<#
.SYNOPSIS
	Checks the swap space status
.DESCRIPTION
	This PowerShell script queries the status of the swap space and prints it.
.PARAMETER MinLevel
	Specifies the minimum level (10 GB by default)
.EXAMPLE
	PS> ./check-swap-space.ps1
	✅ 1GB Swap space at 42%, 748MB free
.LINK
	https://github.com/fleschutz/PowerShell
.NOTES
	Author: Markus Fleschutz | License: CC0
#>

param([int]$MinLevel = 10) # minimum level in GB

function MB2String { param([int64]$Bytes)
        if ($Bytes -lt 1000) { return "$($Bytes)MB" }
        $Bytes /= 1000
        if ($Bytes -lt 1000) { return "$($Bytes)GB" }
        $Bytes /= 1000
        if ($Bytes -lt 1000) { return "$($Bytes)TB" }
        $Bytes /= 1000
        if ($Bytes -lt 1000) { return "$($Bytes)PB" }
        $Bytes /= 1000
        if ($Bytes -lt 1000) { return "$($Bytes)EB" }
}

try {
	[int]$Total = [int]$Used = [int]$Free = 0
	if ($IsLinux) {
		$Result = $(free --mega | grep Swap:)
		[int]$Total = $Result.subString(5,14)
		[int]$Used = $Result.substring(20,13)
		[int]$Free = $Result.substring(32,11)
	} else {
		$Items = Get-WmiObject -class "Win32_PageFileUsage" -namespace "root\CIMV2" -computername localhost 
		foreach ($Item in $Items) { 
			$Total = $Item.AllocatedBaseSize
			$Used = $Item.CurrentUsage
			$Free = ($Total - $Used)
		} 
	}
	if ($Total -eq 0) {
        	Write-Output "⚠️ No swap space configured"
	} elseif ($Free -eq 0) {
		Write-Output "⚠️ $(MB2String $Total) Swap space is full"
	} elseif ($Free -lt $MinLevel) {
		Write-Output "⚠️ $(MB2String $Total) Swap space is nearly full, only $(MB2String $Free) free"
	} elseif ($Used -eq 0) {
		Write-Output "✅ $(MB2String $Total) Swap space reserved"
	} else {
		[int]$Percent = ($Used * 100) / $Total
		if ($Percent -ge 90) {
			Write-Output "✅ $(MB2String $Total) Swap space is $Percent% full, only $(MB2String $Free) free"
		} else {
			Write-Output "✅ $(MB2String $Total) Swap space at $Percent%, $(MB2String $Free) free"
		}
	}
	exit 0 # success
} catch {
	"⚠️ Error in line $($_.InvocationInfo.ScriptLineNumber): $($Error[0])"
	exit 1
}