param(
	[string]$server = 'unifi.domain.com',
	[string]$port = '8443',
	[string]$site = 'default',
	[string]$username = 'admin',
	[string]$password = '123456',
	[string]$validIPRegex = '192.168*',
	[switch]$debug = $false
)

#Ignore SSL Errors
[System.Net.ServicePointManager]::ServerCertificateValidationCallback = {$true}  

#Define supported Protocols
[System.Net.ServicePointManager]::SecurityProtocol = @("Tls12","Tls11","Tls","Ssl3")

# Confirm Powershell Version.
if ($PSVersionTable.PSVersion.Major -lt 3) {
	Write-Output "<prtg>"
	Write-Output "<error>1</error>"
	Write-Output "<text>Powershell Version is $($PSVersionTable.PSVersion.Major) Requires at least 3. </text>"
	Write-Output "</prtg>"
	Exit
}

# Create $controller and $credential using multiple variables/parameters.
[string]$controller = "https://$($server):$($port)"
[string]$credential = "`{`"username`":`"$username`",`"password`":`"$password`"`}"

# Start debug timer
$queryMeasurement = [System.Diagnostics.Stopwatch]::StartNew()

# Perform the authentication and store the token to myWebSession
try {
$null = Invoke-Restmethod -Uri "$controller/api/login" -method post -body $credential -ContentType "application/json; charset=utf-8"  -SessionVariable myWebSession
}catch{
	Write-Output "<prtg>"
	Write-Output "<error>1</error>"
	Write-Output "<text>Authentication Failed: $($_.Exception.Message)</text>"
	Write-Output "</prtg>"
	Exit
}

#Query API providing token from first query.
try {
$jsonresultat = Invoke-Restmethod -Uri "$controller/api/s/$site/stat/device/" -WebSession $myWebSession
$jsonresultat2 = Invoke-Restmethod -Uri "$controller/api/s/$site/stat/sta/" -WebSession $myWebSession
$jsonresultat3 = Invoke-Restmethod -Uri "$controller/api/s/$site/stat/sysinfo/" -WebSession $myWebSession

}catch{
	Write-Output "<prtg>"
	Write-Output "<error>1</error>"
	Write-Output "<text>API Query Failed: $($_.Exception.Message)</text>"
	Write-Output "</prtg>"
	Exit
}

# Stop debug timer
$queryMeasurement.Stop()


# Iterate jsonresultat and count the number of APs. 
#   $_.state -eq "1" = Connected 
#   $_.type -like "uap" = Access Point ?

$apCount = 0
Foreach ($entry in ($jsonresultat.data | where-object { $_.state -eq "1" -and $_.type -like "uap"})){
	$apCount ++
}

$apUpgradeable = 0
Foreach ($entry in ($jsonresultat.data | where-object { $_.state -eq "1" -and $_.type -like "uap" -and $_.upgradable -eq "true"})){
	$apUpgradeable ++
}

$userCount = 0
Foreach ($entry in ($jsonresultat.data | where-object { $_.type -like "uap"})){
	$userCount += $entry.'num_sta'
}

$guestCount = 0
Foreach ($entry in ($jsonresultat.data | where-object { $_.type -like "uap"})){
	$guestCount += $entry.'guest-num_sta'
}

# Now get data about connected clients

$invalidClientIPs = 0
Foreach ($entry in ($jsonresultat2.data | where-object { $_.ip -notlike $validIPRegex})){
	$invalidClientIPs ++
}

$validClientIPs = 0
Foreach ($entry in ($jsonresultat2.data | where-object { $_.ip -like $validIPRegex})){
	$validClientIPs ++
}

$invalidClientHostnames = ''
Foreach ($entry in ($jsonresultat2.data | where-object { $_.ip -notlike $validIPRegex})){
	if ($entry.hostname -ne $null){
		$invalidClientHostnames += $entry.'hostname' + ', '
	}
	else {
		$invalidClientHostnames += $entry.'mac' + ', '
	}
}

# Now get controller information
$controllerVersion = [version]$jsonresultat3.data.'version'
$controllerUpdateAvailable = $jsonresultat3.data.'update_available'
$controllerUpdateDownloaded = $jsonresultat3.data.'update_downloaded'

#Write Results

Write-Host "<prtg>"

# APs

Write-Host "<result>"
Write-Host "<channel>Access Points Connected</channel>"
Write-Host "<value>$($apCount)</value>"
Write-Host "</result>"

Write-Host "<result>"
Write-Host "<channel>Access Points Upgradeable</channel>"
Write-Host "<value>$($apUpgradeable)</value>"
Write-Host "</result>"

Write-Host "<result>"
Write-Host "<channel>Clients (Total)</channel>"
Write-Host "<value>$($userCount)</value>"
Write-Host "</result>"

Write-Host "<result>"
Write-Host "<channel>Guests</channel>"
Write-Host "<value>$($guestCount)</value>"
Write-Host "</result>"

# Clients

Write-Host "<result>"
Write-Host "<channel>Devices with Invalid Client IPs</channel>"
Write-Host "<LimitMode>1</LimitMode>"
Write-Host "<LimitMaxWarning>3</LimitMaxWarning>"
Write-Host "<LimitMaxError>4</LimitMaxError>"
Write-Host "<value>$($invalidClientIPs)</value>"
Write-Host "<LimitWarningMsg>$($invalidClientHostnames)</LimitWarningMsg>"
Write-Host "<LimitErrorMsg>$($invalidClientHostnames)</LimitErrorMsg>"
Write-Host "</result>"

Write-Host "<result>"
Write-Host "<channel>Devices with Valid Client IPs</channel>"
Write-Host "<value>$($validClientIPs)</value>"
Write-Host "</result>"

# Controller

Write-Host "<result>"
Write-Host "<channel>UniFi Controller Version</channel>"
Write-Host "<value>$($controllerVersion.Major)$($controllerVersion.Minor)$($controllerVersion.Build)</value>"
Write-Host "</result>"

Write-Host "<result>"
Write-Host "<channel>UniFi Controller Update Available</channel>"
Write-Host "<value>$($controllerUpdateAvailable)</value>"
Write-Host "</result>"

Write-Host "<result>"
Write-Host "<channel>UniFi Controller Update Downloaded</channel>"
Write-Host "<value>$($controllerUpdateDownloaded)</value>"
Write-Host "</result>"

Write-Host "<result>"
Write-Host "<channel>Response Time</channel>"
Write-Host "<value>$($queryMeasurement.ElapsedMilliseconds)</value>"
Write-Host "<CustomUnit>msecs</CustomUnit>"
Write-Host "</result>"

Write-Host "<Text>Controller: $($controllerVersion.ToString()). Invalid hostnames: $($invalidClientHostnames)</Text>"

Write-Host "</prtg>"

# Write JSON file to disk when -debug is set. For troubleshooting only.
if ($debug){
	[string]$logPath = ((Get-ItemProperty -Path "hklm:SOFTWARE\Wow6432Node\Paessler\PRTG Network Monitor\Server\Core" -Name "Datapath").DataPath) + "Logs (Sensors)\"
	$timeStamp = (Get-Date -format yyyy-dd-MM-hh-mm-ss)

	$json = $jsonresultat | ConvertTo-Json
	$json | Out-File $logPath"unifi_sensor$($timeStamp)_log.json"
}