") {
					write-host "  Host is 127.0.0.1:  SKIP" 
				}
				elseif ($device.host -match "^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$") {
					write-host ("  Host is IP-Address. Adding IP:" + $device.host)
					$devicelist.add($device.host,$device.objid)
					# DNS Queries take too long if name not resolvable. so i had to disable that
					#	$hostname=[System.Net.Dns]::GetHostByAddress($device.host).hostname
				}
				else {
					write-host "  Host is a DNS-Name. Adding Host " $device.host
					$devicelist.add($device.host,$device.objid)
	#				foreach ($dnsanswer in ([System.Net.Dns]::GetHostAddresses($device.host))){
	#					write-host ("  Resolved to IP-Address:" + $dnsanswer.IPAddressToString)
	#					try {
	#						$devicelist.add(($dnsanswer.IPAddressToString),$device.objid)
	#					}
	#					catch {
	#						write-host ("  Problem adding:" + $dnsanswer.IPAddressToString + " Maybe duplicate IP")
	#					}
	#				}
				}
			}
			[datetime]$devicelistage = get-date  # Update DeviceList Age
		}
		else {
			write-host "Reusing existing device table"
		}
	}
	#$devicelist
	write-host "Loading HTMLTemplate"
	[string]$htmltemplate = get-content $htmltemplatefile    #  enable that to load template für every request
	[string]$htmlpage = $htmltemplate   # use the templated loaded during startup
	$htmlpage = $htmlpage.replace("%IPADDRESS%",$remoteip)
	$htmlpage = $htmlpage.replace("%TIMESTAMP%",(get-date))

	$deviceobjid=""
	write-host ("Searching für device in List: " + $remoteip) -nonewline
	if ($devicelist.containskey($remoteip)){
		write-host " Found by IP" -nonewline
		$deviceobjid = $devicelist.item($remoteip)
	}
	else {
		try {
			$devicename = ""
			$devicename = [System.Net.Dns]::GetHostByAddress($remoteip).hostname
		}
		catch {
			$script:lasterror  = $_.Exception.Message
			write-host ("ERROR Resolving Reverse DNS" + $script:lasterror)
		}
		if ($devicelist.containskey($devicename)){
			write-host " Found by ReverseDNS" -nonewline
			$deviceobjid = $devicelist.item($devicename)
		}
	}

	
	if ($deviceobjid -ne ""){
		write-host ".. Found System in Device List"
		if ($Request.RawURL.startswith("/pause")) {
			write-host "Pausing Device"
			$result = Invoke-WebRequest -Uri ($prtgserveruri+"/api/pauseobjectfor.htm?id="+$deviceobjid+"&action=0&pausemsg=PausedbyPRTG-Pause&duration=15&Username="+$prtgUsername+"&passhash="+$prtgpasshash) 
		}
		elseif ($Request.RawURL.startswith("/resume")) {
			write-host "Pausing Device"
			$result = Invoke-WebRequest -Uri ($prtgserveruri+"/api/pause.htm?id="+$deviceobjid+"&action=1&Username="+$prtgUsername+"&passhash="+$prtgpasshash) 
		}
		elseif ($Request.RawURL.startswith("/ackalarm")) {
			write-host "AckAlarm 15 Min"
			$result = Invoke-WebRequest -Uri ($prtgserveruri+"/api/acknowledgealarm.htm?id="+$deviceobjid+"&ackmsg=AckAlarmByPRTGPause&duration=15&Username="+$prtgUsername+"&passhash="+$prtgpasshash) 
		}
		elseif ($Request.RawURL.startswith("/scannow")) {
			write-host "AckAlarm 15 Min"
			$result = Invoke-WebRequest -Uri ($prtgserveruri+"/api/scannow.htm?id="+$deviceobjid+"&Username="+$prtgUsername+"&passhash="+$prtgpasshash) 
		}
		
		elseif ($Request.RawURL.startswith("/quit")) {
			write-host "Quit received"
			$quit = $true
		}
		
		else {
			write-host "No Special Command"
		}

		if ($true -or ($Request.RawURL -eq "/") -or ($Request.RawURL -eq "/?")) {
			write-host "------- Generating Response Page ------------"

			$htmlpage = $htmlpage.replace("%DEVICEID%",("<a href="""+$prtgserveruri+"/device.htm?id="+$deviceobjid+"&tabid=1"" >"+$deviceobjid+"</a>"))
		
			[xml]$status = Invoke-WebRequest -Uri ($prtgserveruri+"/api/getsensordetails.xml?columns=datetime,name,status,message&id="+$deviceobjid+"&Username="+$prtgUsername+"&passhash="+$prtgpasshash) 
			if ($status.sensordata.statusid.'#cdata-section' -eq "12") {
				write-host "  Found Status: 12"
				$htmlpage = $htmlpage.replace("%STATUS%",($status.sensordata.statustext.'#cdata-section'))
				$htmlpage = $htmlpage.replace("%BUTTON%","<a href = ""/resume"">Resume</a><a href = ""/AckAlarm"">AckAlarm 15Min</a><a href=""/scannow"">ScanNow</a>")
			}
			elseif ($status.sensordata.statusid.'#cdata-section' -eq "3") {
				write-host "  Found Status: Ok"
				$htmlpage = $htmlpage.replace("%STATUS%","OK")
				$htmlpage = $htmlpage.replace("%BUTTON%","<a href = ""/pause"">Pause 15Min</a><a href = ""/AckAlarm"">AckAlarm  15Min</a><a href=""/scannow"">ScanNow</a>")
			}
			else {
				write-host ("  Found Status: unknown" + $status.sensordata.statustext.'#cdata-section')
				$htmlpage = $htmlpage.replace("%STATUS%",("unknown:"+$status.sensordata.statustext.'#cdata-section' + "XX"))
				$htmlpage = $htmlpage.replace("%BUTTON%","<a href=""/scannow"">ScanNow</a>")
			}
				
			[xml]$result = Invoke-WebRequest -Uri ($prtgserveruri+"/api/table.xml?content=sensors&columns=objid,group,device,sensor,status,message,lastvalue,priority,favorite&id="+$deviceobjid+"&count=10&Username="+$prtgUsername+"&passhash="+$prtgpasshash) 
			$htmlpage = $htmlpage.replace("%SENSORTABLE%",($result.sensors.item | select sensor,status,lastvalue | convertto-html -Fragment ))

			[xml]$result = Invoke-WebRequest -Uri ($prtgserveruri+"/api/table.xml?content=messages&count=10&output=xml&columns=datetime,name,status,message&id="+$deviceobjid+"&count=10&Username="+$prtgUsername+"&passhash="+$prtgpasshash) 
			$htmlpage = $htmlpage.replace("%MESAGETABLE%",($result.messages.item | select datetime,name,status,message_raw | convertto-html -Fragment ))
		}

	}
	else {
		write-host " NOT System in Device List"
		$htmlpage = $htmlpage.replace("%STATUS%","NOT IN DEVICE LIST")
		$htmlpage = $htmlpage.replace("%BUTTON%","")
		$htmlpage = $htmlpage.replace("%SENSORTABLE%","<span  style=""color:red"">Device not found in List</span>")
		$htmlpage = $htmlpage.replace("%MESAGETABLE%","<span  style=""color:red"">Device not found in List</span>")
	}

	write-host "Sending HTML Response"
	$response = $context.Response
	$response.ContentType = 'text/html'
	$response.ContentEncoding =  [System.Text.Encoding]::UTF8;
	$htmlpage = $htmlpage.replace("%LASTERROR%",$script:lasterror.tostring())
	[byte[]] $buffer = [System.Text.Encoding]::UTF8.GetBytes($htmlpage)
	$response.ContentLength64 = $buffer.length
	$response.OutputStream.Write($buffer, 0, $buffer.length)
	$response.OutputStream.close()
	write-host "--- DONE ---"
}
$listener.Stop() 
write-host "--- Normal End ---"